Tsvetkov D S, Ivanov I L, Malyshkin D A, Zuev A Yu
Department of Chemistry, Institute of Natural Sciences, Ural Federal University, Ekaterinburg, 620000, Russia.
Dalton Trans. 2014 Aug 21;43(31):11862-6. doi: 10.1039/c4dt00847b.
PrBaCo2-xFexO6-δ (x = 0-0.6) double perovskites were shown to have a tetragonal P4/mmm structure in air over the complete temperature range investigated despite the oxygen content reaching a threshold value of 5.5 at temperatures from 850 °C for x = 0 up to 1078 °C for x = 0.6. However the P4/mmm→Pmmm structure transition was found to occur in PrBaCo2O6-δ under reducing conditions at temperatures from 500 °C at pO2 = 10(-3) atm down to 350 °C at pO2 = 10(-4) atm. The lattice chemical expansion along the a-axis and contraction along the c-axis, with decreasing oxygen content, 6 - δ, were found to completely compensate each other in the double perovskites and, therefore, their volume chemical expansion became negligible. As a result the cell volume linearly increases with temperature contrary to simple cubic perovskites.
研究表明，PrBaCo2-xFexO6-δ（x = 0 - 0.6）双钙钛矿在整个研究温度范围内于空气中具有四方P4/mmm结构，尽管氧含量在温度从x = 0时的850 °C到x = 0.6时的1078 °C达到了5.5的阈值。然而，发现PrBaCo2O6-δ在还原条件下于温度从pO2 = 10(-3) atm时的500 °C到pO2 = 10(-4) atm时的350 °C发生P4/mmm→Pmmm结构转变。随着氧含量6 - δ的降低，沿a轴的晶格化学膨胀和沿c轴的收缩在双钙钛矿中被发现完全相互补偿，因此，它们的体积化学膨胀变得可以忽略不计。结果，与简单立方钙钛矿相反，电池体积随温度线性增加。
