101
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Erhart P, Sadigh B. Low-temperature criticality of martensitic transformations of Cu nanoprecipitates in α-Fe. PHYSICAL REVIEW LETTERS 2013; 111:025701. [PMID: 23889419 DOI: 10.1103/physrevlett.111.025701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 05/24/2013] [Indexed: 06/02/2023]
Abstract
Nanoprecipitates form during nucleation of multiphase equilibria in phase segregating multicomponent systems. In spite of their ubiquity, their size-dependent physical chemistry, in particular, at the boundary between phases with incompatible topologies, is still rather arcane. Here, we use extensive atomistic simulations to map out the size-temperature phase diagram of Cu nanoprecipitates in α-Fe. The growing precipitates undergo martensitic transformations from the body-centered cubic (bcc) phase to multiply twinned 9R structures. At high temperatures, the transitions exhibit strong first-order character and prominent hysteresis. Upon cooling, the discontinuities become less pronounced and the transitions occur at ever smaller cluster sizes. Below 300 K, the hysteresis vanishes while the transition remains discontinuous with a finite but diminishing latent heat. This unusual size-temperature phase diagram results from the entropy generated by the soft modes of the bcc-Cu phase, which are stabilized through confinement by the α-Fe lattice.
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Affiliation(s)
- Paul Erhart
- Department of Applied Physics, Chalmers University of Technology, 41296 Gothenburg, Sweden.
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102
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Samiee L, Beitollahi A. Critical effect of sol ageing conditions on thermal stability and organization of titania mesoporous powder. RESEARCH ON CHEMICAL INTERMEDIATES 2013. [DOI: 10.1007/s11164-013-1329-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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103
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Pandey M, Pala RGS. Hydroxylation induced stabilization of near-surface rocksalt nanostructure on wurtzite ZnO structure. J Chem Phys 2013; 138:224701. [DOI: 10.1063/1.4809526] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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104
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Wang X, Fu C, Wang P, Yu H, Yu J. Hierarchically porous metastable β-Ag2WO4 hollow nanospheres: controlled synthesis and high photocatalytic activity. NANOTECHNOLOGY 2013; 24:165602. [PMID: 23538294 DOI: 10.1088/0957-4484/24/16/165602] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Metastable materials have received extensive attention due to their unique physical and chemical properties which are different from those of the thermodynamically stable phase. However, the variety of reported metastable materials is still very limited owing to difficulties in the effective synthesis of pure metastable materials because they can easily transform into the corresponding stable phases. Therefore, it is crucial and a great challenge to explore new metastable materials with novel and fascinating functions. In this study, hierarchically porous metastable β-Ag2WO4 hollow nanospheres with a diameter of 50-500 nm were prepared for the first time by a facile precipitation reaction between AgNO3 and Na2WO4 in the presence of poly(methacrylic acid) (PMAA). It was found that the PMAA not only provided a spherical soft template to induce the formation of hollow nanospheres but also worked as an inhibitor to prevent the phase transformation from thermodynamically unstable β-Ag2WO4 to stable α-Ag2WO4 phase. The resultant metastable β-Ag2WO4 hollow nanospheres show a larger specific surface area (165.5 m(2) g(-1)) owing to the hierarchically porous structure (micropores, mesopores, and macropores), resulting in a high photocatalytic performance for the decomposition of methyl orange and phenol aqueous solutions. The present work can provide some new insight into the smart design and preparation of other new metastable hollow materials, and the prepared metastable β-Ag2WO4 hollow nanospheres have various potential applications in chemical reactors, drug-delivery carriers, solar cells, catalysis, and separation and purification fields.
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Affiliation(s)
- Xuefei Wang
- Department of Chemistry, School of Science, Wuhan University of Technology, Wuhan 430070, People's Republic of China
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105
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Lin YC, Chou WC, Susha AS, Kershaw SV, Rogach AL. Photoluminescence and time-resolved carrier dynamics in thiol-capped CdTe nanocrystals under high pressure. NANOSCALE 2013; 5:3400-3405. [PMID: 23471137 DOI: 10.1039/c3nr33928a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The application of static high pressure provides a method for precisely controlling and investigating many fundamental and unique properties of semiconductor nanocrystals (NCs). This study systematically investigates the high-pressure photoluminescence (PL) and time-resolved carrier dynamics of thiol-capped CdTe NCs of different sizes, at different concentrations, and in various stress environments. The zincblende-to-rocksalt phase transition in thiol-capped CdTe NCs is observed at a pressure far in excess of the bulk phase transition pressure. Additionally, the process of transformation depends strongly on NC size, and the phase transition pressure increases with NC size. These peculiar phenomena are attributed to the distinctive bonding of thiols to the NC surface. In a nonhydrostatic environment, considerable flattening of the PL energy of CdTe NC powder is observed above 3.0 GPa. Furthermore, asymmetric and double-peak PL emissions are obtained from a concentrated solution of CdTe NCs under hydrostatic pressure, implying the feasibility of pressure-induced interparticle coupling.
