Thermal expansion of layered cobaltitesY(Ba1 − xSrx)Co2O5 + δ withx = 0, 0.05 and 0.10

Abstract

The crystal structure and thermal expansion of Sr-doped layered cobaltitesY(Ba1 − xSrx)Co2O5 + δ (x = 0,0.05 and 0.10) were studied by means of in situ neutron thermodiffraction in the temperature range20 K ≤ T ≤ 570 K. The evolution with temperature of lattice parameters for the phases which crystallize inthis system is presented, as well as their dependence on the oxygen non-stoichiometryδ. Each phase’s volume has been fitted using available models based on the Grüneisenapproximation to the zero-pressure equation of state and using the Ruffa modelbased on the Morse potential, both using a Debye model for the internal energy.The coefficient of volumetric thermal expansion, Debye temperature and otherthermodynamic parameters are presented and compared with other perovskite compounds.