Characterization of potassium lithium niobate (KLN) ceramic system

The room temperature stability region of the tetragonal tungsten bronze-type potassium lithium niobate (K3Li2Nb5O15, KLN) has been determined by X-ray phase analysis on ceramic samples synthesized by solid state reaction in the composition range of [K2O] = 28-33 mol%, [Li2O] 12.5-20.5 mol% and [Nb2O5] = 50.5-55.5 mol%. Lattice parameters and temperature dependence of the dielectric constants were measured on single phase samples. The axial a/c ratio of the cell parameters, the density and the Curie temperature of the ferroelectric samples have been found predominantly characteristic for the Nb2O5 content, varying progressively between 3.11-3.14, 4.431-4.596 g/cm3 and 492-460 deg. C, respectively. The results are discussed from the points of view of defect chemistry and phase stability. The concentration of intrinsic defects formed primarily by antisite Nb atoms at Li sites has been estimated on the basis of 'alkali cation vacancy formation model'