scholarly journals Investigation of temperature dependence of Raman and photoluminescence analysis of YBa2Cu3O7 (YBCO) doped with SiO2 nanoparticles

2018 ◽  
Vol 50 (1) ◽  
pp. 63-76
Author(s):  
Munirah Almessiere
Keyword(s):  
Environmental Scanning Electron Microscopy ◽  
Sio2 Nanoparticles ◽  
Solid State Reaction Method ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Resonant Raman ◽  
Pl Intensity ◽  
Bose Einstein ◽  
Pure Ybco

We report the effect of SiO2 nanoparticles (12 nm) in YBa2Cu3O7 (YBCO) matrix. The samples YBCO and SiO2+YBCO are fabricated by a conventional solid-state reaction method, in ambiance conditions. We analyze these samples using X-ray diffraction (XRD), resonant Raman, environmental scanning electron microscopy (ESEM), and Photoluminescence (PL) as a function of temperature in the range from 77 to 837 K. The XRD confirm that the doped YBCO still displays a perovskite structure with the orthorhombic Pmmm phase. The Rietveld refinement confirms that SiO2 nanoparticles induce not only a strong effect on the oxygen?s O(5) and O(8) positions but also an elongation of the unit cell along the c-axis. The PL intensity of pure YBCO is more intense than the doped one that is mainly composed of two bands located at 2.4 eV and 1.88 eV. We simulate the PL intensity with temperature using the Bose-Einstein model with two activation energies corresponding to some specific vibration mode energies. The simulation reveals that the exchange energy between different levels in pure and doped YBCO is conducted by only two vibrations modes that are strongly linked to the oxygen and copper atoms in the YBCO matrix. We determine the evolution of Raman mode frequencies at 340 and 500 cm?1 with temperature using the Lorentzian function at q = 0 of the Balkanski model.

Environmental scanning electron microscopy of fresh human gallstones reveals new morphologies of precipitated calcium salts

1992 ◽  
Vol 50 (2) ◽  
pp. 1322-1323
Author(s):  
Howard S. Kaufman ◽  
Keith D. Lillemoe ◽  
John T. Mastovich ◽  
Henry A. Pitt
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Calcium Salts ◽  
Cholesterol Gallstones ◽  
X Ray ◽  
Ca Carbonate ◽  
Scanning Electron

Gallstones contain precipitated cholesterol, calcium salts, and proteins. Calcium (Ca) bilirubinate, palmitate, phosphate, and carbonate occurring in gallstones have variable morphologies but characteristic windowless energy dispersive x-ray (EDX) spectra. Previous studies of gallstone microstructure and composition using scanning electron microscopy (SEM) with EDX have been limited to dehydrated samples. In this state, Ca bilirubinates appear as either glassy masses, which predominate in black pigment stones, or as clusters, which are found mostly in cholesterol gallstones. The three polymorphs of Ca carbonate, calcite, vaterite, and aragonite, have been identified in gallstones by x-ray diffraction, however; the morphologies of these crystals vary in the literature. The purpose of this experiment was to study fresh gallstones by environmental SEM (ESEM) to determine if dehydration affects gallstone Ca salt morphology.Gallstones and bile were obtained fresh at cholecystectomy from 6 patients. To prevent dehydration, stones were stored in bile at 37°C. All samples were studied within 4 days of procurement.

scholarly journals Iterative regularity and parent-offspring growth mold of stable grain array in bismuth silicate micro-crystals

2011 ◽  
Vol 43 (1) ◽  
pp. 105-112
Author(s):  
Z.G. Zhang ◽  
X.F. Wang ◽  
Q.Q. Tian
Keyword(s):  
Environmental Scanning Electron Microscopy ◽  
Morphological Properties ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Bismuth Silicate ◽  
X Ray ◽  
Offspring Growth ◽  
Line Spacing ◽  
Array Structure ◽  
Sintering Method

Bismuth silicate micro-crystals with grain array structure were prepared by sintering method under atmosphere pressure. The samples were characterized for structural and surface morphological properties by X-ray diffraction (XRD) and Environmental scanning electron microscopy (ESEM). The result shows that stable grain arrays grow by iterative mode. If a stable grain array eliminates, a new stable grain array will generate. In a stable parent array, an offspring array may generate after the corresponding partial elimination of its parent array. If one part of an offspring array stops growing, it will be as a new parent array, and then its offspring grain array will create. The sum of the lengths of an offspring array and the corresponding eliminated part of its parent array is equal to the length of the next eliminated part of its parent array. It means the growth rate of an offspring array is equal to that of the corresponding survived part of its parent array. There is a highly correlation between grain array length and average grain line spacing. It means that larger average grain line spacing corresponds to the stable grain array with lager length. When average grain line spacing increases 1?m, the corresponding array length will increase approximately 7.6?m.

