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NdF 3 layers were grown on Si (1 1 1) substrates at 400°C, 550°C and 700°C by molecular beam epitaxy. Their images scanned by atomic force microscope showed that the NdF 3 layers on Si (1 1 1) substrates grew as islands with spiral step patterns. As function of growth temperature, their interfacial characteristics such as orientational alignment, defects, and crystallinity were investigated by transmission electron microscope (TEM) combined with selected area electron diffractometer. In particular, the relationship between interfacial microstructure and crystalline quality of overall NdF 3 layers were explained by comparing the result of TEM observation with full-width at half-maximum values for X-ray rocking curves of both (1 1 2 0) in-plane and (0 0 0 2) out-of-plane diffractions of NdF 3 layers.

One of the least desirable calcifications in the human body is the mineral deposition in atherosclerosis plaques. These plaques principally consist of lipids such as cholesterol, cholesteryl esters, phospholipids and triglycerides. Chemical analysis of advanced plaques have shown the presence of considerable amounts of free cholesterol identified as cholesterol monohydrate crystals. Cholesterol has been crystallized in vitro. The extracts of some of the Indian medicinal plants detailed below were used as additives to study their effect on the crystallization behaviour of cholesterol. It has been found that many of the herbs have inhibitory effect on the crystallization such as nucleation, crystal size and habit modification. The inhibitory effect of the plants are graded as Commiphora mughul > Aegle marmeleos > Cynoden dactylon > Musa paradisiaca > Polygala javana > Alphinia officinarum > Solanum trilobatum > Enicostemma lyssopifolium.

Large bulk single crystals of the Sr2CuO2Cl2 compound with dimensions of 15 × 6 × 4 mm3 have been grown directly from the melt by the floating-zone method using a light-image furnace. The optimal growth conditions are found in a mixed atmosphere of 0.2 bar oxygen and 1.2 bar argon. Results of the characterisation have revealed the high quality of the as-grown crystals. Furthermore, a possible congruent route of formation from the melt as well as the chemical stability of this compound is discussed.

Bi-2212 superconducting single crystals were grown by the travelling solvent floating zone method at different oxygen ambient pressures. Electron probe micro-analysis showed a systematic increase of the Sr/Ca ration in the as-grown crystals with increasing oxygen ambient pressure and a maximal superconducting transition temperature of Tc-onset = 95 K, and ΔTc = 1.5 K was obtained for crystals grown at an oxygen ambient pressure of 200 kPa. Thermogravimetric and post-annealing experiments in air at 500 and 800°C have shown that the oxygen content and the Tc-onset values in the crystal do not depend only on the annealing temperature, but also on its chemical composition. The in-field current density Jc measured at 5 K on crystals grown at 200 kPa oxygen ambient pressure was considerably smaller than that of crystals grown in air.

We have investigated Sn doping of GaAs and AlGaAs grown by metal-organic molecular beam epitaxy (MOMBE) by growing layers in which the Sn flux, as generated by an elemental Sn source, is periodically raised or lowered by changing the source temperature. The maximum doping levels obtained were 8 x 1018 cm-3 at 500°C and 1 x 1019 cm-3 at 600°C. The activation energy for Sn incorporation was ∽ 3.22 eV for both GaAs and Al0.25Ga0.75As. Comparison of SIMS and Hall data shows that most of the Sn is electrically active. The shape of the profiles and the variation of Sn with oven temperature suggest that the Sn incorporation mechanism is the same as for material grown by molecular beam epitaxy (MBE). The presence of Sn surface accumulation and the absence of a growth rate dependence on Sn concentration indicate that the incorporation behavior is quite different than that of metalorganic chemical vapor deposition (MOCVD), in spite of the similar Group III sources employed.

A method for preparing close to 100% β cerium is reported. The method involves repeated steps of thermal cycling cerium samples between room temperature and liquid helium temperature followed by annealing for long periods at 75 °C. The preparation of single phase α cerium by using a pressure-cooling-depressurizing cycle is described.

The surface preparation and characterization of InP substrates have been studied. It is shown that a 1–3% bromine-methanol etching solution gives a smooth surface if 10 μm or more has been removed. Auger spectrometry detected some contamination of carbon and oxygen by the atmosphere during substrate preparation. The concentration of carbon impurities is less than in the case of GaAs. Liquid phase epitaxy of InP and GaxIn1−xAs1−yPy was achieved by a slider technique. Equilibrium cooling, supercooling and step-cooling processes have been tried. It is demonstrated that misorientation from a (111) plane gives a “scale” structure, the orientation of which is exactly (111). Smooth LPE surfaces have been obtained with the supercooling and the step-cooling processes.

Defects in monocrystalline InP have been studied by using specific etchants. (111) P, (100) and (110) surfaces have been investigated. A new etchant (H 3 PO 4 85% 2 vol, HBr 47% 1 vol) is proposed: it is shown that successive etching by this etchant and the AB solution develops more types of dislocations than others presently known.

The application of glancing angle X-ray extended X-ray absorption fine structure (EXAFS) to studies of ionic adsorbed habit modifiers is outlined and applied to the case of Fe 3+ doped ammonium dihydrogen phosphate. These studies reveal that Fe 3+ ions adsorbed on (100) surfaces are coordinated with two oxygen and two phosphorous atoms. Comparison was made of the experimental spectra with spectra calculated for Fe 3+ occupying interstitial and substitutional sites and indicates that the Fe 3+ occupies the interstitial site (0.25, 0.22, 0.125). Structurally the incorporation appears to disturb the hydrogen bonding network in this material which results in the generation of lattice strain, the latter, in turn, causes a reduction in the growth rate of the modified surface. This habit modification mechanism contrasts with the usually accepted models of surface step/terrace blocking.

A study has been made of the distribution of line defects in pure and doped crystals of anthracene. These distributions indicate that residual impurities may act as line defect sources. The effects of known impurities on the dislocation and sub-grain boundary distributions were examined and the annealing properties of the dislocations studied.

A precise determination of the phase diagram of 3–5 compounds (GaP−GaAs−InP) has been performed. The method consists of measurements of the solubility of GaP and GaAs in Ga, and of InP in In at various temperatures under typical LPE growth conditions. Experimental results are then compared to published data and it is pointed out that these data are not exact and precise enough for use in epitaxial growth.