Raman signature of partial zircon to scheelite-type phase conversion in GdVO4 nanosystem due to structural disordering induced by Eu3+ inclusions

This work reports Raman analysis of zircon-to-scheelite partial phase conversion encountered in GdVO₄ nanosystem with Eu³⁺ around permissible substitutional doping. To be specific, among the Raman modes featured, the A_1g mode is attributed to O-V-O vibration while B_2 g represents the translatory vibrational mode (∼258 cm⁻¹) attributed to the Eu–O stretching. The intense high-frequency mode, ν₂ = 880 cm^–1 would describe stretching internal vibration in the tetrahedral [VO₄]^3- anionic group for an ideal zircon-type conformation with tetragonal symmetry. Importantly, at room temperature Raman studies of GdVO₄ nanosystem, the overlap of two Raman active modes namely, A_1g (scissoring) and B_2g (twisting) characterize scheelite-type characteristics in the nanosystem under study. Incorporation of Eu³⁺ in the system resulted in enhancing the intensity of the scheelite-type characteristics due to possible localized phase transition around Eu³⁺ sites in the matrix. The observed scheelite-type signal enhancement and consequently partial zircon lattice to scheelite lattice conversion due to inclusion of Eu³⁺ doping (1–7 %) has been highlighted and analyzed emphasizing manifested modes in detail.