ORCID Profile
0000-0003-4976-862X
Current Organisations
Ain Shams University
,
Royal Institute of Technology
,
Cairo University
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Publisher: Elsevier BV
Date: 10-2011
Publisher: AIP Publishing
Date: 28-01-2005
DOI: 10.1063/1.1852072
Abstract: The properties of Te-doped Co(Sb1−yTey)3 and Te-Ni double-doped Co1−xNix(Sb1−yTey)3 nanostructured skutterudites were evaluated by means of x-ray powder diffraction, and transport properties measured on the synthesized s les have been compared with ab initio theoretical modeling. Theoretical optimal dopant contents have been evaluated according to the maximum value of the power factor, calculating the electronic transport properties from the ab initio material band structure using semiclassical Boltzmann transport theory. The s les have been synthesized by chemical alloying with Te substitution for Sb up to 2.5at.% and Ni substitution for Co up to 2.0at.%. X-ray powder diffraction has been performed on all s les to reveal information about phase purity and Rietveld refinement was performed for the phase composition and cell parameter. The thermoelectric properties of the resulting consolidates were investigated in a temperature range from 300to723K using various measurement facilities. A standardization and round robin program was started among the participating evaluation laboratories in order to ensure reliability of the data obtained. The significant reduction in thermal conductivity, when compared to highly annealed CoSb3, could be proved which is caused by the nanostructuring, resulting in a high concentration of grain boundaries. A combination of substitution levels for Ni and Te has been found resulting in the largest ZT value of 0.65 at 680K among unfilled skutterudite materials.
Publisher: IEEE
Date: 2003
Publisher: IEEE
Date: 2003
Publisher: AIP Publishing
Date: 02-09-2004
DOI: 10.1063/1.1781762
Abstract: We present neutron and synchrotron powder-diffraction investigations as well as ab initio calculations to elucidate delicate structural features in doped skutterudites. S les with assumed Fe doping were investigated (FeyCo4Sb12, y=0.4, 0.8, 1.0, and 1.6), as well as s les with formal Ni substitution (Co4−xNixSb12, x=0, 0.4, 0.8, and 1.2). The present study serves as a case story for the determination of fine structural details of thermoelectric skutterudites by diffraction methods in combination with ab initio calculations. We illustrate the problem of fluorescence in the conventional x-ray powder diffraction on the Fe-doped s les by a comparison with the neutron powder-diffraction data. On the series of the Ni-substituted s les, the neutron powder-diffraction data were collected to investigate the exact sitting of the Ni. The s le with the highest Ni substitution (Co2.8Ni1.2Sb12) was also used for high resolution, high-energy synchrotron powder diffraction measurements. These revealed that the s le consists of two skutterudite phases. A complete description of the Ni-substituted s les was obtained in tandem with ab initio calculations, which show that the system contains a Ni-rich (Co0.38Ni3.62Sb12) and a Ni-poor (Co3.76Ni0.24Sb12)) skutterudite phases.
Publisher: IEEE
Date: 2003
Publisher: IEEE
Date: 2003
Publisher: IEEE
Date: 2003
No related grants have been discovered for Mamoun Muhammed.