Detail publikace

Effective infrared reflectivity and dielectric function of polycrystalline alumina ceramics

NUZHNYY, D. PETZELT, J. BORODAVKA, F. VANĚK, P. ŠIMEK, D. TRUNEC, M. MACA, K.

Originální název

Effective infrared reflectivity and dielectric function of polycrystalline alumina ceramics

Anglický název

Effective infrared reflectivity and dielectric function of polycrystalline alumina ceramics

Jazyk

en

Originální abstrakt

Room-temperature infrared (IR) reflectivity, terahertz transmission and evaluated effective complex dielectric response of four polycrystalline alumina ceramics (corundum) with highly anisotropic grains in the IR range were determined. The spectra were compared with modelled spectra based on the known IR response of sapphire single crystal and Bruggeman and Lichtenecker models of the effective medium approximation (EMA). The results are extremely sensitive to the surface treatment (polishing), but do not depend on the grain size in the range of 0.3–1 mm and on the weak doping, needed for processing of optically transparent ceramics. As all the samples show similar grain shapes and topology, no measurable differences among the fully dense samples were observed. Agreement with the modelled spectra is reasonable, but shows a higher effective mode damping. A weak geometrical resonance was revealed near 500 cm1, better described by the Bruggeman model. The small sample porosity up to 6.2% is revealed mainly as a reduced reflectivity above 650 cm1, which produces weak losses in the high-frequency range above the TO phonon modes, better described by the Lichtenecker model.

Anglický abstrakt

Room-temperature infrared (IR) reflectivity, terahertz transmission and evaluated effective complex dielectric response of four polycrystalline alumina ceramics (corundum) with highly anisotropic grains in the IR range were determined. The spectra were compared with modelled spectra based on the known IR response of sapphire single crystal and Bruggeman and Lichtenecker models of the effective medium approximation (EMA). The results are extremely sensitive to the surface treatment (polishing), but do not depend on the grain size in the range of 0.3–1 mm and on the weak doping, needed for processing of optically transparent ceramics. As all the samples show similar grain shapes and topology, no measurable differences among the fully dense samples were observed. Agreement with the modelled spectra is reasonable, but shows a higher effective mode damping. A weak geometrical resonance was revealed near 500 cm1, better described by the Bruggeman model. The small sample porosity up to 6.2% is revealed mainly as a reduced reflectivity above 650 cm1, which produces weak losses in the high-frequency range above the TO phonon modes, better described by the Lichtenecker model.

Dokumenty

BibTex


@article{BUT137370,
  author="Dimitry {Nuzhnyy} and Jan {Petzelt} and Fedir {Borodavka} and Přemysl {Vaněk} and Daniel {Šimek} and Martin {Trunec} and Karel {Maca}",
  title="Effective infrared reflectivity and dielectric function of polycrystalline alumina ceramics",
  annote="Room-temperature infrared (IR) reflectivity, terahertz
transmission and evaluated effective complex dielectric
response of four polycrystalline alumina ceramics (corundum)
with highly anisotropic grains in the IR range were
determined. The spectra were compared with modelled
spectra based on the known IR response of sapphire single
crystal and Bruggeman and Lichtenecker models of the
effective medium approximation (EMA). The results are
extremely sensitive to the surface treatment (polishing),
but do not depend on the grain size in the range of
0.3–1 mm and on the weak doping, needed for processing
of optically transparent ceramics. As all the samples show
similar grain shapes and topology, no measurable differences
among the fully dense samples were observed.
Agreement with the modelled spectra is reasonable, but
shows a higher effective mode damping. A weak
geometrical resonance was revealed near 500 cm1, better
described by the Bruggeman model. The small sample
porosity up to 6.2% is revealed mainly as a reduced
reflectivity above 650 cm1, which produces weak losses
in the high-frequency range above the TO phonon modes,
better described by the Lichtenecker model.",
  chapter="137370",
  doi="10.1002/pssb.201600607",
  howpublished="print",
  number="5",
  volume="254",
  year="2017",
  month="may",
  pages="1--8",
  type="journal article in Web of Science"
}