1
|
Synthesis, Phase Transition, and Optical Studies of Ba2−xSrxZnWO6 (x = 1.00, 1.25, 1.50, 1.75, 2.00) Tungsten Double Perovskite Oxides. CRYSTALS 2020. [DOI: 10.3390/cryst10040299] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Ba2−xSrxZnWO6 double perovskite (DP) oxide compounds (x = 1, 1.25, 1.5, 1.75, 2) were successfully created by means of conventional solid-state techniques. The crystal structures of our series were studied using an X-ray diffractometer. The x = 1 compound has a cubic (Fm-3m) crystal structure, the 1 ≤ x ≤ 2 compounds have tetragonal (I4/m) symmetry, and the phase was transferred to monoclinic (P21/n) symmetry for the Sr2ZnWO6 (x = 2) compound. Scanning electron microscopy (SEM) was used to investigate the morphology of the series, showing that the samples had crystallized microstructures. Molecular bonds were investigated using Fourier transform infrared and Raman spectroscopies, which confirmed the double perovskite octahedral geometry for the samples in our series. Furthermore, the octahedral W–O6 anti-symmetric stretching mode was found to occur. The optical properties of the Ba2−xSrxZnWO6 series were studied using Ultraviolet–visible (UV–vis) diffuse reflectance and photoluminescence (PL) spectroscopies. The absorption edge of the samples appeared around the near-violet and visible spectra, between 336–360 nm. The band gap energy was investigated in two ways—using the absorption cutoff and Tauc plots—which increased from 3.52 to 3.7 eV with increasing substitution of Ba2+ by Sr2+. Furthermore, excitation and emission spectra were collected at room temperature. A broad band at 260–360 nm appeared in the PLE spectra for all samples, and the PL spectra of the samples had a band that spread from 320–450 nm.
Collapse
|
2
|
Djikaev YS, Ruckenstein E. Free energy of formation of a crystal nucleus in incongruent solidification: Implication for modeling the crystallization of aqueous nitric acid droplets in polar stratospheric clouds. J Chem Phys 2017; 146:134709. [DOI: 10.1063/1.4979069] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
3
|
Park SJ, Kim AR, Hong JT, Park JY, Lee S, Ahn YH. Crystallization Kinetics of Lead Halide Perovskite Film Monitored by In Situ Terahertz Spectroscopy. J Phys Chem Lett 2017; 8:401-406. [PMID: 28050908 DOI: 10.1021/acs.jpclett.6b02691] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Vibrational modes in the terahertz (THz) frequency range are good indicators of lead halide perovskite's crystallization phase. We performed real-time THz spectroscopy to monitor the crystallization kinetics in the perovskite films. First, THz absorptance was measured while the perovskite film was annealed at different temperatures. By analyzing the Avrami exponent, we observed an abrupt dimensionality switch (from 1D to 2D) with increasing temperature starting at approximately 90 °C. We also monitored the laser-induced crystallinity enhancement of the preannealed perovskite film. The THz absorptance increased initially, then subsequently decayed over a couple of hours, although the enhancement factor varies depending on the film crystallinity. In particular, the Avrami analysis implied that the light-induced crystallization was assisted by the 1D diffusion processes. The activation photon energy was measured at 2.3 eV, which indicated that enhanced crystallization originated from the photoinduced structural change of residual lead iodide at the grain boundary.
Collapse
Affiliation(s)
- S J Park
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
| | - A R Kim
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
| | - J T Hong
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
| | - J Y Park
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
| | - S Lee
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
| | - Y H Ahn
- Department of Physics and Department of Energy Systems Research, Ajou University , Suwon 16499, Korea
| |
Collapse
|
4
|
Weiss F, Kubel F, Gálvez Ó, Hoelzel M, Parker SF, Baloh P, Iannarelli R, Rossi MJ, Grothe H. Metastable Nitric Acid Trihydrate in Ice Clouds. Angew Chem Int Ed Engl 2016; 55:3276-80. [PMID: 26879259 PMCID: PMC4819521 DOI: 10.1002/anie.201510841] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Indexed: 11/09/2022]
Abstract
The composition of high‐altitude ice clouds is still a matter of intense discussion. The constituents in question are ice and nitric acid hydrates, but the exact phase composition of clouds and its formation mechanisms are still unknown. In this work, conclusive evidence for a long‐predicted phase, alpha‐nitric acid trihydrate (alpha‐NAT), is presented. This phase was characterized by a combination of X‐ray and neutron diffraction experiments, allowing a convincing structure solution. Furthermore, vibrational spectra (infrared and inelastic neutron scattering) were recorded and compared with theoretical calculations. A strong interaction between water ice and alpha‐NAT was found, which explains the experimental spectra and the phase‐transition kinetics. On the basis of these results, we propose a new three‐step mechanism for NAT formation in high‐altitude ice clouds.
