NMR study of the relaxation mechanisms in single crystals of the nonlinear optical material bismuth triborate

Abstract

The (11)B NMR spectrum and relaxation processes in BiB(3)O(6) crystals were investigated by determining the spin- lattice relaxation rates, 1/T(1), of (11)B NMR. The (11)B spectrum obtained at room temperature indicates the presence of two types of chemically inequivalent (11)B nuclei, designated B(1) and B(2). The relaxation rates of the (11)B nuclei in the crystals were found to increase with increasing temperature, and could be described by the relation 1/T(1)/ alpha 1 - beta T(2). The dominant relaxation mechanism for nuclei possessing electric quadrupole moments is provided by the coupling of these moments to the thermal fluctuations of the local electric field gradients via Raman spinphonon process. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim