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Results for “Cd-Te”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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9 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1982

Application of the regular associated solution model to the Cd-Te and Hg-Te binary systems

The regular associated solution model is used to treat the phase diagrams of the binary II-VI semiconductor alloy systems Hg-Te and Cd-Te. The equations for the species activity coefficients are used without approximations regarding the magnitudes of the various binary interchange energies or the functional dependence on component mol fraction. The values of the four-adjustable parameters required for description of each system are fixed by fitting liquidus data, and the resulting activity coefficients are used to calculate component partial pressures, which are compared with experimental values as an indpendent check of the validity of the model. The results show that the regular associated solution model provides a usefully accurate, but not complete, description for both the Hg-Te and Cd-Te systems. The relationship of this work to previous investigations is discussed.

Kelley, J. D.↗
DOE OSTI2025

A first principles study on the adsorbate-adsorbate interactions on the CdTe(111) surface with Cd, Te, Zn, and Se adatoms

The study of adsorbate-adsorbate interactions is essential to understanding early crystal growth dynamics. Here, we employ planewave density functional theory to study the binary adatom pair interactions between Cd-Cd, Te-Te, Zn-Zn, Se-Se, Cd-Te, Cd-Se, Cd-Zn, Te-Se, Te-Zn, and Se-Zn adatom pairs on two CdTe(111) surfaces. An analysis of the interaction energies between binary adatom pairs suggests repulsive interactions are common regardless of the relative distance between adatoms. For the CdTe(111)A surface, attractive interactions occur between neighboring chalcogen (i.e., Te and Se) and Group 12 (i.e., Cd and Zn) adatom pairs. For the CdTe(111)B surface, attractive interactions occur between neighboring Group 12 adatoms forming a surface dimer configuration. Furthermore, the formation energy of an adatom pair is decomposed in terms of the electronic, elastic, and adatom binding contributions. For smaller interatomic distances between the adatoms, the formation energy is primarily a function of the electronic interactions, with null contributions from the elastic and adatom binding interactions for Group 12-containing pairs. Because of the less favorable electronic interactions for larger interatomic distances between the adatoms, the formation energies are typically more positive. Lastly, neighboring adatoms significantly increase the barriers of migration on the CdTe(111)A surface relative to unary adatoms for the top-to-fcc and fcc-to-fcc sites, while the migration barriers on the CdTe(111)B surface only increases for the fcc-to-fcc migration of chalcogen species. From this analysis, we illustrate the role of adatom interactions during the early stages of the surface nucleation processes on CdTe(111) thin films.

CdTe↗
NASA NTRS1992

Experimental results and numerical modeling of solidification during aircraft high-g arcs

The question of how the Coriolis and gravity gradient forces during high-gravity maneuvers compare to that for common centrifuges is addressed. Microstructural examination of samples solidified during high-gravity arcs reveals no evidence of convection dampening. As a first approximation, the high-gravity arc is modeled as a centrifuge with a radius of 20,480 ft and angular speed of 0.318 rpm. Scaling analysis indicates that the Coriolis and gravity gradient expected on the aircraft high gravity arc are less than that for the centrifuges by a factor of 100. Detailed Navier-Stokes analysis of the fluid flow and thermal fields during solidification of aluminum and Cd-Te during KC-135 high gravity show that convective flows of about 1 mm/s are induced. The thermal field is only slightly modified by the convection. Coriolis and gravity gradient during solidification in KC-135 high-gravity arcs, even at accelerations that have been shown to produce significant convective flow dampening in the centrifuge systems, are found to have no significant influence on the melt thermal and flowfields.

Curreri, P. A.↗
DOE OSTI2020

Materials Data on CdTe by Materials Project

CdTe is Wurtzite structured and crystallizes in the hexagonal P6_3mc space group. The structure is three-dimensional. Cd2+ is bonded to four equivalent Te2- atoms to form corner-sharing CdTe4 tetrahedra. There are three shorter (2.87 Å) and one longer (2.88 Å) Cd–Te bond lengths. Te2- is bonded to four equivalent Cd2+ atoms to form corner-sharing TeCd4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CdTe by Materials Project

CdTe crystallizes in the trigonal P3_121 space group. The structure is three-dimensional. Cd2+ is bonded in a distorted rectangular see-saw-like geometry to four equivalent Te2- atoms. There are two shorter (2.89 Å) and two longer (2.91 Å) Cd–Te bond lengths. Te2- is bonded in a distorted rectangular see-saw-like geometry to four equivalent Cd2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CdTe by Materials Project

CdTe is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Cd2+ is bonded to six equivalent Te2- atoms to form a mixture of edge and corner-sharing CdTe6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Cd–Te bond lengths are 3.07 Å. Te2- is bonded to six equivalent Cd2+ atoms to form a mixture of edge and corner-sharing TeCd6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CdTe by Materials Project

CdTe is Zincblende, Sphalerite structured and crystallizes in the cubic F-43m space group. The structure is three-dimensional. Cd2+ is bonded to four equivalent Te2- atoms to form corner-sharing CdTe4 tetrahedra. All Cd–Te bond lengths are 2.87 Å. Te2- is bonded to four equivalent Cd2+ atoms to form corner-sharing TeCd4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CdTe by Materials Project

CdTe is Wurtzite structured and crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Cd2+ is bonded to four equivalent Te2- atoms to form corner-sharing CdTe4 tetrahedra. There are one shorter (2.86 Å) and three longer (2.88 Å) Cd–Te bond lengths. Te2- is bonded to four equivalent Cd2+ atoms to form corner-sharing TeCd4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CdTe by Materials Project

CdTe is Millerite-like structured and crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Cd2+ is bonded to five equivalent Te2- atoms to form a mixture of corner and edge-sharing CdTe5 trigonal bipyramids. There are a spread of Cd–Te bond distances ranging from 2.95–3.04 Å. Te2- is bonded to five equivalent Cd2+ atoms to form a mixture of distorted corner and edge-sharing TeCd5 square pyramids.

36 MATERIALS SCIENCE↗