Structure and Electrical Characteristics of BaTiO3 and Ba0.99Er0.01TiO3 Ceramics

2018 ◽  
Vol 280 ◽  
pp. 127-133 ◽  
Author(s):  
F. A. Ismail ◽  
Rozana Aina Maulat Osman ◽  
Mohd Sobri Idris ◽  
N.A.M. Ahmad Hambali
Keyword(s):  
Perovskite Phase ◽  
Microstructural Analysis ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Grain Sizes ◽  
Capacitance Voltage ◽  
Ion Incorporation ◽  
Voltage Breakdown

Conventional solid state reaction method was used to prepare BaTiO3 and Ba0.99Er0.01TiO3 ceramics. Influence of Er3+ ion incorporation on their structural, microstructural and electrical properties was studied. The phase pure samples were obtained when heated at 1400 °C for overnight. The tetragonal perovskite phase of BaTiO3 and Ba0.99Er0.01TiO3 was confirmed by using X-ray Diffraction (XRD) analysis which is in agreement with results obtained from Rietveld refinement analysis. The lattice parameters and unit cell volume of BaTiO3 increased when doped with Erbium. Microstructural analysis of BaTiO3 and Ba0.99Er0.01TiO3 ceramics showed that the grain sizes of BaTiO3 and Ba0.99Er0.01TiO3 significantly decreased. The dielectric properties of BaTiO3 and Ba0.99Er0.01TiO3 were investigated as a function of temperature and frequency. It revealed that the Curie temperature (TC) increased by doping Er content from 110 °C to 120 °C. Ba0.99Er0.01TiO3 exhibited the high value of dielectric constant (ε=5929) at TC of 120 °C. The capacitance-voltage characteristic revealed that the voltage breakdown for both BaTiO3 and Ba0.99Er0.01TiO3 exceeded 30 V.

Temperature Dependence on Dielectric Response of La0.7Ba0.3Mn0.4Ti0.6O3 Ceramic

2015 ◽  
Vol 1107 ◽  
pp. 45-52
Author(s):  
Aaliyawani Ezzerin Sinin ◽  
Walter Charles Primus ◽  
Abdul Halim Shaari ◽  
Zainal Abidin Talib ◽  
Sinin Hamdan
Keyword(s):  
Dielectric Properties ◽  
Temperature Dependence ◽  
Low Frequency ◽  
Sintered Sample ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Low Frequencies ◽  
X Ray ◽  
Lcr Meter

Ceramic sample of La0.70Ba0.30Mn0.40Ti0.60O3 oxide has been prepared by the conventional solid-state reaction method. The sintered sample was characterized by using x-ray diffraction (XRD) and low frequency LCR meter. XRD result shows that the sample has a cubic structure with the existence of impurity phase. The dielectric properties of La0.70Ba0.30Mn0.40Ti0.60O3 measured from room temperature to 200°C shows that the dielectric permittivity is temperature dependence with strong dispersion at low frequencies. A circuit model based on the universal capacitor response function is also being used to represent the dielectric properties of the sample.

The structure and chemical layering of Proterozoic stromatolites in the Mojave Desert

2015 ◽  
Vol 14 (3) ◽  
pp. 517-526 ◽  
Author(s):  
Susanne Douglas ◽  
Meredith E. Perry ◽  
William J. Abbey ◽  
Zuki Tanaka ◽  
Bin Chen ◽  
...  
Keyword(s):  
Elemental Analysis ◽  
Mojave Desert ◽  
Environmental Scanning Electron Microscopy ◽  
Xrd Analysis ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Mars Rover ◽  
X Ray ◽  
High K ◽  
Representative Samples

