Features of the Structure and Thermal Properties of LnBWO6 (La = Ln, La0.999Nd0.001, La0.99Gd0.01) Synthesized by the Sol-Gel Method

Borate tungstates LnBWO6 (Ln = La, La0.999Nd0.001, La0.99Gd0.01) were synthesized by the Pechini method with subsequent annealing of intermediates. They were analyzed by X-ray diffraction (XRD) and DSC methods. Crystallographic parameters of synthesized LnBWO6 were refined by powder X-ray diffraction in two systems: monoclinic, space group P21, and orthorhombic, space group P222. The presence of reversible first-order phase transitions in synthesized LnBWO6 was detected using the DSC method, and the temperatures and enthalpies of phase transformations were determined. It has been shown that Nd3+ and Gd3+ dopants lowers the L- → H- phase transition temperature of LaBWO6. According to experimental electron paramagnetic resonance (EPR) data gadolinium has two independent positions in the La0.99Gd0.01BWO6 structure.