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Hill JA, Murray CA, Tang CC, Thygesen PMM, Thompson AL, Goodwin AL. Inorganic co-crystal formation and thermal disproportionation in a dicyanometallate ‘superperovskite’. Chem Commun (Camb) 2019; 55:5439-5442. [DOI: 10.1039/c8cc10277e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The dicyanometallate superperovskite co-crystal [NBu4]Mn[Au(CN)2]3·[NBu4]ClO4 illustrates a new type of structural and phase complexity accessible to dicyanometallate perovskites.
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Affiliation(s)
- Joshua A. Hill
- Department of Chemistry
- University of Oxford
- Inorganic Chemistry Laboratory
- Oxford OX1 3QR
- UK
| | - Claire A. Murray
- Diamond Light Source Ltd
- Harwell Science and Innovation Campus
- Didcot
- UK
| | - Chiu C. Tang
- Diamond Light Source Ltd
- Harwell Science and Innovation Campus
- Didcot
- UK
| | - Peter M. M. Thygesen
- Department of Chemistry
- University of Oxford
- Inorganic Chemistry Laboratory
- Oxford OX1 3QR
- UK
| | - Amber L. Thompson
- Department of Chemistry
- University of Oxford
- Inorganic Chemistry Laboratory
- Oxford OX1 3QR
- UK
| | - Andrew L. Goodwin
- Department of Chemistry
- University of Oxford
- Inorganic Chemistry Laboratory
- Oxford OX1 3QR
- UK
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Thygesen PMM, Paddison JAM, Zhang R, Beyer KA, Chapman KW, Playford HY, Tucker MG, Keen DA, Hayward MA, Goodwin AL. Orbital Dimer Model for the Spin-Glass State in Y_{2}Mo_{2}O_{7}. Phys Rev Lett 2017; 118:067201. [PMID: 28234510 DOI: 10.1103/physrevlett.118.067201] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Indexed: 06/06/2023]
Abstract
The formation of a spin glass generally requires that magnetic exchange interactions are both frustrated and disordered. Consequently, the origin of spin-glass behavior in Y_{2}Mo_{2}O_{7}-in which magnetic Mo^{4+} ions occupy a frustrated pyrochlore lattice with minimal compositional disorder-has been a longstanding question. Here, we use neutron and x-ray pair-distribution function (PDF) analysis to develop a disorder model that resolves apparent incompatibilities between previously reported PDF, extended x-ray-absorption fine structure spectroscopy, and NMR studies, and provides a new and physical explanation of the exchange disorder responsible for spin-glass formation. We show that Mo^{4+} ions displace according to a local "two-in-two-out" rule on each Mo_{4} tetrahedron, driven by orbital dimerization of Jahn-Teller active Mo^{4+} ions. Long-range orbital order is prevented by the macroscopic degeneracy of dimer coverings permitted by the pyrochlore lattice. Cooperative O^{2-} displacements yield a distribution of Mo-O-Mo angles, which in turn introduces disorder into magnetic interactions. Our study demonstrates experimentally how frustration of atomic displacements can assume the role of compositional disorder in driving a spin-glass transition.
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Affiliation(s)
- Peter M M Thygesen
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Joseph A M Paddison
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
- School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, Georgia 30332-0430, USA
| | - Ronghuan Zhang
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Kevin A Beyer
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Karena W Chapman
- Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Helen Y Playford
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Matthew G Tucker
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
- Diamond Light Source, Chilton, Oxfordshire OX11 0DE, United Kingdom
- Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - David A Keen
- ISIS Facility, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire OX11 0QX, United Kingdom
| | - Michael A Hayward
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
| | - Andrew L Goodwin
- Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, United Kingdom
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Evans NL, Thygesen PMM, Boström HLB, Reynolds EM, Collings IE, Phillips AE, Goodwin AL. Control of Multipolar and Orbital Order in Perovskite-like [C(NH2)3]CuxCd1-x(HCOO)3 Metal-Organic Frameworks. J Am Chem Soc 2016; 138:9393-6. [PMID: 27414161 DOI: 10.1021/jacs.6b05208] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We study the compositional dependence of molecular orientation (multipolar) and orbital (quadrupolar) order in the perovskite-like metal-organic frameworks [C(NH2)3]CuxCd1-x(HCOO)3. Upon increasing the fraction x of Jahn-Teller-active Cu(2+), we observe an orbital disorder/order transition and a multipolar reorientation transition, each occurring at distinct critical compositions xo = 0.45(5) and xm = 0.55(5). We attribute these transitions to a combination of size, charge distribution, and percolation effects. Our results establish the accessibility in formate perovskites of novel structural degrees of freedom beyond the familiar dipolar terms responsible for (anti)ferroelectric order. We discuss the implications of cooperative quadrupolar and multipolar states for the design of relaxor-like hybrid perovskites.
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Affiliation(s)
- Nicole L Evans
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QR, U.K
| | - Peter M M Thygesen
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QR, U.K
| | - Hanna L B Boström
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QR, U.K
| | - Emily M Reynolds
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QR, U.K
| | - Ines E Collings
- Laboratory of Crystallography, University of Bayreuth , D-95440 Bayreuth, Germany
| | - Anthony E Phillips
- School of Physics and Astronomy, Queen Mary, University of London , 327 Mile End Road, London E1 4NS, U.K
| | - Andrew L Goodwin
- Department of Chemistry, Inorganic Chemistry Laboratory, University of Oxford , South Parks Road, Oxford OX1 3QR, U.K
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