A facile route for synthesis of highly pure α-CaB4O7 compound

Abstract

In this study, a facile route was developed for the synthesis of α-CaB4O7 compound. Ammonium tetraborate tetrahydrate (ATB) was used as the source of Boron. The compound was obtained using high-temperature solid-state reaction technique (840 °C) and heat treatment process was introduced to enhance the phase purity and crystallinity. To control the formation of calcium tetraborate single phase, an excess amount of B2O3 (2 wt%) was added to the starting powder mixture. Various analytical methods such as x-ray diffraction (XRD), Raman and Fourier transform infrared (FTIR) spectroscopies, Field emission scanning electron microscopy (FE-SEM), and x-ray photoelectron spectroscopy (XPS) were employed to characterize the prepared sample. Phase purity and crystallinity were evaluated by x-ray diffraction analytic method. Raman and FTIR spectroscopies were performed to confirm the atomic bond formation and its borate anionic group. FE-SEM was carried out for the morphological study of α-CaB4O7 compound and Energy dispersive x-ray (EDX) analysis was used to investigate the elemental composition of the prepared sample. XRD analysis confirmed that the prepared sample has alpha phase structure with monoclinic symmetry. The peaks correspond to unwanted phases (CaB2O4, Ca2B6O11) were not observed in the x-ray diffraction pattern of the prepared CaB4O7 compound. XPS was performed and its spectrum showed all expected characterization peaks for the first time, which is in agreement with FE-SEM and EDX results.