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Title: Relationship between the defect structure and fluorine-ion conductivity of La{sub 1−y}Sr{sub y}F{sub 3−y} (0 ⩽ y ⩽ 0.15) crystals according to X-ray and neutron diffraction data

Abstract

The defect structure of crystals of as-grown nonstoichiometric tysonite (LaF{sub 3} type) La{sub 1−y}Sr{sub y}F{sub 3−y} phase (y = 0, 0.05, 0.07, and 0.15) has been investigated by X-ray diffraction and neutron diffraction. A concentration-driven structural transition from the β-La{sub 1−y}Sr{sub y}F{sub 3−y} modification to the α-La{sub 1−y}Sr{sub y}F{sub 3−}y modification in the range y = 0.05–0.10 has been observed for the first time. This transition correlates with the maximum of fluorine-ion conductivity (y = 0.05 ± 0.02) and the maximum in the melting curve (y = 0.07 ± 0.03). β-LaF{sub 3} and β-La{sub 0.95}Sr{sub 0.05}F{sub 2.95} crystals belong to the trigonal system (sp. gr. P3̄c1, Z = 6) and are twinned according to the merohedral twin law. Fine changes in the fluorine sublattice of β-La{sub 0.95}Sr{sub 0.05}F{sub 2.95} increase conductivity σ{sub 293K} to 3 × 10{sup −4} S/cm; hence, these crystals can be used as fluorine-conducting solid electrolytes (FCSEs) in solid-state ionics devices. Additional possibilities of ion transport over twin joints are discussed. In α-La{sub 0.85}Sr{sub 0.15}F{sub 2.85} crystal the symmetry group changes to P6{sub 3}/mmc, Z = 2; it is not twinned and its fluorine-ion conductivity is reduced.

Authors:
; ; ; ;  [1]; ;  [2];  [1]
  1. Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)
  2. Karpov Institute of Physical Chemistry (Obninsk branch) (Russian Federation)
Publication Date:
OSTI Identifier:
22722862
Resource Type:
Journal Article
Journal Name:
Crystallography Reports
Additional Journal Information:
Journal Volume: 60; Journal Issue: 3; Other Information: Copyright (c) 2015 Pleiades Publishing, Inc.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1063-7745
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; CONCENTRATION RATIO; CRYSTALS; DEFECTS; ELECTRIC CONDUCTIVITY; FLUORINE IONS; LANTHANUM FLUORIDES; MELTING; NEUTRON DIFFRACTION; SOLID ELECTROLYTES; SYMMETRY GROUPS; X-RAY DIFFRACTION

Citation Formats

Bolotina, N. B., E-mail: nb-bolotina@mail.ru, Chernaya, T. S., Kalyukanov, A. I., Verin, I. A., Sorokin, N. I., Fykin, L. E., Isakova, N. N., and Sobolev, B. P. Relationship between the defect structure and fluorine-ion conductivity of La{sub 1−y}Sr{sub y}F{sub 3−y} (0 ⩽ y ⩽ 0.15) crystals according to X-ray and neutron diffraction data. United States: N. p., 2015. Web. doi:10.1134/S1063774515030050.
Bolotina, N. B., E-mail: nb-bolotina@mail.ru, Chernaya, T. S., Kalyukanov, A. I., Verin, I. A., Sorokin, N. I., Fykin, L. E., Isakova, N. N., & Sobolev, B. P. Relationship between the defect structure and fluorine-ion conductivity of La{sub 1−y}Sr{sub y}F{sub 3−y} (0 ⩽ y ⩽ 0.15) crystals according to X-ray and neutron diffraction data. United States. doi:10.1134/S1063774515030050.
Bolotina, N. B., E-mail: nb-bolotina@mail.ru, Chernaya, T. S., Kalyukanov, A. I., Verin, I. A., Sorokin, N. I., Fykin, L. E., Isakova, N. N., and Sobolev, B. P. Fri . "Relationship between the defect structure and fluorine-ion conductivity of La{sub 1−y}Sr{sub y}F{sub 3−y} (0 ⩽ y ⩽ 0.15) crystals according to X-ray and neutron diffraction data". United States. doi:10.1134/S1063774515030050.
@article{osti_22722862,
title = {Relationship between the defect structure and fluorine-ion conductivity of La{sub 1−y}Sr{sub y}F{sub 3−y} (0 ⩽ y ⩽ 0.15) crystals according to X-ray and neutron diffraction data},
author = {Bolotina, N. B., E-mail: nb-bolotina@mail.ru and Chernaya, T. S. and Kalyukanov, A. I. and Verin, I. A. and Sorokin, N. I. and Fykin, L. E. and Isakova, N. N. and Sobolev, B. P.},
abstractNote = {The defect structure of crystals of as-grown nonstoichiometric tysonite (LaF{sub 3} type) La{sub 1−y}Sr{sub y}F{sub 3−y} phase (y = 0, 0.05, 0.07, and 0.15) has been investigated by X-ray diffraction and neutron diffraction. A concentration-driven structural transition from the β-La{sub 1−y}Sr{sub y}F{sub 3−y} modification to the α-La{sub 1−y}Sr{sub y}F{sub 3−}y modification in the range y = 0.05–0.10 has been observed for the first time. This transition correlates with the maximum of fluorine-ion conductivity (y = 0.05 ± 0.02) and the maximum in the melting curve (y = 0.07 ± 0.03). β-LaF{sub 3} and β-La{sub 0.95}Sr{sub 0.05}F{sub 2.95} crystals belong to the trigonal system (sp. gr. P3̄c1, Z = 6) and are twinned according to the merohedral twin law. Fine changes in the fluorine sublattice of β-La{sub 0.95}Sr{sub 0.05}F{sub 2.95} increase conductivity σ{sub 293K} to 3 × 10{sup −4} S/cm; hence, these crystals can be used as fluorine-conducting solid electrolytes (FCSEs) in solid-state ionics devices. Additional possibilities of ion transport over twin joints are discussed. In α-La{sub 0.85}Sr{sub 0.15}F{sub 2.85} crystal the symmetry group changes to P6{sub 3}/mmc, Z = 2; it is not twinned and its fluorine-ion conductivity is reduced.},
doi = {10.1134/S1063774515030050},
journal = {Crystallography Reports},
issn = {1063-7745},
number = 3,
volume = 60,
place = {United States},
year = {2015},
month = {5}
}