Effect of crucible design on crystalline perfection and the enhanced optical properties of benzimidazole single crystals grown by the vertical Bridgman technique

2013 ◽  
Vol 46 (1) ◽  
pp. 276-278 ◽  
Author(s):  
B. Riscob ◽  
N. Vijayan ◽  
Mohd Shakir ◽  
M. A. Wahab ◽  
G. Bhagavannarayana
Keyword(s):  
Optical Properties ◽  
Melting Point ◽  
High Resolution ◽  
Single Crystals ◽  
X Ray Diffraction ◽  
Crystalline Perfection ◽  
Bridgman Technique ◽  
X Ray ◽  
Vertical Bridgman ◽  
Double Wall

Good quality benzimidazole (BMZ) single crystals were successfully grown by the vertical Bridgman technique (VBT). The unavoidable thermal-induced structural grain boundaries formed in the normal VBT growth of these crystals with low melting point were controlled by using a double-wall ampoule. The grown single crystals were subjected to high-resolution X-ray diffraction to assess their crystallinity. The enhancement of optical properties due to the improvement in crystalline perfection is also reported.

Enhanced crystalline perfection and fluorescence properties of p-terphenyl single crystals grown by the vertical Bridgman technique with a novel modified growth vessel

2017 ◽  
Vol 50 (1) ◽  
pp. 278-282 ◽  
Author(s):  
Qing Ai ◽  
Peifeng Chen ◽  
Yuxiang Feng ◽  
Yebin Xu
Keyword(s):  
Single Crystals ◽  
Fluorescence Properties ◽  
Organic Crystals ◽  
X Ray Diffraction ◽  
Crystalline Perfection ◽  
Bridgman Technique ◽  
X Ray ◽  
Vertical Bridgman ◽  
Growth Vessel ◽  
Double Wall

During the growth process of organic crystals, it is easy to induce thermal defects and impurities when using the conventional Bridgman technique. In the present study, a specially designed double-wall ampoule was used to solve this problem. High-quality p-terphenyl single crystals were successfully grown by the vertical Bridgman method with the improved ampoule. Powder X-ray diffraction analyses were performed to evaluate the crystallinity of the grown single crystals. Fluorescence spectrum studies show an enhancement of fluorescence properties due to the improvement in crystalline perfection.

A study of as-grown, poled and reduced Rh-doped KNbO3 single crystals by high-resolution X-ray diffraction, Raman scattering, photoluminescence and dielectric measurements

2014 ◽  
Vol 47 (4) ◽  
pp. 1324-1328 ◽  
Author(s):  
G. Bhagavannarayana ◽  
A. Choubey ◽  
S. K. Kushwaha ◽  
S. N. Sharma ◽  
R. Rani ◽  
...  
Keyword(s):  
High Resolution ◽  
Raman Scattering ◽  
Single Crystals ◽  
Chemical Reduction ◽  
Great Influence ◽  
Excess Oxygen ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Crystalline Perfection ◽  
X Ray

As-grown and chemically reduced Rh-doped (1500 p.p.m.) KnbO3 single crystals grown by the Czochralski method have been characterized. Reduction of the grown crystals at different levels was carried out under a mixture of CO and CO2 gases as the crystals were grown with excess oxygen. The effect of reduction and poling on crystalline perfection was studied by high-resolution X-ray diffraction (HRXRD) using a multi-crystal X-ray diffractometer developed in-house. The diffraction curves of the as-grown, electrically poled, moderately reduced and heavily reduced single-crystal specimens show remarkable differences. The studies by HRXRD reveal that poling has some influence on the improvement of crystalline perfection, while chemical reduction has a great influence on crystalline perfection; at moderate reduction the crystal becomes nearly perfect, but when the reduction is very heavy the crystal quality decreases slightly, although it is still better than for unreduced samples. Asymmetry of the diffraction curves with respect to the peak position reveals that the as-grown specimens contain a high concentration of both vacancies and self-interstitials. After poling, the concentration of self-interstitial defects is lowered to some extent. When the specimen is moderately chemically reduced, the scattered intensity on both sides of the peak is greatly reduced, showing that the concentrations of both vacancies and interstitials are reduced to a great extent owing to chemical reduction. This clearly indicates that, as a result of the chemical reduction of oxygen in the crystal, crystalline perfection is enhanced significantly. However, under heavy chemical reduction, the number of vacancy defects is increased to a significant extent. Raman scattering, dielectric and photoluminescence studies also show interesting features, with excellent correlation with the degree of crystalline perfection influenced by the processes of reduction and poling.

