Synthesis, characterization, and electrical and optical properties of magnesium-type boracite

Synthesis of the magnesium type of the mineral boracite (Mg$_{3}$B$_{7}$O$_{13}$Cl) was studied. Several parameters affecting boracite synthesis were investigated. The raw materials selected were magnesium chloride hexahydrate (MgCl$_{2}$.6H$_{2}$O), magnesium oxide (MgO), and boron oxide (B$_{2}$O$_{3})$. Reaction temperatures were selected between 600~$^{\circ}$C and 900 $^{\circ}$C. Moreover, three different reaction times of 4, 1, and 0.5 h were studied with the determined optimum molar ratio, reaction temperature, and reaction medium. Synthesized boracite characterization analyses were done by the techniques of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM). Reaction yields were also calculated. From the results of this study the magnesium type of boracite was obtained as a single phase with high XRD crystal score. Optimum conditions for the synthesis were as follows: MgCl$_{2}$.6H$_{2}$O to B$_{2}$O$_{3}$ mole ratios of 5:6.5, 5:7.5, 6:6.5, 6:7.5, 7:6.5, 7:7.5; 600 $^{\circ}$C reaction temperature; 1 h reaction time; and reaction medium as air atmosphere. Reaction yields were between 58.81 $\pm $ 1.65{\%} and 77.49 $\pm $ 1.86{\%}. Some selected magnesium type of boracite minerals, electrical resistivity, and optical absorbance properties were also measured for the determination of physical properties.