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Engel S, Gießelmann ECJ, Schumacher L, Zhang Y, Müller F, Janka O. Synthesis, magnetic and NMR spectroscopic properties of the MAl 5Pt 3 series (M = Ca, Y, La-Nd, Sm-Er). Dalton Trans 2024; 53:12176-12188. [PMID: 38967221 DOI: 10.1039/d4dt01296h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/06/2024]
Abstract
Following recent investigation in the ternary system Sr-Al-Pt led to the discovery of SrAl5Pt3 which crystallizes in the orthorhombic YNi5Si3 type (Pnma) structure. Interestingly, only two more aluminum representatives, CeAl5Pt3 and EuAl5Pt3, have been reported to adopt this structure type. Therefore, we decided to investigate the existence range of compounds adopting the YNi5Si3 type structure. Besides the already known Sr, Ce and Eu members, the series could be extended to Ca, Y and La-Nd as well as Sm-Er. All compounds were synthesized from the elements and characterized by powder X-ray diffraction. While for CaAl5Pt3 and LaAl5Pt3 also the respective M2Al16Pt9 members were observed, the other compounds could be obtained either as X-ray pure materials or with small amounts of Al3Pt2 as a side phase. The structure of ErAl5Pt3 could be refined from single crystal data, verifying that also the small rare-earth elements adopt the YNi5Si3 type structure. Selected members of the series were furthermore characterized by magnetization and susceptibility measurements. Since YAl5Pt3 could be obtained as a phase pure material and exhibits no paramagnetic behaviour it was investigated by 27Al MAS NMR investigations. Also, XPS measurements were conducted on this compound to gain an insight into the charge distribution. Finally, quantum-chemical calculations supported the NMR measurements and gave an insight into the chemical bonding and the charge distribution.
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Affiliation(s)
- Stefan Engel
- Inorganic Solid State Chemistry, Saarland University, Campus C4 1, 66123 Saarbrücken, Germany.
| | - Elias C J Gießelmann
- Inorganic Solid State Chemistry, Saarland University, Campus C4 1, 66123 Saarbrücken, Germany.
| | - Lars Schumacher
- Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 28/30, 48149 Münster, Germany
| | - Yuemei Zhang
- Department of Chemistry and Physics, Warren Wilson College, Swannanoa, NC, 28778, USA
| | - Frank Müller
- Experimental Physics and Center for Biophysics, Saarland University, Campus E2 9, 66123 Saarbrücken, Germany
| | - Oliver Janka
- Inorganic Solid State Chemistry, Saarland University, Campus C4 1, 66123 Saarbrücken, Germany.
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2
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Mandal I, Gangareddy J, Sethurajaperumal A, Nk M, Majji M, Bera S, Rudra P, Ravichandran V, Bysakh S, Jacob N, Rao KDM, Singh RK, Krishnan NMA, Chirumamilla M, Palanisamy T, Motapothula M, Varrla E, Ghosh S, Allu AR. H-Glass Supported Hybrid Gold Nano-Islands for Visible-Light-Driven Hydrogen Evolution. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2401131. [PMID: 38563587 DOI: 10.1002/smll.202401131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2024] [Revised: 03/16/2024] [Indexed: 04/04/2024]
Abstract
Flat panel reactors, coated with photocatalytic materials, offer a sustainable approach for the commercial production of hydrogen (H2) with zero carbon footprint. Despite this, achieving high solar-to-hydrogen (STH) conversion efficiency with these reactors is still a significant challenge due to the low utilization efficiency of solar light and rapid charge recombination. Herein, hybrid gold nano-islands (HGNIs) are developed on transparent glass support to improve the STH efficiency. Plasmonic HGNIs are grown on an in-house developed active glass sheet composed of sodium aluminum phosphosilicate oxide glass (H-glass) using the thermal dewetting method at 550 °C under an ambient atmosphere. HGNIs with various oxidation states (Au0, Au+, and Au-) and multiple interfaces are obtained due to the diffusion of the elements from the glass structure, which also facilitates the lifetime of the hot electron to be ≈2.94 ps. H-glass-supported HGNIs demonstrate significant STH conversion efficiency of 0.6%, without any sacrificial agents, via water dissociation. This study unveils the specific role of H-glass-supported HGNIs in facilitating light-driven chemical conversions, offering new avenues for the development of high-performance photocatalysts in various chemical conversion reactions for large-scale commercial applications.
