S. Gokul Raj

Swift ion beam irradiation on lithium niobate single crystals

Single crystals of lithium niobate were irradiated by 50 MeV Li3+ion irradiation at various ion fluences. The irradiated single crystals were subjected to various studies such as X-ray diffractometry, UV–VIS–NIR analysis and refractive index measurements. Atomic force microscopy patterns were recorded to study the surface changes after irradiation. Micro-Raman measurements were also recorded for irradiated specimens and the result of the measurements are discussed in detail.

Growth and characterization of potassium acid phthalte for third order NLO applications

Nonlinear optical crystals of potassium acid phthalate (COOK C6H4 COOH)-KAP were grown from aqueous solution. Transparent crystals of size (21×17×4) mm3 with well defined morphology were grown from slow cooling techniques. The grown crystals were characterized by single crystal X-ray diffraction. The crystal structure of Potassium Acid Phthalate C8H5K+O4 was orthorhombic with the following unit-cell dimensions at 298(2) K; a = 9.5970(3) A; b = 13.2869(5) A; c = 6.4643(3) A; α = 90°; β = 90°; γ = 90°; with a space group PCa21. Spectral analysis were carried out to investigate confirm its presence of various functional groups and to study the optical absorption properties. Third order nonliner studies have also been studied by Z-scan techniques. Nonlinear absorption and nonlinear refractive index were found out and the third order bulk susceptibility of compound was also estimated. The results have been discussed in detail.

Combustion synthesis and structural analysis of nanocrystalline nickel ferrite at low temperature regime

Combustion synthesis of single phase Nickel ferrite was successfully achieved at low temperature regime. The obtained powders were calcinated to increase the crystallinity and their characterization change due to calcinations is investigated in detail. Citric acid used as a chelating agent for the synthesis of nickel ferrite. Pure single phase nickel ferrites were found at this low temperature. The average crystalline sizes were measured by using powder XRD measurements. Surface morphology was investigated through Transmission Electron Microscope (TEM). Particle size calculated in XRD is compared with TEM results. Magnetic behaviour of the samples is analyzed by using Vibrating Sample Magnetometer (VSM). Saturation magnetization, coercivity and retentivity are measured and their results are discussed in detail.

A co-precipitation preparation, crystal structure and photoluminescent properties of Er5%:Gd2O3 nanorods

An inexpensive preparation method is being reported for obtaining erbium doped gadolinium oxide (Er5%:Gd2O3) nanoscale rods. The elongated nanoscale systems, as-formed through a co-precipitation process, are characterized by using X-ray powder diffraction (XRD) patterns, scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) mapping, Ultra Violet-visible (UV-vis.) absorption spectroscopy and photoluminescence (PL) spectroscopy. In addition, the Williamson–Hall (W–H) plot is also performed to distinguish the effect of crystalline size-induced broadening and strain-induced broadening at full-width at half-maximum (FWHM) of the XRD profile. The XRD patterns of as-formed and calcined products show that the phase confirmation. As revealed from the SEM micrographs, the morphology of the products show that the rod-like nanoparticles. The EDX micrographs show that the presence of elements in our samples. The band gap values in calcined samples are found to be in the range of 3.569 eV. Upon 230u2005nm e...

Rapid phase synthesis of nanocrystalline cobalt ferrite

Synthesis of single phase nanocrystalline Cobalt Ferrite (CoFe2O4) was achieved by single step autocombustion technique with the use of citric acid as a chelating agent in mono proportion with metal. Specimens prepared with this method showed significantly higher initial permeabilitys than with the conventional process. Single phase nanocrystalline cobalt ferrites were formed at very low temperature. Surface morphology identification were carried out by transmission electron microscopy (TEM) analysis. The average grain size and density at low temperature increased gradually with increasing the temperature. The single phase formation is confirmed through powder X-ray diffraction analysis. Magnetization measurements were obtained at room temperature by using a vibrating sample magnetometer (VSM), which showed that the calcined samples exhibited typical magnetic behaviors. Temperature dependent magnetization results showed improved behavior for the nanocrystalline form of cobalt ferrite when compared to the...

Structural, morphological and optical investigations on Sm3+ doped gadolinium oxide nanorods

One dimensional uniform Sm3+ doped gadolinium hydroxide nanorods have been prepared via simple co– precipitation technique at 60 °C temperature for 1 hour. The samples were calcinated at 750 °C to obtain Sm3+ doped gadolinium oxide nanorods. The 1D nanorods were then subjected to different characterization techniques to ascertain its structural stability and its morphology were investigated using high–resolution transmission electron microscopy. Photoluminescence (PL) spectrophotometry was investigated and the obtained results were discussed in detail.

Structural and optical properties of Nd3+ doped gadolinium oxide 1D nanorods

Neodymium doped gadolinium hydroxide [Nd:Gd(OH)3] nanorods were successfully synthesized at 60 °C through co-precipitation method. The dopant percentage was maintained at 5% and calcination was done at 750 °C temperature for 1 hour to form the respective neodymium doped gadolinium oxide [Nd:Gd2O3] nanorods. The as-formed and annealed products were investigated in detail by using powder X-ray diffraction (XRD) pattern, scanning electron microscopy (SEM) with an energy dispersive X-ray spectrum (EDX), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) spectrophotometry.

Structural and topographical analysis of Nd:Gd{sub 2}O{sub 3} nanorods

Nanocrystalline form of pure and Nd doped gadolinium hydroxide [Nd:Gd(OH(3] nanorods were successfully synthesized at 60 °C through simple co-precipitation method of Gd(NO3)3.6H2O and Nd(NO3)3.6H2O solutions with a specified pH, adjusted using NH3 as buffer solution. The dopant percentage was maintained at 5%. The as-synthesized Gd(OH)3 and Nd:Gd(OH(3 nanorods were annealed at 500 °C for 1 h to form the respective Gd2O3 and Nd:Gd2O3 nanorods. Powder X-ray diffraction (XRD) pattern, scanning electron microscopy with energy dispersive X-ray (SEM/EDX) and high-resolution transmission electron microscopy (HRTEM) analyses were used to characterize these as-synthesized [Gd(OH)3 and Nd:Gd(OH(3] and annealed [Gd2O3 and Nd:Gd2O3] nanorods.