scholarly journals The Bridgman method growth and spectroscopic characterization of calcium fluoride single crystals

2016 ◽  
Vol 48 (3) ◽  
pp. 333-341 ◽  
Author(s):  
Ibrahim Elswie ◽  
Zorica Lazarevic ◽  
Vesna Radojevic ◽  
Martina Gilic ◽  
Maja Rabasovic ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Calcium Fluoride ◽  
Spectroscopic Characterization ◽  
Growth Conditions ◽  
Optical Quality ◽  
X Ray Diffraction ◽  
Caf2 Single Crystal ◽  
Optical Modes ◽  
Diamond Saw

It must be noted that the main objective of this study was to obtain single crystals of calcium fluoride - CaF2, and after that the crystals were characterized with various spectroscopic methods. The crystals were grown using the Bridgman technique. By optimizing growth conditions, <111> oriented CaF2 crystals up to 20 mm in diameter were grown. Number of dislocations in CaF2 crystals was 5?104 - 2?105 per cm2. Selected CaF2 single crystal is cut into several tiles with the diamond saw. The plates were polished, first with the silicon carbide, then the paraffin oil, and finally with a diamond paste. The obtained crystal w?s studied by Raman and infrared -IR spectroscopy. The crystal structure is confirmed by X-ray diffraction (XRD). One Raman and two IR optical modes predicted by group theory are observed. A low photoluminescence testifies that the concentration of oxygen defects within the host CaF2 is small. All performed investigations show that the obtained CaF2 single crystal has good optical quality, which was the goal of this work.

GROWTH AND CHARACTERIZATION OF GLYCINE HYDROBROMIDE SINGLE CRYSTAL FOR NONLINEAR OPTICAL APPLICATIONS

2008 ◽  
Vol 22 (21) ◽  
pp. 2035-2042 ◽  
Author(s):  
K. KIRUBAVATHI ◽  
K. SELVARAJU ◽  
N. VIJAYAN ◽  
S. KUMARARAMAN
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Nonlinear Optical ◽  
Grown Crystal ◽  
Visible Spectrum ◽  
Optical Quality ◽  
X Ray Diffraction ◽  
Optical Applications ◽  
Nonlinear Optical Applications

Single crystals of a new semi-organic nonlinear optical material glycine hydrobromide were grown from solution by slow evaporation at room temperature. Good optical quality single crystals with dimensions 17×8×5 mm3 were obtained. The grown crystal had been confirmed by single-crystal X-ray diffraction and the vibrational frequencies of various functional groups in the crystals had been derived from Fourier transform infrared spectrum. The optical quality of the grown crystals was analyzed by the Ultraviolet visible spectrum method. The mechanical behavior of the grown crystal was evaluated by Vickers' micro-hardness indentation method. The nonlinear optical property of the crystal was confirmed by the Kurtz powder technique using Nd : YAG laser as a source.

scholarly journals Characterization of neodymium doped calcium tungstate single crystal by Raman, IR and luminescence spectroscopy

2018 ◽  
Vol 50 (4) ◽  
pp. 445-455 ◽  
Author(s):  
Rouaida Abozaid ◽  
Zorica Lazarevic ◽  
Vesna Radojevic ◽  
Maja Rabasovic ◽  
Dragutin Sevic ◽  
...  
Keyword(s):  
Single Crystal ◽  
Czochralski Method ◽  
Growth Conditions ◽  
Optical Quality ◽  
Luminescence Lifetime ◽  
Luminescence Spectroscopy ◽  
Calcium Tungstate ◽  
Stretching Vibration ◽  
Raman And Infrared Spectroscopy ◽  
Diamond Saw

The aim of the current work was to assess obtain a single crystal of calcium tungstate doped with neodymium - (CaWO4:Nd3+), and after that, the crystal was characterized with various spectroscopic methods. The single crystal was grown from the melt using the Czochralski method in air. By optimizing growth conditions, <001>-oriented CaWO4:Nd3+ crystal? up to 10 mm in diameter were grown. Number of dislocations in obtained crystal was 102 per cm2. Micro hardness was measured with the Vickers pyramid. Anisotropy in <001> direction was not observed. Selected CaWO4:Nd3+ single crystal was cut into several tiles with the diamond saw. The plates were polished with a diamond paste. The crystal structure is confirmed by X-ray diffraction. The obtained crystal w?s studied by Raman and infrared spectroscopy. Seven Raman and six IR optical active modes predicted by group theory are observed. FTIR confirmed the occurrence of all the functional groups and bonds in this material. From the FTIR spectrum, a strong peak of 862 cm-1 has been obtained due to the stretching vibration of WO42- in scheelite structure, and a weak but sharp band at 433 cm-1 has been noticed due to the metal-oxygen (Ca-O) band. Estimated luminescence lifetime of 4F5/2 - the 4I9/2 transition is about 120 ?s; estimated luminescence lifetime of 4F3/2 - the 4I9/2 transition is about 140 ?s. All performed investigations show that the obtained CaWO4:Nd3+ single crystal has good optical quality, which was the goal of this work.

