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Abstract: Undoped and MgO-doped near-stoichiometric lithium tantalate (SLT) crystals were grown by the zone-leveling Czochralski (ZLCz) technique for the first time from Li-rich solutions (mixed with 1.2mol% MgO for MgO-doped SLT crystal) having Li-excess feed supplied from below in an iridium crucible. Inclusion-free crystals were obtained. The transmittance along the growth axis was found to be satisfactory (75±1%) having an absorption edge at 264.1±0.5nm for undoped and 264.8±0.4nm for MgO-doped SLT crystals. The refractive indices of the crystals were found to be n o=2.1768 and n e=2.1750±0.0002 for undoped and n o=2.1768 and n e=2.1784±0.0006 for MgO-doped SLT crystals, respectively. The Curie temperature and coercive field for the crystals were measured to be 680±3°C and 1.95±0.65kV/mm for undoped and 689±0.7°C and 3.55±0.95kV/mm for MgO-doped SLT crystals, respectively. ICP measurement gives the Li/Ta ratios as 0.995±0.002 and 0.9755±0.0145 in undoped and MgO-doped SLT crystals, respectively. The Mg/Ta ratio in MgO-doped crystal was measured to be 0.001235±0.00035. The Li/Ta ratio was found to vary along the crystal length in undoped and MgO-doped SLT crystals. The variation of the Mg/Ta ratio in MgO-doped SLT crystals is explained by mass balance equation. [Copyright &y& Elsevier]

Abstract: ZnO-doped near-stoichiometric lithium niobate (SLN) crystals were grown by the zone-leveling Czochralski (ZLCz) technique. The crystal was pulled from a Li-rich (60mol% of Li2O) solution having an SLN solid supplied from below in a slender platinum crucible. The segregation coefficient of ZnO was found being about 0.58, and this could cause dopant segregation along the grown crystal. However, with a higher ZnO concentration in the solution zone, the composition homogeneity along grown crystal could be achieved. The properties of SLN at different zinc concentrations were measured, and the Curie temperature and cutoff wavelength showed a transition with the zinc concentration at about 1mol%. Based on the reported mechanism, the anti-site defects of the grown crystals were about at the same concentration. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]