Effects of mechanical pressure on potassium tantalate UHF dielectric resonators

A study has been made of the effects of uniaxial mechanical pressure on the dielectric constant and dielectric loss of $KTaO_3$ crystals at 4.2 К over the range 0.5-1.28 GHz. As the pressure increases, the resonant frequency of the $H_{01\delta}$ mode in a cylindrical resonator decreases monotonically. There is a considerable increase in the dielectric loss in $KTaO_3$ when an inhomogeneous pressure is applied. This agrees with the view that charged line defects (dislocations) multiply in $KTaO_3$ crystals under pressure.