Dielectric and thermal expansion properties of LHPG grown potassium lithium niobate single crystals

Abstract

Compositions of potassium lithium niobate K₆Li_4+xNb₁₀O₃₀ (x for excess mole % of Li₂O) with tetragonal tungsten bronze structure were prepared as crystal fibers by the Laser Heated Pedestal Growth technique. The lattice constants of KLN were measured by using X-ray diffraction and typical values for a = 12.5703 ± 0.0018 and c = 3.9485 ± 0.0012 were measured. This paper reports the dielectric permittivity measurements on single crystal along the a- and c- axis in the temperature range of 90–450K and frequency range of 10²−10⁵ Hz. The dielectric permittivity at room temperature along a- and c- axis was 430 and 330 respectively. Mechanism for the low temperature dielectric relaxation will be discussed. Thermal expansion behavier in the a- and the c-direction will also be reported.