scholarly journals Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Durga Sankar Vavilapalli ◽  
Ambrose A. Melvin ◽  
F. Bellarmine ◽  
Ramanjaneyulu Mannam ◽  
Srihari Velaga ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
First Principle ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Principle Calculations ◽  
Photodegradation Efficiency

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.

scholarly journals Modeling of magneto-conductivity of bismuth selenide: a topological insulator

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Yogesh Kumar ◽  
Rabia Sultana ◽  
Prince Sharma ◽  
V. P. S. Awana
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Single Crystal ◽  
Single Crystals ◽  
X Ray Diffraction ◽  
Field Range ◽  
X Ray ◽  
Bulk Carriers ◽  
Different Temperatures

AbstractWe report the magneto-conductivity analysis of Bi2Se3 single crystal at different temperatures in a magnetic field range of ± 14 T. The single crystals are grown by the self-flux method and characterized through X-ray diffraction, Scanning Electron Microscopy, and Raman Spectroscopy. The single crystals show magnetoresistance (MR%) of around 380% at a magnetic field of 14 T and a temperature of 5 K. The Hikami–Larkin–Nagaoka (HLN) equation has been used to fit the magneto-conductivity (MC) data. However, the HLN fitted curve deviates at higher magnetic fields above 1 T, suggesting that the role of surface-driven conductivity suppresses with an increasing magnetic field. This article proposes a speculative model comprising of surface-driven HLN and added quantum diffusive and bulk carriers-driven classical terms. The model successfully explains the MC of the Bi2Se3 single crystal at various temperatures (5–200 K) and applied magnetic fields (up to 14 T).

scholarly journals Controlled Synthesis of Large Single Crystals of Metal‐Organic Framework CPO‐27‐Ni Prepared by a Modulation Approach: In situ Single Crystal X‐ray Diffraction Studies

2021 ◽  
Author(s):  
Simon Maximilian Vornholt ◽  
Caroline G. Elliott ◽  
Cameron M. Rice ◽  
Samantha E. Russell ◽  
Peter J. Kerr ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Metal Organic Framework ◽  
Controlled Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Metal Organic ◽  
Organic Framework

Synchrotron white beam x-ray topography (SWBXT) and high resolution triple axis diffraction studies on AlN layers grown on 4H- and 6H-SiC seeds

2004 ◽  
Vol 831 ◽  
Author(s):  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
Rafael Dalmau ◽  
Raoul Schlesser ◽  
Zlatko Sitar
Keyword(s):  
High Resolution ◽  
Single Crystal ◽  
Large Diameter ◽  
Laser Diodes ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
White Beam ◽  
Strain Data ◽  
Growth Experiments

ABSTRACTFor nitride based devices such as LEDs, high power FETs and laser diodes, single crystal substrates of AlN are highly desirable. While the sublimation technique is suitable for growing bulk AlN crystals, appropriate seeds are also necessary for growing large diameter oriented boules. 4H- and 6H-SiC substrates which are readily available commercially can potentially be implemented as seeds for bulk AlN growth. However, issues regarding SiC decomposition at high temperatures, thermal expansion mismatch, single crystal growth, etc. need to be addressed. Towards this end, a series of growth experiments have been carried out in a resistively heated reactor using on and off-axis 4H- and 6H-SiC substrates as seeds for AlN growth from the vapor phase. Several hundred microns thick AlN layers have been grown under different growth conditions. Synchrotron white beam x-ray topography (SWBXT) has been used to map the defect distribution in the grown layers and high resolution triple axis x-ray diffraction (HRTXD) experiments were carried out to record reciprocal space maps from which tilt, mismatch and strain data can be obtained. These results are analyzed with respect to the growth conditions in order to gain a better understanding of this growth process.

scholarly journals Rubidium tetrafluoridobromate(III): redetermination of the crystal structure from single-crystal X-ray diffraction data

IUCrData ◽  
2019 ◽  
Vol 4 (11) ◽  
Author(s):  
Artem V. Malin ◽  
Sergei I. Ivlev ◽  
Roman V. Ostvald ◽  
Florian Kraus
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Diffraction Data ◽  
Structure Type ◽  
X Ray Diffraction ◽  
X Ray ◽  
Square Planar ◽  
Atomic Coordinates

Single crystals of rubidium tetrafluoridobromate(III), RbBrF4, were grown by melting and recrystallizing RbBrF4 from its melt. This is the first determination of the crystal structure of RbBrF4 using single-crystal X-ray diffraction data. We confirmed that the structure contains square-planar [BrF4]− anions and rubidium cations that are coordinated by F atoms in a square-antiprismatic manner. The compound crystallizes in the KBrF4 structure type. Atomic coordinates and bond lengths and angles were determined with higher precision than in a previous report based on powder X-ray diffraction data [Ivlev et al. (2015). Z. Anorg. Allg. Chem. 641, 2593–2598].

