Journal of the American Ceramic Society, Vol.99, No.10, 3443-3448, 2016
Insight into the Growth Reaction Mechanism of Ceramic Co3TeO6: Synchrotron Structural and Thermal Analysis
A two-step solid-state reaction is proposed to synthesize monophasic cobalt tellurate Co3TeO6 (CTO), a type II multiferroic, using Co3O4 and TeO2 as the starting reagents. First step of the reaction results in the secondary monoclinic (P2(1)/c) CoTeO4 compound, which on further calcination (second step) leads to the primary monoclinic (C2/c) Co3TeO6 phase. High-resolution synchrotron X-ray diffraction and the subsequent Rietveld analysis are used to probe different phases present in the synthesized CTO and to achieve its single phase. X-ray absorption near-edge structure studies at Co K and Te L edges reveal mixed oxidation states (Co2+/3+) of Co and hexavalent Te, respectively. Charge imbalance due to mixed valence Co ions has been attributed to cations vacancies. Enhanced multiferroic properties, such as effective magnetic moment, spin phonon coupling, etc., have been attributed to the aforementioned observations in grown ceramic CTO via proposed synthesis route.
Keywords:multiferroics;X-ray methods;thermal properties;magnetic materials/properties;tellurium/tellurium compounds