Synthesis and Luminescence Properties of Alumina Encapsulated InN Nanorods

2008 ◽  
Vol 8 (12) ◽  
pp. 6290-6296
Author(s):  
Ajay Kumar Mann ◽  
Deepak Varandani ◽  
Bodh Raj Mehta ◽  
Lalit Kumar Malhotra ◽  
G. Mangamma ◽  
...  
Keyword(s):  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Alumina Membrane ◽  
Temperature Plasma ◽  
Cross Sectional ◽  
Scanning Electron Microscope Study ◽  
X Ray ◽  
Step Procedure ◽  
Plasma Annealing

The present study reports a two-step procedure to synthesize InN nanorods inside the pores of an anodic alumina membrane. In the first step, pores of the membrane are filled with indium via electrodeposition. The second step involves nitridation of the as-deposited nanorods by room temperature plasma annealing. X-ray diffraction studies reveal that as-deposited nanorods consist of In, In2O3 and In(OH)3 phases which get converted to mixed hexagonal and cubic phase InN on plasma annealing. Cross sectional scanning electron microscope study reveals nanorod diameter and length to be 150 nm and 1 μm respectively. X-ray mapping results establish that uniform distribution of nitrogen throughout the length of nanorod has been achieved as a result of plasma annealing. Observation of photoluminescence peaks at 1.4 and 1.6 eV corresponding, to the absorption edges of cubic and hexagonal phases of InN show that room temperature photoemission is due to band to band recombination. The use of alumina as a template for nanorod growth prevents postdeposition agglomeration and provides mechanical strength. Possibility of total internal reflection at the InN-Al2O3 interface makes these structures ideally suitable to reduce the emitted light intensity losses.

X-ray diffraction study of oxygen-conducting compoundsLn2Mo2O9(Ln= La, Pr)

2014 ◽  
Vol 70 (4) ◽  
pp. 669-675 ◽  
Author(s):  
Alexander M. Antipin ◽  
Olga A. Alekseeva ◽  
Natalia I. Sorokina ◽  
Alexandra N. Kuskova ◽  
Michail Yu. Presniakov ◽  
...  
Keyword(s):  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Ion Migration ◽  
Transmission Microscopy ◽  
Coordination Environment ◽  
X Ray ◽  
Oxygen Ions ◽  
Oxygen Ion ◽  
Oxygen Ion Migration

The La2Mo2O9(LM) and Pr2Mo2O9(PM) single crystals are studied using precision X-ray diffraction and high-resolution transmission microscopy at room temperature. The crystal structures are determined in the space groupP213. La and Pr atoms, as well as Mo1 and O1 atoms, are located in the vicinity of the threefold axes rather than on the axes as in the high-temperature cubic phase. In both structures studied, the O2 and O3 positions are partially occupied. The coexistence of different configurations of the Mo coordination environment facilitates the oxygen-ion migration in the structure. Based on the X-ray data, the activation energies of O atoms are calculated and the migration paths of oxygen ions in the structures are analysed. The conductivity of PM crystals is close to that of LM crystals. The O2 and O3 atoms are the main contributors to the ion conductivity of LM and PM.

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.

Low-temperature crystal structure of RS-thiocamphor

2004 ◽  
Vol 219 (9) ◽  
Author(s):  
E. Louise R. Robins ◽  
Michela Brunelli ◽  
Asiloé J. Mora ◽  
Andrew N. Fitch
Keyword(s):  
Crystal Structure ◽  
Phase Transitions ◽  
Low Temperature ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Orthorhombic Space Group ◽  
Two Phase ◽  
X Ray ◽  
Low Temperature Crystal Structure

AbstractDSC and high-resolution powder X-ray diffraction measurements in the range 295 K–100 K show that RS-thiocamphor undergoes two phase transitions. The first, at around 260 K on cooling, is from the room-temperature body-centred-cubic phase to a short-lived intermediate. At 258 K the low-temperature form starts to appear. The crystal structure of the latter is orthorhombic, space group

Study on Phase Structure and Electrical Properties of La-Doped (K0.5Na0.5)0.94Li0.06NbO3 Ceramics

2011 ◽  
Vol 328-330 ◽  
pp. 1127-1130 ◽  
Author(s):  
Yong Liu ◽  
Rui Qing Chu ◽  
Zhi Jun Xu ◽  
Qian Chen ◽  
Lin Shao ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Phase Structure ◽  
Room Temperature ◽  
Cubic Phase ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
La Doping ◽  
La Doped ◽  
Lower Loss

Lead-free piezoceramics (K0.5Na0.5)0.94-3xLi0.06LaxNbO3were synthesized by the conventional solid-state reaction process. The effect of La-doping on the phase structure and electrical properties of (K0.5Na0.5)0.94Li0.06NbO3ceramics was investigated. X-ray diffraction analysis showed that the crystal structure of the ceramics changed from coexistence of orthorhombic and tetragonal phases to pseudo-cubic phase with the increase of La-doping level, and the change of phase structure seriously weakened the dielectric, ferroelectric and piezoelectric properties of the ceramics. In addition, it was found that the La-doping improved the density of the ceramics and the ceramics became dense. Meanwhile, the ceramics with La-doping displayed a relative lower loss tangent (tanδ) from room temperature to approximately 350°C.

