Fabrication and Optical Properties of Cr3+:YSAG Transparent Ceramics

2010 ◽  
Vol 434-435 ◽  
pp. 664-667 ◽  
Author(s):  
Tao Feng ◽  
Dan Yu Jiang ◽  
Jian Lin Shi
Keyword(s):  
Optical Properties ◽  
Crystal Field ◽  
Powder Compact ◽  
Combustion Method ◽  
Crystal Field Parameter ◽  
Emission Peak ◽  
Absorption Peak ◽  
Cubic Phase ◽  
Transparent Ceramics ◽  
Octahedral Crystal Field

Cr-doped Y3ScxAl(5-x)O12(Nd:YSAG) powder have been prepared with a combustion method. The powders are nanosized and a pure cubic phase when calcined at 900°C. Transparent Cr:YSAG ceramics were successfully fabricated by sintering the powder compact at 1800°C under H2 atmosphere. The optical properties were investigated in detail. It was found that after Sc substitute for Al, the The octahedral crystal-field parameter Dq and Dq/B was reduced, and that is why the absorption peak move to the longer wavelength side but the emission peak not moved.

Fabrication and Spectroscopic Properties of (Ho0.01La0.10Y0.89)2O3 Transparent Ceramics

2011 ◽  
Vol 299-300 ◽  
pp. 641-644 ◽  
Author(s):  
Dong Dong Huang ◽  
Qiu Hong Yang ◽  
Yong Gang Wang ◽  
Hao Jia Zhang
Keyword(s):  
Grain Size ◽  
Optical Properties ◽  
Spectroscopic Properties ◽  
Gain Medium ◽  
Emission Peak ◽  
Transparent Ceramics ◽  
Laser Gain

Highly transparent (Ho0.01La0.10Y0.89)2O3 transparent ceramics were fabricated by the conventional ceramics processing with nanopowders. The microstructure, the optical properties and the spectroscopic properties of (Ho0.01La0.10Y0.89)2O3 ceramics were investigated. (Ho0.01La0.10Y0.89)2O3 ceramics with the grain size of ~50 μm were obtained by sintering at 1530 °C for 45 h. The highest in-line transmittance reaches 65%. The emission peak located at 2 μm wavelength indicates (Ho0.01La0.10Y0.89)2O3 transparent ceramics is suitable for 2 μm laser gain medium.

Microstructure and Optical Properties of ZnS:Mn Nanocrystals

2013 ◽  
Vol 652-654 ◽  
pp. 192-196
Author(s):  
Jin Hua Ma ◽  
Chang Zheng Wang ◽  
Chang Yong Sun
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Hexagonal Phase ◽  
Blue Shift ◽  
Emission Peak ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Strong Emission ◽  
Luminescence Peak ◽  
Structure Morphology

Abstract. By using Na2S•9H2O as source precursor and citric acid as stabilizer, ZnS:Mn nanocrystallines were synthesized by solvothermal method. They were annealed at 800 oC in the charcoal powder. The structure, morphology and optical properties were investigated by using X-ray diffraction spectra (XRD), scanning electron microscopy (SEM), and Spectrofluorophotometer respectively. The results showed that all unannealed ZnS:Mn nanocrystallines were about 3~5 nm of particle size and have cubic structure, and all annealed samples were about 30-70 nm of particle size and have mixed structure of the cubic phase and hexagonal phase. Moreover, Mn2+ took the place of Zn2+ in ZnS:Mn. With the increment of Mn2+ content, there occurred a strong emission peak at about 596nm which can be attributed to the Mn2 + leap from 4T1 to 6A1. In addition, the intensity of 596nm emission peak first increased and then decreased with the increment of Mn2+ content, reaching a maximum at about 15% of Mn2+ content. After annealing Mn2+ emission peak intensity is about 20 times that before annealing, and the luminescence peak also showed slightly blue shift.

scholarly journals Structural and Magnetic Property of Cr3+ Substituted Cobalt Ferrite Nanomaterials Prepared by the Sol-Gel Method

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2095 ◽  
Author(s):  
Jinpei Lin ◽  
Jiaqi Zhang ◽  
Hao Sun ◽  
Qing Lin ◽  
Zeping Guo ◽  
...  
Keyword(s):  
Saturation Magnetization ◽  
Sol Gel ◽  
Combustion Method ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Cobalt Chromium ◽  
X Ray Diffraction ◽  
Chromium Doping ◽  
Auto Combustion ◽  
Cr Concentration

Cobalt-chromium ferrite, CoCrxFe2−xO4 (x = 0–1.2), has been synthesized by the sol-gel auto-combustion method. X-ray diffraction (XRD) indicates that samples calcined at 800 °C for 3 h were a single-cubic phase. The lattice parameter decreased with increasing Cr concentration. Scanning electron microscopy (SEM) confirmed that the sample powders were nanoparticles. It was confirmed from the room temperature Mössbauer spectra that transition from the ferrimagnetic state to the superparamagnetic state occurred with the doping of chromium. Both the saturation magnetization and the coercivity decreased with the chromium doping. With a higher annealing temperature, the saturation magnetization increased and the coercivity increased initially and then decreased for CoCr0.2Fe1.8O4.

