arXiv subjects

Shamima Hussain

Publications and source records attributed to Shamima Hussain.

5 recordsLinked to original sources

arXiv2026

Effect of Indium doping on structural and thermoelec-tric properties of SnTe

The solid state reaction method is employed to synthesize Sn1-xInxTe samples. Power Factors of synthesized samples are estimated from resistivity and thermopower data. Modifications in structural parameters, resistivity and thermopower owing to In doping in SnTe thermoelectric material are reported. In-depth structural analysis, employing Rietveld refinement of X-ray diffraction data, confirms the substitution of Sn by In. A minute amount of embedded phases in synthesized samples is revealed from the refinement of X-ray diffraction data. Williamson-Hall and modified Williamson-Hall methods are employed to estimate dislocation density and strain. The highest power factor and maximum host phases are simultaneously achieved for the Sn0.96In0.04Te sample amid the synthesized Sn1-xInxTe samples.

cond-mat.mtrl-sci↗

arXiv2026

Favorable half-Heusler structure of synthesized TiCoSb alloy: a theoretical and experimental study

The most favorable structure of the synthesized TiCoSb half-Heusler alloy is explored theoretically and experimentally, and the best structure for thermoelectric conversion is reported. Rietveld refinement of the X-ray diffraction data employing four probable structures of the HH alloy is performed to obtain the best fit and identify the crystallized structure. However, microstructural characterization is performed using the energy dispersive X-ray spectroscopy and transmission electron microscopy to reveal the stoichiometry and Bragg reflection planes of the synthesized polycrystalline lattice structure of TiCoSb HH alloy. Theoretical investigation is performed by implementing the first principle calculation using the Full Potential Linearized Augmented Plane Wave method in the Quantum Espresso software package. The most probable structure is explored by estimating the minimum energy at equilibrium volume and electronic structure of the TiCoSb half-Heusler alloy of the four probable structures considered. The theoretical and experimental data are corroborated, and the most probable structure is identified for the crystallized TiCoSb HH alloy. The thermoelectric properties of the most probable structure are estimated.

cond-mat.mtrl-sci↗

arXiv2025

Anomalous Power Factor Enhancement and Local Structural Transition in Ni-Doped TiCoSb

We report a significant enhancement (~269%) in the power factor (PF) and a local structural transition in Ni-doped TiCoSb samples (TiCo_{1-x}Ni_xSb, (x= 0.0, 0.01, 0.02, 0.03, 0.04, and 0.06). First-principles calculations reveal that even minute Ni doping induces a substantial shift in the Fermi level (EF) and alters the density of states (DOS). Structural analysis via Rietveld refinement of X-ray diffraction (XRD) data shows anomalous behavior at x = 0.02, supported by Williamson-Hall and modified methods. X-ray absorption spectroscopy (XAS) at the Ti and Co K-edges further confirms a pronounced local structural change at this composition. These structural transitions are consistent with temperature-dependent resistivity (\rho(T)) and thermopower (S(T)) data, which reflect changes in EF and disorder. Analysis of Lorentz number and scattering parameters reinforces the observed modifications in the electronic structure. The simultaneous enhancement of S and electrical conductivity at x = 0.02 is attributed to the disorder-to-order transition, leading to the marked rise in PF.

cond-mat.mtrl-sci↗

arXiv2024

Drastic modification in thermal conductivity of TiCoSb Half-Heusler alloy: Phonon engineering by lattice softening and ionic polarization

A drastic variation (~47%) in thermal conductivity (\k{appa}) for synthesized samples (TiCoSb1+x, x=0.0, 0.01, 0.02, 0.03, 0.04, and 0.06) is observed. The lowest \k{appa} is reported for the TiCoSb1.02 sample. Thermal variation of \k{appa} is estimated from the temperature and power-dependent Raman spectroscopy data. Embedded phases and Co vacancy are analysed, employing scanning electron microscopy and transmission electron microscopy data. X-ray absorption fine structure (XAFS) spectroscopy reveals the Co vacancy in synthesized samples, and the most ordered phase is TiCoSb1.02 amid the synthesized samples. X-ray photoelectron spectroscopy measurement of the synthesized samples provides direct evidence of Co vacancies and their increase with Sb concentration (x). Lattice dynamics are revealed using Raman Spectroscopy (RS) measurements. RS data accomplishes that variation in \k{appa} as a function of Sb concentration is observed owing to an alteration in phonon group velocity, related to lattice softening. The polar nature of the TiCoSb half-Heusler (HH) sample is revealed. Longitudinal Optical and Transvers Optical phonon (LO-TO) splitting in RS is observed due to the polar nature of TiCoSb1+x synthesized samples. Tailoring in LO-TO splitting due to the screening effect, correlated with Co vacancies, is reported for TiCoSb1+x synthesized samples. Lattice softening and LO-TO splitting lead to a minimum \k{appa} for the TiCoSb1.02 synthesized sample.

cond-mat.mtrl-sci↗

arXiv2019

Strategy for enhanced thermoelectric performance of Bi2S3 nanorods by Bi nanoinclusions

This is the first report on the enhanced thermoelectric (TE) properties of novel Bi2S3-Bi nanocomposites synthesized using a one-step polyol method at different reaction temperatures (TRe) and time. They are well-characterized as nanorod-composites, coexistent with orthorhombic Bi2S3 and rhombohedral Bi phases together in which the latter coats the former forming Bi2S3-Bi core-shell type structures along with independent Bi nanoparticles (NPs). There is a very significant observation of systematic reduction in electri-cal resistivity \r{ho} with reaction temperature and time duration increase, revealing a promising approach for reduction of \r{ho} in this highly resistive Bi2S3 and hence resolving the earlier obstacles for its thermoelectric application potentials for the past few decades. Most astonishingly, TE power factor at 300 K of highest Bi content nanocomposite pellet, made at 27 oC using ~900 MPa pressure, is 3 orders of magnitude greater than that of hot-pressed Bi2S3, or even 23% better than that of spark plasma-sintered core-shell Bi2S3@Bi sample reported earlier (Tarachand et al. Nano Res. 2016, 9, 3291; Ge et al. ACS Appl. Mater. Interfaces 2017, 9, 4828). Considering the probable greatly reduced thermal conductivity due to their complex nanostructures, the significantly improved TE performance potential near 300 K is highly anticipated for these toxic- and rare earth element-free TE nanocomposites, making the present synthesis method as a pioneering approach for developing enhanced thermoelectric properties of Bi2S3-based materials without using extra sintering steps.

cond-mat.mtrl-sci↗