Structural and magnetic study of the cation-ordered perovskites Ba2−xSrxErMoO6
2006; Elsevier BV; Volume: 180; Issue: 2 Linguagem: Inglês
10.1016/j.jssc.2006.11.007
ISSN1095-726X
Autores Tópico(s)Thermal Expansion and Ionic Conductivity
ResumoA series of perovskite phases have been prepared from the appropriate carbonates and oxides by heating under reducing conditions at temperatures up to 1300 °C. Complete ordering between ErO6 and MoO6 octahedra and a disordered distribution of Sr2+ and Ba2+ occur in all compounds. Neutron powder diffraction experiments show that the substitution of Sr2+ into Ba2ErMoO6 introduces a progressive reduction in symmetry from Fm3¯m (x=0) to I4/m (x=0.5, 0.8) to P21/n (x=1.25, 1.75, 2.0). Magnetic susceptibility measurements indicate that all of these compounds show Curie–Weiss paramagnetism and that for x<1.25 this behaviour persists down to 2 K. The monoclinically distorted compounds show magnetic transitions at low temperature and neutron diffraction has confirmed the presence of long-range antiferromagnetic order below 2.5 and 4 K in Ba0.25Sr1.75ErMoO6 and Sr2ErMoO6, respectively. Ba0.75Sr1.25ErMoO6, Ba0.25Sr1.75ErMoO6 and Sr2ErMoO6 do not undergo structural distortion on cooling from room temperature.
Referência(s)