Microstructure and Optical Properties of Co Sputter Deposited Si-Al Nanocomposite Thin Films

2000 ◽  
Vol 648 ◽  
Author(s):  
F. Niu ◽  
P.J. Dobson ◽  
B. Cantor
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Optical Absorption ◽  
Absorption Peak ◽  
Al Content ◽  
Al Nanoparticles ◽  
Transmission Electron ◽  
Effective Medium Theories ◽  
Nanocomposite Thin Films ◽  
Sputter Deposited

AbstractNovel Si-Al nanocomposite thin films were made by radio frequency co-sputtering of Si and Al with Al content from 0 at.% to 69 at.%. Microstructure and optical properties of the films were characterised by conventional and high resolution transmission electron microscopyand spectrometry in the wavelength range from 200 to 3000 nm. The film microstructure consisted of Al nanoparticles (2-9 nm) embedded in an amorphous Si-Al matrix. Optical absorption spectra of the films up to 50 at.% Al exhibited a sharp absorption peak below500 nm and relatively low absorption above 500 nm. In addition, the absorption peak shifted towards longer wavelengths and the general absorption above 500 nm increased remarkably as Al content increased. For the Si-69at.%Al films, however, an absorption plateau appeared between 300 nm to 700 nm and a second weak and broad absorption peak appeared at around 900 nm. The results are analysed and compared with the optical absorption predicted by various effective medium theories.

scholarly journals Cubic InGaN Grown by MOCVD

1999 ◽  
Vol 4 (S1) ◽  
pp. 239-243
Author(s):  
J.B. Li ◽  
Hui Yang ◽  
L.X. Zheng ◽  
D.P. Xu ◽  
Y.T. Wang
Keyword(s):  
Room Temperature ◽  
Emission Peak ◽  
Buffer Layers ◽  
Cubic Phase ◽  
Yellow Luminescence ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Cubic Gan ◽  
Pl Emission

We report on the growth of high-quality cubic phase InGaN on GaAs by MOCVD. The cubic InGaN layers are grown on cubic GaN buffer layers on GaAs (001) substrates. The surface morphology of the films are mirror-like. The cubic nature of the InGaN films is obtained by X-ray diffraction (XRD) measurements. The InGaN layers show strong photoluminescence (PL) at room temperature. Neither emission peak from wurtzite GaN nor yellow luminescence is observed in our films. The highest In content as determined by XRD is about 17% with an PL emission wavelength of 450 nm. The FWHM of the cubic InGaN PL peak are 153 meV and 216 meV for 427 nm and 450 nm emissions, respectively. It is found that the In compositions determined from XRD are not in agreement with those estimated from PL measurements. The reasons for this disagreement are discussed.

scholarly journals Effect of CeO2-ZnO Nanocomposite for Photocatalytic and Antibacterial Activities

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 817
Author(s):  
Asad Syed ◽  
Lakshmi Sagar Reddy Yadav ◽  
Ali H. Bahkali ◽  
Abdallah M. Elgorban ◽  
Deshmukh Abdul Hakeem ◽  
...  
Keyword(s):  
Surface Defects ◽  
Uv Light ◽  
Antibacterial Properties ◽  
Combustion Method ◽  
Antibacterial Activities ◽  
Cubic Phase ◽  
Solution Combustion ◽  
Tem Analysis ◽  
Bet Specific Surface Area ◽  
The Impact

The impact of a CeO2-ZnO nanocomposite on the photocatalytic and antibacterial properties compared to bare ZnO was investigated. A CeO2-ZnO nanocomposite was synthesized using Acacia nilotica fruit extract as a novel fuel by a simple solution combustion method. The obtained CeO2-ZnO nanocomposite was confirmed structurally by XRD, FTIR, Raman and UV-DRS and morphologically by SEM/TEM analysis. The XRD pattern indicates the presence of both hexagonal Wurtzite-structured ZnO (major) and cubic-phase CeO2 (minor). FTIR shows the presence of a Ce-O-Ce vibration at 468 cm−1 and Zn-O vibration at 445 cm−1. The existence of a band at 460 cm−1 confirmed the F2g Raman-active mode of the fluorite cubic crystalline structure for CeO2. Diffused reflectance spectroscopy was used to estimate the bandgap (Eg) from Kubelka–Munk (K–M) theory which was found to be 3.4 eV. TEM analysis shows almost spherical-shaped particles, at a size of about 10–15 nm. The CeO2-ZnO nanocomposite shows a good BET specific surface area of 30 m2g−1. The surface defects and porosity of the CeO2-ZnO nanocomposite caused methylene blue (MB) dye to degrade under sunlight (88%) and UV light (92%). The CeO2-ZnO nanocomposite also exhibited considerable antibacterial activity against a pathogenic bacterial strain.

