Phase transitions in CdTe to 28 GPa

Nelmes, R. J.; McMahon, M. I.; Wright, N. G.; Allan, D. R.

doi:10.1103/physrevb.51.15723

Cited by 68 publications

(58 citation statements)

References 21 publications

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“…Our results unambiguously show the distortions are related to the Cmcm space group, and the features of AgSbTe 2 before amorphization indicate the distortions are similar to those observed in lead, calcium, and cadmium chalcogenides during the B1-B2 transition. 23,24,25,26 These results closely agree with the earlier theoretical models explaining the rearrangement of atoms displaced between the layers during the B1-B2 transitions.…”

supporting

confidence: 91%

“…The compound undergoes a B1 to B2 transition; the transition proceeds through an intermediate amorphous phase found between [17][18][19][20][21][22][23][24][25][26] GPa that is quenchable down to ambient conditions. The pressure induced structural transition observed in this compound is the first of its type reported in this ternary cubic family, and it is new for the B1-B2 transition pathway reported to date.…”

mentioning

confidence: 99%

“…Previous high pressure structural studies on II-VI chalcogenides have shown transformation of NaCl phase to an intermediate orthorhombic phase (Cmcm or Pbnm), 23,24,25 we have examined the XRD pattern obtained at 16 GPa for similar types of distortions with Cmcm and Pbnm structures. Both Pbnm and Cmcm structures were considered during the Rietveld refinement, and a reliable fit has been obtained using the Cmcm space group, with the Ag/Sb atoms located at 4a sites (0, 0, 0) and Te atoms occupying the 8d sites (0.75, 0.25, 0.5).…”

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confidence: 99%

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Pressure induced structural phase transition inAgSbTe2

et al. 2005

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We report a novel high pressure structural sequence for the functionally graded thermoelectric, narrow band gap semiconductor AgSbTe2, using angle dispersive x-ray diffraction in a diamond anvil cell with synchrotron radiation at room temperature. The compound undergoes a B1 to B2 transition; the transition proceeds through an intermediate amorphous phase found between 17-26 GPa that is quenchable down to ambient conditions. The pressure induced structural transition observed in this compound is the first of its type reported in this ternary cubic family, and it is new for the B1-B2 transition pathway reported to date. Density Functional Theory (DFT) calculations performed for the B1 and B2 phases are in good agreement with the experimental results.PACS numbers: 61.43.Dq, 61.5. Ks, 61.10.Nz, 71.15.Mb Ternary semiconductors with a general formula ABX 2 (A= Cu,Ag ; B=In,Ga,Sb; X= S,Se,Te) with chalcopyrite or rock salt structure are widely used for important technical and device applications. These compounds are found to be excellent candidates for the fabrication of optical frequency converters in solid state laser systems, photovoltaic devices and development of solar cells.1,2,3 While the Cu based chalcopyrites are mainly studied in connection with their photovoltaic applications, the Ag compounds find importance in thermoelectric, optical phase change and frequency conversion applications.4,5 Cubic AgSbTe 2 compounds with Pb doping have been recently shown to be excellent thermoelectric materials with high figures of merit, and are considered promising candidates for future energy production from heat sources.6 AgSbTe 2 with In and V doping undergo, rapid crystalline -amorphous phase transitions on local melting; a property that is used widely to write and rewrite Compact Disks (CD) and Digital Versatile Disks (DVD). 7,8 In comparison with the classical GeSbTe phase change memory alloy, AgVInSbTe is reported to have better erasability and cyclablity in memory switching . 7,8,9,10 The phase changes in these materials are temperature driven, and the previous studies focus mainly on doped thin films of AgSbTe 2 . To our knowledge, no detailed structural reports are available for the host compound AgSbTe 2 , under different temperature or pressure conditions. AgSbTe 2 is isostructural to the rocksalt type II-VI chalcogenides. As the rock salt structure of most of the II-VI compounds is sensitive to pressure, changing from B1 to B2, 11,12 one may expect AgSbTe 2 to display a similar crystallographic transition under pressure. The aim of the present study is to investigate AgSbTe 2 under pressure to explore the structural similarities with its binary analogues. In this paper, we present experimental evidence, for the first time, of a pressure induced structural transition from B1 (crystalline) to B2 (crystalline) with an intermediate amorphous state. This is a new pathway for this structural sequence and is unique in the ABX 2 family. This finding may open up new directions in the search for similar compounds of ...

