Temperature Dependent Optical Response of Si(100): Theory vs. Experiment

2011 ◽  
Vol 1370 ◽  
Author(s):  
A.I. Shkrebtii ◽  
J. Heron ◽  
J.L. Cabellos ◽  
N. Witkowski ◽  
O. Pluchery ◽  
...  
Keyword(s):  
Optical Response ◽  
Layer By Layer ◽  
Temperature Dependent ◽  
Reflectance Anisotropy ◽  
Surface Optical ◽  
Wide Range ◽  
Different Temperatures ◽  
Linear Optical Properties ◽  
First Time ◽  
Good Agreement

ABSTRACTWe investigate theoretically and experimentally the temperature-dependent linear optical properties of the clean c(4×2) reconstructed Si(100) surface for a wide range of temperatures. We combine two theoretical formalisms: the first one incorporates the contribution of temperature-dependent atomic motion to the surface optical response and, the second uses a dielectric function layer-by-layer separation method. Using these formalisms, we model temperature-dependent reflectance anisotropy (RA) of this surface for the first time: finite temperature ab-initio Car-Parrinello Molecular Dynamics (CPMD) at different temperatures up to 1000 K provide temperature-dependent atomic structural inputs for optical calculations and subsequent average of dielectric functions. Experimentally, one-domain c(4x2) Si(100) surface was prepared and characterised by Reflectance Anisotropy Spectroscopy (RAS) in a temperature range between 300 K and 800 K. Good agreement between experiment and theory is demonstrated, including a temperature-induced red shift of both the surface and bulk optical peaks. Theoretical results indicate that the temperature-induced modification of the optical response is substantially more pronounced for the surface than for the bulk.

scholarly journals Effect of Sintering Temperature on Metal-Insulator Phase Transition in La1-xCaxMnO3 Perovskites

2020 ◽  
Vol 2 (1) ◽  
pp. 37-42
Author(s):  
Arunachalam M ◽  
Thamilmaran P ◽  
Sakthipandi K
Keyword(s):  
Phase Transition ◽  
Bulk Modulus ◽  
Sintering Temperature ◽  
Magnetic Sensors ◽  
Temperature Dependent ◽  
Metal Insulator ◽  
Wide Range ◽  
Different Temperatures ◽  
Insulator Phase Transition

Lanthanum calcium based perovskites are found to be advantageous for the possible applications in magnetic sensors/reading heads, cathodes in solid oxide fuel cells, and frequency switching devices. In the present investigation La0.3Ca0.7MnO3 perovskites were synthesised through solid state reaction and sintered at four different temperatures such as 900, 1000, 1100 and 1200˚ C. X-ray powder diffraction pattern confirms that the prepared La0.3Ca0.7MnO3 perovskites have orthorhombic structure with Pnma space group. Ultrasonic in-situ measurements have been carried out on the La0.3Ca0.7MnO3 perovskites over wide range of temperature and elastic constants such as bulk modulus of the prepared La0.3Ca0.7MnO3 perovskites was obtained as function of temperature. The temperature-dependent bulk modulus has shown an interesting anomaly at the metal-insulator phase transition. The metal insulator transition temperature derived from temperature-dependent bulk modulus increases from temperature 352˚ C to 367˚ C with the increase of sintering temperature from 900 to 1200˚ C.

RAP — ACOUSTIC DETECTION OF PARTICLES: FIRST RESULTS AT 4.2 K

2005 ◽  
Vol 20 (29) ◽  
pp. 7054-7056
Author(s):  
C. LIGI ◽  
M. BASSAN ◽  
S. BERTOLUCCI ◽  
B. BUONOMO ◽  
E. COCCIA ◽  
...  
Keyword(s):  
Cryogenic Temperature ◽  
Dilution Refrigerator ◽  
Test Facility ◽  
Acoustic Detection ◽  
Beam Test ◽  
Mechanical Vibrations ◽  
First Results ◽  
Different Temperatures ◽  
First Time ◽  
Good Agreement

RAP (Rivelazione Acustica di Particelle) is a small cylindrical aluminum bar (l = 500 mm , d = 181.7 mm ) placed at the DAΦNE Beam Test Facility, where it is hit by a 510 MeV electron beam, coming from the DAΦNE Linac. Aim of the experiment is to measure the mechanical vibrations of the bar caused by the interaction with the beam. On June, 2004 RAP successfully collected data for the first time at cryogenic temperature. Several runs at different temperatures (4.5, 70 and 273 K) have been performed and a number of shots in normal-conducting state of the bar were detected. The preliminary results are in good agreement with the Thermo-Acoustic Model. In the next months the mounting of a dilution refrigerator and the data taking of the bar in the superconducting state (T = 100 mK ) have been planned.

