Mössbauer study of Er3+ in ErH3 and YH3

The Mössbauer spectra of ¹⁶⁶Er in ErH₃ and YH₃ have been measured. Using and axial Hamiltonian, the electronic gyromagnetic rations for the ground state of Er³⁺ in YH₃ have been deduced: g| = 11.6 ± 0.1 and g⊥ = 4.4 ± 0.1. The analysis yields crystal field parameters which provide the correct λ₇ ground state with these g-values.