Solution Combustion Synthesis and Characterization of Magnesium Copper Vanadates

Magnesium vanadate (MgV2O6) andits alloyswith copper vanadate were synthesized via the solution combustiontechnique. Phase purity and solid solution formation were confirmedby a variety of experimental techniques, supported by electronic structuresimulations based on density functional theory (DFT). Powder X-raydiffraction combined with Rietveld refinement, laser Raman spectroscopy,diffuse reflectance spectroscopy, and high-resolution transmissionelectron microscopy showed single-phase alloy formation despite theMgV(2)O(6) and CuV2O6 endmembers exhibiting monoclinic and triclinic crystal systems, respectively.DFT-calculated optical band gaps showed close agreement in the computedoptical bandgaps with experimentally derived values. Surface photovoltagespectroscopy, ambient-pressure photoemission spectroscopy, and Kelvinprobe contact potential difference (work function) measurements confirmeda systematic variation in the optical bandgap modification and bandalignment as a function of stoichiometry in the alloy composition.These data indicated n-type semiconductor behavior for all the sampleswhich was confirmed by photoelectrochemical measurements. The sample colors reflect the ternaryoxide or alloy chemicalcomposition.