scholarly journals Thermal expansion for ordered Cu3Au alloy at higher temperature and under pressure.

2020 ◽  
Vol 1506 ◽  
pp. 012017
Author(s):  
Pham Duy Tan ◽  
Pham Dinh Tam ◽  
Bui Duc Tinh
Keyword(s):  
Thermal Expansion ◽  
Higher Temperature ◽  
Cu3au Alloy

Thermally boosted upconversion and downshifting luminescence in Sc2(MoO4)3:Yb/Er with two-dimensional negative thermal expansion

2021 ◽  
Author(s):  
Jinsheng Liao ◽  
Minghua Wang ◽  
Fulin Lin ◽  
Zhuo Han ◽  
Datao Tu ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Near Infrared ◽  
Negative Thermal Expansion ◽  
Thermal Quenching ◽  
Relative Sensitivity ◽  
Strong Temperature Dependence ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
Higher Temperature

Abstract Lanthanide (Ln3+)-doped phosphors generally suffer from thermal quenching, in which their photoluminescence (PL) intensities decrease at the higher temperature. Herein, we report a class of unique two-dimensional negative-thermal-expansion phosphor of Sc2(MoO4)3:Yb/Er. By virtue of the reduced distances between sensitizers and emitters as well as confined energy migration with increasing the temperature, a 45-fold enhancement of green upconversion (UC) luminescence and a 450-fold enhancement of near-infrared downshifting (DS) luminescence of Er3+ are achieved from 25 to 500 ˚C. The thermally boosted UC and DS luminescence mechanism is systematically investigated through in situ temperature-dependent Raman spectroscopy, synchrotron X-ray diffraction and PL dynamics. Moreover, the luminescence lifetime of 4I11/2 of Er3+ in Sc2(MoO4)3:Yb/Er displays a strong temperature dependence, enabling ratiometric thermometry with the highest relative sensitivity of 13.4%/K at 298 K. These findings may gain a vital insight into the design of negative-thermal-expansion Ln3+-doped phosphors for versatile applications.

scholarly journals Augite-anorthite glass-ceramics from residues of basalt quarry and ceramic wastes

2015 ◽  
Vol 9 (2) ◽  
pp. 117-123 ◽  
Author(s):  
Gamal Khater ◽  
Safiah Abu ◽  
Esmat Hamzawy
Keyword(s):  
Thermal Expansion ◽  
Glass Ceramic ◽  
Crystallization Process ◽  
Coefficient Of Thermal Expansion ◽  
Glass Ceramics ◽  
Ceramic Samples ◽  
Heat Treated ◽  
Prepared Glass ◽  
Higher Temperature ◽  
Dominant Phase

Dark brown glasses were prepared from residues of basalt quarries and wastes of ceramic factories. Addition of CaF2, Cr2O3 and their mixture CaF2-Cr2O3 were used as nucleation catalysts. Generally, structures with augite and anorthite as major phases and small amount of magnetite and olivine phases were developed through the crystallization process. In the samples heat treated at 900?C the dominant phase is augite, whereas the content of anorthite usually overcomes the augite at higher temperature (1100?C). Fine to medium homogenous microstructures were detected in the prepared glass-ceramic samples. The coefficient of thermal expansion and microhardnessmeasurements of the glass-ceramic samples were from 6.16?10-6 to 8.96?10-6?C-1 (in the 20-500?C) and 5.58 to 7.16GP, respectively.

