M.M. Abutalib

Novel and facile microwave-assisted synthesis of Mo-doped hydroxyapatite nanorods: Characterization, gamma absorption coefficient, and bioactivity

In the current work, the authors report the microwave-assisted synthesis Molybdenum-doped (from 0.05 to 5wt%) hydroxyapatite (HAp) for the first time. The morphology of Mo-doped HAp is nanorods of diameter in the range of 25-70nm and length in the range of 25nm to 200nm. The good crystalline nature was confirmed from X-ray diffraction patterns and also lattice parameters, grain size, strain and dislocation density were determined. The crystallite size was found to be in the range 16 to 30nm and crystallinity was found to be enhanced from 0.5 to 0.7 with doping. The field emission SEM micrographs show that the morphology of the synthesized nanostructures of pure and Mo-doped HAp are nanorods of few nanometers. The vibrational modes were identified using the FT-Raman and FT-IR spectroscopy. The dielectric properties were studied and the AC electrical conductivity was found to be increased with increasing the concentration of Mo ions doping in HAp. Moreover, antimicrobial studies were also carried out to understand the anti-bacterial and anti-fungi properties. The results suggest that it may be a good bio-ceramics material for bio-medical applications. Mo-doped HAp was subjected to the gamma irradiation produced from Cs-137 (662keV) and its related parameters such as linear absorption coefficient, the half-value layer (HVL) and the tenth value layer TVL were calculated and analyzed.

Facile microwave-assisted synthesis of Al:Mn co-doped PbI2 nanosheets: structural, vibrational, morphological, dielectric and radiation activity studies

Abstract Herein, we report a successful development of nano-scale pure and Al and Mn co-doped PbI2 using facile microwaveassisted route. Structural study was done through X-ray diffraction analysis of grain size, dislocation density and lattice strain. The crystallite size was found to vary from 28 nm to 40 nm due to Al:Mn co-doping in PbI2. The presence of various vibrational modes was confirmed by FT-IR spectroscopy and red shifting was observed in peak positions compared to the bulk. Surface morphology, examined using a scanning electron microscope, confirmed the formation of single crystal nanosheets of a thickness in the range of 10 nm to 30 nm. The single crystal nanosheets were found to be transformed to large area nanosheets due to the doping. Enhancement in dielectric constant from ~7.5 to 11 was observed with increasing Al doping concentration. Linear attenuation coefficient was calculated and showed the enhancement of blocking gamma rays with increasing doping concentration. Its value was found to increase from 7.5 to 12.8 with the doping. The results suggest that the synthesized nanostructures can be used for detection and absorption of gamma rays emitted by 137Cs and 241Am sources.

Bulk growth, structural, vibrational, crystalline perfection, optical and dielectric properties of L-threonine doped KDP single crystals grown by Sankaranarayanan-Ramasamy (SR) method

In the present work, the authors have grown the bulk-sized single crystals of pure (Size ~ 45 × 10 × 10 mm3) and first time L-threonine (LT)-doped (Size ~ 85 × 10 × 8 mm3) KDP with high quality by Sankaranarayana-Ramasamy (SR) method in an aqueous solution at constant temperature. A remarkable enhancement in the growth rate was observed from 3.2 mm/day (pure) to 6 mm/day (LT doped), respectively. The crystal structure, lattice parameters and growth direction were confirmed by powder X-ray diffraction analysis. FT-IR study confirms the presence of L-Threonine doping in KDP. Further, the vibrational modes and surface morphology was studied by FT-Raman spectroscopy along with etching treatment and shows remarkable reduction of surface defects. The optical transparency of SR-grown KDP crystals was found to be enhanced from 76 to 88% due to LT doping. The optical band gap was calculated for both the crystals and found to be 5.68 and 5.53 eV. Crystalline perfection of the grown crystals was assessed by high-resolution X-ray diffraction, dielectric and wet chemical etching studies and found to be good. The obtained result shows that the grown crystals can be used for laser applications.