AbstractThe Proterozoic carbonate stromatolites of the Pahrump Group from the Crystal Spring formation exhibit interesting layering patterns. In continuous vertical formations, there are sections of chevron-shaped stromatolites alternating with sections of simple horizontal layering. This apparent cycle of stromatolite formation and lack of formation repeats several times over a vertical distance of at least 30 m at the locality investigated. Small representative samples from each layer were taken and analysed using X-ray diffraction (XRD), X-ray fluorescence (XRF), environmental scanning electron microscopy – energy dispersive X-ray spectrometry, and were optically analysed in thin section. Optical and spectroscopic analyses of stromatolite and of non-stromatolite samples were undertaken with the objective of determining the differences between them. Elemental analysis of samples from within each of the four stromatolite layers and the four intervening layers shows that the two types of layers are chemically and mineralogically distinct. In the layers that contain stromatolites the Ca/Si ratio is high; in layers without stromatolites the Ca/Si ratio is low. In the high Si layers, both K and Al are positively correlated with the presence and levels of Si. This, together with XRD analysis, suggested a high K-feldspar (microcline) content in the non-stromatolitic layers. This variation between these two types of rocks could be due to changes in biological growth rates in an otherwise uniform environment or variations in detrital influx and the resultant impact on biology. The current analysis does not allow us to choose between these two alternatives. A Mars rover would have adequate resolution to image these structures and instrumentation capable of conducting a similar elemental analysis.

MULTIFERROIC MATERIALS Bi1-xSmxFeO3: A STUDY OF RAMAN AND ABSORPTION SPECTROSCOPIES

2010 ◽  
Vol 19 (02) ◽  
pp. 247-254 ◽  
Author(s):  
NGUYEN VAN MINH ◽  
DAO VIET THANG
Keyword(s):  
Lattice Dynamics ◽  
Optical Band Gap ◽  
Solid State Reaction Method ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Lattice Constants ◽  
Raman Measurement

Multiferroic Bi 1-x Sm x FeO 3(x = 0.00, 0.05, 0.1, 0.15, 0.2) ceramics were prepared by conventional solid state reaction method. X-ray diffraction measurement was carried out to characterize the crystal structure and to detect the impurities existing in these ceramics. The substitution of rare earth Sm for Bi was found to decrease the impurity phase in BiFeO 3 ceramics. There is strong evidence that both lattice constants a and c of the unit cell become smaller as the Sm 3+ content is increased. The effect of introducing Sm 3+ is shown to decrease the optical band gap for doped sample Bi 1-x Sm x FeO 3. Additionally, the temperature-dependent Raman measurement performed for the lattice dynamics study of Bi 1-x Sm x FeO 3 samples reveals a strong band centered at around 1000–1300 cm-1 which is associated with the resonant enhancement of two-phonon Raman scattering in the multiferroic Bi 1-x Sm x FeO 3 samples. This two-phonon signal is shown to broaden with increasing x. The Raman spectra at low wavenumbers are suggested to be related with magnon in this system.

The Microstructure and Thermochromic Properties of La1-XSrXMnO3 Smart Materials

2013 ◽  
Vol 690-693 ◽  
pp. 648-653 ◽  
Author(s):  
Min Xu ◽  
Zhao Hui Fu ◽  
Lin Li ◽  
Jie Bing Wang ◽  
Chun Hua Wu ◽  
...  
Keyword(s):  
Smart Materials ◽  
Thermal Control ◽  
Solid State Reaction Method ◽  
Thermal Design ◽  
Radiative Properties ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Thermal Radiative Properties ◽  
Potential Applications ◽  
Thermochromic Properties

The La1-xSrxMnO3 materials have potential applications in thermal control systems of microsatellites. The microstructure of La1-xSrxMnO3 materials is very sensitive to the compound of Sr incorporated into it. In this paper, preparation process of La1-xSrxMnO3 compounds was explored. Ceramic sintering process combined with a conventional solid state reaction method was used to prepare various components of La1-xSrxMnO3。 Annealing temperature, time and doped ratio were controlled in the experiment. X-ray diffraction and Raman spectroscopy were used to analyze phase structure and crystalline. Thermal radiative properties were measured on a Calorimetric Emissometer at 175K～375K. These investigations reveal that microstructure of La1-xSrxMnO3 compounds are affected by Sr2+doping level(x).Thermal emissivity of La0.825Sr0.175MnO3 materials vary widely from 0.68 to 0.37, which can meet requirement of future space thermal design.

