Spectroscopic properties of Nd0.5Gd0.5Fe3(BO3)4 single crystal

The polarized absorption spectra of trigonal single crystal Nd0.5Gd0.5Fe3(BO3)4 were measured in the spectral range 10,000–22,000 cm−1. The d–d and f–f transitions spectra were separated. The f–f transitions intensities were analyzed in terms of the Judd–Ofelt theory in a ferroborate with huntite structure for the first time, and the following parameters of the theory were obtained: Ω2 = 4.4 × 10−20 cm2, Ω4 = 8.04 × 10−20 cm2, and Ω6 = 8.25 × 10−20 cm2. The strengths, spontaneous emission probabilities, branching ratios, spectroscopic quality factor and excited state lifetime were calculated for transitions from the 4F3/2 state to 4IJ manifold. All the obtained spectroscopic characteristics were compared with those of alumoborates with the same crystal structure.

► d–d and f–f transitions spectra of Nd0.5Gd0.5Fe3(BO3)4 were obtained separately.
► Judd–Ofelt parameters of f–f transitions were found in a ferroborate for the first time.
► Spectroscopic characteristics of the laser transitions were obtained.
► Spectroscopic quality of the ferroborate is better than of isostructural alumoborate.
► Doubly-forbidden d–d transitions and f–f transitions have similar intensities.