Temperature dependence of the electric field gradient at tantalum in group IIIb metals: scandium, yttrium, lutetium

The electric field gradient at ¹⁸¹Ta in hcp Sc, Y and Lu was determined in the temperature range between 4.2 and 450K by the time differential perturbed angular correlation technique. A uniform, axially symmetric, essentially undamped quadrupole interaction was found at all temperatures. The field gradients at room temperature have the values mod eq mod =5.1(2), 5.9(3), 5.0(2)*10¹⁷V cm^-2 for Sc, Y and Lu respectively. The temperature dependence of the field gradients at Ta in Lu can be explained fully by the lattice expansion. The results for TaSc and in particular for TaY indicate a thermal repopulation of conduction electron states.