Distribution of Rings and Intermediate Range Correlations in Silica Glass Under Pressure-A Molecular Dynamics Study

1995 ◽  
Vol 408 ◽  
Author(s):  
José Pedro Rino ◽  
Gonzalo Gutiérrez ◽  
Ingvar Ebbsjö ◽  
Rajiv K. Kalia ◽  
Priya Vashishta
Keyword(s):  
Molecular Dynamics ◽  
Silica Glass ◽  
Diffraction Peak ◽  
Full Width ◽  
Half Maximum ◽  
Systematic Analysis ◽  
Effect Of Pressure ◽  
Intermediate Range ◽  
Temperature Ranges

AbstractUsing the molecular dynamics (MD) method, we have studied the effect of pressure on the distribution of rings and their relationship to intermediate range correlations manifested as the first sharp diffraction peak (FSDP) for Si02 glass. A systematic analysis of the modifications observed in the FSDP for densities ranging from 2.0 to 3.2 g/cm3 and temperatures from 0 to 1500 K is reported. The decrease in the height of the FSDP with increasing density is found to be proportional to the decrease in the number of 6-fold rings. For the density and temperature ranges studied in SiO2 glass, the full width at half maximum (FWHM) of the FSDP remains unchanged.

Effect of GeO2 additive on fluorescence intensity enhancement in bismuth-doped silica glass

2007 ◽  
Vol 22 (3) ◽  
pp. 565-568 ◽  
Author(s):  
Yasushi Fujimoto ◽  
Yuki Hirata ◽  
Yoshiyuki Kuwada ◽  
Takahiro Sato ◽  
Masahiro Nakatsuka
Keyword(s):  
Fluorescence Intensity ◽  
Silica Glass ◽  
Experimental Results ◽  
Full Width ◽  
Half Maximum ◽  
Intensity Enhancement ◽  
Luminescent Centers

We observed the enhancement of fluorescence intensity due to the addition of GeO2 in bismuth-doped silica glass (BiSG), which has a peculiar fluorescence at 1.25 μm with a full width at half-maximum of 300 nm. Experimental results revealed that the fluorescence intensity from BiSG with 5.0 mol% GeO2 increased remarkably to be 26.3 times greater than that without GeO2 additive for the same Bi2O3 concentration (0.1 mol%). Furthermore, the enhanced sample showed almost the same intensity as BiSG without GeO2 for 1.0 mol% Bi2O3. These results demonstrate that GeO2 additive effectively promotes the generation of peculiar luminescent centers.

Effect of Annealing on Electrical Degradation Characteristics of ZnO Varistors

2008 ◽  
Vol 388 ◽  
pp. 7-10 ◽  
Author(s):  
Masayuki Takada ◽  
Shinzo Yoshikado
Keyword(s):  
Grain Boundaries ◽  
Diffraction Peak ◽  
Full Width ◽  
Half Maximum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Annealing Conditions ◽  
Electrical Degradation ◽  
Zno Varistors ◽  
Triple Points

The effects of the thermally annealing of Bi-Mn-Co-Sb2O3-added ZnO varistors on their electrical degradation were investigated. For the samples with 0.01mol% Sb2O3added and without Sb2O3, no marked difference in the non linearity index of the voltage-current (V-I) characteristics was observed upon electrical degradation for the annealed and nonannealed samples. Upon increasing the amount of Sb2O3 added, the values of  increased after electrical degradation for the annealed samples. Moreover, the value of  after electrical degradation was proportional to the full width at half maximum (FWHM) of the X-ray diffraction peak for Zn2.33Sb0.67O4-type spinel particles under various annealing conditions. The added Sb2O3 did not dissolve in the ZnO grains but became segregated at grain boundaries. Therefore, it is speculated that the increase in the FWHM for the spinel particles is due to the increase in the numbers of fine spinel particles at grain boundaries and triple points.

ATOMIC ENVIRONMENT IN LEAD-BISMUTHATE GLASSES CONTAINING MANGANESE

2003 ◽  
Vol 17 (07) ◽  
pp. 291-301 ◽  
Author(s):  
V. SIMON ◽  
H. BAKO-SZILAGYI ◽  
M. NEUMANN ◽  
S. G. CHIUZBĂIAN ◽  
S. SIMON
Keyword(s):  
Heat Treatment ◽  
Electronic Structure ◽  
Field Strength ◽  
Structural Changes ◽  
Full Width ◽  
Half Maximum ◽  
X Ray ◽  
Gaussian Functions ◽  
Intermediate Range ◽  
Simulation Based

The atomic environment of 20MnO · 80(x Bi 2 O 3 · y PbO ) glass samples having the ratio of bismuth to lead atoms of 8:1 and 3:1 was investigated with respect to the thermal induced structural changes, cationic field strength and electronic structure of the compound. The position and full width at half maximum of X-ray photoelectron peaks were estimated using spectra simulation based on the summation of Lorentzian and Gaussian functions. Data obtained from XPS core-level spectra Bi 4f, Pb 4f, Mn 2p, and O 1s indicate a reduction of glass disorder both by heat treatment and by increasing the PbO content in the samples. The cations behave essentially as network formers that could be correlated with an intermediate range structure.

