Thermodynamic and High-Temperature Properties of KFe0.33W1.67O6

A. G. Shvareva; Шварева А. Г.; V. M. Smirnova; Кяшкин В. М.; N. N. Smirnova; Смирнова Н. Н.; A. V. Markin; Маркин А. В.; D. G. Fukina; Фукина Д. Г.; A. V. Knyazev; Князев А. В.

doi:10.31857/S0044453723080265

Thermodynamic and High-Temperature Properties of KFe0.33W1.67O6

Authors: Shvareva A.G.¹, Smirnova V.M.², Smirnova N.N.¹, Markin A.V.¹, Fukina D.G.¹, Knyazev A.V.¹
Affiliations:
1. National Research Lobachevsky State University of Nizhny Novgorod
2. National Research Ogarev Mordovia State University
Issue: Vol 97, No 8 (2023)
Pages: 1087-1096
Section: ХИМИЧЕСКАЯ ТЕРМОДИНАМИКА И ТЕРМОХИМИЯ
Submitted: 26.02.2025
Published: 01.08.2023
URL: https://rjonco.com/0044-4537/article/view/668673
DOI: https://doi.org/10.31857/S0044453723080265
EDN: https://elibrary.ru/RAAJQP
ID: 668673

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Abstract

This paper presents the results of a study of the KFe0.33W1.67O6 system. The compound was obtained by a solid-phase synthesis method at a temperature of 1073 K. The structural, morphological, and spectroscopic properties of KFe0.33W1.67O6 were characterized using XRD, SEM-EDS. The compound crystallizes in a cubic lattice with the space group Fd–3m (227). The obtained lattice parameter a = 10.3697 (3) Å. The phase transitions of KFe0.33W1.67O6 were determined by low-temperature and high-temperature X-ray diffraction. The temperature dependence of heat capacity of KFe0.33W1.67O6 has been measured for the first time in the range from 5 to 638 K by precision adiabatic vacuum calorimetry and differential scanning calorimetry. The experimental data were used to calculate standard thermodynamic functions, namely the heat capacity C∘p∘(T), enthalpy H°(T) − H°(0), entropy S°(T) − S°(0), and Gibbs function G°(T) − H°(0), for the range from T → 0 to 630 K.

Keywords

pyrochlore, KFe_0.33W_1.67O₆, adiabatic vacuum calorimetry, heat capacity, thermodynamic functions

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