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Affiliation(s)
- Indrajeet Mandal
- CSIR-Central Glass and Ceramic Research Institute, 196 Raja S C Mullick Road, Kolkata, 700 032, India
| | - Jagannath Gangareddy
- CSIR-Central Glass and Ceramic Research Institute, 196 Raja S C Mullick Road, Kolkata, 700 032, India
| | - Abimannan Sethurajaperumal
- Sustainable Nanomaterials and Technologies Lab, Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur, Chengalpattu, Tamil Nadu, 603203, India
| | - Murugasenapathi Nk
- Electrodics and Electrocatalysis Division (EEC), CSIR-Central Electrochemical Research Institute (CECRI), Karaikudi, Tamil Nadu, 630003, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Manikanta Majji
- Department of Physics, SRM University AP, Amaravati, Andhra Pradesh, 522502, India
| | - Susmita Bera
- Research Institute for Sustainable Energy (RISE), TCG Centres for Research and Education in Science and Technology (TCG CREST), Sector V, Salt Lake, Kolkata, 700091, India
| | - Pratyasha Rudra
- CSIR-Central Glass and Ceramic Research Institute, 196 Raja S C Mullick Road, Kolkata, 700 032, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Vanmathi Ravichandran
- Sustainable Nanomaterials and Technologies Lab, Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur, Chengalpattu, Tamil Nadu, 603203, India
| | - Sandip Bysakh
- CSIR-Central Glass and Ceramic Research Institute, 196 Raja S C Mullick Road, Kolkata, 700 032, India
| | - Noah Jacob
- Department of Physics, SRM University AP, Amaravati, Andhra Pradesh, 522502, India
| | - K D M Rao
- School of Applied & Interdisciplinary Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S. C. Mullick Road, Jadavpur, Kolkata, 700032, India
| | - Rajiv K Singh
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
- Photovoltaic Metrology Section, Advanced Material and Devices Metrology Division, CSIR-National Physical Laboratory, New Delhi, 110012, India
| | - N M Anoop Krishnan
- Department of Civil Engineering, Indian Institute of Technology Delhi, New Delhi, 110016, India
| | - Manohar Chirumamilla
- Department of Materials and Production, Aalborg University, Skjernvej 4A, Aalborg, 9220, Denmark
- Institute of Optical and Electronic Materials, Hamburg University of Technology, Eissendorfer Strasse 38, 21073, Hamburg, Germany
| | - Tamilarasan Palanisamy
- Electrodics and Electrocatalysis Division (EEC), CSIR-Central Electrochemical Research Institute (CECRI), Karaikudi, Tamil Nadu, 630003, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - M Motapothula
- Department of Physics, SRM University AP, Amaravati, Andhra Pradesh, 522502, India
| | - Eswaraiah Varrla
- Sustainable Nanomaterials and Technologies Lab, Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattankulathur, Chengalpattu, Tamil Nadu, 603203, India
| | - Srabanti Ghosh
- CSIR-Central Glass and Ceramic Research Institute, 196 Raja S C Mullick Road, Kolkata, 700 032, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Amarnath R Allu
- CSIR-Central Glass and Ceramic Research Institute, 196 Raja S C Mullick Road, Kolkata, 700 032, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
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3
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Gießelmann ECJ, Engel S, Baldauf J, Kösters J, Matar SF, Kickelbick G, Janka O. Searching for Laves Phase Superstructures: Structural and 27Al NMR Spectroscopic Investigations in the Hf-V-Al System. Inorg Chem 2024; 63:8180-8193. [PMID: 38652050 DOI: 10.1021/acs.inorgchem.4c00391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Laves phases exhibit a plethora of different structures and a multitude of physical properties. Investigations in the ternary system Hf-V-Al led to the discovery of numerous members of the solid solution Hf(V1-xAlx)2, which adopt the hexagonal MgZn2 type (C14) for medium to high amounts of Al (x = 0.2-1) and the cubic MgCu2 type (C15) for small Al amounts (x = 