Collapse
Affiliation(s)
- Fabian Weiss
- Institut für Materialchemie, Technische Universität Wien, Getreidemarkt 9/BC/01, 1060, Wien, Austria
| | - Frank Kubel
- Institut für Chemische Technologie und Analytik, TU Wien, Austria
| | - Óscar Gálvez
- Instituto de Estructura de la Materia, IEM-CSIC, Madrid, Spain
| | - Markus Hoelzel
- Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II), Technische Universität München, Germany
| | - Stewart F Parker
- ISIS Facility, STFC Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, UK
| | - Philipp Baloh
- Institut für Materialchemie, Technische Universität Wien, Getreidemarkt 9/BC/01, 1060, Wien, Austria
| | - Riccardo Iannarelli
- Paul Scherrer Institute, Laboratory for Atmospheric Chemistry, 5232, Villigen, Switzerland
| | - Michel J Rossi
- Paul Scherrer Institute, Laboratory for Atmospheric Chemistry, 5232, Villigen, Switzerland
| | - Hinrich Grothe
- Institut für Materialchemie, Technische Universität Wien, Getreidemarkt 9/BC/01, 1060, Wien, Austria.
| |
Collapse
|
5
|
Weiss F, Kubel F, Gálvez Ó, Hoelzel M, Parker SF, Baloh P, Iannarelli R, Rossi MJ, Grothe H. Metastabiles Salpetersäuretrihydrat in Eiswolken. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201510841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Fabian Weiss
- Institut für Materialchemie; Technische Universität Wien; Getreidemarkt 9/BC/01 1060 Wien Österreich
| | - Frank Kubel
- Institut für Chemische Technologie und Analytik; TU Wien; Österreich
| | - Óscar Gálvez
- Instituto de Estructura de la Materia, IEM-CSIC; Madrid Spanien
| | - Markus Hoelzel
- Forschungsneutronenquelle Heinz Maier-Leibnitz (FRM II); Technische Universität München; Deutschland
| | - Stewart F. Parker
- ISIS Facility; STFC Rutherford Appleton Laboratory, Chilton; Didcot OX11 0QX Großbritannien
| | - Philipp Baloh
- Institut für Materialchemie; Technische Universität Wien; Getreidemarkt 9/BC/01 1060 Wien Österreich
| | - Riccardo Iannarelli
- Paul-Scherrer Institute, Laboratory for Atmospheric Chemistry; 5232 Villigen Schweiz
| | - Michel J. Rossi
- Paul-Scherrer Institute, Laboratory for Atmospheric Chemistry; 5232 Villigen Schweiz
| | - Hinrich Grothe
- Institut für Materialchemie; Technische Universität Wien; Getreidemarkt 9/BC/01 1060 Wien Österreich
| |
Collapse
|
6
|
Malkin TL, Murray BJ, Salzmann CG, Molinero V, Pickering SJ, Whale TF. Stacking disorder in ice I. Phys Chem Chem Phys 2015; 17:60-76. [PMID: 25380218 DOI: 10.1039/c4cp02893g] [Citation(s) in RCA: 141] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Traditionally, ice I was considered to exist in two well-defined crystalline forms at ambient pressure: stable hexagonal ice (ice Ih) and metastable cubic ice (ice Ic). However, it is becoming increasingly evident that what has been called cubic ice in the past does not have a structure consistent with the cubic crystal system. Instead, it is a stacking-disordered material containing cubic sequences interlaced with hexagonal sequences, which is termed stacking-disordered ice (ice Isd). In this article, we summarise previous work on ice with stacking disorder including ice that was called cubic ice in the past. We also present new experimental data which shows that ice which crystallises after heterogeneous nucleation in water droplets containing solid inclusions also contains stacking disorder even at freezing temperatures of around -15 °C. This supports the results from molecular simulations, that the structure of ice that crystallises initially from supercooled water is always stacking-disordered and that this metastable ice can transform to the stable hexagonal phase subject to the kinetics of recrystallization. We also show that stacking disorder in ice which forms from water droplets is quantitatively distinct from ice made via other routes. The emerging picture of ice I is that of a very complex material which frequently contains stacking disorder and this stacking disorder can vary in complexity depending on the route of formation and thermal history.
