Size effects on Debye temperature, Einstein temperature, and volume thermal expansion coefficient of nanocrystals

2006 ◽  
Vol 139 (4) ◽  
pp. 148-152 ◽  
Author(s):  
C.C. Yang ◽  
M.X. Xiao ◽  
W. Li ◽  
Q. Jiang
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Debye Temperature ◽  
Expansion Coefficient ◽  
Size Effects ◽  
Einstein Temperature ◽  
Volume Thermal Expansion Coefficient

scholarly journals First-principles investigation of mechanical and thermodynamic properties of nickel silicides at finite temperature -=SUP=-*-=/SUP=-

2018 ◽  
Vol 60 (5) ◽  
pp. 964
Author(s):  
Zhiqin Wen ◽  
Yuhong Zhao ◽  
Hua Hou ◽  
Liwen Chen
Keyword(s):  
Heat Capacity ◽  
Thermal Expansion ◽  
High Temperature ◽  
Thermodynamic Properties ◽  
Thermal Expansion Coefficient ◽  
Debye Temperature ◽  
Expansion Coefficient ◽  
Finite Temperature ◽  
Volumetric Thermal Expansion Coefficient ◽  
Nickel Silicides

AbstractFirst-principles calculations are performed to investigate lattice parameters, elastic constants and 3D directional Young’s modulus E of nickel silicides (i.e., β-Ni_3Si, δ-Ni_2Si, θ-Ni_2Si, ε-NiSi, and θ-Ni_2Si), and thermodynamic properties, such as the Debye temperature, heat capacity, volumetric thermal expansion coefficient, at finite temperature are also explored in combination with the quasi-harmonic Debye model. The calculated results are in a good agreement with available experimental and theoretical values. The five compounds demonstrate elastic anisotropy. The dependence on the direction of stiffness is the greatest for δ-Ni_2Si and θ-Ni_2Si, when the stress is applied, while that for β-Ni_3Si is minimal. The bulk modulus B reduces with increasing temperature, implying that the resistance to volume deformation will weaken with temperature, and the capacity gradually descend for the compound sequence of β-Ni_3Si > δ-Ni_2Si > θ-Ni_2Si > ε-NiSi > θ-Ni_2Si. The temperature dependence of the Debye temperature ΘD is related to the change of lattice parameters, and ΘD gradually decreases for the compound sequence of ε-NiSi > β-Ni_3Si > δ-Ni_2Si > θ-Ni_2Si > θ-Ni_2Si. The volumetric thermal expansion coefficient αV, isochoric heat capacity and isobaric heat capacity C _ p of nickel silicides are proportional to T ^3 at low temperature, subsequently, αV and C _ p show modest linear change at high temperature, whereas C _v obeys the Dulong-Petit limit. In addition, β-Ni_3Si has the largest capability to store or release heat at high temperature. From the perspective of solid state physics, the thermodynamic properties at finite temperature can be used to guide further experimental works and design of novel nickel–silicon alloys.

scholarly journals Effect of ZnO on the Thermal Properties of Tellurite Glass

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
H. A. A. Sidek ◽  
S. Rosmawati ◽  
B. Z. Azmi ◽  
A. H. Shaari
Keyword(s):  
Thermal Expansion ◽  
Glass Transition ◽  
Thermal Properties ◽  
Thermal Expansion Coefficient ◽  
Debye Temperature ◽  
Expansion Coefficient ◽  
Glass Sample ◽  
Tellurite Glass ◽  
Softening Temperature ◽  
Tellurite Glasses

Systematic series of binary zinc tellurite glasses in the form(ZnO)x(TeO2)(wherex=0to 0.4 with an interval of 0.05 mole fraction) have been successfully prepared via conventional melt cast-quenching technique. Their density was determined by Archimedes method with acetone as buoyant liquid. The thermal expansion coefficient of each zinc tellurite glasses was measured using L75D1250 dilatometer, while their glass transition temperature (Tg) was determined by the SETARAM Labsys DTA/6 differential thermogravimetric analysis at a heating rate of 20 K min−1. The acoustic Debye temperature and the softening temperature (Ts) were estimated based on the longitudinal (VL) and shear ultrasonic (Vs) wave velocities propagated in each glass sample. For ultrasonic velocity measurement of the glass sample, MATEC MBS 8000 Ultrasonic Data Acquisition System was used. All measurements were taken at 10 MHz frequency and at room temperature. All the thermal properties of such binary tellurite glasses were measured as a function of ZnO composition. The composition dependence was discussed in terms of ZnO modifiers that were expected to change the thermal properties of tellurite glasses. Experimental results show their density, and the thermal expansion coefficient increases as more ZnO content is added to the tellurite glass network, while their glass transition, Debye temperature, and the softening temperature decrease due to a change in the coordination number (CN) of the network forming atoms and the destruction of the network structure brought about by the formation of some nonbridging oxygen (NBO) atoms.

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