Study of the influence of dopants on the crystalline perfection of ferroelectric glycine phosphite single crystals using high-resolution X-ray diffraction analysis

2011 ◽  
Vol 44 (2) ◽  
pp. 313-318 ◽  
Author(s):  
Krishnamurthy Senthil Kumar ◽  
Sridharan Moorthy Babu ◽  
G. Bhagavannarayana
Keyword(s):  
High Resolution ◽  
Single Crystals ◽  
Point Defects ◽  
Room Temperature ◽  
Rare Earth Metals ◽  
X Ray Diffraction ◽  
Crystalline Perfection ◽  
X Ray ◽  
Tilt Boundaries

Good quality and optically transparent single crystals of pure and doped glycine phosphite (GPI) were grown by both solvent-evaporation and temperature-cooling techniques. Dopants were chosen in different categories, namely transition metals (Cr, Mn, Co, Ni, Zn, Mg, Cd), rare-earth metals (Ce, Nd, La), dyes (rhodamine B, malachite green, fluorescein) and an amino acid (L-proline). The concentration of dopants was chosen depending on the category of dopants and the quality of crystallization during the growth process. The crystalline perfection of the as-grown pure and doped GPI crystals was investigated by high-resolution X-ray diffraction at room temperature. A multicrystal X-ray diffractometer employing a well collimated and highly monochromated Mo Kα1beam and set in the (+, −, −, +) configuration was employed. Most of the crystal specimens show excellent crystalline perfection. However, grain boundaries, low-angle tilt boundaries, and vacancy and interstitial point defects were observed in some crystal specimens.

Growth, Optical Adsorption and Resistivity of (Ga0.6In0.4)2Se3 and (Ga0.594In0.396Er0.01)2Se3 Single Crystals

2013 ◽  
Vol 200 ◽  
pp. 50-53
Author(s):  
Inna A. Ivashchenko ◽  
Volodumur V. Halyan ◽  
Irina V. Danylyuk ◽  
Volodumur Z. Pankevuch ◽  
Georgij Y. Davydyuk ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Phase Diagram ◽  
Differential Thermal Analysis ◽  
Band Gap ◽  
Single Crystals ◽  
Optical Band Gap ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vertical Bridgman ◽  
Xrd Method

The phase diagram of the Ga2Se3–In2Se3 system was investigated by differential-thermal analysis (DTA) and X-ray diffraction (XRD) method. The single crystals from the area of existence of the γ2 phase with the compositions (Ga0.6In0.4)2Se3 and (Ga0.594In0.396Er0.01)2Se3 were grown by a vertical Bridgman method. Absorption spectra of the grown crystals were studied. The estimated optical band gap is 1.95±0. 01 eV. The resistance of the single crystals of (Ga0.6In0.4)2Se3 (R=500 MΩ) and (Ga0.594In0.396Er0.01)2Se3 (R=210 MΩ) was measured.

Crystallization kinetics and high-resolution X-ray diffraction analysis on nonlinear optical l-threonine single crystals

2007 ◽  
Vol 61 (27) ◽  
pp. 4932-4936 ◽  
Author(s):  
G. Ramesh Kumar ◽  
S. Gokul Raj ◽  
Thenneti Raghavalu ◽  
V. Mathivanan ◽  
M. Kovendhan ◽  
...  
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Single Crystals ◽  
Crystallization Kinetics ◽  
Nonlinear Optical ◽  
X Ray Diffraction ◽  
X Ray

In situ growth of an ethyl p-hydroxybenzoate single crystal by the vertical Bridgman technique: a potential nonlinear optical material for third-harmonic generation

2021 ◽  
Vol 54 (5) ◽  
pp. 1340-1348
Author(s):  
Debabrata Nayak ◽  
N. Vijayan ◽  
Manju Kumari ◽  
Kiran ◽  
Nikita Vashistha ◽  
...  
Keyword(s):  
Single Crystal ◽  
Laser Damage Threshold ◽  
Laser Source ◽  
Dihydrogen Phosphate ◽  
X Ray Diffraction ◽  
Bridgman Technique ◽  
Third Order ◽  
X Ray ◽  
The Third ◽  
Vertical Bridgman

Optically transparent single crystals of ethyl p-hydroxybenzoate (EPHB) were successfully grown by the vertical Bridgman technique. The crystalline phase and unit-cell dimensions were obtained from powder X-ray diffraction using Rietveld analysis. The presence of defects and grain boundaries was investigated by high-resolution X-ray diffraction. The optical quality of the grown single crystal was assessed by UV–Vis and photoluminescent spectroscopies. A blue emission, with a bi-exponential decay time, was obtained from time-resolved photoluminescence upon laser excitation at 266 nm. The mechanical strength of the EPHB single crystal was studied by Vickers hardness testing. A decrease in the laser-damage threshold was observed with a nanosecond Nd:YAG laser source for increased pulse repetition rates. The third-order nonlinearity, nonlinear absorption coefficient and nonlinear refractive index were measured using the Z-scan technique with a femtosecond Ti:sapphire laser. The third-order nonlinear coefficient values for the grown crystal were compared with those of a potassium dihydrogen phosphate single crystal.

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