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Title of article :
B-site disordering in Ba3Ln2MoO9 (Ln=Ho, Er) perovskites: A neutron diffraction study
Author/Authors :
S.A. Larrégola، نويسنده , , J.A. Alonso، نويسنده , , M. Garcia-Hernandez، نويسنده , , M.T. Fernandez-D?az، نويسنده , , J.C. Pedregosa، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2009
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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 :
Paramagnetic rare earth cations , Barium perovskite , Neutron powder diffraction , X-ray powder diffraction , Joint Rietveld refinement , B-site disordering
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