Electrical resistivity of zirconium hydrides and deuterides at high temperatures

Electrical resistivity rho of zirconium hydrides ZrH sub x and deuterides ZrD sub x has been measured over the range of hydrogen concentration 0 < = x < 0.9 (x: H/Zr or D/Zr) and temperature 700K < = T < = 1100K. It has been found that rho increases linearly with x in the alpha phase and exhibits a parabolic change in the beta phase, shows almost no difference for H and D in the range 0 < = x < 0.9 and deviates from Matthiessen's rule in the alpha phase. To help discuss the findings, we have made energy band calculations of ZrH sub x and computed quantities that are closely related to rho . The observed change in rho with x can be explained by assuming that H atoms form independent electron scatterers in the alpha phase and H atom vacancies additionally form electron scatterers in the beta phase. The lack of difference observed in rho for H and D can be explained by the fact that electron-optical phonon coupling constant obtained from the energy band calculations is much smaller than the electron-acoustic phonon coupling constant. It is difficult to give a reasonable explanation of the deviation from Matthiessen's rule only by the energy band calculation result.