63,65 Cu NQR Spectra and Spin–Lattice Relaxation in Thermoelectric CuAlO 2

The 63,65 Cu nuclear quadrupole resonance spectra and spin–lattice relaxation rate (1/ T 1 ) have been measured in the semiconductor compound CuAlO 2 . The value of the nuclei quadrupole interaction constant Q CC = 56.24(6) MHz ( T = 298 K) has been obtained. The broad maximum has been found in the temperature dependence of 1/ T 1 in the low-temperature region (below 276 K). This maximum can be associated with the presence of energy levels in the forbidden band. The activation energy has been estimated in CuAlO 2 [ E A = 45(2) meV], assuming the activation character of the mobility of holes.