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Affiliation(s)
- Yan-Cheng Lin
- Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan.
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106
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Grünwald M, Lutker K, Alivisatos AP, Rabani E, Geissler PL. Metastability in pressure-induced structural transformations of CdSe/ZnS core/shell nanocrystals. NANO LETTERS 2013; 13:1367-1372. [PMID: 22800435 DOI: 10.1021/nl3007165] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The kinetics and thermodynamics of structural transformations under pressure depend strongly on particle size due to the influence of surface free energy. By suitable design of surface structure, composition, and passivation it is possible, in principle, to prepare nanocrystals in structures inaccessible to bulk materials. However, few realizations of such extreme size-dependent behavior exist. Here, we show with molecular dynamics computer simulation that in a model of CdSe/ZnS core/shell nanocrystals the core high-pressure structure can be made metastable under ambient conditions by tuning the thickness of the shell. In nanocrystals with thick shells, we furthermore observe a wurtzite to NiAs transformation, which does not occur in the pure bulk materials. These phenomena are linked to a fundamental change in the atomistic transformation mechanism from heterogeneous nucleation at the surface to homogeneous nucleation in the crystal core.
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Affiliation(s)
- Michael Grünwald
- Department of Chemistry, University of California, Berkeley, California 94720, United States.
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107
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Dumont MF, Risset ON, Knowles ES, Yamamoto T, Pajerowski DM, Meisel MW, Talham DR. Synthesis and Size Control of Iron(II) Hexacyanochromate(III) Nanoparticles and the Effect of Particle Size on Linkage Isomerism. Inorg Chem 2013; 52:4494-501. [DOI: 10.1021/ic302764k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Matthieu F. Dumont
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
- Department of Physics and the National High
Magnetic Field Laboratory, University of Florida, Gainesville, Florida 32611-8440, United States
| | - Olivia N. Risset
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
| | - Elisabeth S. Knowles
- Department of Physics and the National High
Magnetic Field Laboratory, University of Florida, Gainesville, Florida 32611-8440, United States
| | - Takashi Yamamoto
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
- Department of Chemistry, Keio University, 3-14-1 Hiyoshi, Yokohama, 223-8522, Japan
| | - Daniel M. Pajerowski
- Department of Physics and the National High
Magnetic Field Laboratory, University of Florida, Gainesville, Florida 32611-8440, United States
| | - Mark W. Meisel
- Department of Physics and the National High
Magnetic Field Laboratory, University of Florida, Gainesville, Florida 32611-8440, United States
| | - Daniel R. Talham
- Department of Chemistry, University of Florida, Gainesville, Florida 32611-7200, United States
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108
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Gommes CJ. Three-dimensional reconstruction of liquid phases in disordered mesopores usingin situsmall-angle scattering. J Appl Crystallogr 2013. [DOI: 10.1107/s0021889813003816] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Small-angle scattering of X-rays (SAXS) or neutrons is one of the few experimental methods currently available for thein situanalysis of phenomena in mesoporous materials at the mesoscopic scale. In the case of disordered mesoporous materials, however, the main difficulty of the method lies in the data analysis. A stochastic model is presented, which enables one to reconstruct the three-dimensional nanostructure of liquids confined in disordered mesopores starting from small-angle scattering data. This so-called plurigaussian model is a multi-phase generalization of clipped Gaussian random field models. Its potential is illustrated through the synchrotron SAXS analysis of a gel permeated with a critical nitrobenzene/hexane solution that is progressively cooled below its consolute temperature. The reconstruction brings to light a wetting transition whereby the nanostructure of the pore-filling liquids passes from wetting layers that uniformly cover the solid phase of the gel to plugs that locally occlude the pores. Using the plurigaussian model, the dewetting phenomenon is analyzed quantitatively at the nanometre scale in terms of changing specific interface areas, contact angle and specific length of the triple line.
