# Chemical and Thermal Stability of Sr1.9VMoO6−δ: Implications for High Temperature Energy Conversion Applications

## TL;DR

This study examines the thermal and chemical stability of Sr1.9VMoO6−δ under high-temperature conditions relevant to energy conversion technologies.

## Contribution

The paper provides new insights into the phase stability and degradation mechanisms of Sr1.9VMoO6−δ under various atmospheres and temperatures.

## Key findings

- SVMO-19 is stable up to 1000 °C in reducing, inert, and CO2 atmospheres.
- In air, SVMO-19 phase separates at ≥ 600 °C, forming SrMoO4, SrVO3, and Sr2V2O7.
- SVMO degradation in air begins as low as 400 °C, with an activation energy of 0.48–0.65 eV.

## Abstract

Raman spectroscopy and thermal gravimetric analysis (TGA)
were
used to evaluate the thermal and atmosphere stability of Sr1.9VMoO6−δ (SVMO-19), an A-site deficient double
perovskite. Motivated by previous reports describing SVMO-19’s
unprecedented electrical conductivity under reducing atmospheres,
studies described in this work determine SVMO-19’s stability
under conditions commonly encountered in high temperature solid oxide
electrolysis and fuel cell applications. Vibrational Raman data show
that SVMO-19 is stable up to 1000 °C under reducing, inert, and
CO2 containing atmospheres. Under air, however, in situ Raman data show that SVMO-19 phase separates at
temperatures ≥ 600 °C. The primary degradation products
include a scheelite phase (SrMoO4) as well as a vanadium
containing single perovskite, SrVO3, and a vanadium containing
pyrochlore Sr2V2O7. TGA measurements
suggest that SVMO decomposition in air begins at even lower temperatures
(400 °C). TGA data show that SVMO is stable under N2 at temperatures as high as 900 °C, consistent with Raman data.
SVMO oxidation kinetics are analyzed using both a simple kinetic model
consisting of two independent first-order processes and an Avrami
model. The data are better described by the pair of first order processes,
but an Arrhenius analysis using both models result in an activation
energy (E
a) for SVMO degradation between
0.48 and 0.65 eV. Taken together, these findings are considered in
the context of properties required by electrode materials used in
reversible solid oxide electrochemical cells.