Nanoindentation and structural studies of MgO-doped congruent LiNbO3 single crystals

The mechanical properties of undoped and 2.0, 4.0 and 6.0 mol% Mg-doped LN single crystals, grown by the Czochralski technique, have been investigated using nanoindentation studies to understand the mechanical deformation behaviour as doping is increased. This has been correlated with structural investigations by powder XRD analysis and Raman spectroscopy. Powder X-ray diffraction measurements show a slight increase in the lattice parameters as the Mg content is increased in the crystal. The lattice strain developed due to the doping has been calculated by the Williamson-Hall relation. The influence of Mg incorporation on lattice vibrations was analysed using Raman spectroscopy, which indicated no shift in the peak positions with doping, and only slight variation in the intensity and width of the peaks. The grown crystals were subjected to nanoindentation and the Young's modulus and hardness values were obtained by using the Oliver-Pharr method. The results reveal the optimal doping levels of Mg which result in enhanced mechanical strength of lithium niobate single crystals.publishe

Effect of Mn(II) doping on crystalline perfection, nonlinear, optical and mechanical properties of KDP single crystals

The effect on crystalline perfection, second harmonic generation (SHG) efficiency, optical transparency and mechanical properties due to Mn(II) doping in KDP single crystals grown by slow evaporation solution technique by adding different quantities of MnCl2 in the solution has been investigated. The actual incorporated quantity of Mn(II) in the crystals was evaluated by atomic absorption spectroscopy. Powder XRD study confirms the crystal system of KDP and found no additional phases at all doping levels (1 to 5 mol%). The influence of Mn(II) doping on the crystalline perfection has been assessed by high-resolution XRD and these studies revealed that the grown crystals could accommodate Mn(II) in the interstitial positions of the crystalline matrix of KDP only up to some critical concentration, above which the crystal developed structural grain boundaries. The relative SHG efficiency of the crystals was found to be increased sharply at low concentrations (1 mol%), and above this value it was decreased as the concentration increases though it is still higher than that of pure KDP. UV-Vis studies also revealed the same behavior with a significant enhancement at 1 mol% concentration and later gradually decreased. Good increment in the hardness values has been observed by increasing the doping concentrations

Effect of organic ligands (L-Proline and L-Methionine) on growth, structural, vibrational, crystalline perfection, SHG efficiency, microscopic and optical properties of KDP single crystals

The effect of L-Proline (LP) and L-Methionine (LM) doping on the various properties of KDP single crystals grown by slow evaporation solution technique has been investigated. The external morphology of the grown crystals was found to vary due to different dopants and doping concentrations. The change in powder X-ray diffraction intensity patterns due to doping shows the lattice distortion within resolution limit and confirms that there is no extra phase. Further, the same was confirmed by FT-Raman analysis. Infra red microscopic study also exhibits the effectiveness of doping in terms of varying surface morphology. Crystalline perfection of KDP crystals with LP and LM doping was examined by high-resolution X-ray diffraction. This shows very interesting features on the ability of accommodating the dopants in the crystalline matrix. Second harmonic generation efficiency was also found to be in similar fashion as of crystalline perfection. The optical transparency of doped crystals was tested. (C) 2014 Elsevier B.V. All rights reserved

Growth, optical, mechanical and thermal studies of diglycine cadmium chloride single crystal

Transparent single crystals of diglycine cadmium chloride were grown by slow evaporation solution technique. To confirm the crystal structure, the grown crystals were subjected to single crystal as well as powder X-ray diffraction measurements and the structure was found to be monoclinic. The elemental analysis was carried out by energy dispersive X-ray spectroscopy. The crystalline perfection of the grown crystal was assessed by high-resolution X-ray diffractometry and found that the crystal quality is fairly good. The optical study reveals that the grown crystal is highly transparent in the region 250-900 nm. Thermal studies reveal that the grown crystal is stable up to 245 A degrees C. The michrohardness analysis revealed that the grown crystal belongs to soft material category. The high dielectric constant (> 30) and low loss (< 0.01) value also confirms that the grown crystal is a good candidate for device fabrications

Synthesis, crystal growth and mechanical properties of Bismuth Silicon Oxide (BSO) single crystal

