Thermo-analysis of Preparation Processfor Electron Trapping Materials

The heated process of raw materials for electron trapping materials (ETM) is investigated by thermo-analysis method. The temperature ranges of raw materials experienced some physical and chemical change processes, such as dehydration, organic solvent removal, crystal sulphur burning, oxidation of alkaline earth sulfides and solid phase reaction (rare earth doped) and so on, are obtained. The experimental results also show that the presence of trace oxygen in shielded gas is very harmful to prepare the ETM.The raw material thermo-analysis results provide very important experimental reference for optimizing the ETM preparation techniques.

Effect of Calcium Leaching on the Properties of Cement-based Composites

Leaching is one of the major factors that alter the mechanical properties of cement-based composites.This study is aimed to investigate the effect of leaching on the properties of cement-based composites.Specimens with two water/cementitious ratios and two mineral admixtures were tested.An electrical potential was applied to accelerate the leaching process.Compressive strength test,scanning electronic microscopy,thermogravimetric analysis and X-ray diffraction analysis were conducted.Test results demonstrated that the calcium leaching reduced compressive strengths of concrete specimens,and such effect was prominent on the specimens without mineral admixtures.The leaching resistance increased with a decrease in water/cementitious ratio and an increase in amount of mineral admixtures.The mineral admixtures would reduce the amount of calcium hydroxide and refine the pore structure through pozzolanic reactions.A fair relationship was found between the calcium leaching and the compressive strength.

Synthesis, Growth and Characterization of Nonlinear Optical Single Crystal of Serine Succinate

Nonlinear optical single crystal of Serine Succinate (SSA) was grown from a mixed solvent of water, ethanol and methanol. Since amino acid exhibits nonlinear optical property, it is of interest to dope them in serine. The overwhelming success of molecular engineering in controlling nonlinear optical properties in last decade has prompted better initiative in crystal engineering. In the present study single crystals of serine doped with succinic acid in different ratios have been grown by slow evaporation solution growth method. Grown serine succinate crystals were subjected to various characterization techniques. The cell parameters of the grown crystals were characterized by X-ray diffraction analysis. FT-Raman spectral studies were carried out on the SAA grown material to confirm the synthesized compound and the functional groups of serine succinate single crystal were identified from FTIR analysis. The optical transparency and upper cut off value of UV transmission spectrum of SSA crystal were recorded. Fluorescence study was also carried out for the grown materials. The mechanical hardness was estimated by Vickers’s micro hardness tester. The second harmonic generation (SHG) of the grown crystal was confirmed by Kurtz powder technique. Thermal properties of serine succinate crystal were evaluated with thermogravimetric, differential thermal and differential scanning calorimetric analyses. The SEM studies were also reported.

Synthesis and characterization of sodium-lithium niobate ceramic structures and their composites with biopolymers

Ceramic powders of Na_(1−x)Li_(x)NbO_(3)(LNN)have been synthesized by an aqueous sol-gel route.These solid solutions were prepared from Na-Li-Nb precursor gel.The precursor was synthesized from Na-EDTA,Li-EDTA and Nb-citrate complexes and they acted as the source of Na,Li and Nb,respectively.Citric acid and ethylenediaminetetraacetic acid(EDTA)were used as the chelating agents for Na,Li and Nb.The precursor gel was calcinated on a muffle furnace at 750℃for one hour and this provided the ceramic structures.Composites of LNN-biopolymers were prepared by the encapsulation of the ceramic structures into the biopolymeric scaffolds.The ceramic structures and composites were characterized by FTIR,NMR,TG and SEM analysis.