Characterization and physical properties of hydrated zinc borates synthesized from sodium borates

Abstract

In this study, Zn3B6O12·3.5H2O, a type of a zinc borate hydrate, was synthesized from the sodium borate mineral Na2B4O7·5H2O. Two different zinc sources, i.e. ZnSO4·7H2O and ZnCl2, were used in the hydrothermal synthesis. Products were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy. Product morphologies were studied using scanning electron microscopy (SEM). Then optical absorption characteristics and electrical properties were investigated. Based on these results, Zn3B6O12·3.5H2O was obtained under many synthetic conditions as a single phase with high reaction efficiencies and sub-micrometer (100 nm to 1 μm) particle sizes. The electrical resistivity and optical energy gap were found as 8.8×1010 Ω cm and 4.13 eV, respectively. The novelty obtained in this study is the synthesis of zinc borate hydrate compound with high crystallinity without using any modification agent or organic solvent.