Vacuum ultraviolet spectra and crystal field analysis of YAlO₃ doped with Nd³⁺ and Er³⁺

The synchrotron radiation excited emission and excitation spectra are reported at temperatures of 298 and 10 K for YAlO₃ (YAP) doped with 1 at. % Nd³⁺ or Er³⁺. For both systems, no d-f emission is observed and these results are rationalized and compared with other hosts. For YAP:Nd³⁺, excitation into the 4f²5d electronic configuration of Nd³⁺ gives intraconfigurational luminescence from ²G(2)_9∕2 and ⁴F_3∕2 and there is no evidence for emission from other multiplet terms. Luminescence from ²P_3∕2 is observed for YAP:Er³⁺, with additional transitions from ⁴S_3∕2, ⁴F_9∕2, ⁴I_9∕2, and ⁴I_11∕2. The emission spectra have been assigned in detail. The literature energy level datasets are mostly consistent with the derived energy levels from the present study. The f-d excitation spectra show that the lowest d-electron levels are energetically situated below the intrinsic absorption of the host. Crystal field analyses have been performed by using 100 energy levels for each system and the resulting standard deviations were 12.4 and 15.5 cm⁻¹ for Er³⁺ and Nd³⁺, respectively. The multiplet term barycenters are better fitted for the case of Nd³⁺, whereas crystal field splittings are better modeled for Er³⁺. The fitted free ion parameters exhibit considerably less uncertainty for Nd³⁺.