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109
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Synthesis and Characterization of CdS Nanoparticles via Cyclic Microwave from Cadmium Oxalate. J CLUST SCI 2013. [DOI: 10.1007/s10876-013-0556-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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110
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Wu G, Tan XY, Li GY, Hu CW. Effect of molar ratio of citric acid to metal nitrate on the structure and catalytic activity of NiO nanoparticles. Chem Res Chin Univ 2013. [DOI: 10.1007/s40242-013-2059-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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111
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Sakata Y, Furukawa S, Kondo M, Hirai K, Horike N, Takashima Y, Uehara H, Louvain N, Meilikhov M, Tsuruoka T, Isoda S, Kosaka W, Sakata O, Kitagawa S. Shape-Memory Nanopores Induced in Coordination Frameworks by Crystal Downsizing. Science 2013; 339:193-6. [DOI: 10.1126/science.1231451] [Citation(s) in RCA: 409] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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112
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Soni U, Arora V, Sapra S. Wurtzite or zinc blende? Surface decides the crystal structure of nanocrystals. CrystEngComm 2013. [DOI: 10.1039/c3ce40267c] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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113
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Shen Q, Xue J, Mi A, Jia H, Liu X, Xu B. The study on properties of CdS photocatalyst with different ratios of zinc-blende and wurtzite structure. RSC Adv 2013. [DOI: 10.1039/c3ra42179a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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114
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Shen Q, Xue J, Liu J, Jia H, Liu X, Xu B. Shape-controlled synthesis of three-dimensional branched CdS nanostructure arrays: structural characteristics and formation mechanism. CrystEngComm 2013. [DOI: 10.1039/c2ce26655e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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115
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Upcher A, Ezersky V, Berman A, Golan Y. Nanometer size effects in nucleation, growth and characterization of templated CdS nanocrystal assemblies. NANOSCALE 2012; 4:7655-7663. [PMID: 23070093 DOI: 10.1039/c2nr32492j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We report on the oriented nucleation of CdS nanocrystals on well-defined polydiacetylene Langmuir film templates. Nucleation on the red phase of polydiacetylene resulted in ordered linear arrays of CdS nanocrystals that are aligned with respect to the template. High resolution transmission electron microscopy showed crystalline particles of ~5 to 8 nm size. Selected area electron diffraction micrographs showed spot patterns which are attributed to the well-defined orientations of both polymorphs: the cubic zinc blende and the hexagonal wurtzite polymorphs of CdS. We present a unique growth mechanism where oriented nucleation of CdS on the polydiacetylene template initially takes place in the zinc blende phase. Beyond a certain size threshold, growth proceeds in the more stable wurtzite phase. This transformation keeps the stacking direction of the close packed planes, while altering only their stacking sequence. Notably, size-confinement effects were observed in electron diffraction patterns from the wurtzite phase. These effects originated from off-axis planes that do not fulfill the Bragg conditions, yet their elongated Bragg rods intersect with the Ewald sphere, giving rise to unexpected reflections.
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Affiliation(s)
- Alexander Upcher
- Materials Engineering Department and Ilse Katz Institute for Nanoscale Science and Technology, Ben Gurion University of the Negev, Beer-Sheva 84105, Israel
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116
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Xiao N, Zhu L, Wang K, Dai Q, Wang Y, Li S, Sui Y, Ma Y, Liu J, Liu B, Zou G, Zou B. Synthesis and high-pressure transformation of metastable wurtzite-structured CuGaS2 nanocrystals. NANOSCALE 2012; 4:7443-7447. [PMID: 23086438 DOI: 10.1039/c2nr31629c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The metastable wurtzite nanocrystals of CuGaS(2) have been synthesized through a facile and effective one-pot solvothermal approach. Through the Rietveld refinement on experimental X-ray diffraction patterns, we have unambiguously determined the structural parameters and the disordered nature of this wurtzite phase. The metastability of wurtzite structure with respect to the stable chalcopyrite structure was testified by a precise theoretical total energy calculation. Subsequent high-pressure experiments were performed to establish the isothermal phase stability of this wurtzite phase in the pressure range of 0-15.9 GPa, above which another disordered rock salt phase crystallized and remained stable up to 30.3 GPa, the highest pressure studied. Upon release of pressure, the sample was irreversible and intriguingly converted into the energetically more favorable and ordered chalcopyrite structure as revealed by the synchrotron X-ray diffraction and the high-resolution transmission electron microscopic measurements. The observed phase transitions were rationalized by first-principles calculations. The current research surely establishes a novel phase transition sequence of disorder → disorder → order, where pressure has played a significant role in effectively tuning stabilities of these different phases.
