Specific features in the synthesis, crystal structure and electrical conductivity of BICUTIVOX

Crystal structure and conductivity of bismuth-containing complex oxides

“…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].…”

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

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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.

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“…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.…”

“…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].…”

“…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.…”