Thermal conductivity of disordered garnets from infrared spectroscopy

Giesting, Paul A.; Hofmeister, Anne M.

doi:10.1103/physrevb.65.144305

Cited by 51 publications

(37 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The lines are regression curves to the data of the transient method that are calculated by using the model of Roufosse and Klemens (1974) and two different polynomials. Giesting and Hofmeister (2002) and Hofmeister (2006). The thermal diffusivity at 1000 °C in (a) and (b) is extrapolated from our data by using the model of Roufosse and Klemens (1974).…”

Section: Discussionmentioning

confidence: 99%

“…Fig. 4b also contains previously published data of Giesting and Hofmeister (2002) and Hofmeister (2006). The thermal diffusivity data from Giesting and Hofmeister (2002) are calculated from infrared spectra and it can be seen in fig.…”

Section: Room-temperature Behaviourmentioning

confidence: 99%

“…4b also contains previously published data of Giesting and Hofmeister (2002) and Hofmeister (2006). The thermal diffusivity data from Giesting and Hofmeister (2002) are calculated from infrared spectra and it can be seen in fig. 4b that their data also suggest a minimum, but the absolute values do not agree with the data of this study and the results from Hofmeister (2006).…”

Section: Room-temperature Behaviourmentioning

confidence: 99%

“…It has been shown for a variety of solid solution series that a minimum in thermal transport properties occurs for an intermediate composition (e.g. Horai & Simmons, 1969;Padture & Klemens, 1997;Patel et al, 2001;Giesting & Hofmeister, 2002;Giesting et al, 2004). Garnets are the ideal candidates for studying substitution-effects on thermal transport properties as they form a variety of solid solution series.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Thermal diffusivity of natural and synthetic garnet solid solution series

2008

View full text Add to dashboard Cite

Knowledge of heat transport properties as a function of mineral-and rock-composition and temperature is of major relevance to understand and model heat transfer in the Earth's interior. A systematic study on 13 natural and 4 synthetic garnets was carried out in an attempt to obtain a better systematic understanding of the processes that affect the heat transport in minerals, especially the effect of chemical substitution in solid solution series. It is found that substitution significantly lowers the thermal diffusivity from end-member values for both synthetic and natural garnets with a minimum of thermal diffusivity at an intermediate composition. The thermal diffusivity as a function of the degree of substitution can be described by the approach of Padture and Klemens (1997). With increasing temperature the thermal diffusivity decreases due to phononphonon-scattering effects. A quantitative analysis of the high-temperature behaviour was carried out by using the model of Roufosse and Klemens (1974), which takes a lower limit of thermal diffusivity at elevated temperatures into account. The model allows for an extrapolation of the deduced room temperature thermal diffusivities to higher temperatures. Furthermore, the model was modified to determine the high temperature limit of the thermal diffusivity for all investigated natural garnets D min to be 0.64±0.03 mm 2 /s.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Room-temperature Behaviourmentioning

confidence: 99%

Section: Room-temperature Behaviourmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Thermal diffusivity of natural and synthetic garnet solid solution series

2008

View full text Add to dashboard Cite

show abstract

“…β-SiC has poorly resolved peaks; this is problematic for a Kramers-Kronig calculation, but not for classical dispersion analysis (e.g., Giesting & Hofmeister 2002). Values of n and k from our best fits are presented in Figs.…”

Section: Ir Data Analysismentioning

confidence: 99%

Optical properties of silicon carbide for astrophysical applications

Pitman¹,

Hofmeister²,

Corman³

et al. 2008

A&A

Self Cite

View full text Add to dashboard Cite

Aims. The SiC optical constants are fundamental inputs for radiative transfer (RT) models of astrophysical dust environments. However, previously published values contain errors and do not adequately represent the bulk physical properties of the cubic (β) SiC polytype usually found around carbon stars. We provide new, uncompromised optical constants for β-and α-SiC derived from single-crystal reflectance spectra and investigate quantitatively (i) whether there is any difference between α-and β-SiC that can be seen in infrared (IR) spectra and optical functions and (ii) whether weak features from λ ∼ 12.5−13.0 µm need to be fitted. Methods. We measured mid-and far-IR reflectance spectra for two samples of 3C (β-)SiC and four samples of 6H (α-)SiC. For the latter group, we acquired polarized data (E⊥c, E c orientations). We calculated the real and imaginary parts of the complex refractive index (n(λ) + ik(λ)) and the ideal absorption coefficients via classical dispersion fits to our reflectance spectra. Results. We find that β-SiC and E⊥c α-SiC have almost identical optical functions but that n(λ) and k(λ) for E c α-SiC are shifted to lower frequency. Peak positions determined for both 3C (β-) and 6H (α-)SiC polytypes agree with Raman measurements and show that a systematic error of 4 cm −1 exists in previously published IR analyses, attributable to inadequate resolution of older instruments for the steep, sharp modes of SiC. Weak modes are present for samples with impurities. Our calculated absorption coefficients are much higher than laboratory measurements. Whereas astrophysical dust grain sizes remain fairly unconstrained, SiC grains larger than about 1 µm in diameter will be opaque at frequencies near the peak center. Conclusions. Previous optical constants for SiC do not reflect the true bulk properties, and they are only valid for a narrow grain size range. The new optical constants presented here will allow narrow constraints to be placed on the grain size and shape distribution that dominate in astrophysical environments.

show abstract

Glass‐Crystallized Luminescence Translucent Ceramics toward High‐Performance Broadband NIR LEDs

Zheng

Xiao

et al. 2022

Advanced Science

View full text Add to dashboard Cite

Near‐infrared (NIR) phosphor‐converted light‐emitting diodes (pc‐LEDs) are newly emergent broadband light sources for miniaturizing optical systems like spectrometers. However, traditional converters with NIR phosphors encapsulated by organic resins suffer from low external quantum efficiency (EQE), strong thermal quenching as well as low thermal conductivity, thus limiting the device efficiency and output power. Through pressureless crystallization from the designed aluminosilicate glasses, here broadband Near‐infrared (NIR) emitting translucent ceramics are developed with high EQE (59.5%) and excellent thermal stability (<10% intensity loss and negligible variation of emission profile at 150 °C) to serve as all‐inorganic visible‐to‐NIR converters. A high‐performance NIR phosphor‐converted light emitting diodes is further demonstrated with a record NIR photoelectric efficiency (output power) of 21.2% (62.6 mW) at 100 mA and a luminescence saturation threshold up to 184 W cm−2. The results can substantially expand the applications of pc‐LEDs, and may open up new opportunity to design efficient broadband emitting materials.

show abstract

Thermal conductivity of disordered garnets from infrared spectroscopy

Cited by 51 publications

References 48 publications

Thermal diffusivity of natural and synthetic garnet solid solution series

Thermal diffusivity of natural and synthetic garnet solid solution series

Optical properties of silicon carbide for astrophysical applications

Glass‐Crystallized Luminescence Translucent Ceramics toward High‐Performance Broadband NIR LEDs

Contact Info

Product

Resources

About