Hydrothermal-induced growth of Ca10V6O25 crystals with various morphologies in a strong basic medium at different temperatures

The Ca10V6O25 crystals with various morphologies were synthesized by a facile hydrothermal method in a strong basic medium. The effects of the pH of synthesizing solution, hydrothermal reaction temperature and time on the morphology and crystallinity of Ca10V6O25 powders were investigated. The as-synthesized powders were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis spectrophotometer and vibrating sample magnetometer. The experimental results demonstrate that phase-pure Ca10V6O25 powders could be hydrothermally obtained at temperatures ranging from 120 degrees C to 180 degrees C for 12-48 h with the pH >= 12.5 of synthesizing solution. The morphology of Ca10V6O25 powders was strongly dependent on the synthesis parameters, such as pH, temperature and time. The Ca10V6O25 microspheres were obtained at 180 degrees C for 48 h with the pH = 12.5 of synthesizing solution. The UV-vis diffuse reflectance spectra have shown that the Ca10V6O25 powders efficiently absorb UV light with an absorption edge at about 380 nm. All the samples noticeably exhibit a superparamagnetic behavior with a nearly zero magnetic remanence (remanent magnetization). The hydrothermally synthesized Ca10V6O25 powders may be employed as a potential candidate in novel electronic and biomedical applications. (C) 2012 Elsevier Ltd. All rights reserved.