Abstract
The quadrupole frequency e2qQ/h for 175Hf in a Lu single crystal has been determined by nuclear orientation at temperatures down to 4 mK as +307-90+50 MHz. With the known groundstate quadrupole moment of Q=+2.7(4) barn for 175Hf the electric field gradient of HfLu is deduced to be eq=+(4.7-1.5+1.0)*1017 V cm-2. The magnitude and the sign fit well into the frame of a recently proposed correlation of electric field gradients in hexagonal transition metals.