Photoluminescence properties of Na1.45La8.55(SiO4)6(F0.9O1.1):Eu for applications as a reddish orange phosphor

2014 ◽  
Vol 07 (05) ◽  
pp. 1450060 ◽  
Author(s):  
Qun Shi ◽  
Dhia A. Hassan ◽  
Renjie Zeng
Keyword(s):  
Spectral Analysis ◽  
Solid State Reaction Method ◽  
Photoluminescence Properties ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Reaction Method ◽  
X Ray ◽  
Analysis System ◽  
Reddish Orange ◽  
The Eu

Europium-doped Na 1.45 La 8.55-8.55x( SiO 4)6( F 0.9 O 1.1)(0.000 ≤ x ≤ 0.045) phosphors were prepared by a conventional solid-state reaction method at 1200°C and their properties were studied by X-ray diffraction (XRD), and a spectral analysis system. No impurities were observed. The phosphor could be excited at 254 nm, 395 nm and 465 nm to yield a reddish orange emission which was attributed to the 5 D 0 → 7 F j (j = 0–2) transitions of the Eu ion.

Evaluation of Pulsed Laser Deposited Li4Ti5O12 Thin Film Anodes by CV and EIS

2013 ◽  
Vol 743-744 ◽  
pp. 13-19 ◽  
Author(s):  
Jian Qiu Deng ◽  
Zhou Guang Lu ◽  
Chi Yuen Chung ◽  
Zhong Min Wang ◽  
Huai Ying Zhou
Keyword(s):  
Thin Film ◽  
Electrochemical Impedance ◽  
Discharge Rate ◽  
Pulsed Laser ◽  
Environmental Scanning Electron Microscopy ◽  
Cycling Performance ◽  
Laser Deposition ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
X Ray

Li4Ti5O12thin film anodes were prepared successfully using pulsed laser deposition technique. The thin films were characterized by X-ray diffraction and environmental scanning electron microscopy. The effects of thickness and scan rate on the electrochemical properties of Li4Ti5O12thin film electrodes were discussed in detail. The thin film anodes deliver favorable capacity and excellent cycling performance. The discharge capacity maintains at 141 mAhg-1after 20 cycles at 1C charge-discharge rate for the thin film anodes deposited for 20 minutes. The charge-transfer resistances were also investigated by electrochemical impedance spectroscopy.

A Promising Energy-Saving and Environmental-Friendly Lighting Device: High CRI White LED with Phosphor Materials

2016 ◽  
Vol 848 ◽  
pp. 446-453
Author(s):  
Sheng Liu ◽  
Bei Ying Zhou ◽  
Shi Jia Gu ◽  
Lian Jun Wang ◽  
Wan Jiang ◽  
...  
Keyword(s):  
Environmental Scanning Electron Microscopy ◽  
Luminescence Spectra ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Green Phosphor ◽  
Red Phosphor ◽  
White Leds ◽  
Phase Surface ◽  
Color Rendering ◽  
Fluorescence Spectrometer

Two kinds of commercial LED phosphors (green phosphor LuAG:Ce3+ and red phosphor CaAlSiN3:Eu2+) with polymethyl methacrylate (PMMA) powders were mixed to prepare film phosphors with tunable emission peak in photoluminescence spectrum by flat vulcanizing machine under the temperature of 170 oC and pressure of 2 MPa. The physical phase, surface morphology, transmittance, luminescence spectra of samples were characterized by means of X-ray diffraction (XRD), Environmental scanning electron microscopy (ESEM), Ultraviolet-Visible (UV-Vis) spectrophotometry and Fluorescence spectrometer. The results show that the film phosphors phase was consistent with raw phosphors, phosphor particles were uniformly distributed, and fluorescence spectra with different proportions of phosphors in different position can be adjusted. Tested by HSP 3000 spectrum analyzer, the white LEDs fabricated by blue chip and composite film phosphor containing 5 wt% green phosphor and 1.5 wt.% red phosphor, which refers to the remote excitation technique, possessed color coordinate of (0.3715, 0.3280) and color rendering index (CRI) of 87 when it was driven at power of 36 V/140 mA, reaching the international advanced level.

Sign in / Sign up

Export Citation Format

Share Document