Metastable scheelite EuVO 4 was stabilized by a high temperature and pressure method, which was transformed into a stable zircon phase by annealing treatment in air. Scheelite EuVO 4 gave strong emissions with a dominant peak at 617 nm associated with the 5 D 0 -7 F 2 transition of Eu 3ϩ . 151 Eu Mössbauer spectra indicated that the isomer shift for the metastable scheelite phase was ca. 0.5 mm/s lower than that for the zircon phase, which was ascribed to a reduced covalency in the Eu-O bond originated via a charge transfer from oxygen to Eu 3ϩ in scheelite lattice by producing an enhanced shielding of 4f electrons on the s orbital as well as a decrease in s electron density around Eu 3ϩ nucleus. Impedance spectra for the zircon phase clearly demonstrated an ionic hopping in the bulk with a conductivity of ca. 1.0 ϫ 10 Ϫ3 S cm Ϫ1 at 500°C. EuVO 4 is proved to be both a potential phosphor and a potential ionic conductor.Oxide materials usually exhibit several novel physical phenomena under high pressures including pressure-induced ferroelectric transformations, amorphorization, and electronic transitions. 1-3 Zircon ZrSiO 4 exists in the earth's crust, a common accessory mineral of igneous rocks and sediments. It has excellent physical properties such as low thermal conductivity and high melting points, and shows great potential in industrial applications. It is found that zircon ZrSiO 4 transforms into a scheelite structure, a common feature for other zircon oxides at high pressures. 4 To well understand these pressure-induced behaviors, one has to introduce some probe ions at the framework sites to follow the microstructural variations. REVO 4 ͑RE rare earth ions, V vanadium͒ shows a similar crystallographic habit to ZrSiO 4 at high pressures with RE being framework ions. Recently, research 5-7 was carried out focusing on the phase behaviors and physical properties of REVO 4 at high pressures on the basis of considerations that ͑i͒ REVO 4 could become a promising host material for phosphors when some rare earth ions ͑such as Eu 3ϩ and Tb 3ϩ ͒ were doped at RE sites. On the other hand, these dopants can also be taken as the efficient probes for identification of local structures and electronic transitions after excitation of the host and subsequent energy transfer to the dopants, and (ii) such studies could provide insight on the nature of phase transitions in these kinds of minerals, and furthermore, on finding new materials of different physical properties. However, there exist some controversies about both microstructural and physical properties for such materials.With regard to the microstructures, zircon and scheelite phases are recognized to show some structural similarities. The former one has a space group of I4 1 /a at room temperature. Each unit cell contains four molecules, in which four equivalent rare earth ions are of D 2d site symmetry. 8 At high pressures, zircon REVO 4 transforms reversibly into a tetragonal scheelite phase that is ca. 10% more dense than zircon. 9 In a scheelite lattice, rare ea...