Topic
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.
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TL;DR: In this paper, the authors measured the thermal expansion coefficients of periclase and olivine in a range of temperature from -250 to 1500°C based on the Gruneisen's theory of thermal expansion.
Abstract: Thermal expansions of single-crystal periclase and olivine were measured by a dilatometric method in a temperature range from room-leve1 to 1000°C. The calculated thermal expansion coefficients of periclase and olivine are given in a range of temperature from -250 to 1500°C based on the Gruneisen's theory of thermal expansion. This theory involves several harmonic and anharmonic parameters. The parameters determined in this study are well related to acoustic wave velocities, pressure and temperature derivatives of bulk modulus, Gruneisen's parameter, which have been determined by other means. It is shown that the accurate thermal expansion data provide a good estimation of elastic wave velocities and other physical constants, which are important in the study of the equation of state of the deep interior of the earth.
306 citations
TL;DR: In situ neutron diffraction experiments show that at pressures above 2 kilobars, cubic zirconium tungstate (ZrW2O8) undergoes a quenchable phase transition to an orthorhombic phase, the structure of which has been solved from powder diffraction data.
Abstract: In situ neutron diffraction experiments show that at pressures above 2 kilobars, cubic zirconium tungstate (ZrW2O8) undergoes a quenchable phase transition to an orthorhombic phase, the structure of which has been solved from powder diffraction data. This phase transition can be reversed by heating at 393 kelvin and 1 atmosphere and involves the migration of oxygen atoms in the lattice. The high-pressure phase shows negative thermal expansion from 20 to 300 kelvin. The relative thermal expansion and compressibilities of the cubic and orthorhombic forms can be explained in terms of the “cross-bracing” between polyhedra that occurs as a result of the phase transition.
306 citations
TL;DR: Rietveld refinement as a function of temperature suggests that the intrinsic negative thermal expansion can be related to transverse vibrations of bridging oxygen atoms in the structure, which leads to coupled tilting of the quasi-rigid framework polyhedra and causes the structure to become more dense with increasing temperature.
302 citations
TL;DR: In this article, an improved thermodynamic formalism that incorporates a new physical property, the chemical expansivity, was proposed for modeling stress and strain in materials, probing defect structure, and analyzing transport and kinetic properties.
Abstract: To better understand thermal strain in electrochemical ceramics, the temperature and oxidation-state dependence of lattice volume in La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) were measured. Large values in the apparent thermal expansion coefficient at high temperature (>50 ppm/°C) were caused by changes in oxygen content, not increases in thermal expansivity. This material can be described using an improved thermodynamic formalism that incorporates a new physical property, the chemical expansivity. Our approach opens new avenues for modeling stress and strain in materials, probing defect structure, and analyzing transport and kinetic properties.
302 citations
TL;DR: In this paper, a linear absolute capacitance dilatometer was used to estimate thermal expansion from 6 to 340 K on a high-purity silicon sample using a linear ACD.
Abstract: Linear thermal expansion measurements have been carried out from 6 to 340 K on a high‐purity silicon sample using a linear absolute capacitance dilatometer. The accuracy of the measurements varies from ±0.01×10−8 K−1 at the lowest temperatures to ±0.1×10−8 K−1 or 0.1%, whichever is greater, near room temperature, and is sufficient to establish silicon as a thermal expansion standard for these temperatures. The agreement with previous data is satisfactory at low temperatures and excellent above room temperature where laser‐interferometry data of comparable accuracy exist. Thermal expansions calculated from ultrasonic and heat‐capacity data are preferred below 13 K where experimental problems occurred.
296 citations