The effect of a complex coefficient of thermal expansion upon the thermoelastic relaxation mechanism is analyzed. A phase angle in the thermal expansion has the effect of generating a very broad band of mechanical damping, in addition to the peak usually observed. Phase angles in the thermal expansion have been observed in several polymers, and they may be generated in composite materials in wh...

A moiré interferometer is used to measure the thermal expansion of two ferroelectric crystals, LiNbO3 and KTiOPO4. The crystal samples are patterned with a chromium reflective grating and used as a diffractive component in a reflective grating interferometer. The thermal expansion of all the three axes of congruent LiNbO3 and of x and y axes of the flux-grown KTiOPO4 were measured from room tem...

For engineering applications where tight dimensional tolerances are required, or for applications where materials are subjected to a wide range of temperatures it becomes desirable to reduce a material’s coefficient of thermal expansion. By carefully designing lattice microstructures, zero thermal expansion can be achieved. This work describes lattice microstructures that achieve zero expansion...

Original information on local thermal expansion can be obtained through a cumulant analysis of EXAFS. The different sensitivity to correlation of the first and third EXAFS cumulants, and their comparison with crystallographic distance, can help in disentangling the contribution of potential anharmonicity to thermal expansion from geometrical effects. These possibilities are illustrated by recen...

Thermal expansion of several compositions of Sr and Mg-doped LaGaO3 including an A-site deficient composition (La0⋅9Sr0⋅1)0⋅98(Ga0⋅8Mg0⋅2)O2⋅821 were measured in the temperature range from 298 to 1273 K. The effect of doping on thermal expansion was studied by varying the composition at one site of the perovskite structure (either A or B), while keeping the composition at the other site invaria...

Designing structures that have minimal or zero coefficients of thermal expansion (CTE) are useful in many engineering applications. Zero thermal expansion is achievable with the design of porous materials. The behavior is primarily stretch-dominated, resulting in favorable stiffness. Two and three-dimensional lattices are designed using ribs consisting of straight tubes containing two nested sh...

Miniaturized Whispering Gallery Mode (WGM) temperature sensor has great potentials of high resolution and great on-chip integration capability. This study focuses on the development of this kind of sensor based on the shifting wavelength of the optical resonance due to thermal expansion and thermo-optic effects of a silica microsphere. Excellent linear dependence of the wavelength shift versus ...

longitudinal heat conduction is an important parameter in the cryogenic field, especially in cryogenic heat exchangers. in the present work, the parasitic effect of tube wall longitudinal heat conduction on temperature measurement has been studied in cryogenic laminar hydrogen flow. the effects of various parameters such as wall cold end temperature, wall thermal conductivity, gas volumetric fl...

The effects of applied strain on the resistivity of Al thin film metallization interconnects have been measured with a novel methodology that uses thermal expansion mismatch to produce the strain. The interconnect volumetric strain is induced by thermal cycling of passivated and unpassivated interconnects between '70 and 373 K. The coefficient of piezoresistivity, defined as dr/dev, where r5res...