21 Result(s)
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Article
Defect Clustering and Nanostructure Formation in PbTe-based Bulk Thermoelectrics
In recent years, LAST-m (AgPbmSbTem+2) and related materials have emerged as potential high performance high temperature thermoelectrics. One example is LAST-18. When optimally doped, this compound has thermoelec...
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Article
Atomic Ordering, Electronic Structure, and Transport Properties of LAST-m Systems
In recent years, LAST-m (AgPbmSbTem+2) and related materials have emerged as potential high performance high temperature thermoelectrics. These compounds are obtained by starting from PbTe, and replacing pairs of...
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Article
Ab initio studies of electronic structure of defects on the Te sites in PbTe
Ab initio electronic structure calculations have been carried out to understand the nature of anionic defect states in PbTe. We find that Te vacancies strongly perturb the electronic density of states (DOS) near...
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Article
Electronic Structure of AgPbmSbTem+2 Compounds – Implications on Thermoelectric Properties
Novel quaternary compounds AgPbmSbTem+2 (LAST-m) with different m values have been synthesized recently and some of these compounds show promising thermoelectric properties at high temperatures. The two end membe...
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Article
Ab initio Studies of Electronic Structure of Defects in PbTe
Ab initio electronics structure calculations have been carried out in a series of RPb2n-1Te2n, n=16, compounds to understand the nature of “defect” states introduced by R where R = vacancy, monovalent Na, K, Rb,...
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Article
Structure and Properties of the Semiconductors Tl2SnAs2Q6 (Q = S, Se)
We describe the Tl2SnAs2Q6, (Q= S, Se) compounds which consist of [SnAs2S6]2- layers with the Tl+ cations lying in between. Tl2SnAs2S6 and Tl2SnAs2Se6 crystallize in the space group P-3 with a = 6.706(4) Å, c = 7...
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Article
Theoretical studies of Electronic Structures and Optical Absorptions of Encapsulated Guest Alkali Metal Atoms in ITQ-4 Zeolite
An ab-initio study of the electronic structures and optical absorption spectrum of the guest Cs and Na atoms absorbed in the pure silica ITQ-4 zeolite channels was carried out using density functional theory (...
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Article
Electronic Structure Of (AgSb)xFbn-2xTen
Complex quaternary chalcogenides (AgSb)xPbn-2xTen (0<x<n/2) are thought to be narrow band-gap semiconductors which are very good candidates for room and high temperature thermoelectric applications. These systems...
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Article
Theoretical Study of Electronic Structures of Bi2Te3 /Sb2Te3 Superlattices
To understand thermoelectric properties of multiplayer Bi2Te3 /Sb2Te3 superlattices, especially their charge transport properties, electronic structure calculations were carried out using ab-initio gradient corre...
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Article
Anisotropy in Thermoelectric Properties of CsBi4Te6
CsBi4Te6 (ZT ~ 0.8 at 225 K) shows highly anisotropic features in its crystal morphology and structure as expressed by the parallel infinite [Bi4Te6] rods which are linked via Bi-Bi bonds. Band calculations also ...
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Article
Effect of K/Bi ordering on the electronic structure of K2Bi8Se13
K2Bi8Se13 belongs to a class of complex chalcogenides which show potential for superior thermoelectric performance. This compound forms in two distinct phases, α and β. The β-phase, which has several sites with m...
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Article
Synthesis and Thermoelectric Properties of AgBi3S5
The known mineral Pavonite AgBi3S5 shows a complex structure composed of NaCl type fragments but has not been studied from the thermoelectric point of view. We present initial results on the synthesis and themoel...
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Article
Electronic Structure of K2Bi8Se13
K2Bi8 Se13 belongs to a class of complex Bi-Te-Se systems which show great potential for thermoelectric performance. This compound forms in two distinct phases α-K2Bi8 Se13 (triclinic with space group P-1) and β-...
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Article
Electronic Structure of CsBi4Te6
Recently, CsBi4Te6 has been reported as a high-performance thermoelectric material for low temperature applications with a higher thermoelectric figure of merit (ZT ∼ 0.8 at 225 Kelvin) than conventional Bi2- xSb
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Article
Electronic Structure of Complex Bismuth Chalcogenides and Other Narrow-Gap Thermoelectric Materials
There is considerable current effort to discover new thermoelectric materials with a high figure of merit Z. Some of these new materials are narrow-gap semiconductors with rather complex crystal structures. In...
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Article
Observed Properties and Electronic Structure of RNiSb Compounds (R = Ho, Er, Tm, Yb and Y). Potential Thermoelectric Materials
The RNiSb compounds (R=Ho, Er, Tm, Yb and Y) and some selected solid solution members such as (Zr1-x Erx )Ni(Sn1-x Sbx ) and ErNiSb1-x Pnx (Pn=As, Sb, Bi) have been studied. They all crystallize in the MgAgAs str...
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Article
Ionic Overlayers on Corrugated Surfaces III: Dynamics in the Fluid Phase
Using molecular dynamics simulation, we have studied the dynamics in the fluid phase of ionic overlayers on corrugated substrates. This is a good model to probe the dynamics of intercalants inside the gallerie...
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Article
Ionic Overlayers on Corrugated Surfaces II: Melting
Using molecular dynamics simulation we have investigated the melting properties of a 2-dimensional system of ions interacting through a screened Coulomb potential in the presence of a substrate. We focus on th...
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Article
Ionic Overlayers on Corrugated Surfaces I: Structure
Structural and dynamic properties of a large class of intercalation compounds can be modelled by a collection of ions interacting via a screened Coulomb potential and subjected to the corrugation potential pro...
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Article
Rigidity of Layered Random Alloys
Randomly intercalated layered alloys are excellent models for two-dimensional microporous systems. We have studied the nonlinear gallery expansion and the gallery height fluctuations by constructing a double l...