Aluminum Nitride fibers from a Thermoplastic Organoaluminum Precursor

1987 ◽  
Vol 108 ◽  
Author(s):  
John D. Bolt ◽  
Fred N. Tebbe
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Thermal Expansion ◽  
High Temperature ◽  
Aluminum Nitride ◽  
Melt Spinning ◽  
Elevated Temperatures ◽  
Fine Particles ◽  
Bulk Ceramic ◽  
Higher Temperature

ABSTRACTA new organoaluminum polymer (EtAINH)n(Et2AlNH2)m·AlEt3 derived from triethylaluminum and ammonia, is thermoplastic at elevated temperatures and a glassy solid at ambient temperature. As a thermoplastic it can be processed in certain shapes, solidified, cured and transformed to dense aluminum nitride with retention of its shape. Aluminum nitride fibers are prepared by melt spinning the polymer, pyrolyzing in ammonia and at high temperature in nitrogen. The AlN microstructure forms as very fine particles at 400–600°C, coarsens at higher temperature, and densifies at 1600–1800 °C into polycrystalline AlN with submicron grains. Mechanical strength, thermal expansion and dielectric constant are consistent with bulk ceramic values. Initial thermal conductivity deduced from composite measurements is 82 W/m°K in fibers containing 0.5 to 1.0 percent oxygen.

Lattice parameters and thermal expansion of GaN

2000 ◽  
Vol 15 (1) ◽  
pp. 40-44 ◽  
Author(s):  
Robert R. Reeber ◽  
Kai Wang
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Gallium Nitride ◽  
Powder Diffraction ◽  
Rietveld Analysis ◽  
Neutron Powder Diffraction ◽  
Lattice Parameters ◽  
Higher Temperature

Neutron powder diffraction methods with Rietveld analysis are utilized to determine GaN lattice parameters from 15 to 298.1 K. Using these measurements and literature data, we calculated the thermal expansion of gallium nitride (GaN) and predicted its higher temperature thermal expansion. The results are compared with available experimental data and earlier work.

A Study on Crystallization of Fused Silica/Zirconia Ceramic Composites

2013 ◽  
Vol 652-654 ◽  
pp. 286-289
Author(s):  
Yong Wu He ◽  
Rui Sheng Wang ◽  
Jing Long Bu ◽  
Jun Xing Chen ◽  
Zhi Fa Wang
Keyword(s):  
Thermal Expansion ◽  
Sintering Temperature ◽  
Ceramic Composites ◽  
Fused Silica ◽  
Raw Material ◽  
Zirconia Ceramic ◽  
Composite Powders ◽  
Wet Chemical Synthesis ◽  
Higher Temperature ◽  
Xrd Patterns

Fused silica particles and zirconyl chloride were used as main raw material. Meanwhile, ammonia was used as precipitator and polyethylene glycol as dispersant. Firstly, the composite powders were prepared by wet chemical synthesis. Then, fused silica/zirconia ceramic composites containing zirconia with different contents (5%, 15%, 25%, 35% and 45%) were fabricated in reduction atmosphere at 1300°C, 1350°C and 1400°C for 1 h. The thermal expansion ratios and XRD of samples were examined. The analysis of XRD indicated that the cristobalite peaks intensity of sample with more zirconia is lower at the same sintering temperature, and the intensity of cristobalite was higher while sintered at higher temperature. Zircons were found in all samples’ XRD patterns. The results of thermal expansion ratios showed the ratios of samples with more zirconia were lower, especially at higher sintering temperature. So, existence of zirconia can inhibit crystallization of fused silica/zirconia ceramic composites effectively.

Neutron and X-Ray Scattering Studies of (FeF2) M (CoF2)n Multilayers

1993 ◽  
Vol 313 ◽  
Author(s):  
D. Lederman ◽  
D. P. Belanger ◽  
J. Wang ◽  
S-J. Han ◽  
C. Paduani ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Specific Heat ◽  
Temperature Anomaly ◽  
Magnetic Contribution ◽  
X Ray Diffraction ◽  
Neutron Data ◽  
Elastic Neutron ◽  
X Ray ◽  
X Ray Scattering ◽  
Higher Temperature

