Photoreflectance Characterization of InGaAs Lattice Matched to InP

1993 ◽  
Vol 324 ◽  
Author(s):  
V. Bellani ◽  
M. Amiotti ◽  
M. Geddo ◽  
G. Guizzetti ◽  
G. Landgren
Keyword(s):  
Energy Gap ◽  
Lattice Mismatch ◽  
Blue Shift ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Interfacial Strain ◽  
Valence Bands ◽  
Lattice Matched

AbstractWe measured photoreflectance (PR) spectra at different temperatures between 80 and 300 K, and optical absorption (OA) at 3 K on MOVPE grown Inl-xGaxAs nearly lattice-matched to InP. x-ray diffraction measurements gave a lattice mismatch δa/ao = -0.9.10−3 between ternary alloy and InP, corresponding to × = 0.485. We obtained the energy gap dependence on T from PR spectra. The blue shift of the gap was accounted for in terms of compositional difference with respect to the perfectly lattice matched alloy (× = 0.472), and elastic strain; moreover PR and OA showed evidence of the valence bands splitting at k = 0 due to interfacial strain, in fine agreement with theory.

scholarly journals Structural and morphological characterization of rare earth modified lead titanate

Cerâmica ◽  
2007 ◽  
Vol 53 (328) ◽  
pp. 422-447
Author(s):  
F. C. D. Lemos ◽  
D. M. A. Melo ◽  
P. S. de Lima ◽  
C. A. Paskocimas ◽  
E. Longo ◽  
...  
Keyword(s):  
Rare Earth ◽  
Lead Titanate ◽  
Pechini Method ◽  
Morphological Characterization ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Crystallite Sizes ◽  
Modifier Cation

Rare earth modified lead titanate powders Pb1-xRExTiO3 (REPT), x = 0.01, 0.05, 0.07 and RE = Yb, Y, were prepared by the Pechini method. The materials were calcined under flowing oxygen at different temperatures from 300 to 700 ºC. Nanostructured REPT were investigated using X-ray diffraction, scanning electron microscopy and surface area analysis (BET). The results suggest that the modifier cation incorporated into the system has notable influence in the microstructure and a notable decrease in the crystallite sizes.

Synthesis and Characterization of Green Tea Stabilized Iron Nanocatalysts for Brymothymol Blue (BTB) Degradation

2016 ◽  
Vol 42 ◽  
pp. 1-13
Author(s):  
David Mutuku Katithi ◽  
Immaculate N. Michira ◽  
Peterson M. Guto ◽  
Priscilla Gloria Lorraine Baker ◽  
Geoffrey N. Kamau ◽  
...  
Keyword(s):  
Green Tea ◽  
Dye Degradation ◽  
Degradation Kinetics ◽  
Environmental Pollutant ◽  
X Ray Diffraction ◽  
Tunneling Microscopy ◽  
X Ray ◽  
First Order Kinetics ◽  
Different Temperatures

Iron nanoparticles (FeNPs) were prepared from the green tea extracts at different temperatures through green synthesis procedure and characterized by various physicochemical techniques like UV-Visible spectroscopy, FTIR Spectroscopy, energy dispersive X-ray spectrometry (EDS), X-ray diffraction and high resolution tunneling microscopy (HRTEM) and the results confirmed the synthesis of polydisperse and stable FeNPs by the tea extracts. The catalytic activity of FeNPs was investigated using a common environmental pollutant BTB often used in textile industries for dyeing purposes. In these tests, catalytic degradation of BTB with FeNPs at a 10 μL or 30 μL concentration was done in the presence of 2% hydrogen peroxide. Results show no BTB degradation in the absence of the FeNPs. However, a 38% and 68% degradation of BTB was realized in the presence of 10μL and 30 μL FeNPs respectively indicating that the iron nanocatalysts were responsible for the dye degradation. The BTB degradation kinetics was found to follow pseudo-first order kinetics with rate constants at the two catalyst concentrations being 0.023 min-1 and 0.063 min-1 respectively.

Preparation and Characterization of Doped Nanometer TiO2

2007 ◽  
Vol 26-28 ◽  
pp. 649-652 ◽  
Author(s):  
Lin Yun Song ◽  
Yu Cheng Wu ◽  
Xiang Fen Lu
Keyword(s):  
Degradation Rate ◽  
Sol Gel ◽  
Complexing Agent ◽  
Gel Formation ◽  
X Ray Diffraction ◽  
Nano Tio2 ◽  
Doped Tio2 ◽  
X Ray ◽  
Different Temperatures

With Ti(OBu)4 as precursor, and HAC as complexing agent, pure and Fe-doped TiO2 gelatins were prepared by sol-gel method. During the process of gel formation, metal ions were dispersed into the porous TiO2 matrix. Then, powders of pure nano-TiO2 and Fe-doped nano-TiO2 were prepared by drying, grinding and calcining at different temperatures. The grain size and phase structure of pure and Fe-doped TiO2 after calcined at different temperatures, were studied by X-ray diffraction (XRD) and Beckman Coulter Sorption Analysis. The results showed that, the Fe3+-TiO2 had better photocatalytic activity in degradation rate of methyl orange under sunlight. The degradation rate was up to 93% as the system was placed under sunlight for 5 h. The optimum calcination temperature for the best catalytic activity was determined to be 500°C, and the mechanism was discussed.

