Systematic Study of Stable Palladium and Nickel Based Half-Heusler Compounds for Thermoelectric Generators
52 Pages Posted: 27 Nov 2019 Last revised: 12 May 2023
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Systematic Study of Stable Palladium and Nickel Based Half-Heusler Compounds for Thermoelectric Generators
Delineating Urban Areas Using Building Density
Abstract
We develop a new dartboard methodology to delineate urban areas using detailed information about building location, which we implement using a map of all buildings in France. For each pixel, our approach compares actual building density after smoothing to counterfactual smoothed building density computed after randomly redistributing buildings. We define as urban any area with statistically significant excess building density. Within urban areas, extensions to our approach allow us to distinguish ‘core’ urban pixels and detect centres and subcentres. Finally, we develop novel one- and two-sided tests that provide a statistical basis to compare maps with different delineations, which we use to assess the robustness of our approach and to document large differences between our preferred delineation and the corresponding official one.
A comprehensive study was carried out on MXAs compounds (M = Ni and Pd; X = Lu and Sc) within the framework of Density functional theory (DFT) based on projected augmented waves to determine their viability as thermopower generator. The electronic properties were computed and the results predicted that NiLuAs, NiScAs and PdScAs compounds are semicondutors with indirect bandgaps of 0.48 eV 0.50 ev and 0.44 eV respectively while PdLuAs compound is predicted to be semi-metallic in nature. The computed elastic constants were observed to satisfy the general criteria for stability for cubic symmetry. The corresponding mechanical properties revealed that all the compounds are ductile and anisotropic. The computed phonon dispersion also affirmed the dynamical stability of the compounds as evident in the absence of imaginary frequencies in the entire Brillouin zone for all the compounds. The calculated thermoelectric properties further verified that MXAs compounds are promising candidates for efficient thermoelectric materials. The P-type PdScAs compound was predicted to be the most efficient thermoelectric materials with highest zT of 0.75 at temperature of 300 - 500 K.. Our results demonstrate that these compounds are prospective materials for thermoelectric applications.
Keywords: semi-metallic, electronic properties, lattice thermal conductivity, thermoelectric properties
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