Very high or close to zero thermal expansion by the variation of the Sr/Ba ratio in Ba1−xSrxZn2Si2O7 – solid solutions

2016 ◽  
Vol 45 (11) ◽  
pp. 4888-4895 ◽  
Author(s):  
Christian Thieme ◽  
Christian Rüssel
Keyword(s):  
Thermal Expansion ◽  
Solid Solutions ◽  
Coefficient Of Thermal Expansion ◽  
Positive Coefficient ◽  
Negative Coefficient ◽  
Very High

The compound BaZn2Si2O7 shows a highly positive coefficient of thermal expansion, while replacement of more than 10% of Ba2+ by Sr2+ results in a negative coefficient of thermal expansion.

The Stabilization of Central Wavelength of Fiber Bragg Gratings by Thermal Contraction Effect of Kovar Substrate

2010 ◽  
Vol 160-162 ◽  
pp. 1270-1275
Author(s):  
Sheng Ching Wang ◽  
Hsi Hsun Tsai
Keyword(s):  
Communication Network ◽  
Thermal Expansion ◽  
Optical Fiber ◽  
Ambient Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Fiber Bragg Gratings ◽  
Bragg Gratings ◽  
Tension Force ◽  
Negative Coefficient ◽  
Central Wavelength

A stabilized laser is essential for optical fiber communication network. One of the passive technique for stabilization of central wavelength of laser is based on the application of fiber Bragg gratings. Due to the positive coefficient of thermal expansion of optical fiber, the Bragg gratings within the fiber written by excimer laser gives about 0.01nm/oC shift on the central wavelength respect to the ambient temperature which leads serious problem in the communication network. Since both the temperature and tension force are linearly proportional to the central wavelength of fiber Bragg gratings. A feasible approach to derive the wavelength stabilization is to decrease the tension force of fiber Bragg gratings respect to the increase of ambient temperature. In this paper, a Kovar substrate with negative coefficient of thermal expansion is used to decrease the tension force while the environmental temperature increases. The experimental results show that the coefficient of thermal expansion of the Kovar substrate is negative and linearly proportional to the temperature. Thus, this Kovar substrate differing from the constant negative coefficient of thermal expansion ceramic substrate induces about 0.0085nm/C on the fiber Bragg gratings, which shows the well application of this Kovar for athermalization of the fiber Bragg gratings in optical communication system.

scholarly journals Тепловое расширение кристаллов Pb-=SUB=-1-x-=/SUB=-Cd-=SUB=-x-=/SUB=-Te

2021 ◽  
Vol 55 (12) ◽  
pp. 1216
Author(s):  
М.К. Шаров
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Solid Solutions ◽  
Coefficient Of Thermal Expansion ◽  
Cadmium Content ◽  
Lattice Period ◽  
Linear Coefficient ◽  
X Ray ◽  
Temperature Range

The values of the lattice period and the linear coefficient of thermal expansion (alfa) of Pb1-xCdxTe solid solutions are determined depending on the cadmium content and temperature using high-temperature X-ray diffractometry. Аn increase in the concentration of cadmium in Pb1-xCdxTe in the range x = 0.02–0.08 leads to a significant increase in the linear coefficient of thermal expansion. A change in temperature range T = 293–673 K leads to decrease in the linear coefficient of thermal expansion. Besides, an increase in temperature does not affect the value alfa of the undoped PbTe in the indicated temperature range.

Size and crystal symmetry breaking effects on negative thermal expansion in ScF3 nanostructures

2021 ◽  
Author(s):  
Chunyan Wang ◽  
Dahu Chang ◽  
Junfei Wang ◽  
Qilong Gao ◽  
Yinuo Zhang ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Symmetry Breaking ◽  
Coefficient Of Thermal Expansion ◽  
Negative Thermal Expansion ◽  
Crystal Symmetry ◽  
Negative Coefficient ◽  
Membrane Vibration

New membrane vibration and surface symmetry breaking effects determine the negative coefficient of thermal expansion at the nanoscale.