Phase Diagram and Cation Dynamics of Mixed MA1-xFAxPbBr3 Hybrid Perovskites

2021 ◽  
Author(s):  
Mantas Simenas ◽  
Sergejus Balčiūnas ◽  
Sarunas Svirskas ◽  
Martynas Kinka ◽  
Maciej Ptak ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Room Temperature ◽  
Structural Phase ◽  
Cubic Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dielectric Relaxations ◽  
Broadband Dielectric Spectroscopy ◽  
Molecular Cation

<p>We use a multi-technique approach to determine the phase diagram and molecular cation dynamics of mixed methylammonium-formamidinium MA1-xFAxPbBr3 (0 ≤ x ≤ 1) hybrid perovskites. The calorimetric, ultrasonic and X-ray diffraction experiments show a substantial suppression of the structural phase transitions and stabilization of the cubic phase upon mixing. We use the broadband dielectric and Raman spectroscopies to study the MA and FA cations dynamics in these compounds. The broadband dielectric spectroscopy indicates absence of the MA cation ordering and a gradual increase of the rotation barrier upon mixing. The room-temperature dielectric permittivity substantially decreases as the fraction of the FA cations is increased. No significant changes of the permittivity are detected at temperatures where the dielectric relaxations are absent. We also observe weak signatures of a dipolar glass phase for the highest mixing level (x = 0.5). The Raman spectroscopy supports the dielectric results and reveals additional subtle information about the FA cation dynamics.</p><br>

Effect of Time on the Fabrication of Bioresorbable Biphasic Granules of Gypsum-Carbonated Apatite for Paediatric Orthopaedic Application

2016 ◽  
Vol 1133 ◽  
pp. 60-64
Author(s):  
Syazana Abu Bakar ◽  
Siti Farhana Hisham ◽  
Mohamad Azmirruddin Ahmad ◽  
Abdul Yazid Abdul Manaf ◽  
Siti Noorzidah Mohd Sabri
Keyword(s):  
Room Temperature ◽  
Xrd Analysis ◽  
Calcium Sulphate ◽  
Carbonate Apatite ◽  
Artificial Bone ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Carbonated Apatite ◽  
Paediatric Orthopaedic

A carbonated apatite (CO3Ap) has a closer chemical composition to the bone mineral which may be suit as an artificial bone substitute. In this study, the fabrication works of biphasic gypsum-carbonated apatite granules has been done through the phase transformation by carbonation and phosphorization of the gypsum granules. Gypsum also known as calcium sulphate dihydrate (CSD) granules was immersed into the 2 M of carbonate and phosphate salt solution at 50 °C and room temperature in variable time. The effect of time on the fabrication of biphasic granules were studied using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier transform infrared (FTIR). The XRD analysis was done to confirm the formation of gypsum and hydroxyapatite phases in the biphasic granules. The FTIR spectroscopy indicated that the formation of carbonate apatite was formed in these biphasic granules. The cross sectional morphology of the biphasic granules was observed using SEM. The compositional elucidation was quantitatively measured by CHN analysis to obtain the contents of CO3.Based on the results obtained, it is observed that the CSD was successfully transformed into carbonated apatite to form biphasic granules and time had influenced on the fabrication of these biphasic.

Effects of 0.03MF2 – 0.12LiF (M = Ca, Sr, Ba) on the Sintering and Dielectric Properties of SrTiO3 Ceramics

2013 ◽  
Vol 9 ◽  
pp. 1-12
Author(s):  
Laldja Taïbi-Benziada ◽  
Hassiba Kermoun ◽  
Yasmina Belaroussi
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Sintering Temperature ◽  
Cubic Phase ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Frequency Independent ◽  
Cold Pressed ◽  
Piezoelectric Devices

