Thermal expansion of some diamondlike crystals

Slack, Glen A.; Bartram, S. F.

doi:10.1063/1.321373

Cited by 719 publications

(288 citation statements)

References 88 publications

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“…These cracks originate from stresses built up during cooling as a result of the difference in thermal expansion coefficient between the (001) diamond substrate and the GaN with b ¼ 1Â10 À6 K À1 and b ¼ 6:2Â10 À6 K À1 ; respectively. [33][34][35] The presence of the cracks in the layer also results from the increased coalescence of the GaN islands because cracks can only occur if the stress is built up over large areas. With no coalescence, the stresses are local, and the GaN islands can cope with them.…”

Section: Growth Temperaturementioning

confidence: 99%

Realising epitaxial growth of GaN on (001) diamond

Dreumel

Tinnemans

Heuvel

et al. 2011

Journal of Applied Physics

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By an extensive investigation of the principal growth parameters on the deposition process, we realized the epitaxial growth of crystalline wurtzite GaN thin films on single crystal (001) diamond substrates by metal organic chemical vapor deposition. From the influence of pressure, V/III ratio, and temperature, it was deduced that the growth process is determined by the mass-transport of gallium precursor material toward the substrate. The highest temperature yielded an improved epitaxial relationship between grown layer and substrate. X ray diffraction (XRD) pole figure analysis established the presence of two domains of epitaxial layers, namely (0001) h10 10i GaN k (001) [110] diamond and (0001) h10 10i GaN k (001) ½1 10 diamond, which are 90 rotated with respect to each other. The presence of these domains is explained by the occurrence of areas of (2 Â 1) and (1 Â 2) surface reconstruction of the diamond substrate. When applying highly misoriented diamond substrates toward the [110] diamond direction, one of the growth domains is suppressed and highly epitaxial GaN on (001) diamond is realized.

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Section: Growth Temperaturementioning

confidence: 99%

Realising epitaxial growth of GaN on (001) diamond

Dreumel

Tinnemans

Heuvel

et al. 2011

Journal of Applied Physics

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“…Data from some sources reported as values of instantaneous volumetric COTE have been used in this study, by utilising this approximate relation. The rate of dilation of ceramics with respect to temperature is relatively independent of porosity, allowing thermal expansion coefficients to be calculated from lattice parameter measurements [211], with only slight error resulting from defects in the polycrystalline material [17]. The thermal expansion coefficient of non-cubic crystals is typically anisotropic [210], resulting in change in both shape (deformation) and volume (dilation) when heated [99].…”

Section: Thermal Expansion Coefficientmentioning

confidence: 99%

A review of the processing, composition, and temperature-dependent mechanical and thermal properties of dielectric technical ceramics

et al. 2011

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The current review uses the material requirements of a new space propulsion device, the Variable Specific Impulse Magnetoplasma Rocket (VASIMR ® ) as a basis for presenting the temperature dependent properties of a range of dielectric ceramics, but data presented could be used in the engineering design of any ceramic component with complementary material requirements. A material is required for the gas containment tube (GCT) of VASIMR ® to allow it to operate at higher power levels. The GCT's operating conditions place severe constraints on the choice of material. A dielectric is required with a high thermal conductivity, low dielectric loss factor, and high thermal shock resistance. There is a lack of a representative set of temperature-dependent material property data for materials considered for this application and these are required for accurate thermo-structural modelling. This modelling would facilitate the selection of an optimum material for this component. The goal of this paper is to determine the best material property data values for use in the materials selection and design of such components. A review of both experimentally and theoretically-determined temperature-dependent & room temperature properties of several materials has been undertaken. Data extracted are presented by property. Properties reviewed are density, Young's, bulk and shear moduli, Poisson's ratio, tensile, flexural and compressive strength, thermal conductivity, specific heat capacity, thermal expansion coefficient and the factors affecting maximum service temperature. Materials reviewed are alumina, aluminium nitride, beryllia, fused quartz, sialon and silicon nitride.

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“…The data of Munro [10] is for the mean CTE, so this has been converted to instantaneous CTE values. For aluminium nitride and for beryllia the data presented by Slack & Bartram [17], not included in the preceeding work by the current authors [1], are considered the most reliable are used as the recommended curve. The regression coefficients in Table 4 for aluminium nitride and beryllia are for a curve fit of these data.…”

Section: Coefficient Of Thermal Expansionmentioning

confidence: 99%

“…Fourth-degree polynomials, Equation 15 are used for both properties. For fitting sialon, the following function was found to provide a fit with a lower SEE than either Equation 16 or Equation 17, and was thus used:…”

Section: Thermal Conductivitymentioning

confidence: 99%