N.P Rajesh

Synthesis, crystal growth and FTIR, NMR, SHG studies of 4-methoxy benzaldehyde-N-methyl-4-stilbazolium tosylate (MBST)

A novel organic nonlinear optical material 4-methoxy benzaldehyde-N-methyl-4-stilbazolium tosylate has been synthesized and good optical quality crystals were grown by slow cooling solution growth technique. Powder X-ray diffraction studies have been carried out and the lattice parameters were calculated. FTIR spectra were recorded to identify the various functional groups present in the crystal. NMR spectrum studies have also been done. The powder second harmonic generation studies were done with Kurtz powder technique and the results were compared with urea.

Optical and microhardness studies of KDP crystals grown from aqueous solutions with organic additives

Non-linear optical (NLO) materials have acquired new significance with the advent of a large number of devices utilising solid-state laser sources. From this technological point of view, potassium dihydrogen phosphate (KDP) having superior non-linear optical properties has been exploited for variety of applications. KDP crystals were grown from aqueous solutions added with organic additives by the slow cooling method for obtaining better non-linear properties. The influence of the organic additives on the optical and mechanical properties has been studied. It has been observed that the addition of organic additives improves the mechanical strength of the crystal. It is also observed that the addition of organic additives improves the optical transmission percentage of the crystal.

Influence of chelaters in crystallization of K2SO4

The influence of chelating agents like ethylene diamine tetraacetic acid (EDTA), nitrilo triacetic acid (NTA) and dimethyl sulfoxide (DMSO) on potassium sulfate solution has been analyzed. The enhancement of metastable zone width with the addition of chelaters has been observed. The variation of pH with the addition of chelaters has been monitored. The nucleation parameters were calculated from the measurements of the dependence of the metastable zone width on different cooling rates.

Enhancement of photochemical deposition (PCD) and analysis of surface spread of CdS crystalline thin films

The enhancement of the photochemical deposition (PCD) of polycrystalline thin films of CdS with the addition of EDTA has been established. The effect of concentration of EDTA on the surface coverage of the film has been studied using optical microscope.

Effect of Urea on Metastable Zone Width, Induction Time and Nucleation Parameters of Ammonium Dihydrogen Orthophosphate

Enhancement of the metastable zone width in ammonium dihydrogen ortho phosphate (ADP) was achieved by the addition of the organic compound urea to ADP solution. The metastable zone width studies were carried out for various temperature cooling rates and the nucleation parameters are studied. The induction period was studied and the critical nucleation parameters calculated based on classical theory for homogeneous nucleation are discussed. The critical nucleation parameters increase with the increase in concentration of doping.

Microhardness and slip systems of solution grown MHB crystals

Today nonlinear optical organic materials are widely used for a variety of photonic technologies. Many NLO organic single crystals have been identified as potential candidates in optical and electro-optical devices. In this paper, we report the mechanical anisotropic hardness behaviour of the organic NLO molecular crystal methyl parahydroxybenzoate (MHB). MHB compound was synthesized and the crystals were grown by solution growth technique. Single crystal X-ray diffraction studies were carried out to determine the lattice parameters of the grown crystal and SHG measurements reveal SHG efficiency 15 times higher than Urea. MHB is an aromatic crystal with noncentrosymmetric structure, and exhibits anisotropy in mechanical behaviour. The Vickers microhardness studies were carried out on all the visible planes using Vickers microhardness tester and the microhardness owing to plastic deformation is discussed in terms of various slip systems. A suitable combination of acetone and methanol as etchant was identified for visualizing the slips.

Electrical conductivity measurements on pure and amino acids added triglycine sulphate phosphate single crystals

Pure and amino acids added TGSP single crystals were grown by the solution method. Electrical conductivity measurements were carried out on the c-cut plates of the crystals at various temperatures by the conventional two-probe method. The present study shows that the conductivity in TGSP crystals, for all the impurities considered, increases with the increase in temperature. Activation energies were also determined.

Enhancement of Metastable Zone of Some Aqueous Solutions

The metastable zone width studies were carried out for various temperatures for supersaturated aqueous solutions of various inorganic materials K2SO4, Na2CrO4·4H2O, CuSO4·5H2O, NaBr·2H2O, NH4Cl, KNO2, NH4NO3, NaNO3 with pure and EDTA added solutions. The various factors affecting the metastable zone width are discussed and the critical nucleation parameters are calculated. The effect of temperature, chelating agent and the concentration of the solution are discussed.