Effect of MgO doping on the structure and optical properties of YAG transparent ceramics

2020 ◽  
Vol 40 (3) ◽  
pp. 861-866 ◽  
Author(s):  
I. Vorona ◽  
A. Balabanov ◽  
M. Dobrotvorska ◽  
R. Yavetskiy ◽  
O. Kryzhanovska ◽  
...  
Keyword(s):  
Optical Properties ◽  
Transparent Ceramics

scholarly journals Unraveling the Effects of Co-Crystallization on the UV/Vis Absorption Spectra of an N-Salicylideneaniline Derivative. A Computational RI-CC2 Investigation

Molecules ◽  
2020 ◽  
Vol 25 (19) ◽  
pp. 4512
Author(s):  
Jean Quertinmont ◽  
Tom Leyssens ◽  
Johan Wouters ◽  
Benoît Champagne
Keyword(s):  
Optical Properties ◽  
Crystal Field ◽  
Indirect Effects ◽  
Density Functional ◽  
Crystal Packing ◽  
Density Functional Theory Method ◽  
Oscillator Strengths ◽  
Excitation Energies ◽  
Keto Form ◽  
Cell Parameters

This work aims at unraveling the effects of co-crystallization on the optical properties of an N-salicylideneaniline-derived molecular switch transforming between an enol and a keto form. This is achieved by way of a two-step multi-scale method where (i) the molecular geometry and unit cell parameters are optimized using a periodic boundary conditions density functional theory method and (ii) the optical properties are computed for a selection of clusters embedded in an array of point-charges that reproduce the crystal field electronic potential. The optical properties (vertical excitation energies and oscillator strengths) are obtained at the RI-CC2/def2-TZVPD level of approximation. This method allows us to decompose the effects of co-crystallization into (i) indirect effects, the geometry changes of the chromophore due to crystal packing with the coformer, and (ii) direct ones, the polarization due to the interacting coformer and to the crystal field. For the former effects, variations of a crucial torsion angle lead to modification of the π-conjugation and therefore to the decrease or increase of the excitation energies. About the latter, they are antagonistic: (i) the coformer is not directly involved in the excitations but its polarization decreases the excitation energies while (ii) the crystal field has the opposite effect. For the co-crystals with succinic and fumaric acids, combining these direct and indirect effects leads to a hypsochromic shift of the first absorption band with respect to the reference crystal, in agreement with experimental data.

The Role of Reduced Graphene Oxide Concentration as Ablated Material on Optical Properties of Graphene Quantum Dots

2019 ◽  
Vol 948 ◽  
pp. 267-273 ◽  
Author(s):  
Fiqhri Heda Murdaka ◽  
Ahmad Kusumaatmaja ◽  
Isnaeni ◽  
Iman Santoso
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Graphene Oxide ◽  
Band Gap ◽  
Reduced Graphene Oxide ◽  
Optical Band Gap ◽  
Graphene Quantum Dots ◽  
Absorption Peak ◽  
Oxygen Defect ◽  
Reduced Graphene

We report the synthesize of Graphene Quantum Dots (GQDs) using ablation method with reduced Graphene Oxide (rGO) solution as a starting material. We have varied the concentration of rGO as following: 0.5, 2, 5 mg/ml and then have ablated them using 800 nm Ti-Sapphire femtosecond laser to obtain GQDs. From the UV-Vis data, we observed that the more concentration of rGO is being ablated, the more secondary absorption peak at 255.1 nm appeared. This secondary absorption peak is a characteristic of n-π* bonding due to the presence of oxygen defect which occurs as a result of the interaction between the laser and the water in rGO solution. We conclude that the population of oxigen defect in GQDs is increasing, following the increase of rGO concentration and could alter the optical properties of GQD. On the other hand, using Tauc’s plot, we confirm that the increase of rGO concentration as the ablated material does not alter GQDs optical band gap. However, it will slightly reduce both, direct and indirect Oxygen defect related optical band gap.

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