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Affiliation(s)
- Ningru Xiao
- State Key Laboratory of Superhard Materials, Jilin University, Changchun, 130012, China
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117
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Grünwald M, Zayak A, Neaton JB, Geissler PL, Rabani E. Transferable pair potentials for CdS and ZnS crystals. J Chem Phys 2012; 136:234111. [PMID: 22779585 DOI: 10.1063/1.4729468] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A set of interatomic pair potentials is developed for CdS and ZnS crystals. We show that a simple energy function, which has been used to describe the properties of CdSe [E. Rabani, J. Chem. Phys. 116, 258 (2002)], can be parametrized to accurately describe the lattice and elastic constants, and phonon dispersion relations of bulk CdS and ZnS in the wurtzite and rocksalt crystal structures. The predicted coexistence pressure of the wurtzite and rocksalt structures as well as the equation of state are in good agreement with experimental observations. These new pair potentials enable the study of a wide range of processes in bulk and nanocrystalline II-VI semiconductor materials.
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Affiliation(s)
- Michael Grünwald
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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118
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119
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120
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Singh VK, Chauhan P, Pandey KK. Study of pressure induced phase transformation in CTAB capped CdS nanoparticles. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2012; 92:64-66. [PMID: 22446751 DOI: 10.1016/j.saa.2012.02.024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2011] [Revised: 02/08/2012] [Accepted: 02/09/2012] [Indexed: 05/31/2023]
Abstract
Effect of high pressure on as prepared 20mM CTAB capped CdS nanoparticles (size ~4nm) has been analyzed in this paper. Raman scattering has been used to observe the phase transition pressure. X-ray diffraction pattern is used for structural characterization. Raman scattering predicts the phase transition occur from mixed cubical phase to rock salt phase above 6.6 GPa. One of the representative XRD pattern at 9.7 GPa confirms the existence of rock salt phase above 6.6 GPa.
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121
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122
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Electron Beam Synthesis and Characterization of Poly Vinyl Alcohol/Poly Acrylic Acid Embedded Ni and Ag Nanoparticles. J Inorg Organomet Polym Mater 2012. [DOI: 10.1007/s10904-012-9683-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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123
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Farvid SS, Radovanovic PV. Phase Transformation of Colloidal In2O3 Nanocrystals Driven by the Interface Nucleation Mechanism: A Kinetic Study. J Am Chem Soc 2012; 134:7015-24. [DOI: 10.1021/ja211627r] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Shokouh S. Farvid
- Department of Chemistry
and Waterloo Institute for
Nanotechnology, University of Waterloo,
200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
| | - Pavle V. Radovanovic
- Department of Chemistry
and Waterloo Institute for
Nanotechnology, University of Waterloo,
200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
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124
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Spagnoli D, Gale JD. Atomistic theory and simulation of the morphology and structure of ionic nanoparticles. NANOSCALE 2012; 4:1051-1067. [PMID: 22139365 DOI: 10.1039/c1nr11106j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Computational techniques are widely used to explore the structure and properties of nanomaterials. This review surveys the application of both quantum mechanical and force field based atomistic simulation methods to nanoparticles, with a particular focus on the methodologies available and the ways in which they can be utilised to study structure, phase stability and morphology. The main focus of this article is on partially ionic materials, from binary semiconductors through to mineral nanoparticles, with more detailed considered of three examples, namely titania, zinc sulphide and calcium carbonate.
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Affiliation(s)
- Dino Spagnoli
- Nanochemistry Research Institute, Department of Chemistry, Curtin University, PO Box U1987, Perth, WA 6845, Australia
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125
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Pandey M, Pala RGS. Stabilization and growth of non-native nanocrystals at low and atmospheric pressures. J Chem Phys 2012; 136:044703. [DOI: 10.1063/1.3678181] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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126
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Yuan Y, Du W, Qian X. ZnxGa2O3+x(0 ≤ x ≤ 1) solid solution nanocrystals: tunable composition and optical properties. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c1jm13091a] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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127
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Azpiroz JM, Infante I, Lopez X, Ugalde JM, De Angelis F. A first-principles study of II–VI (II = Zn; VI = O, S, Se, Te) semiconductor nanostructures. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm33744d] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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128
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Chaubey GS, Yao Y, Makongo JPA, Sahoo P, Misra D, Poudeu PFP, Wiley JB. Microstructural and thermal investigations of HfO2 nanoparticles. RSC Adv 2012. [DOI: 10.1039/c2ra21003g] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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129
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Li Q, Li M, Zhu P, Wei S. In vitro synthesis of bioactive hydroxyapatite using sodium hyaluronate as a template. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm33624c] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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130
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KUMAR R, KUMAR MUNISH. SIZE DEPENDENCE OF THERMOELASTIC PROPERTIES OF NANOMATERIALS. INTERNATIONAL JOURNAL OF NANOSCIENCE 2011. [DOI: 10.1142/s0219581x10007113] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A simple theoretical method is developed to study the size dependence of bulk modulus, Young modulus, and coefficient of volume thermal expansion of nanomaterials. We have considered different nanomaterials, viz., Ni (spherical, nanofilm), α-Fe (spherical), and Cu (nanowire). The results obtained are compared with the available experimental data. A good agreement between theory and experiment supports the validity of the model developed in the present work.
