Bindu Raina

Structural, spectroscopic and optical properties of pure and gadolinium doped neodymium phosphate nanoparticles prepared using wet chemical route

ABSTRACT Nanoparticles of neodymium phosphate and 5% gadolinium (Gd) doped neodymium phosphate prepared by co-precipitation technique belong to the monoclinic monazite phase with space group P21/n. The average crystallite size calculated using Debye-Scherrer and Williamson Hall method matches very well with grain size observed from scanning electron microscope images and Image J software. FTIR analysis signifies the presence of vibration modes along with the phosphate group and a slight shift in wave number was observed with the substitution of gadolinium into neodymium phosphate. Ultraviolet absorption spectrophotometer show transitions from ground state to various excited state within the 4f shell and the absorption edge shifts towards the lower wavelength side (blue shift) with the addition of dopant. Raman spectrum further confirms the formation of phosphate group with relevant peaks.

Preparation mechanism for neodymium doped strontium phosphate and its spectroscopic, optical and electrical characteristics

The growth of neodymium doped strontium phosphates (NdSrP) materials involves the system Nd (NO3) SrCl2H3PO4Na2SiO3. The optimum conditions involved for the growth of NdSrP were found out. These are found to be highly efficient laser crystals with good electro-optic and conducting properties. X-ray diffraction (XRD), particle size analyzer, scanning electron microscopy (SEM), ultraviolet spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), and dielectric studies were performed to characterize the samples. The material belongs to triclinic crystal system with well defined and highly resolved crystalline peaks. The electron micrograph clearly depicts the spherulitic morphology that has further grown in the form of elongated plates. The presence of various atomic bonds within a molecule and the functional groups along with the relevant P O bonds were found by Fourier transform infrared (FTIR) method. Ultraviolet (UV) spectroscopy is an important technique to explore the optical properties of a given material viz., electronic transitions and optical band gap.The optical transmittance range and transparency cut off depict that material possess enhanced optical characteristics. The electric analysis establishes the material to be normal dielectric and the dielectric constant is strongly temperature and frequency dependent.

Effect of cadmium doping on structural, spectroscopic and optical properties of samarium manganite multiferroic system

ABSTRACT Cadmium doped samarium manganite Sm0.9Cdo.1MnO3 and Sm0.8Cdo.2MnO3 were synthesized by solid state reaction technique. X-ray diffraction analysis confirms the single phase formation with pervoskites structure having orthorhombic phase with crystallite size in the range of 30 – 50 nm. Scanning electron micrograph shows particle size distribution is almost homogeneous and spherical. Fourier transformation infrared analysis depicts the presence of the Mn-O bond with a slight shift in wave number. Ultraviolet spectroscopy shows low absorbance in the entire visible region, an essential condition for non-linear optical applications. Absorption spectrum give optical band gap which ranges from 1.70 to 2.28 eV. Magnetization study gives an effective magnetic moment from 0.50 to 0.66 e.m.uwhich confirmthe paramagnetic behavior of the material at room temperature.

Preparation of Samarium Doped Calcium Hydrogen Phosphate and Study of Its Density and Thermal and Dielectric Characteristics

Samarium doped calcium hydrogen phosphate was synthesized as single crystal by room temperature solution growth technique, namely, silica gel technique. The kinetics of the growth parameters was studied with regard to variation of pH, dopant concentration, gel ageing, and upper reactant concentration. The optimum conditions for the growth of good quality single crystal were worked out. Single crystal X-ray diffraction analysis establishes that the crystal belongs to monoclinic system. The density observed by the flotation method is greater than the density of the reported pure calcium hydrogen phosphate thereby suggesting the incorporation of the dopant (Sm) ion into the lattice of host (CHP). Thermal analysis gave two sharp endothermic peaks which are due to partial dehydration and phase transition, respectively. Dielectric studies establish a shift in the Curie temperature from 355 to 370°C only at higher frequencies thereby suggesting the relaxational behavior of the material.