Systematic hardness studies on lithium niobate crystals

128

Tris (thiourea) zinc sulphate (ZTS), a semiorganic nonlinear optical (NLO) material has been synthesized at 30°C. The solubility was determined in different solvents such as water, ethanol and water mixture of ethanol (1:1). Good quality single crystals with size 10 x 8 x 6 mm 3 were grown by slow evaporation technique within three weeks with approximate growth rate of 0.5 mm/day. The grown crystals have been subjected to single crystal X-ray diffraction to determine the unit cell dimensions and morphology. The TGA and DTA reveal that the material has good thermal stability. The UV-Vis spectrum shows that the material has wide optical transparency in the entire visible region. The second harmonic generation was confirmed by Kurtz powder method. The birefringence of the crystal was measured in the visible region and it was found to vary with the wavelength. The microhardness test was carried out in (100) plane and the load dependent hardness was measured.

Section: Measurement Of Microhardnessmentioning

confidence: 99%

Crystal growth, thermal, optical and microhardness studies of tris (thiourea) zinc sulphate ‐ a semiorganic NLO material

Ramajothi

Dhanuskodi²,

Nagarajan

2004

128

“…In ideal circumstances, measured hardness values should be independent of the applied load. But in practice, a load dependence is observed [13]. The grown crystal 15 X 12 X 3 mm 3 with smooth and dominant face (001) was selected for microhardness studies.…”

Section: Microhardness Measurementmentioning

confidence: 99%

Optical and microhardness studies of semiorganic nonlinear optical material: L‐ histidine tetrafluoroborate

Ramajothui

Dhanuskodi

2003

L-histidine tetrafluoroborate (L-HFB) a semiorganic nonlinear optical material has been synthesized in aqueous solution at 50ºC and characterized by FT-IR and FT-Raman spectroscopy studies. The solubility was determined in different solvents such as water, methanol and water mixture of methanol. The single crystals with dimensions 15x12x3 mm 3 were grown by slow evaporation method within four weeks with approximate growth rate of 0.25 mm/day. The grown crystals have been subjected to single crystal X-ray diffraction studies to determine the unit cell dimensions and morphology. The Kurtz powder second harmonic generation test shows that the compound is a potential candidate for frequency conversion. The refractive index has been measured using He-Ne laser. The microhardness test was carried out and the load dependence hardness was observed. The material has a wide transparency in the entire visible region.

“…The indentation hardness is measured as the ratio of applied load to the surface area of the indentation [9][10]. The Vicker's microhardness was evaluated for the grown crystal with the size 15 x12 x 3 mm 3 for the smooth and dominant face (001).…”

Section: Measurement Of Microhardness and Work Hardening Coefficientmentioning

confidence: 99%

Crystal growth, thermal and optical studies of L‐histidine tetrafluoroborate: A semiorganic NLO material

Dhanuskodi

Ramajothi

2004

L-histidine tetrafluoroborate (L-HFB), a semiorganic nonlinear optical (NLO) material has been synthesized and characterized by elemental analysis and FT-NMR spectroscopic studies. Solubility of L-HFB has been determined in water and ethanol. The single crystals with dimensions 15x12x3 mm 3 were grown by slow evaporation technique under two different pH conditions. The effect of pH on the morphology of the crystals have been studied. The grown crystals of both pH values has been subjected to single crystal X -ray diffraction to determine the unit cell dimensions and morphology. The thermal stability has been analyzed by TGA and DTA. The microhardness test was carried out in (001) plane and the hardness coefficient was calculated. The birefringence values (∆ n ) were determined in the wavelength region 5540 -6460 Å.