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Affiliation(s)
- R. KUMAR
- Department of Physics, G.B. Pant University of Agriculture and Technology, Pantnagar, 263145, India
| | - MUNISH KUMAR
- Department of Physics, G.B. Pant University of Agriculture and Technology, Pantnagar, 263145, India
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131
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Ketterer B, Heiss M, Uccelli E, Arbiol J, i Morral AF. Untangling the electronic band structure of wurtzite GaAs nanowires by resonant Raman spectroscopy. ACS NANO 2011; 5:7585-7592. [PMID: 21838304 DOI: 10.1021/nn202585j] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
In semiconductor nanowires, the coexistence of wurtzite and zinc-blende phases enables the engineering of the electronic structure within a single material. This presupposes an exact knowledge of the band structure in the wurtzite phase. We demonstrate that resonant Raman scattering is a important tool to probe the electronic structure of novel materials. Exemplarily, we use this technique to elucidate the band structure of wurtzite GaAs at the Γ point. Within the experimental uncertainty we find that the free excitons at the edge of the wurtzite and the zinc-blende band gap exhibit equal energies. For the first time we show that the conduction band minimum in wurtzite GaAs is of Γ(7) symmetry, meaning a small effective mass. We further find evidence for a light-hole-heavy-hole splitting of 103 meV at 10 K.
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Affiliation(s)
- Bernt Ketterer
- Laboratoire des Matériaux Semiconducteurs, Institut des Matériaux, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
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132
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Reddy Channu V, Kalluru RR, Schlesinger M, Mehring M, Holze R. Synthesis and characterization of ZrO2 nanoparticles for optical and electrochemical applications. Colloids Surf A Physicochem Eng Asp 2011. [DOI: 10.1016/j.colsurfa.2011.07.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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133
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Shirinyan AS, Bilogorodskyy YS, Wilde G, Schmelzer JWP. Size-dependent hysteresis and phase formation kinetics during temperature cycling of metal nanopowders. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:245301. [PMID: 21613730 DOI: 10.1088/0953-8984/23/24/245301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We present a description of the evolution of a polymorphically transforming metal nanoparticle ensemble subjected to a temperature cycling with constant rates of temperature change. The calculations of the time dependence of the volume fraction of the new phase show the existence of size-dependent hysteresis and its main features. The statistical analysis makes it possible to introduce and determine the size-dependent superheating limit and supercooling limit.
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Affiliation(s)
- A S Shirinyan
- Department of Physics, Kiev Taras Shevchenko National University, Kiev, Ukraine
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134
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Sun Y, Yang W, Ren Y, Wang L, Lei C. Multiple-step phase transformation in silver nanoplates under high pressure. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2011; 7:606-11. [PMID: 21370464 DOI: 10.1002/smll.201002201] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Revised: 01/05/2011] [Indexed: 05/13/2023]
Affiliation(s)
- Yugang Sun
- Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.
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135
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Liu J, Chen H, Lin Z, Lin JM. Preparation of surface imprinting polymer capped Mn-doped ZnS quantum dots and their application for chemiluminescence detection of 4-nitrophenol in tap water. Anal Chem 2011; 82:7380-6. [PMID: 20701302 DOI: 10.1021/ac101510b] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
In this paper, Mn-doped ZnS quantum dots (QDs) capped by a molecularly imprinted polymer (MIP) were synthesized. The results showed a high selectivity of the MIP-capped Mn-doped ZnS QDs toward the template molecule (4-nitrophenol) by QD fluorescence quenching. The application of MIP-capped Mn-doped ZnS QDs to the chemiluminescence (CL) system was also studied using a KIO(4)-H(2)O(2) system. This application combines the good selectivity of MIP with the high sensitivity of CL. The linear range of this CL system is from 0.1 to 40 microM, and the detection limit (DL) for 4-nitrophenol in the water can reach 76 nM. The method was also used in the real water samples, and the recoveries can fall in the range of 91-96%.
