Helen Merina Albert

Spectral, optical, and thermal studies of pure and Zn(II)-doped l-histidine hydrochloride monohydrate (LHHC) crystals

The influence of doping the transition metal Zn(II) on the growth, spectral, optical, and thermal properties of l-histidine hydrochloride monohydrate (LHHC) crystals grown by slow solvent evaporation method has been investigated. Structural characterizations of the grown crystals were carried out by single crystal X-ray diffraction analysis and it shows slight structural changes as a result of doping. The FT-IR spectral study reveals the presence of various functional groups and confirms the slight distortion of the structure of the crystals due to doping. The energy dispersive X-ray analysis reveals the incorporation of Zn(II) in the crystalline matrix of LHHC crystal. The UV–Vis spectral study was carried out to analyze the optical transmittance of the grown crystals and found that the transmittance is very high in the visible and UV regions for both pure and doped crystals. The second harmonic generation (SHG) for the grown crystals was confirmed by Nd:YAG laser. The scanning electron microscopy reveals the presence of defect centers and crystal voids. The thermal stability and purity of the grown crystals were analyzed by thermogravimetry, differential thermal analysis, and differential scanning calorimetry techniques.

Growth and Characterization of Pure and Thiourea Doped L-Histidine Single Crystals

Pure and thiourea doped L-histidine (TU-LH) organic single crystals were grown by slow solvent evaporation method. Structural characterizations of the grown crystals were carried out by single crystal X-ray diffraction (XRD). The functional groups were identified by Fourier transform infrared (FTIR) spectroscopy. The presence of thiourea in the doped crystal was confirmed by energy dispersive X-ray analysis (EDAX). The UV-Vis-NIR spectral studies were performed to analyze the optical absorption of the grown crystals and found that the absorption is very low in the wavelength region 235–1000 nm for both pure and doped crystals. Second harmonic generations (SHG) for the grown crystals were confirmed using Nd:YAG laser. The surface morphologies of the grown crystals were analyzed by scanning electron microscope (SEM). Thermogravimetric and differential thermal analyses (TG/DTA) show that the grown crystals have good thermal stability.

Effect of high pressure and high temperature on (Nd, Eu, Gd) Ba-Cu-O superconductor

The effect of high pressure and high temperature on electrical resistivity behavior of (Nd, Eu, Gd) Ba-Cu-O superconductor with 10wt %Ag2O addition was studied. This high Tc superconductor was synthesized using the oxygen controlled melt growth process(OCMG). At room temperature, there was an initial drop in the resistivity of the superconductor up to 3GPa, followed by a nearly constant value up to 8GPa pressure. The steady value of resistivity observed between 3 and 8GPa decreased with increasing Ag2O content. The superconducting composite formed exhibited a metallic nature under pressure up to 8GPa.