Electrical Conduction in Deuterated Ammonium Dihydrogen Phosphate Crystals with Different Degrees of Deuteration

Conductivity measurements of deuterated ammonium dihydrogen phosphate (DADP) crystals with different deuterated degrees are described. The conductivities increase with the deuterium content, and the value of the a-direction is larger than that of the c-direction. Compared with DKDP crystals, DADP crystals have larger conductivities, which is partly due to the existence of A defects. The ac conductivity over the temperature range 25–170°C has shown a knee in the curve of ln(σT) versus T^?1. The conductivity activation energy calculated by the slope of the high temperature region decreases with the deuterium content. The previously reported phase transition is not seen.