Crystallinity of YBa2Cu3O7−x single crystals grown by the pulling method

1996 ◽  
Vol 11 (4) ◽  
pp. 804-812 ◽  
Author(s):  
Y. Namikawa ◽  
M. Egami ◽  
S. Koyama ◽  
Y. Shiohara ◽  
H. Kutami
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Growth Direction ◽  
Annealed Sample ◽  
Seed Crystal ◽  
X Ray Diffraction ◽  
Rocking Curve ◽  
X Ray ◽  
Crystal Seed ◽  
Better Than

Large YBa2Cu3O7−x (Y123) single crystals (larger than 13 mm cubed) have been grown along the c-axis reproducibly by the modified pulling method. The crystallinity of Y123 single crystal was investigated by x-ray diffraction and x-ray topography. Crystals grown from an MgO single crystal seed had some low angle subgrain boundaries which tilted 0.1–0.8° from each other. These grain boundaries originated from the seed crystal, and the subgrains were extended along the growth direction from the seed crystal. Y123 single crystals with no marked subgrains in the whole area were obtained by using Y123 single subgrain crystal seeds. FWHM of the x-ray rocking curve for the crystal so produced was about 0.14°, which was much better than the spectrum consisting of several separated peaks obtained from the previous crystals. Tc onset of the annealed sample was about 93.6 K, and the transition width was about 0.9 K. The low angle subgrain boundaries did not seem to be effective pinning centers for the magnetic flux.

Optical, Structural and Spectroscopic Characterization of ZnS Nanocrystals Embedded in KBr Single Crystal Matrix Grown by Czochralski Method

2021 ◽  
Vol 406 ◽  
pp. 274-284
Author(s):  
Soria Zeroual ◽  
Mohammed Sadok Mahboub ◽  
Ghani Rihia ◽  
Mourad Mimouni ◽  
Ghougali Mebrouk ◽  
...  
Keyword(s):  
Single Crystal ◽  
Absorption Edge ◽  
Quantum Confinement Effect ◽  
Blue Shift ◽  
Czochralski Method ◽  
Spectroscopic Characterization ◽  
Czochralski Growth ◽  
X Ray Diffraction ◽  
Crystal Matrix ◽  
Zns Nanocrystals

ZnS nanocrystals were embedded in a KBr single crystal matrix using the Czochralski growth technique. The X-ray diffraction, FT-IR and optical spectroscopy revealed the incorporation of ZnS nanocrystals. A blue shift of the absorption edge of the obtained samples has been observed, indicating the quantum confinement effect. The optical band-gap is estimated to be about 4.67 eV. Two excitonic peaks appeared at 300.4 nm and 271 nm. The average nanocrystal size was derived from the optical spectra. Annealing led to a shift in the absorption edge towards longer wavelengths and an increasing of the emissions intensity. Raman lines of the nanoparticles are broader and frequency-shifted compared to those of the bulk crystals. These results show that KBr is a good matrix-host of ZnS nanocrystals, and that the elaborated samples can be used for important technological applications.

Refinement of the layered titanosilicate AM-1 from single-crystal X-ray diffraction data

2007 ◽  
Vol 63 (11) ◽  
pp. i186-i186 ◽  
Author(s):  
Stanislav Ferdov ◽  
Uwe Kolitsch ◽  
Christian Lengauer ◽  
Ekkehart Tillmanns ◽  
Zhi Lin ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Hydrogen Bonding ◽  
Single Crystal ◽  
Single Crystals ◽  
Diffraction Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Time ◽  
Ir And Raman ◽  
Bonding Scheme

The structure of the layered noncentrosymmetric titanosilicate AM-1 (also known as JDF-L1, disodium titanium tetrasilicate dihydrate), Na4Ti2Si8O22·4H2O, grown as small single crystals without the use of organics, has been refined from single-crystal X-ray diffraction data. The H atom has been located for the first time, and the hydrogen-bonding scheme is also characterized by IR and Raman spectroscopy. All atoms are in general positions except for the Na, the Ti, one Ti-bound O, one Si-bound O and the water O atoms (site symmetries 2, 4, 4, 2 and 2, respectively).

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