0.05-0.1). While all members exhibit Pauli-paramagnetic behavior due to the absence of localized magnetic moments, the V-rich cubic member Hf(V0.95Al0.05)2 additionally exhibits a superconducting state below TC = 7.6(1) K. All synthesized compounds were characterized by powder X-ray diffraction, and selected samples were furthermore investigated by 27Al solid-state magic-angle spinning (MAS) NMR. HfAl2 exhibits two Al resonances, one rather sharp and one significantly broadened signal, in line with the crystal structure and respective coordination environments. The members of the solid solution exhibit extremely broadened resonances due to the mixing of V and Al on the same crystallographic sites. For nominal Hf(V0.125Al0.875)2, however, two distinct sharp NMR signals were observed. This contrasts with the description of a solid solution. Therefore, single-crystal X-ray studies were conducted, showing that Hf(V0.125Al0.875)2 really is an ordered compound with the sum formula Hf4VAl7 (P3̅m1), which exhibits an, thus far, unknown superstructure of MgZn2.
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Affiliation(s)
- Elias C J Gießelmann
- Inorganic Solid State Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany
| | - Stefan Engel
- Inorganic Solid State Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany
| | - Jasper Baldauf
- Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany
| | - Jutta Kösters
- Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany
| | - Samir F Matar
- Lebanese German University, Sahel-Alma, Campus, P.O. Box 206, 1200 Jounieh, Lebanon
| | - Guido Kickelbick
- Inorganic Solid State Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany
| | - Oliver Janka
- Inorganic Solid State Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany
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Gießelmann ECJ, Engel S, Kostusiak W, Zhang Y, Herbeck-Engel P, Kickelbick G, Janka O. Raman and NMR spectroscopic and theoretical investigations of the cubic laves-phases REAl 2 (RE = Sc, Y, La, Yb, Lu). Dalton Trans 2023; 52:3391-3402. [PMID: 36811669 DOI: 10.1039/d3dt00141e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
The cubic Laves-phase aluminides REAl2 with RE = Sc, Y, La, Yb and Lu were prepared from the elements by arc-melting or using refractory metal ampoules and induction heating. They all crystallize in the cubic crystal system with space group Fd3̄m and adopt the MgCu2 type structure. The title compounds were characterized by powder X-ray diffraction and spectroscopically investigated using Raman and 27Al and in the case of ScAl2 by 45Sc solid-state MAS NMR. In both, the Raman and NMR spectra, the aluminides exhibit only one signal due to the crystal structure. DFT calculations were used to calculate Bader charges illustrating the charge transfer in these compounds along with NMR parameters and densities of states. Finally, the bonding situation was assessed by means of ELF calculations rendering these compounds aluminides with positively charged REδ+ cations embedded in an [Al2]δ- polyanion.
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Affiliation(s)
- Elias C J Gießelmann
- Inorganic Solid-State Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany.
| | - Stefan Engel
- Inorganic Solid-State Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany.
| | - Weronika Kostusiak
- Department of Chemistry and Physics, Warren Wilson College, Swannanoa, NC, 28778, USA.,Department of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland
| | - Yuemei Zhang
- Department of Chemistry and Physics, Warren Wilson College, Swannanoa, NC, 28778, USA
| | - Petra Herbeck-Engel
- INM Leibniz Institute for New Materials, Campus D2.2, 66123 Saarbrücken, Germany
| | - Guido Kickelbick
- Inorganic Solid-State Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany.
| | - Oliver Janka
- Inorganic Solid-State Chemistry, Saarland University, Campus C4.1, 66123 Saarbrücken, Germany.
