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 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.

Optical Properties and Defect Study of Ca2+ Co-Doping Lu2Si2O7:Ce3+ Single Crystal Scintillator

2013 ◽  
Vol 652-654 ◽  
pp. 616-621
Author(s):  
He Feng ◽  
Guo Hao Ren ◽  
Dong Zhou Ding ◽  
Huan Ying Li ◽  
Fang Lei
Keyword(s):  
Single Crystal ◽  
Electron Transition ◽  
Czochralski Method ◽  
Optical Quality ◽  
Thermally Stimulated Luminescence ◽  
X Ray ◽  
Co Doping ◽  
Luminescence Efficiency ◽  
Two Peaks ◽  
Excited Luminescence

Single crystal of Lu2Si2O7 (LPS):0.5%Ce,0.1%Ca was grown by the Czochralski method. The X-ray excited luminescence (XEL), photoluminescence excitation (PLE), photoluminescence (PL) and transmittance spectra were measured and discussed. The as grown LPS:Ce,Ca sample presents excellent optical quality with 81% transmittance. Two absorption peaks locate at 300 and 350 nm, corresponding to the electron transition of Ce3+ from 4f ground to 5d1 and 5d2 respectively. According to the Gaussian fitting, the XEL curve of LPS:Ce,Ca can be fitted into two peaks centering at 378 and 407 nm respectively. It is found that the addition of Ca2+ in LPS:Ce introduces more oxygen vacancies, leading to the decreases of the luminescence efficiency of LPS:Ce. Through the thermally stimulated luminescence (TSL) measurement, two kinds of charge trap are found in LPS:Ce,Ca, whose energy depths are 1.20 and 1.47 eV. The trap at 1.20 eV is intrinsic electron trap induced by Ce3+ doping in LPS host and the other trap is formed by the both impact of and defects.

scholarly journals Optimized Growth and Laser Application of Yb:LuAG Single-Crystal Fibers by Micro-Pulling-Down Technique

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 78
Author(s):  
Anye Wang ◽  
Jian Zhang ◽  
Shuai Ye ◽  
Xiaofei Ma ◽  
Baiyi Wu ◽  
...  
Keyword(s):  
Single Crystal ◽  
High Power ◽  
Slope Efficiency ◽  
Continuous Wave ◽  
Beam Quality ◽  
Axial Direction ◽  
Optical Quality ◽  
Central Wavelength ◽  
High Power Lasers ◽  
Crystal Fibers

Single-crystal fibers (SCFs) have a great application potential in high-power lasers due to their excellent performance. In this work, high-quality and crack-free Yb3+:Lu3Al5O12 (Yb:LuAG) SCFs were successfully fabricated by the micro-pulling-down (μ-PD) technology. Based on the laser micrometer and the X-ray Laue diffraction results, these Yb:LuAG SCFs have a less than 5% diameter fluctuation and good crystallinity along the axial direction. More importantly, the distribution of Yb ions is proved to be uniform by electron probe microanalysis (EPMA) and the scanning electron microscope (SEM). In the laser experiment, the continuous-wave (CW) output power using a 1 mm diameter Yb:LuAG single-crystal fiber is determined to be 1.96 W, at the central wavelength of 1047 nm, corresponding to a slope efficiency of 13.55%. Meanwhile, by applying a 3 mm diameter Yb:LuAG SCF, we obtain a 4.7 W CW laser output at 1049 nm with the slope efficiency of 22.17%. The beam quality factor M2 is less than 1.1 in both conditions, indicating a good optical quality of the grown fiber. Our results show that the Yb:LuAG SCF is a potential solid-state laser gain medium for 1 μm high-power lasers.

Single crystal growth of Ga 3 Ni 2 by the Czochralski method

2016 ◽  
Vol 449 ◽  
pp. 114-118 ◽  
Author(s):  
Magdalena Wencka ◽  
Mirtha Pillaca ◽  
Peter Gille
Keyword(s):  
Crystal Growth ◽  
Single Crystal ◽  
Czochralski Method ◽  
Single Crystal Growth

Spectroscopic study of the TbAl3(BO3)4 single crystal: Raman and luminescence spectroscopy

2020 ◽  
Vol 46 (12) ◽  
pp. 1223-1230
Author(s):  
A. V. Peschanskii ◽  
A. Yu. Glamazda ◽  
I. A. Gudim
Keyword(s):  
Single Crystal ◽  
Spectroscopic Study ◽  
Luminescence Spectroscopy

Crucibleless crystal growth and Radioluminescence study of calcium tungstate single crystal fiber

2014 ◽  
Vol 37 ◽  
pp. 51-54 ◽  
Author(s):  
M.S. Silva ◽  
L.M. Jesus ◽  
L.B. Barbosa ◽  
D.R. Ardila ◽  
J.P. Andreeta ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Single Crystal ◽  
Calcium Tungstate ◽  
Crystal Fiber

scholarly journals Bounds on the complex permittivity of polycrystalline materials by analytic continuation

2015 ◽  
Vol 471 (2174) ◽  
pp. 20140702 ◽  
Author(s):  
A. Gully ◽  
J. Lin ◽  
E. Cherkaev ◽  
K. M. Golden
Keyword(s):  
Sea Ice ◽  
Single Crystal ◽  
Analytic Continuation ◽  
Complex Permittivity ◽  
Crystal Orientation ◽  
Fluid Transport ◽  
Continuation Method ◽  
Growth Conditions ◽  
Polycrystalline Materials ◽  
Remote Sensing Techniques

An analytic continuation method for obtaining rigorous bounds on the effective complex permittivity ε * of polycrystalline composite materials is developed. It is assumed that the composite consists of many identical anisotropic crystals, each with a unique orientation. The key step in obtaining the bounds involves deriving an integral representation for ε *, which separates parameter information from geometrical information. Forward bounds are then found using knowledge of the single crystal permittivity tensor and mean crystal orientation. Inverse bounds are also developed, which recover information about the mean crystal orientation from ε *. We apply the polycrystalline bounds to sea ice, a critical component of the climate system. Different ice types, which result from different growth conditions, have different crystal orientation and size statistics. These characteristics significantly influence the fluid transport properties of sea ice, which control many geophysical and biogeochemical processes important to the climate and polar ecosystems. Using a two-scale homogenization scheme, where the single crystal tensor is numerically computed, forward bounds for sea ice are obtained and are in excellent agreement with columnar sea ice data. Furthermore, the inverse bounds are also applied to sea ice, helping to lay the groundwork for determining ice type using remote sensing techniques.

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.

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