Electron spin resonance of Gd(III) in single crystals of La2Mg3(NO3)12.24H2O and La2Zn3(NO3)12.24H2O at room temperature, 77 deg K, and 4.2 deg K

From the angular variation of X-band ESR spectra of Gd(III) in single crystals of La2Mg3.(NO3)12.24H2O(LMN) and La2Zn3(NO3)12.24H2O(LZN) were measured at room temperature, 770K, and 4.20K, the spin Hamiltonian parameters were calculated. The spectra of Gd(III) in LMN and LZN showed similar angular variations at the measured temperatures. The zero-field splittings (or the largest spin Hamiltonian parameter, b20) of Gd (III) increased with decreasing temperature. The values of b20 were larger in LZN than those in LMN. It was found that the variation of the values of b20 with temperature was similar to that of temperature dependence of the lengths of the crystal axes c and a of the double-nitrates. These facts indicate that in the double-nitrate crystals a linear relationship exists approximately between the lengths of the crystal axes and the zero-field splittings associated with the intensities of the crystal field on Gd(III) at each temperature. (auth.)