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5
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Engel S, Gießelmann ECJ, Schank LE, Heymann G, Brix K, Kautenburger R, Beck HP, Janka O. Theoretical and 27Al NMR Spectroscopic Investigations of Binary Intermetallic Alkaline-Earth Aluminides. Inorg Chem 2023; 62:4260-4271. [PMID: 36847349 DOI: 10.1021/acs.inorgchem.2c04391] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/01/2023]
Abstract
The binary alkaline-earth aluminides AEAl2 (AE = Ca and Sr) and AEAl4 (AE = Ca-Ba) have been synthesized from the elements and investigated via powder X-ray diffraction experiments. CaAl2 adopts the cubic MgCu2-type structure (Fd3̅m), while SrAl2 crystallizes in the orthorhombic KHg2-type (Imma). LT-CaAl4 crystallizes with the monoclinic CaGa4-type (C2/m), while HT-CaAl4, SrAl4, and BaAl4 adopt the tetragonal BaAl4-type structure (I4/mmm). The close structural relation of the two CaAl4 polymorphs was established using a group-subgroup relation in the Bärnighausen formalism. In addition to the room-temperature and normal pressure phase of SrAl2, a high-pressure/high-temperature phase has been prepared using multianvil techniques, and its structural and spectroscopic parameters were determined. Elemental analysis by inductively coupled plasma mass spectrometry showed that no significant impurities with other elements besides the weighed ones are present and the chemical compositions match the synthesized ones. The title compounds have been furthermore investigated by 27Al solid-state magic angle spinning NMR experiments to validate the crystal structure and to gain information about the influence of the composition on the electron transfer and the NMR characteristics. This has also been investigated from a quantum chemical point of view using Bader charges, while the stabilities of the binary compounds in the three phase diagrams (Ca-Al, Sr-Al and Ba-Al) have been studied by calculations of formation energies per atom.
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Affiliation(s)
- Stefan Engel
- Anorganische Festkörperchemie, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Elias C J Gießelmann
- Anorganische Festkörperchemie, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Lukas E Schank
- Anorganische Festkörperchemie, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Gunter Heymann
- Institut für Allgemeine, Anorganische und Theoretische Chemie, Universität Innsbruck, Innrain 80-82, A-6020 Innsbruck, Austria
| | - Kristina Brix
- Anorganische Festkörperchemie, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Ralf Kautenburger
- Anorganische Festkörperchemie, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Horst Philipp Beck
- Anorganische Festkörperchemie, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
| | - Oliver Janka
- Anorganische Festkörperchemie, Universität des Saarlandes, Campus C4.1, D-66123 Saarbrücken, Germany
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Witt M, Bönnighausen J, Eustermann F, Savourat A, Scheifers JP, Fokwa BP, Doerenkamp C, Eckert H, Janka O. Extending the knowledge on the quaternary rare earth nickel aluminum germanides of the RENiAl4Ge2 series (RE=Y, Sm, Gd–Tm, Lu) – structural, magnetic and NMR-spectroscopic investigations. ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES 2020. [DOI: 10.1515/znb-2019-0176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The quaternary rare earth nickel aluminum germanide series RENiAl4Ge2 (RE = Y, Sm, Gd–Tm, Lu) has been extended by several members. The compounds were synthesized from the elements by arc-melting, and single crystals of YNiAl4Ge2, GdNiAl4Ge2, and LuNiAl4Ge2 were grown from an aluminum flux. All members crystallize isostructurally in the rhombohedral SmNiAl4Ge2-type structure (R3̅m, Z = 3). The compounds can be described as a stacking of RE
δ+ and [NiAl4Ge2]
δ−
slabs with an ABC stacking sequence, or alternatively as stacking of CsCl and CdI2 building blocks. The results of the magnetic measurements indicate that all rare earth atoms are in a trivalent oxidation state. Of the RENiAl4Ge2 series, the members with RE = Sm, Gd–Dy exhibit antiferromagnetic ordering with a maximum Néel temperature of T
N = 16.4(1) K observed for GdNiAl4Ge2. 27Al NMR spectroscopic investigations yielded spectra with two distinct signals, in line with the crystal structure, however, significantly different resonance frequencies of δ
iso
ms(YNiAl4Ge2) = 77(1) and 482(1) ppm as well as δ
iso
ms(LuNiAl4Ge2) = 90(1) and 467(1) ppm were observed. These indicate significantly different s-electron densities at the two crystallographically different Al atoms, in line with the results from DFT calculations. The Bader charge analysis confirms that the present compounds must be considered as germanides, as expected from the relative electronegativities of the constituent elements, while the low charges on Al and Y indicate significant covalent bonding.
