3D Residual Strain in DKDP Crystals by Neutron Diffraction

Neutron diffraction technique is applied to study the three-dimensional (3D) residual strains in K(H1-xDx)(2)PO4 (DKDP) crystals with various deuterium contents (0 <= x <= 0.99). It is found that the residual strains in the crystalline coordinate are at the magnitude of 10(-3) to 10(-4). The results show that the level of the macro-strain in the crystal bulk is independent of the deuteration level. However, when the deuteration level is below 50%, the average of micro-strain increases first with the increasing of deuteration level, then decreases when the deuteration level is in excess of 50%. According to the residual strains, the internal stresses are calculated through sigma(ij) = C-ijkl epsilon(kl). Finally, the potential sources of the stresses in crystals are discussed and analyzed.