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Title: Characteristics of the Li{sup +}-Ion Conductivity of Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} Crystals (R = Fe, Sc) in the Superionic State

Abstract

The characteristics of Li+-ion conductivity σdc of structural γ modifications of Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} compounds (R = Fe, Sc) existing in the superionic state have been investigated by impedance spectroscopy. The type of structural framework [R{sub 2}P{sub 3}O{sub 12}]{sub ∞}{sup 3-} affects the σdc value and the σdc activation enthalpy in these compounds. The ion transport activation enthalpy in γ-Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} (ΔH{sub σ} = 0.31 ± 0.03 eV) is lower than in γ-Li{sub 3}Fe{sub 2}(PO{sub 4}){sub 3} (ΔH{sub σ} = 0.36 ± 0.03 eV). The conductivity of γ-Li{sub 3}Fe{sub 2}(PO{sub 4}){sub 3} (σ{sub dc} = 0.02 S/cm at 573 K) is twice as high as that of γ-Li{sub 3}R{sub 2}(PO{sub 4}){sub 3}. A decrease in temperature causes a structural transformation of Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} from the superionic γ modification (space group Pcan) through the intermediate metastable β modification (space group P2{sub 1}/n) into the “dielectric” α modification (space group P2{sub 1}/n). Upon cooling, σdc for both phosphates decreases by a factor of about 100 at the superionic TSIC transition. In Li{sub 3}Fe{sub 2}(PO{sub 4}){sub 3} σdc gradually decreases in the temperature range T{sub SIC} = 430–540 K, whereas in Li{sub 3}R{sub 2}(PO{sub 4}){submore » 3} σdc undergoes a jump at T{sub SIC} = 540 ± 25 K. Possible crystallochemical factors responsible for the difference in the σdc and ΔH{sub σ} values and the thermodynamics and kinetics of the superionic transition for Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} are discussed.« less

Authors:
 [1]
  1. Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Scientific Research Centre “Crystallography and Photonics” (Russian Federation)
Publication Date:
OSTI Identifier:
22771122
Resource Type:
Journal Article
Journal Name:
Physics of the Solid State
Additional Journal Information:
Journal Volume: 60; Journal Issue: 5; Other Information: Copyright (c) 2018 Pleiades Publishing, Ltd.; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1063-7834
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COOLING; CRYSTALS; DATA; DIELECTRIC MATERIALS; ENTHALPY; IMPEDANCE; IONIC CONDUCTIVITY; IRON COMPOUNDS; LITHIUM COMPOUNDS; LITHIUM IONS; MODIFICATIONS; ORTHORHOMBIC LATTICES; PHOSPHATES; SCANDIUM COMPOUNDS; SPACE GROUPS; SPECTROSCOPY; THERMODYNAMICS; TRANSFORMATIONS

Citation Formats

Sorokin, N. I., E-mail: nsorokin1@yandex.ru. Characteristics of the Li{sup +}-Ion Conductivity of Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} Crystals (R = Fe, Sc) in the Superionic State. United States: N. p., 2018. Web. doi:10.1134/S106378341805030X.
Sorokin, N. I., E-mail: nsorokin1@yandex.ru. Characteristics of the Li{sup +}-Ion Conductivity of Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} Crystals (R = Fe, Sc) in the Superionic State. United States. doi:10.1134/S106378341805030X.
Sorokin, N. I., E-mail: nsorokin1@yandex.ru. Tue . "Characteristics of the Li{sup +}-Ion Conductivity of Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} Crystals (R = Fe, Sc) in the Superionic State". United States. doi:10.1134/S106378341805030X.
@article{osti_22771122,
title = {Characteristics of the Li{sup +}-Ion Conductivity of Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} Crystals (R = Fe, Sc) in the Superionic State},
author = {Sorokin, N. I., E-mail: nsorokin1@yandex.ru},
abstractNote = {The characteristics of Li+-ion conductivity σdc of structural γ modifications of Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} compounds (R = Fe, Sc) existing in the superionic state have been investigated by impedance spectroscopy. The type of structural framework [R{sub 2}P{sub 3}O{sub 12}]{sub ∞}{sup 3-} affects the σdc value and the σdc activation enthalpy in these compounds. The ion transport activation enthalpy in γ-Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} (ΔH{sub σ} = 0.31 ± 0.03 eV) is lower than in γ-Li{sub 3}Fe{sub 2}(PO{sub 4}){sub 3} (ΔH{sub σ} = 0.36 ± 0.03 eV). The conductivity of γ-Li{sub 3}Fe{sub 2}(PO{sub 4}){sub 3} (σ{sub dc} = 0.02 S/cm at 573 K) is twice as high as that of γ-Li{sub 3}R{sub 2}(PO{sub 4}){sub 3}. A decrease in temperature causes a structural transformation of Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} from the superionic γ modification (space group Pcan) through the intermediate metastable β modification (space group P2{sub 1}/n) into the “dielectric” α modification (space group P2{sub 1}/n). Upon cooling, σdc for both phosphates decreases by a factor of about 100 at the superionic TSIC transition. In Li{sub 3}Fe{sub 2}(PO{sub 4}){sub 3} σdc gradually decreases in the temperature range T{sub SIC} = 430–540 K, whereas in Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} σdc undergoes a jump at T{sub SIC} = 540 ± 25 K. Possible crystallochemical factors responsible for the difference in the σdc and ΔH{sub σ} values and the thermodynamics and kinetics of the superionic transition for Li{sub 3}R{sub 2}(PO{sub 4}){sub 3} are discussed.},
doi = {10.1134/S106378341805030X},
journal = {Physics of the Solid State},
issn = {1063-7834},
number = 5,
volume = 60,
place = {United States},
year = {2018},
month = {5}
}