Structural and Dynamical Correlations in Stishovite and High Density Silica Glass

1992 ◽  
Vol 293 ◽  
Author(s):  
Wei Jin ◽  
Rajiv K. Kalia ◽  
Priya Vashishta
Keyword(s):  
Molecular Dynamics ◽  
Density Of States ◽  
Silica Glass ◽  
Bond Angle ◽  
Diffraction Peak ◽  
Static Structure Factor ◽  
Static Structure ◽  
Coordination Numbers ◽  
Intermediate Range Order ◽  
Vibrational Density

AbstractPressure-induced structural transformation from tetrahedral to octahedral coordination and the destruction of intermediate-range order (IRO) are studied in silica glass (a-SiO 2) using the molecular-dynamics (MD) method. Changes in the position and height of the first sharp diffraction peak (FSDP) in the static structure factor, bond lengths, coordination numbers, bond-angle distributions, and statistics of rings are investigated as a function of density. Modifications of the vibrational density of states and participation ratio are also discussed.

scholarly journals DISCRETE STEPS OF DIAMOND-GRAPHITE PHASE TRANSITION AT ANNEALING OF NANODIAMONDS IN WIDE TEMPERATURE RANGE

2018 ◽  
Vol 59 (9) ◽  
pp. 50 ◽  
Author(s):  
Nikolay E. Kornienko ◽  
Alexey N. Kirichenko
Keyword(s):  
Phase Transition ◽  
Experimental Studies ◽  
Short Review ◽  
Laser Wavelength ◽  
Full Width ◽  
Half Maximum ◽  
Graphite Phase ◽  
Temperature Range ◽  
Spectral Components ◽  
Temperature Ranges

We present the short review of the works on a problem of phase transitions (PT) which are distributed in the temperature range ΔТ of PT.  Experimental studies of Raman spectra (laser wavelength 514.5 nm) of nanodiamonds after annealing at 900-2000 °C and their detailed numerical analysis with decomposition of the allocated oscillatory D and G bands on the compound spectral components D and G, D (k) and G (k’) relating to various states of Brillouin’s zones were conducted. Detection of temperature maxima of intensities, frequencies and full width at half maximum (FWHM) of individual Raman components as well as intensity of a background defines discrete steps of PT of diamond - onion-shaped carbon in temperature ranges of 940-1200 °C and 1500-2000 °C.

Strain in Epitaxial BaTiO3 Thin Films Prepared by MOCVD

1998 ◽  
Vol 541 ◽  
Author(s):  
S. Chattopadhyay ◽  
A. Teren ◽  
B.W. Wessels
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Full Width Half Maximum ◽  
Diffraction Peak ◽  
Full Width ◽  
Half Maximum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Peak Broadening ◽  
Diffraction Peaks

AbstractThe microstrain in epitaxial BaTiO3 thin films has been investigated using x-ray diffraction. The full width half maximum of the (001) diffraction peaks ranged from 0.12 to 0.49 deg. From the analysis of the angular dependence of the diffraction peak broadening, it is concluded that the broadening is due predominantly to strain. The magnitude of the microstrain decreases sharply with increasing film thickness.

scholarly journals Spectroscopic Studies of Laser-Based Far-Ultraviolet Plasma Light Source

2021 ◽  
Vol 11 (15) ◽  
pp. 6919
Author(s):  
Majid Masnavi ◽  
Martin Richardson
Keyword(s):  
Dense Plasma ◽  
Wavelength Region ◽  
Spectroscopic Studies ◽  
Radiation Hydrodynamics ◽  
Full Width ◽  
Half Maximum ◽  
Laser Plasmas ◽  
Series Of Experiments ◽  
Far Ultraviolet ◽  
Radiation Conversion

A series of experiments is described which were conducted to measure the absolute spectral irradiances of laser plasmas created from metal targets over the wavelength region of 123–164 nm by two separate 1.0 μm lasers, i.e., using 100 Hz, 10 ns, 2–20 kHz, 60–100 ns full-width-at-half-maximum pulses. A maximum radiation conversion efficiency of ≈ 3%/2πsr is measured over a wavelength region from ≈ 125 to 160 nm. A developed collisional-radiative solver and radiation-hydrodynamics simulations in comparison to the spectra detected by the Seya–Namioka-type monochromator reveal the strong broadband experimental radiations which mainly originate from bound–bound transitions of low-ionized charges superimposed on a strong continuum from a dense plasma with an electron temperature of less than 10 eV.

scholarly journals Time to peak and full width at half maximum in MR perfusion: valuable indicators for monitoring moyamoya patients after revascularization

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Adam Huang ◽  
Chung-Wei Lee ◽  
Hon-Man Liu
Keyword(s):  
Study Data ◽  
Unknown Etiology ◽  
Dynamic Susceptibility ◽  
Full Width ◽  
Half Maximum ◽  
Mr Perfusion ◽  
Dynamic Susceptibility Contrast ◽  
Time To Peak ◽  
Mr Perfusion Imaging ◽  
Outcome Monitoring

AbstractMoyamoya disease (MMD) is a chronic, steno-occlusive cerebrovascular disorder of unknown etiology. Surgical treatment is the only known effective method to restore blood flow to affected areas of the brain. However, there are lack of generally accepted noninvasive tools for therapeutic outcome monitoring. As dynamic susceptibility contrast (DSC) magnetic resonance imaging (MRI) is the standard MR perfusion imaging technique in the clinical setting, we investigated a dataset of nineteen pediatric MMD patients with one preoperational and multiple periodic DSC MRI examinations for four to thirty-eight months after indirect revascularization. A rigid gamma variate model was used to derive two nondeconvolution-based perfusion parameters: time to peak (TTP) and full width at half maximum (FWHM) for monitoring transitional bolus delay and dispersion changes respectively. TTP and FWHM values were normalized to the cerebellum. Here, we report that 74% (14/19) of patients improve in both TTP and FWHM measurements, and whereof 57% (8/14) improve more noticeably on FWHM. TTP is in good agreement with Tmax in estimating bolus delay. Our study data also suggest bolus dispersion estimated by FWHM is an additional, informative indicator in pediatric MMD monitoring.

Sign in / Sign up

Export Citation Format

Share Document