Synthesis and vibrational properties of aluminum-scandium tungstate solid-solution

Homogeneous solid solutions Al2 - x Sc (x) (WO4)(3)belonging to the orthorhombic structure were synthesized from stoichiometric mixtures of Al2O3, Sc2O3, and WO(3)using solid-state reaction method. The powder X-ray diffraction patterns confirmed the formation of single phase solid-solution and a monotonic variation of the cell parameters over the complete range of composition x. The vibrational properties of the mixed crystals were investigated using Raman spectroscopy. The Raman spectra consisted of lattice modes and internal modes of the tungstate tetrahedra. The end members exhibited large number of sharp Raman peaks while the mixed crystals of intermediate composition contained lesser number of broad peaks suggesting a positional disorder. Most of the prominent modes were found to exhibit the one-mode behaviour.