Collapse
Affiliation(s)
- Tamsin L Malkin
- Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Woodhouse Lane, Leeds, LS2 9JT, UK.
| | | | | | | | | | | |
Collapse
|
7
|
Frey M, Didzoleit H, Gainaru C, Böhmer R. Dynamics in Glass Forming Sulfuric and Nitric Acid Hydrates. J Phys Chem B 2013; 117:12164-74. [DOI: 10.1021/jp407588j] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- M Frey
- Fakultät für Physik, Technische Universität Dortmund , 44221 Dortmund, Germany
| | | | | | | |
Collapse
|
8
|
Allan DR, Marshall WG, Francis DJ, Oswald IDH, Pulham CR, Spanswick C. The crystal structures of the low-temperature and high-pressure polymorphs of nitric acid. Dalton Trans 2010; 39:3736-43. [PMID: 20354626 DOI: 10.1039/b923975h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A new high-pressure phase of pure nitric acid (HNO(3)) has been characterised at 1.6 GPa at room temperature by high-pressure neutron powder and X-ray single-crystal diffraction techniques. This is the first crystalline phase obtained upon compression of liquid nitric acid at room temperature and appears to be the stable phase up to pressures of at least 4 GPa. The crystal structure of this new phase shows some similarities to that of the low-temperature phase of nitric acid at ambient pressure, which has been redetermined as part of this study. Both structures share a herringbone packing of hydrogen-bonded molecular catemers, although the presence of disorder within the hydrogen bonds within one of the catemers of the low-temperature phase makes its structure comparatively more complex.
Collapse
Affiliation(s)
- D R Allan
- Diamond Light Source, Harwell Science and Innovation Campus, Chilton, Oxfordshire, Didcot, UK OX11 0CE.
| | | | | | | | | | | |
Collapse
|
9
|
Waller D, Stokes DJ, Donald AM. Improvements to a cryosystem to observe ice nucleating in a variable pressure scanning electron microscope. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2008; 79:103709. [PMID: 19044721 DOI: 10.1063/1.3005995] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The variable pressure scanning electron microscope (VPSEM) has expanded the scope of the SEM to allow the imaging of dynamic, electrically insulating systems. The use of water vapor as the imaging gas present in the chamber allows the successful imaging of hydrated samples. As awareness of the system capabilities becomes more well known, greater pressure has been put onto the microscopist to push the boundaries of both temperature and resolution for the study of diverse hydrated samples whose dynamics may not occur at the usual room temperatures in a VPSEM. In this article we discuss the stages in the development of a cryosystem that has led to the successful observation of the nucleation of ice from a solution in situ. This investigation also leads to further possibilities of imaging hydrated samples in the little explored temperature range of 188-238 K (from -85 to-35 degrees C). This study includes the exploration of how the temperature of various surfaces inside the microscope will change the system's ability to keep a sample hydrated or in its native state.
Collapse
Affiliation(s)
- D Waller
- Biological and Soft Systems, Cavendish Laboratory, Department of Physics, Cambridge University, Cambridge CB3 0HE, United Kingdom
| | | | | |
Collapse
|
10
|
Murray BJ, Bertram AK. Inhibition of solute crystallisation in aqueous H+–NH4+–SO42−–H2O droplets. Phys Chem Chem Phys 2008; 10:3287-301. [DOI: 10.1039/b802216j] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
11
|
Grothe H, Tizek H, Ortega IK. Metastable nitric acidhydrates—possible constituents of polar stratospheric clouds? Faraday Discuss 2008; 137:223-34; discussion 297-318. [DOI: 10.1039/b702343j] [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]
|
12
|
Herrero VJ, Ortega IK, Maté B, Martín-Llorente B, Escribano R, Grothe H. Comment on “Theoretical investigation of the coexistence of α and β-nitric acid trihydrates (NAT) molecular conformations” [Chem. Phys. 324 (2006) 210]. Chem Phys 2006. [DOI: 10.1016/j.chemphys.2006.10.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|