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B-site disordering in Ba3Ln2MoO9 (Ln=Ho, Er) perovskites: A neutron diffraction study |
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| Authors: | SA Larrégola M García Hernandez JC Pedregosa |
| Institution: | a Área de Química General e Inorgánica, Departamento de Química, Facultad de Química, Bioquímica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, 5700 San Luis, Argentina b Instituto de Ciencia de Materiales de Madrid, C.S.I.C., Cantoblanco, 28049 Madrid, Spain c Institut Max Von Laue Paul Langevin, F-38042 Grenoble, France |
| Abstract: | We describe the preparation, structure determination and magnetic properties of two Ba perovskites containing rare-earth cations at the B-sublattice. Ba3Ln2MoO9 (Ln=Ho3+ and Er3+) were synthesized by ceramic procedures. Joint X-ray (XRPD) and neutron (NPD) powder diffraction refinements were carried out to analyse the crystal structure. At room temperature, both phases are tetragonal, space group I4/mcm, Z=4. Ln and Mo atoms are found to be distributed at random over the octahedral sites of the perovskites. Magnetic measurements at 0.1 T show that both samples are paramagnetic between 3 and 300 K, following a Curie-Weiss law. M vs. H curves show a region of paramagnetic behaviour and above 2.5 T a magnetic saturated system is observed. Finally, the temperature evolution of the NPD patterns of Ba3Ho2MoO9 reveals the absence of long-range magnetic ordering down to 2 K. |
| Keywords: | Barium perovskite Neutron powder diffraction X-ray powder diffraction Joint Rietveld refinement B-site disordering Paramagnetic rare earth cations |
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