Reststrahlen spectra of PbSe1−xTex)

Finkenrath, H.; Franz, Gerhard; Uhle, N.

doi:10.1002/pssb.2220950120

Cited by 10 publications

(4 citation statements)

References 21 publications

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“…for PbTe and 66 to 216 cm-' for PbS) degenerates to an impurity mode. Frequencies of these impurity modes are 01 (PbTe) = 33 cm-' [8] and 01 (PbS) = 153 cm-' (IR, Raman measurements). The relative strength of each mode is approximately proportional to the fractional weight of each component.…”

Section: Resultsmentioning

confidence: 99%

Transport and optical properties of PbTe_1−xSx (x = 0.02 and x = 0.05) mixed crystals

Miljković

Romčević

Popović

et al. 1996

Physica Status Solidi (b)

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Far-infrared and Raman scattering spectra as well as galvanomagnetic measurements of PbTel-,S, (x = 0.02 and 0.05) mixed crystals in the temperature range from 10 to 300 K are presented. The farinfrared reflectivity spectra are analysed using a fitting procedure based on the plasmon-phonon interaction model. Galvanomagnetic and far-infrared measurements indicate the existence of a phase transition at about Tc = 60 K for n = 0.05, whereas for samples with x = 0.02 the phase transition is not observed. Also, it is found that the long-wavelength optical phonon modes of these mixed crystals show a "two-mode'' behaviour.

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Section: Resultsmentioning

confidence: 99%

Transport and optical properties of PbTe_1−xSx (x = 0.02 and x = 0.05) mixed crystals

Miljković

Romčević

Popović

et al. 1996

Physica Status Solidi (b)

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“…Non-diffraction-based experimental data quoted in Table 12 are taken from refs. [13,52,61,63,[126][127][128][129][130][131][132]). For theoretical data, see Table 13 providing the values from refs.…”

Section: Effect Of CD Substitution On Values Of Debye Temperaturementioning

confidence: 99%

“…Abbreviations are explained at the end of this study. References: (a) [61], (b) [52], (c) [126], (d) [127], (e) [128], (f) [129], (g) [130], (h) [131], (i) [13], (j) [132], (k) [63], (l) [57], (m) [29]. (*)-The calculations from elastic constants involved the extrapolation to 0 K. Abbreviations are explained at the end of this study.…”

Section: Effect Of CD Substitution On Values Of Debye Temperaturementioning

confidence: 99%

Thermostructural and Elastic Properties of PbTe and Pb0.884Cd0.116Te: A Combined Low-Temperature and High-Pressure X-ray Diffraction Study of Cd-Substitution Effects

et al. 2021

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Rocksalt-type (Pb,Cd)Te belongs to IV–VI semiconductors exhibiting thermoelectric properties. With the aim of understanding of the influence of Cd substitution in PbTe on thermostructural and elastic properties, we studied PbTe and Pb0.884Cd0.116Te (i) at low temperatures (15 to 300 K) and (ii) at high pressures within the stability range of NaCl-type PbTe (up to 4.5 GPa). For crystal structure studies, powder and single crystal X-ray diffraction methods were used. Modeling of the data included the second-order Grüneisen approximation of the unit-cell-volume variation, V(T), the Debye expression describing the mean square atomic displacements (MSDs), <u2>(T), and Birch–Murnaghan equation of state (BMEOS). The fitting of the temperature-dependent diffraction data provided model variations of lattice parameter, the thermal expansion coefficient, and MSDs with temperature. A comparison of the MSD runs simulated for the PbTe and mixed (Pb,Cd)Te crystal leads to the confirmation of recent findings that the cation displacements are little affected by Cd substitution at the Pb site; whereas the Te displacements are markedly higher for the mixed crystal. Moreover, information about static disorder caused by Cd substitution is obtained. The calculations provided two independent ways to determine the values of the overall Debye temperature, θD. The resulting values differ only marginally, by no more than 1 K for PbTe and 7 K for Pb0.884Cd0.116Te crystals. The θD values for the cationic and anionic sublattices were determined. The Grüneisen parameter is found to be nearly independent of temperature. The variations of unit-cell size with rising pressure (the NaCl structure of Pb0.884Cd0.116Te sample was conserved), modeled with the BMEOS, provided the dependencies of the bulk modulus, K, on pressure for both crystals. The K0 value is 45.6(2.5) GPa for PbTe, whereas that for Pb0.884Cd0.116Te is significantly reduced, 33.5(2.8) GPa, showing that the lattice with fractional Cd substitution is less stiff than that of pure PbTe. The obtained experimental values of θD and K0 for Pb0.884Cd0.116Te are in line with the trends described in recently reported theoretical study for (Pb,Cd)Te mixed crystals.