ABSTRACTWe have performed elastic neutron scattering measurements of the staggered magnetization in (FeF2) M (CoF2) n superlattices. Thermal expansion Measurements, which are proportional to the magnetic contribution to the specific heat, were also carried out using high resolution x-ray diffraction. One of the two measured samples has thicknesses of M = n = 4.5 and the other M = 26 and n = 28 Monolayers, as determined from high angle x-ray θ — 2θ scans. In the M = n = 4.5 sample, only one transition is observed at T/v = 62.9K. Analysis of the neutron data, including the rounding effects, indicates an effective β ≈ 0.42. This does not compare well with the 3D Ising exponent β = 0.325. The X-ray data also show the existence of only one specific heat anomaly at T = 62.8 K. For the M = 26, n = 28 sample, dips in the staggered magnetization and peaks in the thermal expansion were observed at T ≈ 40 K and 74 K. The higher temperature anomaly, associated primarily with the FeF2 layers, is sharper than the lower one, which is presumably rounded by the staggered ordering field imposed by the long range order in the FeF2 regions on the CoF2 regions.

Flat Panel Display Substrates

1994 ◽  
Vol 345 ◽  
Author(s):  
Dawne M. Moffatt
Keyword(s):  
Thermal Expansion ◽  
Glass Substrate ◽  
Substrate Material ◽  
Flat Panel Display ◽  
Flat Panel ◽  
Active Matrix ◽  
Thermal Expansion Coefficients ◽  
Field Emission Displays ◽  
Temperature Capability ◽  
Higher Temperature

AbstractThe performance of advanced flat panel displays is intrinsically linked to critical properties of the substrate material. In the manufacture of active-matrix liquid crystal displays (AMLCDs) and some emissive displays, there are certain process steps that require extreme conditions such as strong chemical washes and temperatures in excess of 600°C. As a result, the glass substrate used in these displays must be able to withstand these environments without degradation of its properties. It has become apparent that the flat panel display (FPD) manufacturers will benefit from substrates with improved acid durability, higher temperature capability, and thermal expansion coefficients consistent with other display materials.This paper focuses on one of the less-understood features of the glass substrate: the expansion characteristics as a function of temperature. Thermal expansion is important as it affects the compatibility of the glass with display materials, which, in the case of AMLCDs and some silicon-microtip field emission displays (FED), require an expansion close to that of silicon. In addition, thermal breakage during processing is directly proportional to the expansion coefficient.This study focused on the thermal expansion characteristics of two different FPD substrate glasses. The first one is code 7059, manufactured by Corning Incorporated and currently the standard in AMLCDs. A new substrate composition, Corning code 1737, with enhanced durability, temperature capability, and expansion tuned to the AMLCD applications will also be discussed.

Two-Wavelength Thermoreflectance and its Application in Temperature Measurement of Micro-Electronic Devices

2018 ◽  
Author(s):  
Hongjie Zhang ◽  
Sy-Bor Wen
Keyword(s):  
Thermal Expansion ◽  
Steady State ◽  
Temperature Measurement ◽  
Imaging Technique ◽  
Electronic Devices ◽  
Target Movement ◽  
Steady State Operation ◽  
Steady State Temperature ◽  
Higher Temperature ◽  
Low Sensitivity

A two-wavelength thermoreflectance (2WTR) imaging technique is developed to conduct steady-state temperature measurement of miniature electronic devices, such as micro-scale gold resistors. Compared with traditional single wavelength thermoreflectance (TR) imaging requiring comparison of TR signals from a target under heated and unheated conditions, 2WTR method obtains temperature information from heated target under operation directly. Therefore, 2WTR is not affected by movement of a heated target due to thermal expansion. Note that thermal expansion of targets between heated and unheated conditions is a main constraint of current TR imaging of miniature targets. In addition to the low sensitivity to the target movement, the new 2WTR can provide even higher temperature resolution than single wavelength TR by appropriately selecting the adopted two wavelength to have different signs of TR coefficients. With this new TR imaging technique, we successfully measure temperature distribution of a microscale gold resistor under steady-state operation, which are challenging to be obtained by traditional single wavelength TR method.

Sign in / Sign up

Export Citation Format

Share Document