Na3Sm(PO4)2: (3+1)-dimensional commensurately modulated structure model and photoluminescence properties

2019 ◽  
Vol 234 (5) ◽  
pp. 281-289 ◽  
Author(s):  
Rui-Juan Zhang ◽  
Dan Zhao ◽  
Qiu Zhong ◽  
Ya-Li Xue ◽  
Guang-Xu Huang
Keyword(s):  
Structure Model ◽  
X Ray Diffraction ◽  
Modulated Structure ◽  
Characteristic Emission ◽  
Wide Range ◽  
Different Temperatures ◽  
Superspace Formalism ◽  
First Time ◽  
Uv Excitation ◽  
Orange Color

Abstract For the first time, we determined the detailed crystal structure of Na3Sm(PO4)2 using single crystal X-ray diffraction and established the commensurately modulated structure model using the superspace formalism. The structure adopts a (3+1)-dimensional superspace group Pca21(0β0)000 with the modulation vector q=1/3b*. At the same time, the photoluminescent properties of Na3Sm(PO4)2 sintered at different temperatures between 800 and 1200°C were studied. Under near-UV excitation (402 nm), Na3Sm(PO4)2 shows intense characteristic emission bands of Sm3+ (561, 596, 642 nm) with the CIE coordinate of (0.5709, 0.4282), corresponding to orange color. The excitation spectrum covers a wide range from 350 nm to 470 nm, which indicates that Na3Sm(PO4)2 can be efficiently activated by near-UV or visuable LED ship.

scholarly journals Electrical Transport properties of Ni-Cr binary alloys

2014 ◽  
Vol 24 (2) ◽  
pp. 135
Author(s):  
P. H. Suthar ◽  
B. Y. Thakore ◽  
P. N. Gajjar
Keyword(s):  
Transport Properties ◽  
Electrical Transport ◽  
Binary Alloys ◽  
Correlation Effect ◽  
Model Potential ◽  
Electrical Transport Properties ◽  
Wide Range ◽  
Different Temperatures ◽  
Cr Concentration ◽  
Good Agreement

Electrical transport properties viz. electrical resistivity and thermal conductivity of Ni-Cr binary alloys are determine by our recognized single parametric model potential in wide range of Cr concentration. In this work, screening functions (Ichimaru and Utsumi, Farid et al. and Sarkar et al.) are employed along with the Hartree and Taylor functions to study the relative influence of the exchange and correlation effect. Given liquid alloys are studied as a function of their composition at three different temperatures according to Faber-Ziman model. Computed values of electrical transport properties are in good agreement with the experimental data available in literature.

Luminescence Properties of Yb-Doped Inp

1993 ◽  
Vol 301 ◽  
Author(s):  
H. J. Lozykowski ◽  
A. K. Alshawa ◽  
G. Pomrenke ◽  
I. Brown
Keyword(s):  
Quantitative Agreement ◽  
Excitation Intensity ◽  
Photoluminescence Intensity ◽  
Photoluminescence Quenching ◽  
Time Resolved ◽  
Wide Range ◽  
Decay Times ◽  
Different Temperatures ◽  
First Time ◽  
Kinetics Of

ABSTRACTThe photoluminescence, time resolved spectra and kinetics of Yb implanted InP samples are studied under pulsed and CW excitations (above and below band-gap) at different temperatures and excitation intensity. The photoluminescence intensity and decay time as a function of temperature is explained by a proposed new quenching mechanism involving Fe ion. The rise and decay times depend on excitation intensity. The above experimental facts was explained using the kinetics model developed by H.J. Lozykowski [2]. The numerically simulated luminescence rise and decay times show a good quantitative agreement with experiment, over a wide range of generation rates. The electric field InP:Yb photoluminescence quenching was investigated and reported for the first time.

Nonlocal Polarizabilities and the AB Initio Calculation of Surface Optical Properties of Gaas (110)

1999 ◽  
Vol 579 ◽  
Author(s):  
C.M.J. Wijers ◽  
P.L. De Boeij
Keyword(s):  
Optical Properties ◽  
Ab Initio ◽  
Ab Initio Calculation ◽  
Quantum Mechanical ◽  
Reflectance Anisotropy ◽  
Surface Optical ◽  
Cellular Method ◽  
Theory And Experiment ◽  
Good Agreement

ABSTRACTWe have calculated the reflectance anisotropy for the GaAs (110) surface using the discrete cellular method. This method extends the range of application of standard discrete dipole calculations by incorporating nonlocal polarizabilitites. The method adds a second quantum mechanical channel of nonlocality, which turns out to be necessary and yields very good agreement between theory and experiment.

scholarly journals Description of laminar-turbulent transition of an airfoil boundary layer measured by differential image thermography using directed percolation theory

