Spectroscopic properties of HoFe3(BO3)4, NdFe3(BO3)4 and Ho0.75Nd0.25Fe3(BO3)4 single crystals

Polarized absorption spectra of ferroborates HoFe3(BO3)4, NdFe3(BO3)4 and Ho0.75Nd0.25Fe3(BO3)4 were measured at room temperature in spectral range 4000-24500 cm−1 (400-2500 nm). The studied single crystals were grown from solution-melts. Intensities of the f-f transitions were measured and the Judd-Ofelt parameters Ωλ of Ho3+ and Nd3+ ions in the studied crystals were calculated. It was revealed that the crystals content not strongly influences the Judd-Ofelt parameters. The Ω2 parameter for Ho3+ ion is the most sensitive to the crystal content. Linear dichroism of the hypersensitive transitions appeared to be the largest one for both rare earth ions.