SUPERHYDROPHOBIC COPPER SURFACES BY SHOT PEENING AND CHEMICAL TREATMENT

In this paper, superhydrophobic surfaces are developed on polycrystalline copper using a combination of mechanical and chemical treatments by shot peening, dislocation etching and stearic acid treatment. The key point in this combined approach is the fabrication of a dislocation forest by shot peening. These sites were dissolved by etching, and hierarchical structures were fabricated. When these etched surfaces are treated by stearic acid, which has low surface energy, they become superhydrophobic with contact angle more than 150[Formula: see text]. Because of the superior properties and low costs involved with this method, it is expected to be widely used in the industry to fabricate superhydrophobic surfaces.

A Comparative Study of Dislocations in HVPE GaN Layers by High-Resolution X-Ray Diffraction and Selective Wet Etching

It has been shown during the present study that the E-etching at elevated temperatures can be adopted for the dislocation etching in hydride vapor-phase epitaxy (HVPE) GaN layers. It has been found that the X-ray diffraction (XRD) evaluation of the dislocation density in the thicker than 6 μm epilayers using conventional Williamson-Hall plots and Dunn-Koch equation is in an excellent agreement with the results of the elevated-temperature E-etching. The dislocation distribution measured for 2-inch GaN-on-sapphire substrate suggests strongly the influence of the inelastic thermal stresses on the formation of the final dislocation pattern in the epilayer.

GROWTH AND DISLOCATION ETCHING OF Sb0.2Bi1.8Te3 SINGLE CRYSTALS

Sb 0.2 Bi 1.8 Te 3 single crystals have been grown by the zone melting and Bridgman–Stockbarger methods. The freezing interface temperature gradients of 90°C/cm and 45°C/cm, respectively, have been found to yield the best quality crytals obtainable at the growth rate of 0.35 cm/h. The crystals have been characterized by the powder XRD technique. The crystals grown by the zone melting method have been observed to exhibit certain typical features on their top free surfaces. A new dislocation etchant has been developed to give reproducible etch-pitting on the cleavage surface. Tests of this dislocation etchant have been carried out successfully and the etchant has been used to obtain dislocation density in the crystals.

CRYSTAL GROWTH AND SURFACE ANISOTROPY IN MICROHARDNESS OF ZINC (TRIS) THIOUREA SULPHATE, AN NLO CRYSTAL

ZTS crystals have been grown by the solution method. The usual habit of the crystals has been identified and dislocation etching on the three major habit planes, (100), (010) and (001), has been carried out. The Vickers microhardness of these planes, its applied load dependence and anisotropy have been studied. (100) has been found to be the hardest of the three planes. The surface anisotropy of hardness of the respective planes has been explored and the hard and soft directions have been identified.