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Affiliation(s)
- Melina Witt
- Institut für Anorganische und Analytische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstrasse 28/30 , 48149 Münster , Germany
| | - Judith Bönnighausen
- Institut für Anorganische und Analytische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstrasse 28/30 , 48149 Münster , Germany
| | - Fabian Eustermann
- Institut für Anorganische und Analytische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstrasse 28/30 , 48149 Münster , Germany
| | - Aline Savourat
- Institut für Anorganische und Analytische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstrasse 28/30 , 48149 Münster , Germany
| | - Jan P. Scheifers
- University of California Riverside, Department of Chemistry , 501 Box Springs Rd , Riverside, CA 92521 , USA
| | - Boniface P.T. Fokwa
- University of California Riverside, Department of Chemistry , 501 Box Springs Rd , Riverside, CA 92521 , USA
| | - Carsten Doerenkamp
- Instituto de Física de São Carlos , Universidade de São Paulo , São Carlos , SP 13566-590 , Brazil
| | - Hellmut Eckert
- Instituto de Física de São Carlos , Universidade de São Paulo , São Carlos , SP 13566-590 , Brazil
- Institut für Physikalische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstrasse 28, 48149 Münster , Germany
| | - Oliver Janka
- Institut für Anorganische und Analytische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstrasse 28/30 , 48149 Münster , Germany , Tel.: +49(0)251-83-36074, Fax: +49(0)251-83-36002
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7
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Stegemann F, Stahl J, Bartsch M, Zacharias H, Johrendt D, Janka O. Temperature induced valence phase transition in intermediate-valent YbPd 2Al 3. Chem Sci 2019; 10:11086-11094. [PMID: 32206257 PMCID: PMC7069237 DOI: 10.1039/c9sc04437j] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 10/13/2019] [Indexed: 12/05/2022] Open
Abstract
A temperature induced valence phase transition from Yb3+ at higher temperatures to Yb2+ at lower temperatures was observed at T = 110(1) K for intermetallic YbPd2Al3. The title compound has been prepared from the elements in sealed tantalum ampoules. The structure was refined from single-crystal data and the title compound was found to crystallize in the hexagonal YNi2Al3 type structure with space group P6/mmm and lattice parameters of a = 929.56(7) and c = 420.16(3) pm (300 K data). Full ordering of the Pd and Al atoms within the [Pd2Al3] δ- polyanion was observed. Magnetic measurements revealed an anomaly in the dc susceptibility data and intermediate valent Yb at higher temperature, as observed from the effective magnetic moment. The proposed valence phase transition was also observed as a λ-type anomaly in heat capacity measurements (T = 108.4(1) K), however, no systematic shift of the λ-peak was observed in field dependent heat capacity measurements. An antiferromagnetic ordering at this temperature, however, could be excluded, based on field-dependent susceptibility measurements and magnetization isotherms. No dynamic phenomenon was observed in ac susceptibility measurements, excluding e.g. spin-glass behavior. Subsequent temperature dependent single-crystal and powder X-ray diffraction experiments indicated a steep increase in the length of the c axis around T = 110 K upon cooling. However, no structural phase transition was found via single-crystal diffraction experiments conducted at 90 K. The anomaly was also observed in other physical measurements of e.g. the electrical resistivity, indicating a clear change in the electronic structure of the material. X-ray photoelectron spectroscopy conducted at room temperature shows the presence of both, Yb2+ and Yb3+, underlining the mixed-valent state. Members of the solid solution Yb1-x Ca x Pd2Al3 (x = 0.33, 0.67, 1) were finally used to further study the charge ordering and the present temperature induced valence phase transition.
