Thermal expansion

About: Thermal expansion is a research topic. Over the lifetime, 21040 publications have been published within this topic receiving 349407 citations. The topic is also known as: heat expansion.

Transition Energy and Volume Change at Three Transitions in Barium Titanate

Abstract: The specific heat and thermal expansion of high purity BaTiO 3 ceramics have been measured at temperatures from -120° to 150°C with the following results:

Thermophysical properties of liquid copper and aluminum

Abstract: The electrical resistivity and equation of state of liquid copper and aluminum have been measured to temperatures of 4500 and 4000 K, respectively, using the isobaric expansion apparatus. The specific heats for the liquid are in good agreement with extrapolation of the 1973 Hultgren tables. The electrical resistivities are presented both with and without correction for thermal expansion. Both resistivity and thermal expansion results for aluminum are compared with the predictions of pseudopotential calculations. The specific volumes observed for both metals are less than those reported in the literature, apparently because of axial hydrodynamic displacement. In addition, sudden rapid acceleration in sample growth rate with a corresponding rapid rise in resistivity were observed.

Elastic modulus, thermal expansion, and specific heat at a phase transition

Abstract: The interrelation of the elastic modulus, thermal-expansion coefficient, and specific heat of a transformed phase relative to the untransformed phase is calculated assuming a particular but useful form of the thermodynamic potential. For second-order phase transitions where this potential applies, measurements of modulus, expansion, and specific heat can yield the general (longitudinal as well as shear) first- and second-order stress (or strain) dependences of the transition temperature and of the order parameter at absolute zero. An exemplary application to one type of phase transition is given. (AIP)

Impact of uniaxial strain and doping on oxygen diffusion in CeO2.

Abstract: Doped ceria is an important electrolyte for solid oxide fuel cell applications. Molecular dynamics simulations have been used to investigate the impact of uniaxial strain along the directions and rare-earth doping (Yb, Er, Ho, Dy, Gd, Sm, Nd and La) on oxygen diffusion. We introduce a new potential model that is able to describe the thermal expansion and elastic properties of ceria to give excellent agreement with experimental data. We calculate the activation energy of oxygen migration in the temperature range 900–1900 K for both unstrained and rare-earth doped ceria systems under tensile strain. Uniaxial strain has a considerable effect in lowering the activation energies of oxygen migration. A more pronounced increase in oxygen diffusivities is predicted at the lower end of the temperature range for all the dopants considered.

Estimation of bulk modulus and sound velocities of oxides at very high temperatures

Abstract: Bulk modulus and sound velocities of oxides and silicates up to very high temperatures are estimated from experimental data on sound velocity obtainable at relatively low temperatures Data for MgO, Al2O3, and Mg2SiO4 are used to illustrate the method The theoretical basis for this method is the establishment of a linear dependence of the bulk modulus on temperature at elevated temperatures by use of the Mie-Gruneisen equation of state The parameters required are the room-temperature values of the bulk modulus, density, thermal expansion, Gruneisen constant, and the measured enthalpy as a function of temperature The variation of the shear and longitudinal velocities with temperature are determined from the calculated variation of the bulk modulus and shear modulus with temperature The relations presented should apply to all materials likely to exist in the earth's mantle and, therefore, should provide a useful means of considering the effect of the geothermal gradient on the properties of rock-forming compounds