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Hydration thermodynamics of proton-conducting perovskite Ba4Ca2Nb2O11.

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Title: Hydration thermodynamics of proton-conducting perovskite Ba4Ca2Nb2O11.
Authors: Sereda, Vladimir1 vladimir.sereda@urfu.ru, Malyshkin, Dmitry1, Tsvetkov, Dmitry1, Zuev, Andrey1
Source: Materials Letters. Jan2019, Vol. 235, p97-100. 4p.
Subjects: Hydration, Phase transitions, Solid oxide fuel cells, Perovskite, Thermodynamic control
Abstract: Graphical abstract Highlights • Defect structure model for Ba 4 Ca 2 Nb 2 O 11 ·xH 2 O was discussed and successfully verified. • Enthalpy of hydration was measured for Ba 4 Ca 2 Nb 2 O 11 at 419 and 200 °C. • Directly measured hydration enthalpies were compared to theoretical ones. • Enthalpy of cubic → monoclinic phase transition in Ba 4 Ca 2 Nb 2 O 11 ·0.92H 2 O was estimated. Abstract The defect structure model based on the single reaction of water incorporation, involving structural oxygen vacancies, was discussed and successfully verified using existing p H 2 O - T - x data for cubic Ba 4 Ca 2 Nb 2 O 11 · x H 2 O – a promising electrolyte material for proton-conducting solid oxide fuel cells. As a result, the enthalpy of hydration ( Δ H h y d r 0) was obtained. It was found to be close to the partial molar enthalpy of water in Ba 4 Ca 2 Nb 2 O 11 · x H 2 O as well as to the calorimetrically measured value of Δ H h y d r 0 = −107.9 ± 14.4 kJ/mol of H 2 O. Using Δ H h y d r 0 and the value of low-temperature heat of hydration, the enthalpy of the hydration-induced cubic → monoclinic phase transition in Ba 4 Ca 2 Nb 2 O 11 ·0.92H 2 O was calculated as 63.9 ± 14.2 kJ/mol of Ba 4 Ca 2 Nb 2 O 11. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Graphical abstract Highlights • Defect structure model for Ba 4 Ca 2 Nb 2 O 11 ·xH 2 O was discussed and successfully verified. • Enthalpy of hydration was measured for Ba 4 Ca 2 Nb 2 O 11 at 419 and 200 °C. • Directly measured hydration enthalpies were compared to theoretical ones. • Enthalpy of cubic → monoclinic phase transition in Ba 4 Ca 2 Nb 2 O 11 ·0.92H 2 O was estimated. Abstract The defect structure model based on the single reaction of water incorporation, involving structural oxygen vacancies, was discussed and successfully verified using existing p H 2 O - T - x data for cubic Ba 4 Ca 2 Nb 2 O 11 · x H 2 O – a promising electrolyte material for proton-conducting solid oxide fuel cells. As a result, the enthalpy of hydration ( Δ H h y d r 0) was obtained. It was found to be close to the partial molar enthalpy of water in Ba 4 Ca 2 Nb 2 O 11 · x H 2 O as well as to the calorimetrically measured value of Δ H h y d r 0 = −107.9 ± 14.4 kJ/mol of H 2 O. Using Δ H h y d r 0 and the value of low-temperature heat of hydration, the enthalpy of the hydration-induced cubic → monoclinic phase transition in Ba 4 Ca 2 Nb 2 O 11 ·0.92H 2 O was calculated as 63.9 ± 14.2 kJ/mol of Ba 4 Ca 2 Nb 2 O 11. [ABSTRACT FROM AUTHOR]
ISSN:0167577X
DOI:10.1016/j.matlet.2018.09.172