scholarly journals Тепловое расширение зонных ферромагнетиков Co-=SUB=-2-=/SUB=-MeAl (Me = Ti, V, Cr, Mn, Fe, Ni)

2018 ◽  
Vol 60 (3) ◽  
pp. 614
Author(s):  
Н.И. Коуров ◽  
В.В. Марченков ◽  
В.А. Казанцев ◽  
Ю.А. Перевозчикова

AbstractThe thermal expansion coefficient (TEC) of Co_2MAl (M = Ti, V, Cr, Mn, Fe, Ni) band ferromagnets is measured in the temperature interval of 80–900 K. The magnetic-fluctuation contribution α_ m , _sf( T ) = α_ m ( T ) + α_sf( T ) to TEC comprised of negative Stoner α_ m ( T ) and positive spin-fluctuation α_sf( T ) contributions is presented. It is assumed that the contribution of α_ m ( T ) component is proportional to the square of spontaneous magnetization. The contribution of α_sf( T ) is stipulated by the effects of inducing local magnetic moments by spin fluctuations and is proportional to the Pauli susceptibility.

Author(s):  
А.А. Повзнер ◽  
А.Г. Волков

AbstractThermodynamic spin fluctuations in strongly correlated plutonium (Pu) phases with exchange and spin–orbit interactions are considered. In α- and δ-Pu phases, the spin fluctuations lead to a negative magnetovolume effect that is determined by the parameter of intermode coupling and depends on features of the electron structure. It is shown that the negative volumetric thermal expansion coefficient of δ-Pu is related to an anomalously strong interaction of spin fluctuation modes.


1993 ◽  
Vol 07 (01n03) ◽  
pp. 691-694 ◽  
Author(s):  
S. MATAR ◽  
J. TEICHMANN ◽  
P. MOHN

Equilibrium values of the energy for the magnetic and non-magnetic structures were derived for Fe3Pt using the scalar relativistic ASW method. The stable ground state is found to be ferromagnetic. Calculations were extended to obtain total energy curves as a function of moment and volume via the FSM method. Results were fitted using a polynomial in M and V within a Landau-Ginzburg model of spin fluctuations. Relevant properties to Invar such as the magnetic contribution to the thermal expansion coefficient and the critical pressure for the disappearance of magnetism and its pressure dependence were derived.


Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 153
Author(s):  
Chuen-Lin Tien ◽  
Tsai-Wei Lin

This paper proposes a measuring apparatus and method for simultaneous determination of the thermal expansion coefficient and biaxial Young’s modulus of indium tin oxide (ITO) thin films. ITO thin films simultaneously coated on N-BK7 and S-TIM35 glass substrates were prepared by direct current (DC) magnetron sputtering deposition. The thermo-mechanical parameters of ITO thin films were investigated experimentally. Thermal stress in sputtered ITO films was evaluated by an improved Twyman–Green interferometer associated with wavelet transform at different temperatures. When the heating temperature increased from 30 °C to 100 °C, the tensile thermal stress of ITO thin films increased. The increase in substrate temperature led to the decrease of total residual stress deposited on two glass substrates. A linear relationship between the thermal stress and substrate heating temperature was found. The thermal expansion coefficient and biaxial Young’s modulus of the films were measured by the double substrate method. The results show that the out of plane thermal expansion coefficient and biaxial Young’s modulus of the ITO film were 5.81 × 10−6 °C−1 and 475 GPa.


2020 ◽  
Vol 59 (1) ◽  
pp. 523-537
Author(s):  
Chaturaphat Tharasana ◽  
Aniruj Wongaunjai ◽  
Puwitoo Sornsanee ◽  
Vichasharn Jitprarop ◽  
Nuchnapa Tangboriboon

AbstractIn general, the main compositions of porcelain and bone china composed of 54-65%wt silica (SiO2), 23-34% wt alumina (Al2O3) and 0.2-0.7%wt calcium oxide (CaO) suitable for preparation high quality ceramic products such as soft-hard porcelain products for teeth and bones, bioceramics, IC substrate and magneto-optoelectroceramics. The quality of ceramic hand mold is depended on raw material and its properties (pH, ionic strength, solid-liquid surface tension, particle size distribution, specific surface area, porosity, density, microstructure, weight ratio between solid and water, drying time, and firing temperatures). The suitable firing conditions for porcelain and bone china hand-mold preparation were firing at 1270°C for 10 h which resulted in superior working molds for making latex films from natural and synthetic rubber. The obtained fired porcelain hand molds at 1270°C for 10 h provided good chemical durability (10%NaOH, 5%HCl and 10%wtNaCl), low thermal expansion coefficient (5.8570 × 10−6 (°C−1)), good compressive (179.40 MPa) and good flexural strength (86 MPa). While thermal expansion coefficient, compressive and flexural strength of obtained fired bone china hand molds are equal to 6.9230 × 10−6 (°C−1), 128.40 and 73.70 MPa, respectively, good acid-base-salt resistance, a smooth mold surface, and easy hand mold fabrication. Both obtained porcelain and bone china hand molds are a low production cost, making them suitable for natural and synthetic rubber latex glove formation.


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