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Title: Bond Valences and Anharmonicity in Vacancy-Ordered Double Perovskite Halides

Abstract

We report that anharmonic lattice dynamics are intimately linked with optical and electronic properties in perovskite halides semiconductors. Vacancy-ordered double perovskites are a subset of the perovskite halide family containing isolated octahedral units. The absence of polyhedral connectivity engenders the vacancy-ordered double perovskites with additional degrees of dynamic freedom, which presents an ideal structural framework to study dynamic-property relationships in perovskite halide semiconductors. In the present study, we examine the structure and bonding origins of anharmonicity in the vacancy-ordered double perovskites Cs 2Sn 1-xTe xI 6. While X-ray diffraction indicates that all members adopt the cubic vacancy-ordered double perovskite structure, the local coordination environment probed by X-ray pair distribution function (XPDF) analysis reveals asymmetry of the Cs–I/I–I pair correlation that smoothly decreases with increasing tellurium content. Temperature-dependent neutron total scattering suggests that this asymmetry in the PDF occurs due to anharmonic lattice dynamics arising from octahedral tilting and Cs + displacements, as supported by Reverse Monte Carlo simulations of the Cs 2SnI 6 and Cs 2TeI 6 end members. We further correlate the trends in asymmetry and anharmonicity with the bond valence sum of the Cs + ion, and find that the anharmonicity vanishes when the bonding preferences of themore » Cs + are satisfied by the size of the cuboctahedral void. Lastly, this study presents a simple and effective approach for understanding the origin of anharmonicity in vacancy-ordered double perovskite materials.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Colorado State Univ., Fort Collins, CO (United States). Department of Chemistry
Publication Date:
Research Org.:
Colorado State Univ., Fort Collins, CO (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1478240
Alternate Identifier(s):
OSTI ID: 1479127
Grant/Contract Number:  
SC0016083; AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Materials Chemistry C
Additional Journal Information:
Journal Volume: 6; Journal Issue: 44; Journal ID: ISSN 2050-7526
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Maughan, Annalise E., Paecklar, Arnold A., and Neilson, James Richmond. Bond Valences and Anharmonicity in Vacancy-Ordered Double Perovskite Halides. United States: N. p., 2018. Web. doi:10.1039/C8TC03527J.
Maughan, Annalise E., Paecklar, Arnold A., & Neilson, James Richmond. Bond Valences and Anharmonicity in Vacancy-Ordered Double Perovskite Halides. United States. doi:10.1039/C8TC03527J.
Maughan, Annalise E., Paecklar, Arnold A., and Neilson, James Richmond. Fri . "Bond Valences and Anharmonicity in Vacancy-Ordered Double Perovskite Halides". United States. doi:10.1039/C8TC03527J.
@article{osti_1478240,
title = {Bond Valences and Anharmonicity in Vacancy-Ordered Double Perovskite Halides},
author = {Maughan, Annalise E. and Paecklar, Arnold A. and Neilson, James Richmond},
abstractNote = {We report that anharmonic lattice dynamics are intimately linked with optical and electronic properties in perovskite halides semiconductors. Vacancy-ordered double perovskites are a subset of the perovskite halide family containing isolated octahedral units. The absence of polyhedral connectivity engenders the vacancy-ordered double perovskites with additional degrees of dynamic freedom, which presents an ideal structural framework to study dynamic-property relationships in perovskite halide semiconductors. In the present study, we examine the structure and bonding origins of anharmonicity in the vacancy-ordered double perovskites Cs2Sn1-xTexI6. While X-ray diffraction indicates that all members adopt the cubic vacancy-ordered double perovskite structure, the local coordination environment probed by X-ray pair distribution function (XPDF) analysis reveals asymmetry of the Cs–I/I–I pair correlation that smoothly decreases with increasing tellurium content. Temperature-dependent neutron total scattering suggests that this asymmetry in the PDF occurs due to anharmonic lattice dynamics arising from octahedral tilting and Cs+ displacements, as supported by Reverse Monte Carlo simulations of the Cs2SnI6 and Cs2TeI6 end members. We further correlate the trends in asymmetry and anharmonicity with the bond valence sum of the Cs+ ion, and find that the anharmonicity vanishes when the bonding preferences of the Cs+ are satisfied by the size of the cuboctahedral void. Lastly, this study presents a simple and effective approach for understanding the origin of anharmonicity in vacancy-ordered double perovskite materials.},
doi = {10.1039/C8TC03527J},
journal = {Journal of Materials Chemistry C},
number = 44,
volume = 6,
place = {United States},
year = {2018},
month = {10}
}

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