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Affiliation(s)
- Frank Stegemann
- Institut für Anorganische und Analytische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstraße 30 , D-48149 Münster , Germany .
| | - Juliane Stahl
- Department Chemie , Ludwig-Maximilians-Universität München , Butenandtstrasse 5-13 (Haus D) , D-81377 München , Germany
| | - Manfred Bartsch
- Center for Soft Nanoscience , Westfälische Wilhelms-Universität Münster , Busso-Peus-Straße 10 , D-48149 Münster , Germany
| | - Helmut Zacharias
- Center for Soft Nanoscience , Westfälische Wilhelms-Universität Münster , Busso-Peus-Straße 10 , D-48149 Münster , Germany
| | - Dirk Johrendt
- Department Chemie , Ludwig-Maximilians-Universität München , Butenandtstrasse 5-13 (Haus D) , D-81377 München , Germany
| | - Oliver Janka
- Institut für Anorganische und Analytische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstraße 30 , D-48149 Münster , Germany .
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Radzieowski M, Stegemann F, Doerenkamp C, Matar SF, Eckert H, Dosche C, Wittstock G, Janka O. Correlations of Crystal and Electronic Structure via NMR and X-ray Photoelectron Spectroscopies in the RETMAl 2 (RE = Sc, Y, La-Nd, Sm, Gd-Tm, Lu; TM = Ni, Pd, Pt) Series. Inorg Chem 2019; 58:7010-7025. [PMID: 31062962 DOI: 10.1021/acs.inorgchem.9b00648] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A total of 35 intermetallic aluminum compounds have been synthesized from the elements via arc melting and characterized by powder X-ray diffraction. A total of 15 of them have been previously reported; however, detailed property investigations were missing. Compounds of the RETMAl2 (rare earth metal RE = Sc, Y, La-Nd, Sm, Gd-Tm, Lu) series with transition metal TM = Ni, Pd, and Pt crystallize isostructurally in the orthorhombic MgCuAl2 type structure ( Cmcm, oC16, fc2). Single-crystal X-ray diffraction investigations were conducted on YNiAl2, LaNiAl2, YPdAl2, ScPtAl2, and YPtAl2. The TM and Al atoms form a [TMAl2]δ- polyanion, the RE atoms reside in cavities within the framework. While the Sc, Y, La, and Lu compounds exhibit Pauli-paramagnetic behavior, consistent with all atoms being closed shell, the other RETMAl2 compounds show paramagnetism along with magnetic ordering at low temperatures, in line with an open-shell trivalent oxidation state for the RE atoms. Solid-state 27Al NMR investigations were carried out on the Pauli-paramagnetic samples, all showing only a single central transition, in line with one crystallographic site for the respective atoms. The observed quadrupolar coupling constants and electric-field-gradient asymmetry parameters were found to be in good agreement with the density-functional-theory-calculated values. Isotropic resonance shifts are dominated by the Fermi-contact interactions with s-conduction electron densities at the Fermi edge (Knight shifts). The bonding characteristics mirror the electronic density of states and crystal chemistry of the family of intermetallic compounds under consideration. Both the Knight shifts and quadrupolar coupling constants can be predicted based on element-specific increments.
