Reactivity at Line Defects in Antimony in Etchants with Dextro- and Levo Tartaric Acid

The (111) cleavage faces of antimony single crystals were etched in aqueous mixtures of fuming nitric acid plus dextro tartaric acid and fuming nitric acid plus levo tartaric acid. Triangular, crystallographically oriented etch pits were observed at sites of dislocations. The activation energies for lateral motion of ledges and the frequency factors were calculated for both types of etchants which were found to be higher in levo tartaric acid containing etchants than in dextro tartaric acid containing etchants. The results are explained in terms of antimony complexes and the difference in the shape of dextro tartaric acid and levo tartaric acid molecular structures.     

FTIR spectroscopic,thermal and growth morphological studies of calcium hydrogen phosphate dihydrate crystals

Calcium hydrogen phosphate dihydrate (CHPD or DCPD) is found quite frequently in urinary calculi (stones). The CHPD crystals were grown by the single diffusion gel growth technique in sodium metasilicate gel. The crystals were found to be having platelet and broad needle type morphologies. The crystals were analyzed by FTIR spectroscopy. The thermal properties were studied by employing the thermogravimetric analysis. Various kinetic and thermodynamic parameters for dehydration were estimated. The selected platelet was studied by SEM for the growth morphologies indicating that the crystals grew in the form of leaflets having prominent (010) faces. This was in agreement with earlier reported studies. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)