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Affiliation(s)
- Junxiao Liu
- The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
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136
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Pang H, Ning G, Gong W, Ye J, Lin Y. Direct synthesis of hexagonal Mg(OH)2 nanoplates from natural brucite without dissolution procedure. Chem Commun (Camb) 2011; 47:6317-9. [DOI: 10.1039/c1cc10279f] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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137
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Kumar S, Chawla AK, Kumar N, Chandra R. High temperature powder diffraction study of (Zn,Cd)S and ZnxCd1−xS nanopowders. RSC Adv 2011. [DOI: 10.1039/c1ra00064k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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138
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Apte SK, Garaje SN, Arbuj SS, Kale BB, Baeg JO, Mulik UP, Naik SD, Amalnerkar DP, Gosavi SW. A novel template free, one pot large scale synthesis of cubic zinc sulfide nanotriangles and its functionality as an efficient photocatalyst for hydrogen production and dye degradation. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm14067a] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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139
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Choi HS, Frangioni JV. Nanoparticles for Biomedical Imaging: Fundamentals of Clinical Translation. Mol Imaging 2010. [DOI: 10.2310/7290.2010.00031] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Affiliation(s)
- Hak Soo Choi
- From the Division of Hematology/Oncology, Department of Medicine, and Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA
| | - John V. Frangioni
- From the Division of Hematology/Oncology, Department of Medicine, and Department of Radiology, Beth Israel Deaconess Medical Center, Boston, MA
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140
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Taghva A, Kim PE, Liu CY, Apuzzo MLJ. Molecular imaging, part 1: apertures into the landscape of genomic medicine. World Neurosurg 2010; 73:307-16. [PMID: 20849785 DOI: 10.1016/j.wneu.2010.01.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Indexed: 01/16/2023]
Abstract
Conventional imaging paradigms rely on the detection of anatomical changes in disease that are preceded by molecular genetic changes that go otherwise undetected. With the advent of molecular imaging, it will be possible to detect these changes prior to the manifestation of disease. Molecular imaging is the amalgamation of molecular biology and imaging technology that was spawned by parallel advances in the two fields. Fundamental to this technique is the ability to directly image biological processes that precede the anatomical changes detected by conventional imaging techniques. The two main strategies for imaging of biologic processes are direct and indirect imaging techniques. Direct techniques use molecules that have specific affinities for targets of interest that can be radiolabeled or otherwise detected on imaging. Indirect imaging uses reporter genes that are coexpressed with therapeutic proteins or other proteins of interest to image vector-transfected cells. Optical imaging and nanotechnology paradigms will also prove to be important additions to the imaging armamentarium. The first installment of this two-part series on molecular imaging seeks to demonstrate basic principles and illustrative examples for the uninitiated neophyte to this field.
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Affiliation(s)
- Alexander Taghva
- Department of Neurological Surgery, Keck School of Medicine, University of Southern California, Los Angeles, California, USA.
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141
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Wang Z, Wen XD, Hoffmann R, Son JS, Li R, Fang CC, Smilgies DM, Hyeon T. Reconstructing a solid-solid phase transformation pathway in CdSe nanosheets with associated soft ligands. Proc Natl Acad Sci U S A 2010; 107:17119-24. [PMID: 20855580 PMCID: PMC2951424 DOI: 10.1073/pnas.1011224107] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Integrated single-crystal-like small and wide-angle X-ray diffraction images of a CdSe nanosheet under pressure provide direct experimental evidence for the detailed pathway of transformation of the CdSe from a wurtzite to a rock-salt structure. Two consecutive planar atomic slips [(001) {110} in parallel and (102) {101}with a distortion angle of ∼40°] convert the wurtzite-based nanosheet into a saw-like rock-salt nanolayer. The transformation pressure is three times that in the bulk CdSe crystal. Theoretical calculations are in accord with the mechanism and the change in transformation pressure, and point to the critical role of the coordinated amines. Soft ligands not only increase the stability of the wurtzite structure, but also improve its elastic strength and fracture toughness. A ligand extension of 2.3 nm appears to be the critical dimension for a turning point in stress distribution, leading to the formation of wurtzite (001)/zinc-blende (111) stacking faults before rock-salt nucleation.
