New Series of Pentanary Oxides, AM2C6Te3O18 (A = Pb, Sr; M = Mn, Cd; C = Ni, Co): Synthesis, Structure, and Magnetic and Optical Properties

Mixed-metal oxides, AM2C6Te3O18 (A = Pb, Sr; M = Mn, Cd; C = Ni, Co), have been synthesized employing traditional solid-state methods. The prepared compounds were characterized by powder X-ray diffraction (PXRD) and the structures refined by Rietveld analysis. The optical absorption studies of the compounds were carried out employing UV–vis spectroscopy and the observed transitions were assigned to the octahedral transition metal ions. Magnetic studies were carried out on PbCd2Co6Te3O18, SrCd2Co6Te3O18, and SrCd2Ni6Te3O18, which indicated that the compounds order antiferromagnetically around 10 K. Computational approaches were employed to fit the observed magnetic behavior.