TEMPERATURE-DEPENDENCE OF THE V-51 NMR-SPECTRUM IN A FERROELASTIC BIVO4 SINGLE-CRYSTAL

The angular dependences of the nuclear magnetic resonance (NMR) spectr um of V-51 in a BiVO4 single crystal on the major crystallographic pla nes were measured at room temperature using an FT NMR spectrometer ope rating at omega0/2pi = 52.608 MHz. The obtained quadrupole coupling co nstant (e2qQ/h = 4.93 +/- 0.03 MHz) and the asymmetry parameter (eta = 0.36 +/- 0.01) are slightly different from those obtained with a cw N MR investigation at room temperature. The temperature dependence of th e V-51 NMR is also studied as an extension of the previous study for t he temperature range of 130 K approximately 400 K e2qQ/h is found to b e decreasing with increasing temperature, and may be roughly explained by Bayer's theory with a single torsional frequency of the (VO4)3- an ion in BiVO4.