Understanding the solid-state calcium metavanadate synthesis pathway

Abstract

The calcium metavanadate (CaV2O6) synthesis was studied by a conventional solid-state reaction in a CaCO3 - V2O5 mixture (1:1) molecular ratio in air. The synthesis began at 400 ºC and at temperatures above 620 ºC speeds up due to formation of an eutectic compound. After one hour at 650 ºC complete synthesis of the metavanadate is achieved. The crystal phase and the particle morphologies of the CaV2O6 were analyzed by Powder X-ray Diffraction (PXRD), Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM). A single phase and rounded particles with smooth faces were found. The combination of several experiments allowed the determination of the synthesis pathway, which occurred from CaCO3 and not from CaO. If the starting calcium compound is the oxide, the first step could be carbonation process with the atmospheric CO2.