Ag2WO4 polymorphs: selective synthesis and characterization

Controlling the synthesis of metastable polymorphs of an inorganic material is a further step in the design of novel properties and unexplored applications. In contrast to their thermodynamically more stable counterparts, metastable phases have been elusive due to their propensity to convert to the stable phase. In this work, we report a simple procedure to effectively control for the synthesis of the crystalline polymorphs of Ag2WO4. The different polymorphs; the stable α- and metastable ?- and ?-Ag2WO4; were prepared via controlled precipitation under ambient conditions over mixture of the precursor salts (AgNO3 and Na2WO4) at adequately select values of concentration and salts stoichiometric ratio. These crystals were structurally characterized by X-ray diffraction (XRD). The shapes and sizes were observed by field emission scanning electron microscopy (FE-SEM). Their optical properties were analyzed by Photoluminescence emission (PL). Finally, the possible mechanism of nucleation and stabilization of the phases is discussed based on driven of the short-range structural and electronic changes of their diverse constitutive clusters [WOx] and [AgOy] (x = 4-6 and y=2, 4-7). This process and the concentration and stoichiometry dependence of the polymorphms is displayed in figure 1. The availability of a facile method to prepare different Ag2WO4 polymorphous is expected to catalyze further empirical studies on the elusive and little-studied metastable phase.