Composite Materials with Adjustable Thermal Expansion for Electronic Applications

1996 ◽  
Vol 445 ◽  
Author(s):  
J. D. Shi ◽  
Z. J. Pu ◽  
K. ‐H. Wu ◽  
G. Larkins
Keyword(s):  
Thermal Expansion ◽  
Composite Materials ◽  
Polymer Matrix ◽  
Polymer Matrix Composites ◽  
Coefficient Of Thermal Expansion ◽  
Large Temperature ◽  
Matrix Composites ◽  
Negative Coefficient ◽  
Volume Fractions ◽  
Low Thermal Expansion

AbstractIn this paper, we discuss a newly characterized compound, ZrW2Og, that has been introduced into the composite materials with an adjustable and low thermal expansion for electronic applications. Offering a negative coefficient of thermal expansion (CTE) of approximate ‐9xlO–6/°C in a large temperature range, ZrW2Og was used as a particle filler in polymer‐matrix composites. The paper presents two kinds of composites, that is, polyester and epoxy with various volume fractions of ZrW20g. The CTEs of the polyester/ZrW2Og and epoxy/ZrW2Og composites have been proven adjustable in the ranges of 94 to 56x10–6 /°C and 54 to 18х 10–6 /°C, respectively, with ZrW2Og filler from 0 to 30 vol%. In addition, the analysis about the interfaces between the matrices and filler indicated that the interfaces may be beneficial to reduce the overall thermal expansion of the composites. The methods to further decrease composite CTEs are also discussed.

scholarly journals Negative thermal coefficient of nanoporous biomaterials

2012 ◽  
Vol 16 (5) ◽  
pp. 1549-1550
Author(s):  
Fu-Juan Liu ◽  
Ji-Huan He ◽  
Li Zhang
Keyword(s):  
Thermal Expansion ◽  
Temperature Change ◽  
Coefficient Of Thermal Expansion ◽  
Thermal Coefficient ◽  
Negative Coefficient

Materials change their sizes when subjected to a temperature change. Generally the coefficient of thermal expansion is positive, however, a negative coefficient in nanoporous biomaterials from enteromorpha is observed.

scholarly journals Эффекты легирования сульфида свинца серебром на решеточных и оптических свойствах твердых растворов Pb-=SUB=-1-x-=/SUB=-Ag-=SUB=-x-=/SUB=-S

2019 ◽  
Vol 53 (12) ◽  
pp. 1675
Author(s):  
С.И. Садовников
Keyword(s):  
Thermal Expansion ◽  
Solid Solutions ◽  
Single Phase ◽  
Coefficient Of Thermal Expansion ◽  
Relative Content ◽  
Atomic Vibrations ◽  
Metal Sublattice ◽  
First Time ◽  
Linear Compressibility ◽  
Silver Atoms

Single-phase limited cubic solid solutions Pb1-xAgxS based on PbS with a metal sublattice alloyed with silver are obtained. The maximum relative content of silver in solid solutions Pb1-xAgxS reaches x = 0.15. For the first time the thermal expansion of semiconductor solid solutions Pb1-xAgxS was measured by dilatometry method in the temperature range 295-580 K. Substitution of lead atoms by silver atoms in Pb1-xAgxS leads to a decrease in the coefficient of thermal expansion associated with a change in the anharmonicity of atomic vibrations and a weak increase in the elastic properties. For single-crystal particles PbS and solid solutions Pb1-xAgxS, spatial distributions of the elastic modulus E, Poisson's ratio , and linear compressibility  as a function of the direction (hkl) are found. The reflection spectra of the synthesized powders PbS, Ag2S and Pb1-xAgxS are measured and it is shown that the replacement of lead with silver in PbS is accompanied by an increase in the width of the band gap.

Sign in / Sign up

Export Citation Format

Share Document