Thermal expansion of layered cobaltites Y(Ba_{1 −x}Sr_x)Co₂O_{5 + δ}withx= 0, 0.05 and 0.10

Abstract

The crystal structure and thermal expansion of Sr-doped layered cobaltites Y(Ba(1 - x)Sr(x))Co(2)O(5 + δ) (x = 0, 0.05 and 0.10) were studied by means of in situ neutron thermodiffraction in the temperature range 20 K ≤ T ≤ 570 K. The evolution with temperature of lattice parameters for the phases which crystallize in this system is presented, as well as their dependence on the oxygen non-stoichiometry δ. Each phase's volume has been fitted using available models based on the Grüneisen approximation to the zero-pressure equation of state and using the Ruffa model based on the Morse potential, both using a Debye model for the internal energy. The coefficient of volumetric thermal expansion, Debye temperature and other thermodynamic parameters are presented and compared with other perovskite compounds.

Studies in materials science and magnetism at Centro Atómico Bariloche using neutron powder diffraction

“…The study on samples substituted with Sr at the Basite confi rmed the phase-separation scenario [19,20]. We found that Sr addition destabilizes the ferrimagnetic SSO phase, as well as the "122" order, favoring instead a tetragonal and less ordered structure (Figure 3).…”