High-temperature infrared properties of sapphire, AlON, fused silica, yttria, and spinel

Sova, Raymond M.; Linevsky, Milton J.; Thomas, Michael E.; Mark, F.

doi:10.1016/s1350-4495(98)00011-5

Cited by 84 publications

(50 citation statements)

References 8 publications

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“…Like the corundum disk the spinel sample has polished surfaces. High-temperature data have already been obtained by Thomas et al (1998a) and by Sova et al (1998). Thomas et al published absorption coefficients in the range of 2.5−10 μm for various temperatures up to 2000 K and a comparison of the results with the multiphonon model.…”

Section: Spinelmentioning

confidence: 98%

“…They compared their model with measured data from several other authors and the FPSQ model. An application of the results of Thomas et al to measured emission spectra of corundum in the wavelength range of 2.5−20 μm is presented in the work of Sova et al (1998). However, the presented measurements on corundum in all of these papers refer only to the ordinary ray.…”

Section: Corundummentioning

confidence: 99%

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Optical constants of refractory oxides at high temperatures

Zeidler

Posch

Mutschke

2013

A&A

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Context. Many cosmic dust species, among them refractory oxides, form at temperatures higher than 300 K. Nevertheless, most astrophysical studies are based on the room-temperature optical constants of solids, such as corundum and spinel. A more realistic approach is needed for these materials, especially in the context of modeling late-type stars. Aims. We aimed at deriving sets of optical constants of selected, astrophysically relevant oxide dust species with high melting points. Methods. A high-temperature, high-pressure cell and a Fourier-transform spectrometer were used to measure reflectance spectra of polished samples. For corundum (α-Al 2 O 3 ), spinel (MgAl 2 O 4 ), and α-quartz (SiO 2 ), temperature-dependent optical constants were measured from 300 K up to more than 900 K. Small particle spectra were also calculated from these data. Results. All three examined oxides show a significant temperature dependence of their mid-IR bands. For the case of corundum, we find that the 13 μm emission feature -seen in the IR spectra of many AGB stars -can very well be assigned to this mineral species. The best fit of the feature is achieved with oblate corundum grains at (mean) temperatures around 550 K. Spinel remains a viable carrier of the 13 μ feature as well, but only for T < 300 K and nearly spherical grain shapes. Under such circumstances, spinel grains may also account for the 31.8 μm band that is frequently seen in sources of the 13 μm feature and which has not yet been identified with certainty.

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Section: Spinelmentioning

confidence: 98%

Section: Corundummentioning

confidence: 99%

Optical constants of refractory oxides at high temperatures

Zeidler

Posch

Mutschke

2013

A&A

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“…Often, they are devoted to determine thermal balances, without focusing on vibration properties. While dealing with lattice dynamics, one can cite Sova et al [79] and Rozenbaum et al [80], who presented reports based on CO 2 laser heating. The latter authors have developed a device devoted to emissivity measurements (Figure 2.17), operational in a large spectral range, from far-infrared to the visible range.…”

Section: 226mentioning

confidence: 99%

Optical Spectroscopy Methods and High‐Pressure–High‐Temperature Studies

Polian

Simon

Pagès³

2010

Thermodynamic Properties of Solids

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This chapter aims to show how optical spectroscopies contribute to the study of vibrational properties under extreme conditions. Now, what do we mean by extreme conditions? We can take it in the other way and mention that ambient conditions have nothing more special as to permit life on earth -that is already not bad! From the point of view of physics, no particular property occurs at ambient conditions. On the contrary, most of the matter in the universe is under extreme pressure (P) and temperature (T), as it is in planets, stars, and more exotic objects. Studies at high pressure and high temperature are hence only the study of matter in its normal conditions. The reason why geoscientists are much interested in such studies is self-explanatory, but other fields are widely studied. The application of high pressure and high temperature enables to explore the repulsive part of the potential energy (fundamental physics), to provoke phase transformations thereby leading to new structures eventually metastable at ambient conditions (materials sciences), to orient chemical reactions in requested directions (chemistry), and even to crystallize proteins, that otherwise would not happen by using other techniques (biology). Another interest to work under variable conditions is that, obviously, more insight is given into the considered phenomenon, in that the pressure and/or temperature derivatives of the phenomenon become available, thus offering a more complete picture to achieve optimum understanding and/or modeling.There are mainly five experimental methods to probe the vibrational properties of matter: optical spectroscopies (of main interest here), ultrasonics (US), inelastic neutron scattering (INS, cf. Chapter 3), more recently inelastic X-ray scattering (IXS, cf. Chapter 4) -that was made possible due to the introduction of third generation synchrotron radiation facilities -and picosecond (PS) acoustics.INS and IXS are used to determine the dispersion of vibration modes, that is, acoustical as well as optical ones, over the whole Brillouin zone (BZ). The most stringent limitations are the needed sources (national-size ones, i.e., a nuclear reactor for INS and a monochromatized X-ray beam as delivered by a synchrotron for IXS), and a limitation to small momentum transfer (q < 0.1q BZB , where q is the magnitude of the wavevector and BZB is the BZ boundary). An additional limitation for INS is

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“…Yttria is one of the most extensively studied and promising infrared transparent ceramics due to its excellent properties required for infrared transparent ceramics like isotropic body centred cubic structure which is stable even at 1800 ℃ [1], moderate refractive index and absence of birefringence [2], high thermal conductivity and low thermal expansion coefficient [3], high thermal shock resistance [4], high melting point [5], low emissivity in the mid infrared range at elevated temperatures [6], and high transparency in the visible and infrared range [7]. But the hardness is at a moderate level compared to other window materials [3,8].…”

Section: Introductionmentioning

confidence: 99%

Influence of La3+ ion in the yttria matrix in improving the microhardness of infrared transparent nano LaxY2-xO3 sintered via hybrid heating

et al. 2017

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Abstract:In the present work, hybrid sintering technique which couples the resistive heating and microwave heating is employed to sinter infrared transparent La 0.15 Y 1.85 O 3 to 99.2% of the theoretical density for the first time to the best of our knowledge. The presence of La 3+ in the yttria matrix improves the hardness properties to a greater extent without affecting the transmittance properties, but there is a deterioration in the thermal properties of the sample. So we have limited our studies to La 0.15 Y 1.85 O 3 which shows better optical, thermal, and hardness properties. The pellets fabricated from the ultra-fine nano powder with average particle size of ~12 nm synthesized by combustion technique and sintered at 1430 ℃ with an average grain size of 0.22 µm show ~80.1% transmittance in the UV-visible region and 81% in mid infrared region. For a comparative study of the optical, mechanical, and thermal properties, two other variants of sintering strategies namely conventional sintering and microwave sintering are also employed. A comprehensive analysis on the hardness reveals that the hardness of the pellets sintered via hybrid heating is 9.73 GPa and is superior to the pellets sintered using the other two techniques. The thermal conductivity of the sample is also analyzed in detail. The results clearly indicate that the La 0.15 Y 1.85 O 3 ultra-fine nano powder synthesised by the single-step combustion method and sintered via microwave hybrid heating shows better transmittance properties without compromising the mechanical properties, and can be used very effectively for the fabrication of infrared transparent windows and domes.

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High-temperature infrared properties of sapphire, AlON, fused silica, yttria, and spinel

Cited by 84 publications

References 8 publications

Optical constants of refractory oxides at high temperatures

Optical constants of refractory oxides at high temperatures

Optical Spectroscopy Methods and High‐Pressure–High‐Temperature Studies

Influence of La3+ ion in the yttria matrix in improving the microhardness of infrared transparent nano LaxY2-xO3 sintered via hybrid heating

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