Structural and thermal stability of BIMEVOX oxygen semiconductors

Морозова, М. В.; Buyanova, E. S.; Петрова, С. А.; Хисаметдинова, В. В.; Emel’yanova, Yu. V.; Shatokhina, A. N.; Zhukovskii, V. M.

doi:10.1134/s1023193511040100

Cited by 5 publications

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“…For all systems the processes of phase formation during their synthesis using a solid-phase, different versions of mortar methods, mechano-chemical activation were systematically investigated, the optimum conditions for obtaining single- 6 . Analysis of reaction products after different stages of thermal processing has shown that in the case of the introduction in the process of synthesis procedures for the tempering of samples, the number and concentration of intermediates is significantly reduced, and single-phase final product forms at a temperature 1073-1123 K. The structural features of the different structural families of complex oxides are investigated, the boundaries of the regions of homogeneity, structural parameters and concentration intervals of existence of polymorphic modifications are defined.…”

Section: Resultsmentioning

confidence: 99%

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Crystal structure and conductivity of bismuth-containing complex oxides

et al. 2015

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In the paper, a comprehensive systematic study of different classes of bismuth containing oxide compounds was carried out. The relationship between composition, temperature and concentration regions of existence of stable, specific structure and properties of solid solutions on the basis of vanadates, molybdates, niobates and bismuth was found. The general regularities of synthesis of solid solutions with different variants of solid-phase and soluble methods were determined. On this basis, the optimal conditions for obtaining single-phase materials were formulated. For the first time the temperature and concentration boundaries of the regions of homogeneity and areas of stable existence of polymorphic modifications of solid solutions were defined and/or refined. The structural parameters of the synthesized phases were determined. By the method of electrochemical impedance spectroscopy the nature and features of impedance spectra, the temperature and concentration dependences of electrical conductivity of ceramic materials based on bismuth containing complex oxides were identified.

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Section: Resultsmentioning

confidence: 99%

“…The features of synthesis for each particular case are described in [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

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confidence: 99%

Crystal structure and conductivity of bismuth-containing complex oxides

et al. 2015

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“…The change of the structure into the orthorhombic one occurs in atmosphere with low oxygen content (lg pO 2 (atm) <-14.0) at temperatures above 773 K. However, decomposition of the sample does not occur. Evaluation of the structural and thermal stability of BIFEVOX in air at long time exposures (at least two weeks at the same temperature) in the temperature range 723-1083 K revealed no changes in the structure or appearance of any additional phases [6].…”

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confidence: 99%

Materials based on BIFEVOX and bismuth or iron simple oxides nanopowders

Krylov¹,

Emel’yanova²,

Buyanova³

et al. 2017

CTA

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“…As the oxygen partial pressure changes from 0.21 to 10 -18 atm, the tetragonal BIFEVOX structure transforms to orthorhombic in a low oxygen medium (logp O 2 [atm] < -14.0) at temperatures above 773 K. However, a sample does not undergo decomposition. The structural and thermal stability of BIFEVOX in air during long expo sures (of at least two weeks at one temperature) over a temperature range of 723-1083 K with 50 K steps was evaluated earlier [6]. Structural alterations or the appearance of additional phases have not been found for γ BIFEVOX phases over the entire temperature range of thermocycling.…”

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Electrochemical characteristics, thermal and chemical compatibility in the La0.7Sr0.3CoO3 electrode-γ-BIFEVOX electrolyte system

Buyanova

Shafigina

Морозова

et al. 2013

Russ. J. Inorg. Chem.

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The family of solid electrolytes having the general formula Bi 4 V 2 -х М х O 11 -δ , referred to as BIMEVOX in scientific literature, features rather high values of oxy gen ion conductivity within a moderate temperature range of 550-950 K. Studies of Bi 4 V 2 -х Fe х O 11 -δ (BIFEVOX) solid solutions established the concentra tion bounds and structural features of BIFEVOX poly morphs and ion transport characteristics depending on composition and temperature, and provided optimal conditions and methods for manufacturing ultrafine BIFEVOX powders [1][2][3][4][5].Regardless of the preparation method, various researchers reported that solid solutions in the concen tration range of 0.3 ≤ х ≤ 0.5 have a tetragonal structure (space group I4/mmm). For low dopant concentrations (х ≤ 0.2) [2], conductivity versus temperature curves feature typical consecutive phase transitions [γ → β (850 K) and β → α (725 K)]; these transitions corre spond to a change in structure (I4/mmm → Amam → P 1) and are accompanied with a change in activation energy of conduction in the solid solutions. For γ phases of the solid solutions (space group I4/mmm), the curves are linear plots, and the activation energies at high tem peratures have values typical of BIMEVOX, namely, 0.2-0.4 eV. Transition to the ordered γ' phase upon lowering temperature is accompanied by an insignif icant change in the slope of the logσ-10 3 /T curve and an increase in activation energy to 0.5-0.7 eV. All transitions observed in the conductivity curves correlate with changes in linear thermal expansion curves. In samples prepared by solution technologies for BIFEVOX, conductivity is always higher than in samples prepared by a solid phase process.Pena et al. [3] discovered that constant current con ductivity decreases at relatively low temperatures (356-433 K) where the iron content increases, whereas the activation energy increases from 0.2 to 0.97 eV; these trends can serve as evidence for a significant contribu tion of oxygen ion conductivity to the overall conduc tivity of Bi 4 V 2 -x Fe x O 11 -y (0 ≤ x ≤ 0.9, 0 ≤ y ≤ 1).A structural study of tetragonal Bi 4 V 2 -x Fe x O 11 -δ as a function of temperature and partial oxygen pressure discovered that this polymorph is stable over a wide range of thermodynamic parameters (T = 298-1073 K, logP O 2 [atm] = -0.68 to -18.0) [4,5]. Under heating, a sample experiences only thermal expansion. As the oxygen partial pressure changes from 0.21 to 10 -18 atm, the tetragonal BIFEVOX structure transforms to orthorhombic in a low oxygen medium (logp O 2 [atm] < -14.0) at temperatures above 773 K. However, a sample does not undergo decomposition. The structural and thermal stability of BIFEVOX in air during long expo sures (of at least two weeks at one temperature) over a temperature range of 723-1083 K with 50 K steps was evaluated earlier [6]. Structural alterations or the appearance of additional phases have not been found for γ BIFEVOX phases over the entire temperature range of thermocycling.Complex oxides of the BIMEVOX fami...

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Structural and thermal stability of BIMEVOX oxygen semiconductors

Cited by 5 publications

References 0 publications

Crystal structure and conductivity of bismuth-containing complex oxides

Crystal structure and conductivity of bismuth-containing complex oxides

Materials based on BIFEVOX and bismuth or iron simple oxides nanopowders

Electrochemical characteristics, thermal and chemical compatibility in the La0.7Sr0.3CoO3 electrode-γ-BIFEVOX electrolyte system

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