2022 ◽  
Author(s):  
Tom Wester ◽  
Joachim Peinke ◽  
Gerd Gülker
Keyword(s):  
Percolation Theory ◽  
Suction Side ◽  
Transition To Turbulence ◽  
Directed Percolation ◽  
Turbulent Transition ◽  
Wide Range ◽  
First Time ◽  
Large Parameter Space ◽  
Experimental Effort ◽  
Good Agreement

Abstract Transition from laminar to turbulent flow is still a challenging problem. Recent studies indicate a good agreement when describing this phase transition with the directed percolation theory. This study presents a new experimental approach by means of differential image thermography (DIT) enabling to investigate this transition on the suction side of a heated airfoil. The results extend the applicability of the directed percolation theory to describe the transition on curves surfaces. The experimental effort allows for the first time an agreement between all three universal exponents of the (1+1)D directed percolation for such airfoil application. Furthermore, this study proves that the theory holds for a wide range of flows, as shown by the various conditions tested. Such a large parameter space was not covered in any examination so far. The findings underline the significance of percolation models in fluid mechanics and show that this theory can be used as a high precision tool for the problem of transition to turbulence.

Treatment of Neutron Cross-Section With Interpolation

2010 ◽  
Author(s):  
Xiang Zhang ◽  
Ganglin Yu ◽  
Guangwen Bi ◽  
Kang Wang
Keyword(s):  
Cross Section ◽  
Neutron Cross Section ◽  
Nuclear Data ◽  
Temperature Dependent ◽  
Benchmark Calculation ◽  
Different Temperatures ◽  
Data Libraries ◽  
Relative Differences ◽  
Nuclear Data Libraries ◽  
Good Agreement

Using NJOY to generate the temperature dependent neutron cross-section is too time-consuming in practice, especially for many nuclides. So an approach involving interpolation between nuclear data libraries at different temperatures is investigated. Based on the ACE data at different temperatures, we used ITND — an neutron cross-section interpolation program, to generate the target temperature ACE data, then we compared it with the ACE data which generated by NJOY at the same temperature. We focused on the interpolation result of 238U, 235U, 232Th, Zr, 16O, 10B and 1H at the temperature of 575K. To that nuclides, several interpolate schemes were studied, and we demonstrated the relative differences, and explain their reasons. Finally we applied these ACE data to benchmark calculation, and good agreement was observed with the benchmark results.

scholarly journals Tensile Behavior of Acrylonitrile Butadiene Styrene at Different Temperatures

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Jiquan Li ◽  
Yadong Jia ◽  
Taidong Li ◽  
Zhou Zhu ◽  
Hangchao Zhou ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Glassy State ◽  
Quantitative Relationship ◽  
Acrylonitrile Butadiene Styrene ◽  
Tensile Behavior ◽  
Fitting Method ◽  
Wide Range ◽  
Different Temperatures ◽  
Good Agreement ◽  
Butadiene Styrene

Temperature greatly influences the mechanical response of acrylonitrile butadiene styrene (ABS). The tensile behavior of ABS was explored in this study. The tensile experiments were conducted at a wide range of temperatures (from 40°C to 130°C). A model was established to reveal the quantitative relationship between temperature and tensile behavior of ABS. The results of tensile experiments showed that tensile behavior of ABS exhibited glassy state and high-elastics state. The model was also divided into two parts that rely on the boundary of glass transition temperature, in which the parameters of the model were calculated by the fitting method. The model predictions showed a good agreement with the results of the experimental tensile test. This study provides the quantitative relationship between temperature and tensile behavior of ABS, which saves time and experimental costs.

Development of a PSPICE Model for 1200 V/800 A SiC Bipolar Junction Transistor Power Module

2015 ◽  
Vol 821-823 ◽  
pp. 830-833
Author(s):  
Daniel Johannesson ◽  
Muhammad Nawaz
Keyword(s):  
Operating Temperature ◽  
Power Module ◽  
Temperature Dependent ◽  
Static And Dynamic Characteristics ◽  
Bipolar Junction Transistor ◽  
Temperature Range ◽  
Different Temperatures ◽  
Junction Transistor ◽  
First Time ◽  
Operating Temperature Range

The characteristics of a 1200 V and 800 A bipolar junction transistor (BJT) power module has been measured, simulated and verified for the first time in the PSPICE platform. The simulation model is based on a silicon carbide (SiC) Gummel-Poon model for high power applications. The implemented model has been extended with temperature dependent equations in order to extend the BJT operating temperature range. PSPICE simulations are performed to extract technology dependent modeling parameters coupled with static and dynamic characteristics of BJTs at different temperatures and validated against the measured data. The performance of the SiC BJT model is fairly accurate and correlates well with the measured results over a wide temperature range.

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