Barium Nitrate Single Crystals Growth by Aqueous Solution Method

The growing conditions of barium nitrate $Ba(NO_3)_2$ single crystals using the aqueous solution method have been studied. Supersaturation can be calculated by measuring the temperature of the solution and its equilibrium temperature. Supersaturation of $Ba(NO_3)_2$ was 0.7% at $32.0^{\circ}C$ and about 3% at $34.0^{\circ}C$. The obtained single crystals have three kind of morphology: tetrahedral, cubic, and, rarely, dodecahedral. The normal growth rate is proportional to the supersaturation; it is necessary to make the solution below 5% supersaturation in order to obtain transparent $Ba(NO_3)_2$ single crystals. The normal growth rate for {1$\bar{1}$1} faces was $2.51{\times}10^{-6}$ mm/s for the 0.7% supersaturation condition ($32.0^{\circ}C$), $6.43{\times}10^{-6}$ mm/s for the the condition of 3.0% supersaturation, and $7.01{\times}10^{-6}$ mm/s for the condition of 5.0% supersaturation. The quality of the grown crystals depends on the nature of the seed, the cooling rate employed, and the agitation of the solution. The faces of the obtained crystals have been identified uising an X-ray diffractometer. The surface diffusion is responsible for the low growth rates of the {1$\bar{1}$1} faces.