Preparation and characterization of certain niobates - Part V: Dielectric and structural studies of potassium and rare-earth doped lead metaniobates

Lead metaniobates have orthorhombic symmetry and are piezoelectric in natur e. Potassium doped niobates were found to be good candidates for ultrasonic device applications. Potassium and rare-earth doped niobates were synthesi zed in this study with a general molecular formula PbI-2x REx Nb2O6 where R E = Gd, Sm, Nd and x = 0.05, 0.10, 0.15. A total of nine ceramics were prep ared using solid state reaction techniques and characterized by X-ray diffr action and scanning electron microscopic techniques. The density, grain dia meter, dielectric constant and loss factor were measured as a function of t emperature and lattice parameters were calculated. The lattice parameters a nd diffuseness increased and grain diameter decreased with increasing conce ntration of the dopant.