Synthesis of new sulphides of transition metal ions in presence of sun light

New sulphides of transition metal ions [M⁺ⁿ = Cu⁺¹, Cu⁺² and Zn⁺²] have been synthesised in sunlight. XRD patterns show that these compounds are not MxSy but are mercaptyl, hydroxyl metal sulphides [M(SH)(OH)(H₂O)₂] which is further ascertained by I.R. spectra showing bands due to T _d-symmetry. ESCA of compound of copper in solid state shows presence of Cu¹⁺ and Cu²⁺ ion. The presence of hydroxyl, mercaptyl, aqua and S^–2 groups has finally been confirmed with TGA, DTA and ESCA. Conductivity and Seebeck coefficient measurements show that compound of copper is p-type semiconductor and compound of zinc is n-type semiconductor. The production of these low cost materials opens an interesting area of research and development for their use in solar cell devices.     

The mechanochemical processing of aerospace metals

The status of mechanochemical processing of aerospace metals (aluminum and titanium) is reviewed. It is demonstrated that the activation of chemical reactions by mechanical energy can lead to many interesting applications including production of advanced materials with novel constitutional and microstructural effects leading to enhanced mechanical properties.     

A versatile data acquisition system for time resolved X-ray scattering using gas proportional detectors with delay line readout

A data acquisition system for time resolved X-ray scattering experiments using linear, quadrant or area gas proportional detectors with delay line readout based on commercially available hardware (National Instruments) is described. The system can easily be configured for recording data from point detectors (e.g. photomultipliers and photodiodes) and/or ancillary data only. Applications involving measurements with two different types of time to digital converters illustrate the features and performances of the system.     

Using ion implantation to adjust the transition temperature of superconducting films

We summarize a continuing investigation into using ion implantation to alter the transition temperature of superconducting thin films. The primary motivation for the work presented here was to study the feasibility of using magnetic ion doping to replace the bi-layer T_c control process currently used for certain cryogenic detector applications at National Institute for Standards and Technology. The results from work with various ion species implanted into aluminum, molybdenum, titanium and tungsten host films are presented.     

Synthesis and Properties of NdMCr2O5 (M = Na, K, Cs) and NdMgCr2O5.5 Chromites

NdMCr₂O₅ (M = Na, K, Cs) and NdMgCr₂O_5.5 are prepared by solid-state reactions between appropriate oxides and carbonates and are shown to have a tetragonal structure. The heat capacity of these chromites, measured from 298.15 to 673 K, exhibits sharp changes attributable to second-order phase transitions. The C _p ⁰(T) data are represented by quadratic best fit equations. The electrical resistivity of the chromites is measured between 303 and 493 K. The results attest to semiconducting behavior of the materials in certain temperature ranges.     

Preparation and Properties of Er- and Yb-Activated TeO2–WO3 Glasses

TeO₂–WO₃ glasses coactivated with Er³⁺ and Yb³⁺ are prepared. The effect of Yb content on the efficiency of Er photoluminescence (PL) in the visible and IR spectral regions is studied. The highest PL efficiency is achieved at an Er : Yb atomic ratio of 1 : 1. The PL lifetime for the Er^{3+ 4} I _13/2 level is determined to be 7–9 ms.