Structural, electrical and luminescence properties of M2V2O7 (M = Mg, Ca, Sr, Ba, Zn)

Alkaline earth and zinc vanadate samples were prepared by solid state reaction method and their structural, electrical and light emission properties were studied. X-ray diffraction and Rietveld refinement studies confirm triclinic structures of Ca2V2O7, Sr2V2O7 and Ba2V2O7 and monoclinic structure of Zn2V2O7. The magnesium vanadate sample contain mixed phases of triclinic Mg2V2O7 and monoclinic MgV2O6. Raman spectra exhibit sharp peaks due to V–O vibrational modes. Electrical studies found that the samples are semi-insulating with maximum electrical conductivity of Ba2V2O7. Intense blue-green photoluminescence is observed in Ba2V2O7 and 1Sm2O3–99Ba2V2O7 samples due to the charge transfer transitions from O2− → V5+ in VO4 units with quantum yield values of 6.6% and 7.8%, respectively, at an excitation wavelength of 350 nm.