Single crystals of sodium bromate are grown at various supersaturations ranging from 3% to 8%. Surface studies have been carried out on as-grown and etched (111) faces of these crystals. Typical and systematically oriented growth hillocks are observed almost on all the faces. Further dislocation studies are made to understand the growth history of these crystals. These studies suggest that the crystals grow by 2D-growth mechanism. In addition to this, studies are also conducted on the formation of overgrowths and inclusions in these crystals.

A study of growth rates of NaClO 3 and NaBrO 3 has been carried out using a small growth cell by in situ observation. Normal growth rates of {100} faces of NaClO 3 and {111} faces of NaBrO 3 along 〈 〈110〉 〉 direction are measured under relatively high supersaturation ranging from 3-8%. In the initial stages of growth, {100}, {110} and {111} faces develop in NaClO 3 and gradually all the faces are replaced by the {100} faces only. In the case of NaBrO 3 , mostly {111} faces develop with occasional occurrence of small {100} faces at the intersection of {111} faces. The growth mechanisms are investigated from growth rate vs supersaturation plots and from the observations of surface features. In the present supersaturation range, the growth mechanism appears to be due to two-dimensional growth mechanism.

Single crystals of NaClO 3 and NaBrO 3 are grown from their aqueous solutions at a constant temperature of 35°C by slow evaporation by using good quality seed crystals. Systematic microhardness studies are made on as-grown faces of these crystals at various loads. Typical cracks are observed at the corners of the impressions in NaClO 3 whereas in addition to the cracks at the corners microcracks also appeared in NaBrO 3 crystals around the impressions. The impressions formed in NaBrO 3 are not very clear as in NaClO 3 , a possible mechanism for it is discussed. The work hardening index number (n) for both these crystals is around 1⋅ ⋅6 suggesting that these are moderately harder samples. The hardness studies point out that NaBrO 3 is harder than NaClO 3 (∆ ∆H ≈ ≈ 100 kg/mm 2), this could be due to strong inter ionic forces acting between Na-Br in NaBrO 3 crystals. Using Gilman's empirical relation, hardness values are calculated from the values of elastic constants (C 44) and are found to be close to the experimental results.

To study the growth mechanism of { 111 } faces of NaBrO a, crystals were grown at different supersaturations ranging from 2% to 8%. The growth mechanisms were investigated based on the growth rate versus supersaturation relation and from the surface features observed on { 111 } faces. The growth mechanism of these crystals appear to be due to 2D nucleation. The growth rate curve has been further investigated using Ohara and Reid equations. Polynucleation model in two-dimensional nucleation growth theory is suggested as the most possible growth mechanism for these crystals in the present supersaturation range.

Single crystals of sodium chlorate were grown in the presence of selective impurities. The morphology of these crystals changed completely from cubic to tetrahedral form. Experiments were performed in the presence of different concentrations of impurities to ascertain their role in modifying the habit of these crystals. The presence of impurity in the solution was found to affect the habit of the crystals, although it does not appear to enter into the lattice.