Rapid hydrothermal synthesis of SrMo1-xWxO4 powders: Structure and luminescence characterization

Strontium molybdate, strontium tungstate particles and their solid solutions (SrMo1-xWxO4) with 0 <= x <= 1.0, were synthesised by means of a hydrothermal process. Crystallisation of SrMo1-xWO4 particles took place rapidly using SrSO4 as the Sr precursor under hydrothermal conditions involving stirring (130 rpm) at 150 or 200 degrees C for 2 h. Structural analyses of the powders were conducted by XRD with Rietveld refinement and FT-Raman spectroscopy, and the particle shape was observed by FE-SEM. Lattice parameter measurements indicated a linear dependence of both "a(o)" and "c(o)" in the scheelite structured SrMo1-xWxO4 with a changing W content following Vegard's law. These analyses also provided evidence of the structural variation localised in the tetrahedral site as a result of the simultaneous incorporation of MoO4 and WO4 in the solid solutions formed in the compositional range of 9 <= x <= 60 mol%. The SrMo1-xWxO4 particles exhibited a predominantly euhedral shuttle-shaped morphology and particle sizes varying between 0.75 and 1.5 mu m. The particle growth was affected by increasing the reaction temperature and the tungsten concentration. Photoluminescence analysis (PL) revealed a marked attenuation of the blue and green emissions preferentially for the powder containing 48.5 mol% of W, which makes it potentially useful for optoelectronic applications. (C) 2016 The Society of Powder Technology Japan.