Iron-doped gallium borate crystals: Synthesis and ESR study of local disorder

High quality Fe x Ga 1-x BO 3 single crystals with 0 ≤ x ≤ 1 were synthesized and studied by electron magnetic resonance in the temperature range from 4 to 290 K. At low x, only the electron spin resonance (ESR) of diluted Fe 3+ ions is present. Fitting to the experimental ESR spectra, assuming distributions of Fe 3+ ligand coordinates, has shown the existence of local disorder in the crystals.