Structural and magnetic properties of Ba3La3Mn2W3O18

A quaternary phase, Ba3La3Mn2W3O18, was synthesized in reduced atmosphere (5% H2/Ar) at 1200 °C and characterized by using powder X-ray diffraction, electron diffraction and high resolution TEM. Ba3La3Mn2W3O18 crystallizes in rhombohedral space group image with the cell parameters, image and image, and can be attributed to the image member in the B-site deficient perovskite family, AnBn−1O3n. The structure can be described as close-packed [La/BaO3] arrays in the sequence of image, wherein the B-site cations, W and Mn, occupy five octahedral layers in every six octahedral layers, which leave a vacant octahedral layers separating the 5-layer perovskite blocks. The B-cation layers in the perovskite block alternate along the c-axis in a sequence of W6+–Mn2+–W5+–Mn2+–W6+. The bond valence calculation and optical reflection spectrum confirm the presence of W5+. This compound behaves paramagnetically in wide temperature range and weak antiferromagnetic interaction only occurs at low temperatures.