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The present work report on physical, structural, optical and thermoluminescence properties of Dy3+ doped manganese potassium borate glasses. The conventional melt quenching technique is used to prepare the glass samples. The amorphous nature of the prepared glass sample is confirmed by X-ray diffraction study. The different B–O vibrational bands and change in the coordination number of boron (BO3 → BO4) with the inclusion of Dy3+ ions in the prepared glasses were analyzed through FTIR. The physical parameters such as density, molar volume, average molecular weight, ion concentration, polaron radius, internuclear distance and optical parameters have been determined. The optical analysis reveals that the optical band gap energy decreases with the increase of dysprosium oxide concentration. The TL glow curve of gamma irradiated samples showed single prominent peak in the temperature range 425–460 K with varying concentration of Dy2O3. Analysis of kinetic parameters reveals that the glasses demonstrate second order kinetics.

The temperature distribution profile above the graphite die used to grow multi-crystalline silicon (Si) sheets by Capillary Action Shaping Technique (CAST) in a resistive heated system, has been controlled by forced argon (Ar) gas cooling. A theoretical model is proposed in which the temperature on the top of the die is related with the gas flow and the solutions to these equations are simulated and plotted using Mathematica 6.0 program. While the crystal growth is better controlled with the forced cooling, the theoretical model helps to set the optimum flow rates for obtaining desired growth speed and thickness of the Si sheets. Thus the experimental growth variables such as thickness and growth rates of the growing silicon sheets have been controlled. Temperature gradient values at the growth interface observed experimentally have also been compared to the theoretical values, which agree closely.

LiF crystals doped with different concentration of Mg from 0 to 2000 ppm have been grown by edge defined film fed growth technique. The X-ray diffraction measurement confirms the incorporation of the Mg in the lattice. Thermoluminescence and optical absorption measurements have been made on as-grown and annealed crystals after they were irradiated with a gamma dose of 15 and 1500 Gy, respectively. The TL glow peak temperature and intensity increase up to 500 ppm in case of the as-grown crystals and up to 1000 ppm in the annealed crystals and decrease thereafter. The normalized peak height of the annealed crystals is nearly three times that of the as grown crystals for the particular concentration. Corresponding optical absorption spectra of the crystals exhibit prominent bands at 250 and 310 nm. The 310 nm band increases with increase in concentration of Mg and also with annealing. The changes in the TL glow curves are correlated with those of the optical absorption bands to conclude that the 310 band is due to the Mg related Z 2 center.

An overview of the recent development of the superconducting FeSe1x and related compounds is presented. Methods to synthesize high purity polycrystalline samples, single crystals and thin films with preferred orientation are described. In addition to the synthesis of FeSe and FeSeTe, the effects of various partial chemical substitutions on Fe and Se/Te site are described. It was found that the effects of chemical doping to the Se-site or Fe-site are rather different. Ionic size of the dopant is found to play a critical role on the occurrence of superconductivity. We also review the physical properties, including transport, magnetic, and thermal properties. There exist interesting transport anomalies in the resistivity at low temperature, and it was found that a structural distortion at low temperature is critical to the occurrence of superconductivity in these materials. However, the exact origin of these observed anomalies is not clear, and the exact pairing symmetry in FeSe-based superconductors is also still in question. 2009 Published by Elsevier B.V.

Infrared imaging furnace was used to grow single crystals of Ba2YRu1-xCuxO6 and Ba2PrRu1-xCuxO6 using high temperature solutions of PbO-PbF2 in the form of a bubble attached to the feed rods. Several small crystals were found deposited on the cooler portions of the sintered rod as well as in the drop like portion at the end of the rod. These crystals were collected and the morphology, microstructure and magnetic properties were studied. The details of these investigations are presented. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A new peak at about 650°C has been observed in the thermoluminescence emission of gamma irradiated natural fluorites containing significant quantities of lanthanide rare-earth (RE) elements as impurities. Thermal activation energy of the corresponding trap has been evaluated to be 2·99 eV with a frequency factor of 1016 sec−1. The optical activation energy, as deduced from photo-transfer-induced-TL from this trap, is 5·36 eV. Many types of natural fluorites as well as synthetically grown CaF2 crystals doped with single and pairs of rare earth elements have been studied and the results indicate that the high temperature peak is associated with Sm impurity coexisting with Y, La or Ce in CaF2. There are indications that this newly observed TL peak can be gainfully employed in ultraviolet dosimetry and geological dating of fluorite deposits.

The undoped samples exhibit five glow peaks at 60, 105, 145, 175 and 285 degrees C. The 60 degrees C peak is tentatively attributed to F' centres, the 105, 175 and 285 degrees C peaks to F centres and the 145 degrees C peak to hole centres. Doped samples exhibit six glow peaks at 85, 106, 145, 177, 230 and 320 degrees C. The 106, 145 and 177 degrees C peaks of doped samples are respectively the same as the 105, 145 and 175 degrees C peaks of the undoped samples, and are explained in a similar fashion. The 85 and 230 degrees C peaks are attributed to F centres and the 320 degrees C peak to hole centres. The TL emission spectra of the doped samples consist of two bands at 410-420 and 570 nm at all temperatures, the 410-420 nm emission being due to the intrinsic luminescence perturbed or allowed by the impurities, and the 570 nm emission being due, at least in the case of the first five peaks, to the host-sensitised secondary luminescence with Mn acting as activator. The emission spectrum observed when irradiated doped samples are excited with 342 nm (F band) light also contains bands at 420 and 570 nm.