Thermal conductivity and specific heat of glass ceramics

Cahill, David G.; Olson, J. R.; Fischer, Henry E.; Watson, Susan K.; Stephens, R. B.; Tait, R. H.; Ashworth, T.; Pohl, Robert Wichard

doi:10.1103/physrevb.44.12226

Cited by 30 publications

(16 citation statements)

References 25 publications

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“…This is shown in Fig. 4 with some recent measurements taken over a wider temperature range [15]. This puzzling result became even more mysterious when another glass ceramic, Corning Code 9606, a magnesium aluminosilicate, behaved exactly as had been previously expected by us, see Fig.…”

Section: Thermal Conductivity Of Glass Ceramics and Disordered Crystalsmentioning

confidence: 57%

“…5, also taken from Ref. [15]: Ceramming did raise its thermal conductivity, at high tem- (1), with those measured on amorphous solids. For a-C (solid squares), films with four different densities and elastic constants were compared with the model at 400 K [8], for all other amorphous solids the comparison was made at 300 K [7,9].…”

Section: Thermal Conductivity Of Glass Ceramics and Disordered Crystalsmentioning

confidence: 96%

“…In the cerammed Code 9606, the major crystalline phase is cordierite, in which the Mg-ions occupy a regular array of lattice sites. Interstitial ions are absent [15]. This led us to the suggestion that interstitial ions in the 9623, causing random stresses, result in a thermal conductivity of a glass, while without such interstitials, as in the 9606, the thermal conductivity is like that of a crystal, in which the heat is carried by waves.…”

Section: Thermal Conductivity Of Glass Ceramics and Disordered Crystalsmentioning

confidence: 97%

See 2 more Smart Citations

Lattice vibrations of glasses

Pohl

2006

Journal of Non-Crystalline Solids

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Section: Thermal Conductivity Of Glass Ceramics and Disordered Crystalsmentioning

confidence: 57%

Section: Thermal Conductivity Of Glass Ceramics and Disordered Crystalsmentioning

confidence: 96%

Section: Thermal Conductivity Of Glass Ceramics and Disordered Crystalsmentioning

confidence: 97%

See 1 more Smart Citation

Lattice vibrations of glasses

Pohl

2006

Journal of Non-Crystalline Solids

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“…Note that the thermal conductivity for x"0.46 was only measured above 30 K, since this sample was slightly milky indicative of some precipitation, and hence additional scattering at grain boundaries had to be expected at lower temperatures. An example of such an effect has been shown in a glass ceramic (25). At high temperatures, however, the phonon mean free path becomes so short in the samples with large x, as the thermal conductivity approaches that predicted by the model based on Einstein's picture (labeled in Fig.…”

Section: Glass-like Lattice Vibrationsmentioning

confidence: 95%

Lattice Vibrations of Boron Carbides

Medwick

Pohl

1997

Journal of Solid State Chemistry

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“…The first of these techniques to become vetted in the literature was pioneered by Cahill and based on modulated electrical resistivity and thermometry [89,90]. The 3ω technique, was used early on to provide thermal transport measurements in very low thermal conductivity oxides.…”

Section: Thermal Transport In Functional Oxidesmentioning

confidence: 99%

Understanding Phonon Interactions with Defects in Functional Oxide Materials

Donovan¹

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Understanding of nano-scale thermal transport has enabled significant advances in a wide variety of fields including microelectronics, alternative energy, optics, and many more [1][2][3][4]. Utilized in many of these applications are a class of materials known as functional oxides. These materials are oxygen compounds with specific functional properties of interest (e.g., dielectrics [5][6][7][8], piezoelectrics [9][10][11], photovoltaics [12][13][14], thermoelectrics [15][16][17][18][19]). Often it is the defects in these materials that enable functionality and, depending on the processing and operating conditions, the concentration and types of defects that are present in these materials can vary widely [20]. In this dissertation, I aim to identify the role that defects play in functional oxide materials with respect to thermal transport.The major thermal carriers in most functional oxide crystals are collective lattice vibrations, or phonons [21]. Phonon-dominated thermal conductivity is dictated by the scattering of these thermal carriers with a variety of other components or the material system, including defects in the crystal [22,23]. I concentrate on three types of defects that are common in functional oxides: boundaries, extrinsic point defects, and intrinsic point defects.Boundaries such as film boundaries and grain boundaries with nano-scale dimensions can be detrimental to the thermal conductivity of a material. As the length of the uninterrupted crystal reduces to the phonon mean free paths in the crystal, phonons will scatter readily off of nano-scale boundaries and will not be able to propagate as they would in a bulk environment. This becomes particularly relevant in technologies such as the microelectronics industry, where device size scales are well below common phonon mean free paths in the constituent materials. To study this, I turn to one of the more common functional oxides used in the microelectronics industry, BaTiO 3 .I study the effects of nano-scale grains on thin films of BaTiO 3 grown via chemical solution deposition. The films studied are 150 nm and range in grain size from 36 nm -63 nm. I show that the thermal conductivity of these nano-grained films scales with the grain size and film thickness and demonstrate agreement of this trend with analytical models. This result demonstrates that despite a complex crystal structure, there is a mean free path spectrum of phonons in BaTiO 3 that significantly exceeds the dimensions of the grains and film (contrary to the common "gray" mean 2 free path assumption seen in literature).To address the role of extrinsic point defects, or dopants, on the thermal conductivity of functional oxides, I study the effects of dysprosium doping in thin films of cadmium oxide deposited by molecular beam epitaxy. In this experiment, the addition of Dy dopants in CdO actually increases the thermal conductivity initially, owing to a reduction in the equilibrium concentration of oxygen vacancies (a type of defect that is intrinsic to all oxides). The de...

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Thermal conductivity and specific heat of glass ceramics

Cited by 30 publications

References 25 publications

Lattice vibrations of glasses

Lattice vibrations of glasses

Lattice Vibrations of Boron Carbides

Understanding Phonon Interactions with Defects in Functional Oxide Materials

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