Cold-pressed pellets were prepared from the mixtures SrTiO3- 0.03MF2- 0.12LiF, M = Ca, Sr or Ba, then air-fired at 950 °C for 2 hours. The obtained samples were investigated by X-ray diffraction and scanning electron microscopy. Each ceramic is a perovskite single phase and the relative density reaches 95% for all ceramics. The addition of 3 mol. % of the eutectic composition 1MF2- 4LiF (Tm~ 760 °C) to SrTiO3lowers the sintering temperature of pure strontium titanate from 1400 °C to 950 °C and induces a strong modification in the SrTiO3cubic phase: superlattice reflections are detected and the unit cell symmetry becomes orthorhombic. Dielectric measurements were performed between - 150 °C and 200 °C in the frequency range 20 Hz - 109Hz. The dielectric permittivity εrshowed no maximum in the temperature range investigated and is almost frequency independent. At room temperature, the dielectric losses tanδ are less than 0.1 %. Moreover, the frequency dependence of the complex permittivity exhibits a resonance in the microwave region. These fluorinated ceramics could be of interest in piezoelectric devices and are promising dielectrics for class I capacitors manufactured at low temperature.

Synthesis and Characterization of A Metastable (SiC)aN4 Phase

1994 ◽  
Vol 354 ◽  
Author(s):  
C. Uslu ◽  
B. Park ◽  
D. B. Poker
Keyword(s):  
Cubic Phase ◽  
High Dose ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Position Sensitive ◽  
New Phase

AbstractA metastable C-Si-N compound has been synthesized by high dose N+ implantation into polycrystalline /8-SiC (cubic phase). The thin films formed upon 100 keV implantations were characterized with respect to various ion doses and target temperatures. X-ray diffraction with a position-sensitive detector and cross-sectional transmission electron microscopy revealed that the as-implanted surfaces contained ∼0.15 jttm thick continuously-buried amorphous layers. Rutherford backscattering spectroscopy showed that the peak concentration of nitrogen saturated up to approximately 54 at. % with increasing doses, suggesting a new phase formation.

scholarly journals Argon irradiation effects on the structural and optical properties of reactively sputtered CrN films

2015 ◽  
Vol 47 (2) ◽  
pp. 187-194 ◽  
Author(s):  
M. Novakovic ◽  
M. Popovic ◽  
N. Bibic
Keyword(s):  
Optical Properties ◽  
Room Temperature ◽  
Optical Parameters ◽  
Total Thickness ◽  
X Ray Diffraction ◽  
Irradiation Effects ◽  
Structural And Optical Properties ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron

The present study deals with CrN films irradiated at room temperature (RT) with 200 keV Ar+ ions. The CrN layers were deposited by d.c. reactive sputtering on Si (100) wafers, at nitrogen partial pressure of 5?10-4 mbar, to a total thickness of 280 nm. The substrates were held at 150?C during deposition. After deposition the CrN layers were irradiated with 200 keV Ar+ ions to the fluences of 5?1015 - 2?1016 ions/cm2. Structural characterization was performed with Rutherford backscattering spectroscopy (RBS), cross-sectional transmission electron microscopy (XTEM) and X-ray diffraction (XRD). Spectroscopic ellipsometry measurements were carried out in order to study optical properties of the samples. The irradiations caused the microstructrual changes in CrN layers, but no amorphization even at the highest argon fluence of 2?1016 ions/cm2. Observed changes in microstructure were correlated with the variation in optical parameters. It was found that both refractive index and extinction coefficient are strongly dependent on the defect concentration in CrN layers.

Phase Diagram and Cation Dynamics of Mixed MA1-xFAxPbBr3 Hybrid Perovskites

2021 ◽  
Author(s):  
Mantas Simenas ◽  
Sergejus Balčiūnas ◽  
Sarunas Svirskas ◽  
Martynas Kinka ◽  
Maciej Ptak ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Room Temperature ◽  
Structural Phase ◽  
Cubic Phase ◽  
Structural Phase Transitions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dielectric Relaxations ◽  
Broadband Dielectric Spectroscopy ◽  
Molecular Cation

<p>We use a multi-technique approach to determine the phase diagram and molecular cation dynamics of mixed methylammonium-formamidinium MA1-xFAxPbBr3 (0 ≤ x ≤ 1) hybrid perovskites. The calorimetric, ultrasonic and X-ray diffraction experiments show a substantial suppression of the structural phase transitions and stabilization of the cubic phase upon mixing. We use the broadband dielectric and Raman spectroscopies to study the MA and FA cations dynamics in these compounds. The broadband dielectric spectroscopy indicates absence of the MA cation ordering and a gradual increase of the rotation barrier upon mixing. The room-temperature dielectric permittivity substantially decreases as the fraction of the FA cations is increased. No significant changes of the permittivity are detected at temperatures where the dielectric relaxations are absent. We also observe weak signatures of a dipolar glass phase for the highest mixing level (x = 0.5). The Raman spectroscopy supports the dielectric results and reveals additional subtle information about the FA cation dynamics.</p><br>

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