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Affiliation(s)
- Zhongwu Wang
- Cornell High Energy Synchrotron Source (CHESS), Wilson Laboratory, Cornell University, Ithaca, NY 14853
| | - Xiao-Dong Wen
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - Roald Hoffmann
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853
| | - Jae Sung Son
- National Creative Research Initiative Center for Oxide Nanocrystalline Materials and School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Korea; and
| | - Ruipeng Li
- Cornell High Energy Synchrotron Source (CHESS), Wilson Laboratory, Cornell University, Ithaca, NY 14853
| | - Chia-Chen Fang
- Department of Materials Science and Engineering, Cornell University, Ithaca, NY 14853
| | - Detlef-M. Smilgies
- Cornell High Energy Synchrotron Source (CHESS), Wilson Laboratory, Cornell University, Ithaca, NY 14853
| | - Taeghwan Hyeon
- National Creative Research Initiative Center for Oxide Nanocrystalline Materials and School of Chemical and Biological Engineering, Seoul National University, Seoul 151-744, Korea; and
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142
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Du YP, Zhang YW, Sun LD, Yan CH. Atomically efficient synthesis of self-assembled monodisperse and ultrathin lanthanide oxychloride nanoplates. J Am Chem Soc 2010; 131:3162-3. [PMID: 19256565 DOI: 10.1021/ja8095416] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Monodisperse and ultrathin LaOCl nanoplates were synthesized via the thermolysis of La(CCl(3)COO)(3) in long chain amine and 1-octadecene. This single source precursor approach is simple but atomically efficient. The uniform amine-capped LaOCl nanoplates can be aligned into nanowire-like and nanorod-like superstructures, as a result of the different strengths of the interchain molecular interactions of the capping molecules during the self-assembly process of the nanoplates.
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Affiliation(s)
- Ya-Ping Du
- Beijing National Laboratory for Molecular Sciences, State Key Laboratory of Rare Earth Materials Chemistry and Applications & PKU-HKU Joint Laboratory in Rare Earth Materials and Bioinorganic Chemistry, Beijing 100871, China
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143
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Zhao F, Zheng JG, Yang X, Li X, Wang J, Zhao F, Wong KS, Liang C, Wu M. Complex ZnO nanotree arrays with tunable top, stem and branch structures. NANOSCALE 2010; 2:1674-1683. [PMID: 20820699 DOI: 10.1039/c0nr00076k] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Hierarchical tree-, mushroom- and cockscomb-like ZnO arrays with increasing branching order and complexities have been grown in situ on cheap zinc plates by a simple hydrothermal oxidation approach. Their morphology, crystal structure and orientation relationship are characterized by powder X-ray diffraction, scanning electron microscopy (SEM) and cross-sectional high-resolution transmission electron microscopy (HRTEM). The wurtzite ZnO arrays, growing mainly in the [0001] direction, show a special orientation relationship between the stem and the branch as well as a novel stem-branch boundary which might be attributed to the least mismatch between [symbol: see text] and (0002) lattice planes. The co-solvent ethylenediamine (en) was used to control the morphology and complexing of these complex ZnO nanostructures. Correspondingly, the physical properties of ZnO nanostructure assembly arrays were tuned and a stronger UV emission was observed with negligible emissions in the visible range, indicating the highly crystalline features of the complex ZnO micro-/nanostructured materials.
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Affiliation(s)
- Fenghua Zhao
- State Key Laboratory of Optoelectronic Materials and Technologies/MOE Key Laboratory of Bioinorganic and Synthetic Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen (Zhongshan) University, Guangzhou, P R China
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144
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Corrado C, Hawker M, Livingston G, Medling S, Bridges F, Zhang JZ. Enhanced Cu emission in ZnS : Cu,Cl/ZnS core-shell nanocrystals. NANOSCALE 2010; 2:1213-1221. [PMID: 20648352 DOI: 10.1039/c0nr00056f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
ZnS : Cu,Cl/ZnS core-shell nanocrystals (NCs) have been synthesized via a facile aqueous synthesis method. The shell growth of the NCs was observed via a red-shift in the UV-Vis absorption spectra with increasing NC size. The Cu photoluminescence (PL) emission was enhanced by capping with a thin ZnS shell. The ZnS : Cu (0.2%) and ZnS : Cu (0.5%) show a more pronounced red-shift in the apparent PL peak position as well as a 37% and 67% increase in emission intensity, respectively, in comparison to the undoped NCs. The observed red-shift is mainly due to an increase in intensity of the Cu PL emission. The 1% Cu-doped NCs exhibit very little red-shift because the observed emission is dominated by the Cu-dopant and thus nearly independent of the size of the NCs. The increase in Cu emission is evidence that Cu atoms occupying non-emissive surface sites in doped ZnS NCs were encapsulated by the ZnS shell. Extended X-Ray Absorption Fine Structure (EXAFS) data also suggests that the Cu had slightly more neighbors upon growth of a ZnS shell, indicating its encapsulation into the core of the NCs. The EXAFS Zn edge data also indicate greater disorder in the ZnS structure when the shell is grown, which may be attributed to the ZnS shell being more amorphous than the core NCs. This study demonstrates that core-shell structures can be used as a simple and yet powerful strategy to enhance PL properties of doped semiconductor NCs.
