Li Doping Effect on Properties and Phase Transfomations of Knbo3

TL;DR

This study investigates how lithium doping affects the dielectric, infrared, and phase transition properties of KNbO3 crystals, revealing relaxations similar to KTaO3 and shifts in phase transition temperatures.

Contribution

First comprehensive analysis of Li doping effects on KNbO3's dielectric and phase transition behaviors, including infrared spectra and phase transition shifts.

Findings

Li doping introduces dielectric relaxation similar to KTaO3.

Li admixture causes phase transition temperature shifts.

Tetragonal-orthorhombic-rhombohedral transitions are affected by Li content.

Abstract

Dielectric permittivity and infrared reflectivity spectra of Li doped KNbO3 single crystals have been studied for the first time for K1-xLixNbO3 (KLN) with x = 0.015, 0.02, 0.065. It was found that like in KTaO3, Li admixture results in appearance of dielectric relaxation with the relaxation parameters very close to those in KTaO3 quantum paraelectric. It was attributed to 90-grad dipole reorientation of Li+ <100> off centers substituted K+, which appear to be presents as in paraelectric cubic phase as in ferroelectric phase down to low temperatures. Besides, Li doping is accompanied by increasing of the cubic-tetragonal phase transition point, decreasing of tetragonal-orthorhombic-rhombohedral phase transition points and TO soft mode stiffen at room temperature.