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Affiliation(s)
- Mathis Radzieowski
- Institut für Anorganische und Analytische Chemie , Universität Münster , Corrensstrasse 30 , 48149 Münster , Germany
| | - Frank Stegemann
- Institut für Anorganische und Analytische Chemie , Universität Münster , Corrensstrasse 30 , 48149 Münster , Germany
| | - Carsten Doerenkamp
- Instituto de Fisica, Sáo Carlos , Universidade de Sáo Paulo , CP 369 , Sáo Carlos 13566-590 , Sáo Paulo , Brazil
| | - Samir F Matar
- Lebanese German University , Sahel-Alma Campus , P.O. Box 206, Jounieh , Lebanon
| | - Hellmut Eckert
- Instituto de Fisica, Sáo Carlos , Universidade de Sáo Paulo , CP 369 , Sáo Carlos 13566-590 , Sáo Paulo , Brazil
| | - Carsten Dosche
- Institut für Chemie , Carl von Ossietzky Universität Oldenburg , 26111 Oldenburg , Germany
| | - Gunther Wittstock
- Institut für Chemie , Carl von Ossietzky Universität Oldenburg , 26111 Oldenburg , Germany
| | - Oliver Janka
- Institut für Anorganische und Analytische Chemie , Universität Münster , Corrensstrasse 30 , 48149 Münster , Germany
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Stegemann F, Janka O. Two series of rare earth metal-rich ternary aluminium transition metallides – RE
6Co2Al (RE=Sc, Y, Nd, Sm, Gd–Tm, Lu) and RE
6Ni2.25Al0.75 (RE=Y, Gd–Tm, Lu). ZEITSCHRIFT FUR NATURFORSCHUNG SECTION B-A JOURNAL OF CHEMICAL SCIENCES 2018. [DOI: 10.1515/znb-2018-0153] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abstract
The rare earth metal-rich cobalt and nickel aluminium compounds with the general compositions RE
6Co2Al (RE=Sc, Y, Nd, Sm, Gd–Tm, Lu) and RE
6Ni2.25Al0.75 (RE=Y, Gd–Tm, Lu) have been synthesised from the elements by arc-melting, followed by annealing. Single-crystal X-ray diffraction experiments on Y6Co2.02(1)Al0.98(1) (Ho6Co2Ga type; Immm; a=944.1(2), b=952.4(2), c=999.0(2) pm; wR2=0.0452, 1123 F
2 values, 35 variables) and Y6Ni2.26(1)Al0.74(1) (Ho6Co2Ga type; Immm; a=938.30(5), b=959.45(5), c=996.05(6) pm; wR2=0.0499, 1131 F
2 values, 35 variables) revealed that the compounds form solid solutions according to the general formula RE
6(Co/Ni)2+
x
Al1−x
with different homogeneity ranges. The compounds of the Ni series can be obtained in X-ray pure form only with the nominal composition RE
6Ni2.25Al0.75. A significant increase of the U
22 component of the anisotropic displacement parameters of the Co/Ni2 atoms (4g site) was observed that requires a description of the structure with a split-position model at RT. Further investigations by low temperature (90 K) single-crystal X-ray diffraction experiments of Y6Co2.02(1)Al0.98(1) showed a significant decrease of U
22. Magnetic measurements were conducted on the X-ray pure members of the RE
6Co2Al (RE=Y, Dy–Tm, Lu) series. Antiferromagnetic ordering was observed for the members with unpaired f electrons with Néel temperatures up to T
N=48.0(1) K and two spin reorientations for Dy6Co2Al.
