arXiv subjects

Marisol Martín-González

Publications and source records attributed to Marisol Martín-González.

3 recordsLinked to original sources

arXiv2026

Off-stoichiometric variable doping for exceptional power factors in L2$_1$ Fe$_2$VAlM$_x$ (M=Ti, W) epitaxial thin films

We show that the addition of Ti or W to stoichiometric L2$_1$ Fe$_2$VAl thin films by sputter codeposition produces off stoichiometric thin film alloys with superior thermoelectric properties than their stoichiometric counterparts. Ti incorporation induces p-type semiconducting behavior, while W incorporation shifts the material toward n-type, hereby enabling simultaneous tuning of both carrier types within a single parent (Fe$_2$VAl) material system, making it highly desirable for thermoelectric devices. The introduction of both Ti and W partly substitutes V in the stoichiometric compound. The partial substitution of V in the stoichiometric alloy allows fine-tuning the band structure of the system and transport properties. With this approach we obtain exceptional maximum power factor values for p and n-type films of 1300 $μ$W/m$\cdot$K$^2$ and 2100 $μ$W/m$\cdot$K$^2$ ,respectively, yielding maximum figures of merit zT of 0.07 and 0.14, respectively.

cond-mat.mtrl-sci↗

arXiv2025

Thermoelectric Performance Boost by Chemical Order in Epitaxial L2$_1$ (100) and (110) Oriented undoped Fe$_2$VAl Thin Films: An Experimental and Theoretical Study

This study demonstrates the direct correlation between the presence of the L2$_1$ ordered phase and the large enhancement in the thermoelectric performance of Fe$_2$VAl thin films deposited on MgO and Al$_2$O$_3$ substrates at temperatures varying between room temperature and 950$^{\circ}$C. We employ both experimental techniques and computational modeling to analyze the influence of crystallographic orientation and deposition temperature on the thermoelectric properties, including the Seebeck coefficient, electrical conductivity, and thermal conductivity. Our findings indicate that the presence of the L2$_1$ phase significantly enhances the power factor (PF) and figure of merit (zT), surpassing previously reported values for both bulk and thin film forms of Fe$_2$VAl, achieving a PF of 480 $μ$W/m$\cdot$K$^2$ and a zT of 0.025.

cond-mat.mtrl-sci↗

arXiv2023

CoSb3-based skutterudite nanocomposites prepared by cold sintering process with enhanced thermoelectric properties

We show here for the first time the use of a cold sintering process (CSP) to sinter CoSb3-based thermoelectric materials. CSP at 150 °C for 90 min under a uniaxial pressure of 750 MPa yields pieces with a relative density of 86 %, which is increased to around 92 % after a post-annealing at temperatures > 500 °C in Ar atmosphere. The reported CSP produces Te doped-CoSb3 nanocomposites with similar morphological and structural characteristics to the starting nanopowders obtained by ball milling in air atmosphere. The post-thermal treatment induces grain coalescence and grain growth, crystallite size growth as well as compositional changes in the nanocomposite, decreasing the amount of the main phase, CoSb3, and increasing the weight of secondary phase, CoSb2, up to a 30 wt% at 600 °C. Remarkably, the average valence for the Co, Sb and Te absorbing atoms is neither transformed by the sintering process nor by the subsequent heat treatment. The functional response of the sintered thermoelectric nanocomposites exhibits a maximum figure of merit of 0.12(3) at room temperature for the nanocomposites sintered by CSP with a subsequent post-annealing at 500 °C. This is mainly due to its low thermal conductivity in comparison with similar powders sintered by other approaches, and it is explained by the morphological and structural properties. These findings represent an attractive alternative for obtaining efficient thermoelectric skutterudites by a scalable and cost-effective route.

cond-mat.mtrl-sci↗