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“…Another mode behavior could not be fit experimentally either to one-or to two-mode patterns (e.g. Ga/InP , 13 , P bSe/T e, 14 K/RbI, 15,16 etc.). This group of mixed crystals was called Type I-II or one-two-mode systems.…”

Section: Introductionmentioning

confidence: 99%

Concept of local polaritons and optical properties of mixed polar crystals

Yamilov

Lisyansky

2000

Phys. Rev. B

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The concept of local polaritons is used to describe optical properties of mixed crystals in the frequency region of their restrahlen band. It is shown that this concept allows for a physically transparent explanation of the presence of weak features in the spectra of so called one-mode crystals, and for one-two mode behavior. The previous models were able to explain these features only with the use of many fitting parameters. We show that under certain conditions new impurity-induced polariton modes may arise within the restrahlen of the host crystals, and study their dispersion laws and density of states. Particularly, we find that the group velocity of these excitations is proportional to the concentration of the impurities and can be thousands of times smaller then the speed of light in vacuum. * Submitted to PRB To explain different types of behavior in mixed polar crystals, a number of theoretical models have been proposed. In the IR experiments, modes with wave numbers q ∼ 0 are excited. The Random Element Isodispacement model (REI) 17,18 takes advantage of this fact, assuming that the sublattices vibrate in phase with q = 0. With some modifications 3 after including the local field, and assuming a dependence of the force constants upon the composition, the modified REI model (MREI) was successfully used to fit two-mode crystals but encountered some problems in the one-mode materials. The fine structure of some mixed crystals was reproduced along the lines of REI by means of a considerable increase in the number of fitting parameters (cluster model 18 ). A different approach made use of the Green's function formalism in order to treat vibrations in the mixed crystals; averaging over disorder was performed either in a simple virtual crystal approximation (VCA) or with the use of the much more elaborate coherent potential approximation 19 (CPA). Interaction with the electromagnetic field in these approaches was included after the averaging procedure was performed. The mean field approximation treats the crystal as if it has atoms of the same sort with some average properties. It reproduces well the one-mode behavior, but could not possibly explain the two-mode systems. CPA combined with an electrostatic treatment of the electric field was used to fit a broader range of experimental data (see, for instance, Ref. 20).An important theoretical problem many researchers have focused upon is to find a simple criterion for different mode behavior, based upon dynamical properties of the crystals. Lucovsky 9 originally considered the significance of whether the original absorption bands overlap or not, which turned out to be a rather rough criterion. Harada and Narita 10 proposed a criterion based on relations between MREI constants (see also review papers in Refs. 1,2). It turned out that one-mode and two-mode crystals can be described using quite simple models with only a few fitting parameter, such as VCA and MREI, respectively. Lucovsky et al. in Ref. 9 made an attempt to establish a connection between the behavior...

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Reststrahlen spectra of PbSe_1−xTe_x)

Cited by 10 publications

References 21 publications

Transport and optical properties of PbTe_1−xSx (x = 0.02 and x = 0.05) mixed crystals

Transport and optical properties of PbTe_1−xSx (x = 0.02 and x = 0.05) mixed crystals

Thermostructural and Elastic Properties of PbTe and Pb0.884Cd0.116Te: A Combined Low-Temperature and High-Pressure X-ray Diffraction Study of Cd-Substitution Effects

Concept of local polaritons and optical properties of mixed polar crystals

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Reststrahlen spectra of PbSe1−xTex)

Cited by 10 publications

References 21 publications

Transport and optical properties of PbTe1−xSx (x = 0.02 and x = 0.05) mixed crystals

Transport and optical properties of PbTe1−xSx (x = 0.02 and x = 0.05) mixed crystals

Thermostructural and Elastic Properties of PbTe and Pb0.884Cd0.116Te: A Combined Low-Temperature and High-Pressure X-ray Diffraction Study of Cd-Substitution Effects

Concept of local polaritons and optical properties of mixed polar crystals

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Product

Resources

About

Reststrahlen spectra of PbSe_1−xTe_x)

Transport and optical properties of PbTe_1−xSx (x = 0.02 and x = 0.05) mixed crystals

Transport and optical properties of PbTe_1−xSx (x = 0.02 and x = 0.05) mixed crystals