Optical and X-Ray Diffraction Characterization of MBE-Grown InGaAs, InAlAs and InGaAIAs on InP

1994 ◽  
Vol 340 ◽  
Author(s):  
Z. C. Feng ◽  
S. J. Chua ◽  
A. Raman ◽  
N.N. Lim
Keyword(s):  
Optical Properties ◽  
Fourier Transform ◽  
Molecular Beam ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
Double Crystal ◽  
X Ray ◽  
Lattice Matched ◽  
Comprehensive Characterization

ABSTRACTA variety of Inl-xGaxAs, Inl-yAlyAs and Inl-x-yGaxAlyAs films have been grown on InP by molecular beam epitaxy. A comprehensive characterization was performed using Raman scattering, photoluminescence (PL), Fourier transform infrared (FTIR) spectroscopy and double crystal X-ray diffraction on these ternary and quaternary heterostructures with different compositions and growth conditions. The lattice matched and mismatched structures are studied. Our analyses show that the interface mismatch exerts an important influence on the optical properties of these heterostructures, and conversely that Raman, PL and FTIR can be used to probe the interface mismatch nondestructively.

Synthesis and Characterization of Co/SBA-15 Catalysts

2016 ◽  
Vol 881 ◽  
pp. 35-40
Author(s):  
Franciele Oliveira Costa ◽  
Carla Gabriela Azevedo Misael ◽  
André Miranda da Silva ◽  
Bianca Viana de Sousa
Keyword(s):  
Molecular Sieve ◽  
Pore Diameter ◽  
Mesoporous Structure ◽  
X Ray Diffraction ◽  
Average Pore ◽  
Wet Impregnation ◽  
X Ray ◽  
Different Temperatures ◽  
Temperature Programmed

The mesoporous silica SBA-15 molecular sieve has been widely studied due to its unidirectional mesoporous structure, its high average pore diameter, its high thermal and hydrothermal stability and its ability to absorb metal ions, allowing its use as support material for catalysts. This study aimed to synthesize the Co/SBA-15 catalyst, and characterize it through the techniques of X-ray diffraction, temperature programmed reduction (TPR) and scanning electron microscopy (SEM). The SBA-15 support was synthesized from the following molar composition of reaction mixture: 1TEOS: 0.017 P123: 5.7 HCl: 173 H2O: 40 EtOH, and after calcined at 550 °C for 6 hours. The Co/SBA-15 catalyst was prepared by incorporating 10% cobalt by wet impregnation. Through the X-ray diffractograms, it was found that the impregnation has not changed the structure of the material. RTP profiles showed the presence of peaks at different temperatures that may be caused by dispersion of the cobalt.

scholarly journals Characterization of Donut-Like SrMoO4Produced by Microwave-Hydrothermal Process

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Surangkana Wannapop ◽  
Titipun Thongtem ◽  
Somchai Thongtem
Keyword(s):  
Vibration Mode ◽  
Energy Gap ◽  
Hydrothermal Process ◽  
X Ray Diffraction ◽  
Hierarchical Nanostructures ◽  
X Ray ◽  
Microwave Hydrothermal ◽  
Stretching Vibration ◽  
One Step

SrMoO4hierarchical nanostructures were successfully produced by a one step of 270 W microwave-hydrothermal process of one of the solutions containing three strontium salts [Sr(NO3)2, Sr(CH3CO2)2, and SrCl2·6H2O] and (NH4)6Mo7O24·4H2O for different lengths of time. The as-produced products were characterized by X-ray diffraction, electron microscopy, and spectroscopy. In this research, they were primitive tetragonal structured donut-like SrMoO4, with the main 881cm−1  ν1(Ag)symmetric stretching vibration mode of[MoO4]2−units and 3.92 eV energy gap.

Fe3O4/MgO Superlattices Grown on MgO(OOl) and Fe/MgO(001) by Molecular Beam Epitaxy

1997 ◽  
Vol 474 ◽  
Author(s):  
G. Chern ◽  
C. L. Chang ◽  
Y. R. Chean
Keyword(s):  
Molecular Beam ◽  
Lattice Mismatch ◽  
High Energy ◽  
High Energy Electron ◽  
X Ray Diffraction ◽  
Oxide Interface ◽  
High Crystalline Quality ◽  
X Ray ◽  
Coated Surface

