Synthesis and Characterization of New AA′BWO6 Perovskites Exhibiting Simultaneous Ordering of A-Site and B-Site Cations

• Published in: Chemistry of materials 2007-12, Vol.19 (26), p.6451-6458
• Main Authors: King, Graham, Thimmaiah, Srinivasa, Dwivedi, Akansha, Woodward, Patrick M
• Format: Article
• Language: eng ; jpn
• Subjects: Inorganic Solids and Ceramics; Magnetic Materials; Structural Characterization (including AFM, NMR, X-ray Diffraction, etc.)
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/cm0716708

Six new AA′BB′O6 perovskites KLaMnWO6, NaLaMnWO6, NaNdMnWO6, NaTbMnWO6, NaNdCoWO6, and NaNdMgWO6 have been prepared. Each possesses the unusual combination of layered ordering of the A-site cations and rock-salt ordering of the B-site cations. The structure and properties of these samples have been characterized using monochromatic X-ray and neutron powder diffraction, UV–vis diffuse reflectance spectroscopy, and SQUID magnetometry. NaLaMnWO6, NaNdMnWO6, and NaTbMnWO6 adopt a structure with monoclinic P21 symmetry arising from the combination of cation ordering and a–a–c+ octahedral tilting. The structures of the other three compounds are similar, but the presence of satellite reflections in the neutron diffraction data suggests a more complicated superstructure. Each of the four AA′MnWO6 samples shows a paramagnetic to antiferromagnetic transition with Néel temperatures ranging from 6 to 15 K. The NaTbMnWO6 compound shows a second magnetic transition at ∼9 K. The origin of two magnetic phase transitions appears to arise from coupling between the Mn2+ sublattice and the Tb3+ sublattice.