EPR of the Kramers ions Er3+, Nd3+, Yb3+ and Ce3+ in Y(NO3)(3)center dot 6H(2)O and Y-2(SO4)(3)center dot 8H(2)O single crystals: Study of hyperfine transitions

摘要

X-band (similar to 9.45 GHz) electron paramagnetic resonance (EPR) spectra of the Kramers ions Er3+, Nd3+, Yb3+ and Ce3+ substituting by about similar to 1% Y3+ ions, in yttrium trinitate hexahydrate [Y(NO3)(3) . 6H(2)O] and yttrium trisulphate octahydrate [Y-2(SO4)(3). 8H(2)O] single crystals were recorded at liquid-helium temperatures. Hyperfine EPR transitions were observed for the isotopes of Er, Nd and Yb, except for the Ce3+ ion which possesses no isotope with non-zero nuclear moment. The spectra indicate the presence of two magnetically- inequivalent R3+ sites in unit cell in the Y-2(SO4)(3) . 8H(2)O crystal, and one site in Y(NO3)(3) . 6H(2)O crystal. The values of the elements of the (anisotropic) g(2) and A(2) tensors were estimated using a rigorous least-squares fitting procedure fitting simultaneously all resonant EPR line positions observed for numerous orientations of the external magnetic field in three mutually perpendicular planes. The absolute signs of the elements of A-matrix and orientations of g- and A-matrices relative to the magnetic axes of the Gd3+ ion, present naturally as impurity in these crystals, were determined. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 32]