A simple aqueous mineralization process to synthesize tetragonal molybdate microcrystallites

Large-scale tetragonal MMoO₄ (M = Ca, Sr) microcrystallites with delicate morphologies, such as ellipsoidal rods, peanuts, notched peaches, dumbbells, and spherules, have been successfully prepared via a very simple, alkalescent aqueous mineralization method, in the absence of any surfactant or template. The products were characterized by X-ray powder diffraction, field-emission scanning electron microscopy, Raman spectroscopy, and PL spectroscopy. Results indicate that both CaMoO₄ and SrMoO₄ samples have a general nucleation and growth process based on their unusual crystallographic nature. In the growth process of CaMoO₄ and SrMoO₄ microcrystallites, a distinct morphology transformation course can be observed from the ellipsoidal rods to peanuts, dumbbells, peaches, and grown spherules in alkalescent aqueous solution. In this alkalescent reaction system, the pH value of the solution does not have a crucial influence on the synthesis and shape evolution of the products. Our experimental results present a simple route for the formation of large-scale inorganic materials with particular morphologies under mild conditions, and it may be extended to the synthesis of other important inorganic materials with special morphologies.