C. F. Desai

Vickers Hardness Anisotropy and Slip System in Zinc (Tris) Thiourea Sulphate Crystals

The Vickers hardness indentations on the two major habit planes (100) and (001) of the solution grown ZTS crystal have been carried out at various azimuthal orientations of the indentor, keeping other variables constant. The observed anisotropic variations have been explained on the basis of effective resolved shear stress on the active slip system in the crystal. The detailed results are reported in the paper.

Temperature dependence of vickers microhardness and creep of InBi single crystals

Variation of Vickers microhardness of InBi single crystals with temperature has been studied. Loading time dependence of the microhardness at different temperatures has been used for the creep study in the temperature range 30° – 85°C. The activation energy for creep has been evaluated and the results are discussed.

Creep activation energy of flow process in Bi2Te2·8Se0·2 single crystals

Temperature dependence of the Vickers microhardness of Bi2Te2·8Se0·2 single crystals has been studied. Loading time dependence of microhardness at different temperatures has been used for creep study in the temperature range 303 K-373 K. The activation energy for indentation creep of the crystals has been evaluated.

Optical bandgap of Sb0.2Bi1.8Te3 thin films

Sb0.2Bi1.8Te3 Thin Films were grown using the thermal evaporation technique on a (001) face of NaCl crystal as a substrate at room temperature. The optical absorption was measured in the wave number range 500 cm−1 to 4000 cm−1. From the optical absorption data the bandgap has been evaluated and studied as a function of the film thickness and deposition temperature. The data indicate absorption through direct interband transition with a bandgap around 0.21 eV. The detailed results are reported.

Growth and Dislocation Etching of InBi0.8Sb0.2 Single Crystal

InBi 0.8 Sb 0.2 single crystals have been grown by zone melting method. The freezing interface temperature gradient of 30°C/cm has been found to yield the best quality crystals obtainable at growth velocity 1.0 cm/hr. Triangular features have been obtained on the free surface of the as grown crystal. A new dislocation etchant based on nitric acid has been found to give reproducible etch-pitting on the cleavage surface. Standard tests for a dislocation etchant have been carried out and results are reported.

Deformation study of anhydrous diglycine sulphate crystal

The nature of deformation of anhydrous diglycine-sulphate has been studied. Static and dynamic indentations were employed to deform the crystal. The slip and fracture modes of deformation occurring in the crystal have been identified.

Microhardness studies on triglycine sulphate and diglycine sulphate single crystals

Abstract The (010) cleavage planes of triglycine sulphate (TGS) and anhydrous diglycine sulphate (DGS) crystals were indented using a diamond pyramidal indenter. The variation in the microhardness with load is reported, and the features accompanying the indentation marks on these crystals are discussed. The hardness of TGS is 215 kgf mm −2 while that of DGS is 78 kgf mm −2 .

Etching characteristics of screw and edge dislocations on the cleavage plane of BiSb single crystals

Abstract The chemical etchant used in the present study is capable of revealing screw and edge dislocations which both intersect and lie in the cleavage plane of BiSb single crystals. It was shown that the etch pattern produced by the motion of dislocations allows edge and screw dislocations to be distinguished between.

Dislocation etching of KClO4 single crystals

Abstract Chemical reagents for revealing dislocations which intersect the cleavage surface of KClO 4 single crystals were developed using various dispersing media with H 2 SO 4 . The etching characteristics of the etchants are discussed. In addition, the apparent activation energies involved in the etching process were determined, and the results are reported in this paper.