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Affiliation(s)
- Carley Corrado
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, CA 95064, USA
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145
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Wang L, Zhao C, Meng F, Huang S, Yuan X, Xu X, Yang Z, Yang H. Optical properties and simultaneous synthesis of ZnS and ZnO nanoparticles via one reverse micellar system. Colloids Surf A Physicochem Eng Asp 2010. [DOI: 10.1016/j.colsurfa.2010.02.033] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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146
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Tai G, Zhou J, Guo W. Inorganic salt-induced phase control and optical characterization of cadmium sulfide nanoparticles. NANOTECHNOLOGY 2010; 21:175601. [PMID: 20357414 DOI: 10.1088/0957-4484/21/17/175601] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Phase-controlled synthesis of CdS nanoparticles from zinc-blende to wurtzite has been successfully realized by an inorganic salt-induced process with no use of surfactants or other ligands in an ultrasound-assisted microwave synthesis system. Pure zinc-blende CdS nanoparticles were produced without adding NaCl, while mixed zinc-blende and wurtzite nanoparticles were obtained by adding NaCl/Cd(2+) molar ratios below 1, and pure wurtzite nanoparticles were produced at a molar ratio of 1. The energy bandgap (E(g)) of the CdS nanoparticles calculated from optical absorption spectra increases as the phase transformation from zinc-blende to wurtzite occurs. Additionally, the CdS nanoparticles showed a 489 nm band-edge emission without adding NaCl, and a 501 nm emission when the molar ratios of NaCl to Cd(2+) are 0.25, 0.5 and 1. It was found that the phase transformation originates from the effect of the halide ion Cl(-). We also found that some other halide ions such as Br(-) and I(-) can induce the phase transformation. It is shown that the phase, size and optical properties of the anisotropic nanoparticles can be well tuned by varying the concentration of the halide ions.
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Affiliation(s)
- Guo'an Tai
- Institute of Nanoscience, Nanjing University of Aeronautics and Astronautics, Nanjing, People's Republic of China.
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147
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Huxter VM, Scholes GD. Acoustic phonon strain induced mixing of the fine structure levels in colloidal CdSe quantum dots observed by a polarization grating technique. J Chem Phys 2010; 132:104506. [DOI: 10.1063/1.3350871] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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148
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Shen S, Wang X. Controlled growth of inorganic nanocrystals: size and surface effects of nuclei. Chem Commun (Camb) 2010; 46:6891-9. [DOI: 10.1039/c0cc00900h] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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149
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Bealing C, Fugallo G, Martonák R, Molteni C. Constant pressure molecular dynamics simulations for ellipsoidal, cylindrical and cuboidal nano-objects based on inertia tensor information. Phys Chem Chem Phys 2010; 12:8542-50. [DOI: 10.1039/c004053c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Clive Bealing
- King's College London, Physics Department, Strand, London WC2R 2LS, UK
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150
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van Huis MA, Young NP, Pandraud G, Creemer JF, Vanmaekelbergh D, Kirkland AI, Zandbergen HW. Atomic imaging of phase transitions and morphology transformations in nanocrystals. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2009; 21:4992-4995. [PMID: 25376645 DOI: 10.1002/adma.200902561] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Indexed: 05/21/2023]
Abstract
A newly developed SiN microhotplate allows specimens to be studied at temperatures up to 1000 K at a resolution of 100 picometer. Aberration-corrected transmission electron microscopy has become a commonplace tool to investigate stable crystals; however, imaging transient nanocrystals is much more demanding. Morphological transformations in gold nanoparticles and layer-by-layer sublimation of PbSe nanocrystals is imaged with atomic resolution.
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Affiliation(s)
- Marijn A van Huis
- Kavli Institute of Nanoscience, Delft University of Technology Lorentzweg 1, 2628 CJ Delft (The Netherlands)
| | - Neil P Young
- Department of Materials, University of Oxford Park Road, Oxford OX1 3PH (UK)
| | - Grégory Pandraud
- Kavli Institute of Nanoscience, Delft University of Technology Lorentzweg 1, 2628 CJ Delft (The Netherlands)
| | - J Fredrik Creemer
- DIMES-ECTM, Delft University of Technology Feldmannweg 17, 2628 CT Delft (The Netherlands)
| | - Daniël Vanmaekelbergh
- Debye Institute for NanoMaterials Science, Utrecht University Princetonplein 1, 3508 TH Utrecht (The Netherlands)
| | - Angus I Kirkland
- Department of Materials, University of Oxford Park Road, Oxford OX1 3PH (UK)
| | - Henny W Zandbergen
- Kavli Institute of Nanoscience, Delft University of Technology Lorentzweg 1, 2628 CJ Delft (The Netherlands)
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