Bismuth Silicon Oxide (BSO) is an efficient material for piezo-electric and electro-optic applications. In this article, growth of BSO single crystal by high temperature Czochralski melt growth technique and its detailed mechanical characterization by Vickers microhardness, fracture toughness, crack propagation, brittleness index and yield strength have been reported. The raw material was synthesized by solid state reaction using the stoichiometric ratio of high purity bismuth tri-oxide and silicon di-oxide. The synthesized material was charged in the platinum crucible and then melted. The required rotation and pulling rate was optimized for BSO single crystal growth and good quality single crystal has been harvested after a time span of 5 days. Powder X-ray diffraction analysis confirms the parent crystallization phase of BSO. The experimentally studied mechanical behavior of the crystal is explained using various theoretical models. The anisotropic nature of the crystals is studied using Knoop indentation technique

Synthesis, growth, crystal structure and characterization of a new organic material: Glycine glutaric acid

Glycine glutaric acid, a new organic compound has been synthesized and good quality single crystals were grown by slow evaporation technique. The structure of the grown crystal was elucidated by using single crystal XRD. The presence of the functional groups was confirmed by using FT-IR spectroscopy. The optical transparency was studied by using UV–vis spectrophotometer and it was found that the crystal is having high optical transparency. The thermal stability of the crystal was studied by using thermo-gravimetric and differential thermal analyses and found that it is stable up to 150 ◦ C. The room temperature dielectric studies were also carried out over the wide frequency range: 10 mHz to 10 MHz

Unidirectional growth of l-asparagine monohydrate single crystal: First time observation of NLO nature and other studies of crystalline perfection, optical, mechanical and dielectric properties

L-asparagine monohydrate (LAM), a new amino acid single crystal, was grown by slow evaporation solution technique (SEST) as well as by recently invented Sankaranarayanan–Ramasamy (SR) method in aqueous medium. Using SR method, LAM single crystal of diameter ∼18 mm and length ∼52 mm was grown for the first time. The growth conditions were optimized and the maximum growth rate of 1.0 mm per day was observed for the SR crystal. The crystal structure was confirmed by powder XRD. The crystalline perfection was assessed by high resolution XRD and etching studies and found that the quality of the SR crystal is better than the SEST crystal. The UV–vis–NIR spectroscopic study revealed that the SR crystal has good optical transparency than that of SEST crystal. The relative second harmonic generation efficiency was measured and found to be ∼0.35 times to that of KDP. The laser damage threshold (LDT) was measured and found that the SR crystal has higher LDT value (5.76 GW cm−2) than SEST crystal (4.75 GW cm−2). The Vickers’s microhardness and dielectric studies were also carried out and discussed

Structural, optical and thermal properties of Zr-Fe co-doped congruent LiNbO3 single crystals

Zr-Fe-doped congruent lithium niobate single crystals were grown by the Czochralski technique. The crystal structure and lattice parameter of the grown crystals were assessed by powder X-ray diffraction and the strain developed as a result of doping has been calculated (-1.19 x 10(-3)) by using the Williamson-Hall relation. The incorporated dopant concentration along with the dopant distribution in the specimen crystal was estimated by X-ray florescence spectrometry. A multi-crystal X-ray diffraction analysis was carried out to identify the crystalline perfection of the sample and revealed that the investigated crystal does not contain any structural grain boundaries but does contain point defects and micrometre size mosaic blocks. Birefringence measurements were carried out using a prism coupler spectrometer and found that the optical birefringence is 0.0822 for 532 nm and 0.705 for 1064 nm. A thermal conductivity (kappa) study reveals that the doped sample has a lower kappa value than the undoped equivalent

Optical spectroscopy, crystalline perfection, etching and mechanical studies on P-nitroaniline (PNA) single crystals

In this work we have presented the bulk growth of P-nitroaniline (PNA) single crystals by slow evaporation solution technique using methanol as a solvent at 300 K. Crystal system and lattice parameters were confirmed by powder X-ray diffraction analysis. Optical absorption and reflectance spectrums were recorded in the wavelength range of 150-3000 nm. Various optical parameters such as transmission (=>57%), optical band gap (=similar to 2.43 eV) were calculated. High-resolution X-ray diffraction study reveals that the grown crystal is having good crystalline perfection as the FWHM was found to be 39 arc s. Etching study was carried on PNA crystal with different etchants and suggests that the grown crystals are of better quality with less dislocation density (=3 x 103). The various mechanical parameters such as hardness, Mayer index, fracture toughness, brittle index were also calculated