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Crystal Chemistry and Phonon Heat Capacity in Quaternary Honeycomb Delafossites: Cu[Li_(1/3)Sn_(2/3)]O)2 and Cu[Na_(1/3)Sn_(2/3)]O_2

Abramchuk, Mykola and Lebedev, Oleg I. and Hellman, Olle and Bahrami, Faranak and Mordvinova, Natalia E. and Krizan, Jason W. and Metz, Kenneth R. and Broido, David and Tafti, Fazel (2018) Crystal Chemistry and Phonon Heat Capacity in Quaternary Honeycomb Delafossites: Cu[Li_(1/3)Sn_(2/3)]O)2 and Cu[Na_(1/3)Sn_(2/3)]O_2. Inorganic Chemistry, 57 (20). pp. 12709-12717. ISSN 0020-1669. doi:10.1021/acs.inorgchem.8b01866.

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This work presents an integrated approach to study the crystal chemistry and phonon heat capacity of complex layered oxides. Two quaternary delafossites are synthesized from ternary parent compounds and copper monohalides via a topochemical exchange reaction that preserves the honeycomb ordering of the parent structures. For each compound, Rietveld refinement of the powder X-ray diffraction patterns is examined in both monoclinic C2/c and rhombohedral R3̅m space groups. Honeycomb ordering occurs only in the monoclinic space group. Bragg peaks associated with honeycomb ordering acquire an asymmetric broadening known as the Warren line shape that is commonly observed in layered structures with stacking disorder. Detailed TEM analysis confirms honeycomb ordering within each layer in both title compounds and establishes a twinning between the adjacent layers instead of the more conventional shifting or skipping stacking faults. The structural model is then used to calculate phonon dispersions and heat capacity from first principles. In both compounds, the calculated heat capacity accurately describes the experimental data. The integrated approach presented here offers a platform to carefully analyze the phonon heat capacity in complex oxides where the crystal structure can produce magnetic frustration. Isolating phonon contribution from total heat capacity is a necessary and challenging step toward a quantitative study of spin liquid materials with exotic magnetic excitations such as spinons and Majorana fermions. A quantitative understanding of phonon density of states based on crystal chemistry as presented here also paves the way toward higher efficiency thermoelectric materials.

Item Type:Article
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URLURL TypeDescription Information
Hellman, Olle0000-0002-3453-2975
Tafti, Fazel0000-0002-5723-4604
Additional Information:© 2018 American Chemical Society. Received: July 5, 2018; Published: October 1, 2018. Accession Codes: CCDC 1855314 and 1855315 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via The authors declare no competing financial interest. F.T. and M.A. acknowledge support from the National Science Foundation, Award No. DMR-1708929. D.B. and O.H. acknowledge support from the EFRI-2DARE program of the National Science Foundation, Award No. 1433467. The authors would like to mention the financial support from the “Agence Nationale de la Recherche” in the framework of the “Investissements d’avenir” program with the reference “ANR-11-EQPX-0020” for EELS data obtained using GIF Quantum.
Funding AgencyGrant Number
Agence Nationale pour la Recherche (ANR)ANR-11-EQPX-0020
Issue or Number:20
Record Number:CaltechAUTHORS:20181002-104711026
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Official Citation:Crystal Chemistry and Phonon Heat Capacity in Quaternary Honeycomb Delafossites: Cu[Li1/3Sn2/3]O2 and Cu[Na1/3Sn2/3]O2. Mykola Abramchuk, Oleg I. Lebedev, Olle Hellman, Faranak Bahrami, Natalia E. Mordvinova, Jason W. Krizan, Kenneth R. Metz, David Broido, and Fazel Tafti. Inorganic Chemistry 2018 57 (20), 12709-12717. DOI: 10.1021/acs.inorgchem.8b01866
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90080
Deposited By: George Porter
Deposited On:03 Oct 2018 17:32
Last Modified:16 Nov 2021 00:40

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