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Affiliation(s)
- Frank Stegemann
- Institut für Anorganische und Analytische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstraße 30 , 48149 Münster , Germany
| | - Oliver Janka
- Institut für Anorganische und Analytische Chemie , Westfälische Wilhelms-Universität Münster , Corrensstraße 30 , 48149 Münster , Germany
- Institut für Chemie , Carl von Ossietzky Universität Oldenburg , Carl-von-Ossietzky Strasse 9–11 , 26129 Oldenburg , Germany
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Benndorf C, Eckert H, Janka O. Structural Characterization of Intermetallic Compounds by 27Al Solid State NMR Spectroscopy. Acc Chem Res 2017; 50:1459-1467. [PMID: 28590712 DOI: 10.1021/acs.accounts.7b00153] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Intermetallic compounds are of broad interest for solid state chemists, condensed matter physicists, and material scientists due to their intriguing crystal chemistry, their physical properties, and their potential applications, ranging from lab curiosities to everyday objects. To characterize and understand the properties of new compounds and novel materials, the availability of structural information, particularly single-crystal X-ray diffraction data, is a mandatory prerequisite. Especially when it comes to the formation of compounds with deficient or mixed site occupancies, superstructures, or representatives crystallizing in other, thus far unknown structure types, a complementary method for structural analysis is of great value. Solid state nuclear magnetic resonance spectroscopy has been a valuable tool in many areas of chemistry, being an element-selective, site-specific, and inherently quantitative tool for detailed structural characterization. Magic-angle spinning conditions eliminate or reduce the effect of anisotropic interactions in the solid state, producing high-resolution spectra. Until recently, 27Al NMR studies of intermetallic aluminum compounds have been relatively sparse and mostly limited to binary systems. In this Account, we will summarize the current state of the art of high-resolution 27Al NMR in intermetallic compounds focusing on recent research efforts in our laboratories and the interpretation of NMR parameters in terms of the structural details of the compounds investigated. Besides theoretical aspects of 27Al NMR spectroscopy, short paragraphs on experimental details and the crystal chemistry of the discussed compounds are given. In the main part of this Account, we focus on three key aspects: (i) crystal structure validation, (ii) structural disorder and mixed site occupancies, and (iii) the electronic structure, all of which can be investigated by spectroscopic means. For the first part, we have chosen the ternary equiatomic compounds CaAuAl (TiNiSi type), BaAuAl (LaIrSi type), and Ba3Pt4Al4 (own type). Structural disorder and mixed site occupancies have been probed in the ScTAl series (T = Cr, Ru, Ag, Re) crystallizing in the TiNiSi, HfRhSn, and MgZn2-type structures. Also Na2Au3Al and the Heusler compounds, Sc(T0.5T'0.5)2Al (T = T' = Ni, Pd, Pt, Cu, Ag, Au), have been used for structure validation purposes, based on the number and signal area ratios of the resonances observed and on the comparison between experimental and theoretically calculated nuclear electric quadrupolar interaction parameters. Electronic structure information available from 27Al magnetic shielding will be discussed based on experimental data obtained for the RET5Al2 series (RE = Y, Lu; T = Pd, Pt), the extended RE10TAl3 series (RE = Y, Lu; T = Fe, Ru, Os, Co, Rh, Ir, Ni, Pd, Pt), and the ordered Heusler compounds ScT2Al (T = Ni, Pd, Pt, Cu, Ag, Au).
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Affiliation(s)
- Christopher Benndorf
- Institut
für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
- Institut
für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
- Institut
für Mineralogie, Kristallographie und Materialwissenschaften, Universität Leipzig, Scharnhorststraße 20, 04275 Leipzig, Germany
| | - Hellmut Eckert
- Institut
für Physikalische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
- Instituto
de Física de São Carlos, Universidade de São Paulo, São
Carlos, SP 13566-590, Brazil
| | - Oliver Janka
- Institut
für Anorganische und Analytische Chemie, Westfälische Wilhelms-Universität Münster, Corrensstraße 28/30, 48149 Münster, Germany
- Institut
für Chemie, Carl von Ossietzky Universität Oldenburg, Carl-von-Ossietzky-Straße
9-11, 26129 Oldenburg, Germany
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