Effect of the crystal surface geometry on the secondary pyroelectric effect in lithium biobate and tantalate crystals

Consideration is being given to the secondary pyroelectric effect in the crystal of lithium (tantalate) niobate possessing configuration of parallelepiped of rectangular cross-section and subjected to heating from lateral surface. The direction of parallelepiped ribs is chosen as matching with crystal physical X3 axis. It is shown that the value and the character of secondary pyroelectric effect of lithium niobate and tantalate crystals depend on crystal sizes, the rate of its temperature change, elastic and thermal anisotropy and largely on crystal geometry. Pyroelectric field is sufficiently non-uniform one and therefore can result in redistribution of space charges, effect on formation of internal residual charges, rotation of ellipsoid axes of optical indicatrix with respect to crystallographic directions, as well as on the fracture mode of crystals