THERMAL PROPERTIES OF DIAMOND

Cubic BC2N. Hetero-diamond B C—N compounds have recently received a great interest because of their possible applications as mechanical and optical devices. The similar properties and structures of carbon and boron nitrides (graphite and hexagonal BN, diamond, and cubic BN) suggested the possible synthesis of dense compounds with all the three elements. Such new materials are expected to combine the best properties of diamond (hardness) and of c-BN (thermal stability and chemical inertness). Several low-density hexagonal phases of B,C, and N have been synthesized [534] while with respect to the high-density phases, different authors report contradictory data [535-538], but the final products are probably solid mixtures of c-BN and dispersed diamonds [539]. 

A.H. Deutchman and R.J. Partyka (Beam Alloy Corporation observe, "Characterization and classification of thin diamond films depend both on advanced surface-analysis techniques capable of analyzing elemental composition and microstructure (morphology and crystallinity), and on measurement of macroscopic mechanical, electrical, optical and thermal properties. Because diamond films are very thin (I to 2 micrometers or less) and grain and crystal sizes are very small, scanning electron microscopy... 

R. Berman, Thermal Properties , Chapter 1 from R. Berman, editor, Physical Properties of Diamond, Clarendon Press, Oxford, 1965. 

Table 2 Mechanical and thermal properties of synthesized diamond...

The extraordinary properties of diamond including hardness, high thermal conductivity, and transparency over large portions of the electromagnetic spectrum make it an ideal material for anvils that also serve as windows. All of the analytical techniques described here take advantage of these properties. 

These defects are generally detrimental to electronic, thermal and mechanical properties of diamond films, although in some cases they may be neutral or beneficial. The frequently occurring defects appear to be stacking faults (twinned clusters with many re-entrant surfaces/comers), which are deemed to play a major role in enhancing diamond growth rates.t ... 

When diamond films are deposited chi non-diamond substrates, stresses may be generated in the films due to lattice mismatch and/or differences in thermal expansion coefiBcients between diamond and the substrate materials.In addition, lateral variations in the grain size, density, or impurities incorporated during growth may also lead to stresses, which may be either tensile or compressive. The stresses are known to generally build up with increasing film thickness, and will influence diamond-substrate adhesion and properties of diamond films. ... 

The thermal properties of ceramics, like many of their other physical properties, vary over a very wide range. A good example is that of thermal conductivity. Diamond, a ceramic material, has the highest known thermal conductivity, whereas the thermal conductivity of a multiphase ceramic such as partially stabilized zirconia is three orders of magnitude lower. Thermal properties of ceramics are dominated primarily by the nature of the interatomic bonding (bond strength and ionicity). In practical ceramics we, of course, have to consider the presence of defects, impurities, and porosity as these all affect thermal properties. 

Berman, R. (1979) in The Properties of Diamond, edited by J.E. Field, Academic Press, London, p. 3. Discusses the thermal conductivity of diamond and the effect different impurities have on this property. Kingery, W.D., Bowen, H.K., and Uhlmann, D.R. (1976) Introduction to Ceramics, 2nd edition, Wiley, New York, pp. 583-645. A very detailed chapter on thermal properties. The discussion of photon conductivity and the thermal properties of glasses are covered in more depth than we do. 

Konings RJM, Benes O (2010) Thermodynamic properties of the f-elements tmd their compounds the lanthanide and actinide metals. J Phys Chem Refer Data 39 043102 Kleykamp H (2000) Thermal properties of beryllium. Thermochim Acta 345 179—184 Digonskii VV, Digonskii SV (1992) Laws of the diamond formation. Nedra, St. Peterbuig (in... 

A diamond-coated cylinder of refractory metal (Nb, Mo, W, or Re) may replace the cylindrical ceramic insulators used in thermionic fuel elements (TFE) for space nuclear-power systems. A TFE converts the thermal energy from a nucleeu reaction into electrical energy and is designed to provide power to a spacecraft for as long as ten years. The unique properties of diamond would prevent power loss due to electrical leakage... 

The classical approach of conduction does not include the above time lag concept or the wavelike response. It expects a delta function-like response of temperature without any time lag with respect to the applied heat pulse. In the classical approach, we use phenomenological models which do not require any knowledge of the mechanism of energy transport or the microstructure of the solids. Fourier s law of heat conduction uses thermal conductivity as a material property which is a function of temperature. This thermal conductivity depends on the microstructure of the solids, which the thermal conductivity data does not show. For example, thermal conductivity of diamond can span an order of magnitude depending on the type of microstructure obtained by chemical vapor deposition. Thermal conductivity of natural... 

Table 10.1 summarizes some of the sahent physical properties of diamond and graphite as they will be needed in the remainder of this chapter. We compare them with those of silicon as the closest Idn to diamond. Some of the outstanding properties of diamond such as its superior hardness, chemical inertness, and high thermal conductivity are generally known nevertheless, it is instructive to briefly review these and other diamond properties in context. 

The development of low-pressure synthesis methods for diamond, such as the chemical vapor deposition (CVD) technique, has generated enormous and increasing interest and has extended the scope of diamond applications. Highly efficient methods have been developed for the economical growth of polycrystalline diamond films on non diamond substrates. Moreover, these methods allow the controlled incorporation of an impurity such as boron into diamond, which in this case forms a ptype semiconductor. By doping the diamond with a high concentration of boron (B/C = O.Ol), conductivity can be increased, and semi-metallic behavior can be obtained, resulting in a new type of electrode material with all of the unique properties of diamond, such as hardness, optical transparency, thermal conductivity and chemical inertness [1,2]. 

Thermal properties of raw miscanthus in the range from 50°C to 550°C were probed using Perkin Elmer DSC7 system. About 5 ag of miscanthus were sealed in the aluminum sample pans with a small hole in the lid for volatile gases to escape, and the temperature scans were performed at 20°C/min rate under N2 environment. Fmther thermal behavior was analyzed using Perkin Elmer Diamond TG/DTA, where the weight loss of the materials was measured as a function of temperature. A... 

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