Etch pits produced by selective etchants such as 1 M HCl, 1 M HNO₃, 4 M BaCl₂, 4 M NH₄Cl and 4 M NH₄Cl-1 M HCl solutions on the as-grown {110} faces of barium oxalate dihydrate crystals are illustrated and explained. The kinetics of etching is studied. From Arrhenius plots, the activation energy of etching and the pre-exponential factor are computed. An empirical equation governing the kinetics has been suggested.

The kinetics and thermodynamics of the thermal dehydration of crystalline powders of BaC₂O₄·2H₂O, CdC₂O₄·3H₂O and Ba_1−xCd_xC₂O₄·2·5H₂O have been studied by means of thermogravimetry, as a function of temperature. The dynamic dehydration kinetics are also examined using DTA, recorded simultaneously with TG as a function of temperature. The validity of the estimated mechanism and kinetic parameters is briefly discussed. From DTA study it is concluded that all dehydration peaks are endothermic and the decomposition peaks of barium oxalate to barium carbonate, cadmium oxalate to cadmium oxide and barium cadmium oxalate to barium carbonate and cadmium oxide are exothermic.

Characterization of the gel-grown barium hydrogen phosphate (BHP) crystals was performed by utilizing the techniques of chemical analysis, X-ray diffraction, infrared and thermal behaviour. The results show that BHP crystals had chemical composition BaHPO₄ at room temperature. TG and DTA studies revealed the BHP crystals to be anhydrous at room temperature and decomposed at temperatures above 370°C and the decomposition was an endothermic process. Magnetic susceptibility measurements indicate the material to be diamagnetic.

We report here on the optical and structural characteristics carried out on strontium doped calcium tartrate tetrahedral single crystalline materials obtained by diffusing calcium and strontium ions through silica gel impregnated with optically active tartaric acid. Linear optical properties of this material such as refractive index, birefringence and transmission characteristics were measured in the wavelength range 200 nm <λ<1500 nm. No dispersion of the birefringence was observed within the experimental accuracy. The packing of tartrate molecules remained unaltered with 12% of the strontium doping.