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confidence: 91%

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confidence: 99%

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confidence: 99%

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Pressure induced structural phase transition inAgSbTe2

et al. 2005

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“…In fact this cinn-like structure has 4ϩ2 coordination, instead of the twofold coordination of ␣-HgS (true cinnabar), and upon compression it approaches the sixfold coordination of NaCl. A further transition is observed at about 10 GPa (Samara and Drickamer, 1962) to a phase that Nelmes et al (1995a) have conclusively identified as site-ordered Cmcm. As in several other cases, this Cmcm phase had previously been reported to have a ␤-Sn-type structure (Owen et al, 1963;Hu, 1987).…”

Section: Cdtementioning

confidence: 90%

“…Once the distortion from NaCl has fully developed ͓b/aϭ1.069, c/a ϭ0. 948,y(Cd)ϭ0.650(3),y(Te)ϭ0.180(3) in CdTe at 18.6 GPa (Nelmes et al, 1995a)] each atom has five unlike nearest neighbors and three next-nearest neighbors a bit further away (two of which are like-atoms). There are in all six different nearest and next-nearest distances.…”

Section: Hexagonal Close Packingsmentioning

confidence: 99%

High-pressure phases of group-IV, III–V, and II–VI compounds

et al. 2003

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Advances in the accuracy and efficiency of first-principles electronic structure calculations have allowed detailed studies of the energetics of materials under high pressures. At the same time, improvements in the resolution of powder x-ray diffraction experiments and more sophisticated methods of data analysis have revealed the existence of many new and unexpected high-pressure phases. The most complete set of theoretical and experimental data obtained to date is for the group-IVA elements and the group-IIIA-VA and IIB-VIA compounds. Here the authors review the currently known structures and high-pressure behavior of these materials and the theoretical work that has been done on them. The capabilities of modern first-principles methods are illustrated by a full comparison with the experimental data. CONTENTS

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Raman spectroscopy study of Zn1−xFexSe under high pressure

Lin

Chuu

1999

J. Raman Spectrosc.

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Zn 1−x Fe x Se, x = 0, 0.018, 0.035 and 0.16, were studied by Raman scattering spectroscopy up to 35.0 GPa. It was found that the semiconductor-metal phase transition pressures for these samples are 14.4, 12.8, 12.0 and 10.9 GPa, respectively. Before the semiconductor-metal phase transition, a visible anomaly of the TO Raman mode splitting was observed at 4.7 and 9.1 GPa for ZnSe, at 3.3 and 5.9 GPa for Zn 0.982 Fe 0.018 Se, and at 4.5 and 7.2 GPa for Zn 0.965 Fe 0.035 Se, respectively, while Zn 0.84 Fe 0.16 Se showed mode splitting at 4.7 GPa only. For these samples, one of the TO splitting modes exhibits phonon softening (red shift), while the other manifests wavenumber increasing (blue shift) with pressure. For x = 0.018, 0.035 and 0.16, a new Raman mode, which was identified as Fe local mode, was observed between the pure ZnSe LO and TO modes. Fe local mode exhibits blue shift behaviour before metallization and disappears as the pressure is higher beyond the metallization pressure. PACS numbers: 62.50. Y p, 64.60. − i , 78.30.Fs.

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Phase transitions in CdTe to 28 GPa

Cited by 68 publications

References 21 publications

Pressure induced structural phase transition inAgSbTe2

Pressure induced structural phase transition inAgSbTe2

High-pressure phases of group-IV, III–V, and II–VI compounds

Raman spectroscopy study of Zn1−xFexSe under high pressure

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