Low-temperature X-ray studies of crystal-lattice parameters and thermal expansion of KTiOPO4 crystals

The unit-cell parameters a, b, and c of KTiOPO₄ crystals have been measured by the X-ray diffraction method in the temperature range 80–320 K. The parameters obtained were used to determine the thermal expansion coefficients α_100], α_010], and α_001] along the principal crystallographic axes. It was established that thermal expansion in the crystals is essentially anisotropic and that α_010] > α _100], whereas α_001] is close to zero.