AbstractThe growth and structural characterization of Fe3O4/MgO superlattices on MgO(001) and Fe-coated MgO(001) are compared. Long modulated coherence and sharp interface are revealed by X-ray diffraction and reflection high energy electron diffraction (RHEED). For the superlattice grown directly on MgO(001), high crystalline quality is comparable to the previous report on the oxide superlattice system. For the superlattice grown on Fe/MgO(001), both chemical and lattice spacing modulations are maintained which is different from the polycrystlline structure of the Fe3O4/NiO grown on Ni-based system. This superiority of the growth on Fe-coated surface results from both the smaller lattice mismatch and the oxidation state of Fe relative to MgO. The changes of the RHEED intensity during the growth of these superlattices are also measured. The evolution of the oxide interface during the growth of Fe3O4/MgO is quantitatively presented.

scholarly journals Growth and Characterization of High-Quality GaN Nanowires on PZnO and PGaN by Thermal Evaporation

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
L. Shekari ◽  
H. Abu Hassan ◽  
S. M. Thahab ◽  
Z. Hassan
Keyword(s):  
Gallium Nitride ◽  
Thermal Evaporation ◽  
Lattice Mismatch ◽  
Growth Direction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gan Nanowires ◽  
Transmission Electron

In the current research, an easy and inexpensive method is used to synthesize highly crystalline gallium nitride (GaN) nanowires (NWs) on two different substrates [i.e., porous zinc oxide (PZnO) and porous gallium nitride (PGaN)] on Si (111) wafer by thermal evaporation without any catalyst. Microstructural studies by scanning electron microscopy and transmission electron microscope measurements reveal the role of the substrates in the nucleation and alignment of the GaN NWs. Further structural and optical characterizations were performed using high-resolution X-ray diffraction, energy-dispersive X-ray spectroscopy, and photoluminescence spectroscopy. Results indicate that the NWs have a single-crystal hexagonal GaN structure and growth direction in the (0001) plane. The quality and density of GaN NWs grown on different substrates are highly dependent on the lattice mismatch between the NWs and their substrates. Results indicate that NWs grown on PGaN have better quality and higher density compared to NWs on PZnO.

scholarly journals Preparation and Characterization of CoevaporatedCd1−xZnxSAlloy Thin Films

2011 ◽  
Vol 2011 ◽  
pp. 1-5 ◽  
Author(s):  
Wei Li ◽  
Jiayi Yang ◽  
Zhen Sun ◽  
Lianghuan Feng ◽  
Jingquan Zhang ◽  
...  
Keyword(s):  
Thin Films ◽  
Fluorescence Spectra ◽  
Zinc Content ◽  
Blue Shift ◽  
Optical Transmittance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Novel Structure ◽  
Vegard’S Law

Cd1-xZnxSthin films have been prepared by the vacuum coevaporation method. The structural, compositional, and optical properties ofCd1-xZnxSthin films have been investigated using X-ray diffraction, X-ray fluorescence, and optical transmittance spectra. As-depositedCd1-xZnxSthin films are polycrystalline and show the cubic structure forx=1and hexagonal one forx<1with the highly preferential orientation. The composition ofCd1-xZnxSthin films determined from Vegard's law and quartz thickness monitors agrees with that determined from the X-ray fluorescence spectra. Optical absorption edge of optical transmittance forCd1-xZnxSthin films shows a blue shift with the increase of the zinc content. The band gap forCd1-xZnxSthin films can be tuned nonlinearly withxfrom about 2.38 eV for CdS to 3.74 eV for ZnS. A novel structure for CuInS2-based solar cells with aCd0.4Zn0.6Slayer is proposed in this paper.

Phase Transformation of Biphasic Granules of Gypsum and Carbonated Apatite at Low Temperatures

2016 ◽  
Vol 1133 ◽  
pp. 50-54 ◽  
Author(s):  
Siti Noorzidah Mohd Sabri ◽  
Syazana Abu Bakar ◽  
Abdul Yazid Abdul Manaf ◽  
Siti Farhana Hisham ◽  
Mohamad Azmirruddin Ahmad ◽  
...  
Keyword(s):  
Cross Section ◽  
Low Temperatures ◽  
Carbonate Content ◽  
X Ray Diffraction ◽  
X Ray ◽  
Carbonated Apatite ◽  
Infra Red ◽  
Different Temperatures ◽  
Bone Apatite

The purpose of this study was to prepare biphasic granules containing gypsum and carbonated apatite at low temperatures. The biphasic granules were prepared using dissolution-precipitation technique at three different temperatures 30°C, 40°C and 50°C. Characterization of the biphasic granules was determined by multiple analytical methods such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra-red (FTIR), and CHN Analysis. The obtained granules were determined by XRD as biphasic granules containing bone apatite and gypsum. The cross-section of biphasic granules was observed by SEM. The formed bone apatite was identified as B-Type carbonated apatite using FTIR The carbonate content in biphasic granules fabricated at 30°C, 40°C and 50°C were recorded by CHN analysis as 5.0 wt%, 6.1 wt% and 6.25 wt%, respectively.

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