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In the last few weeks we had two papers published in materials science journals: “Diboron-porphyrin monolayer: A new 2D semiconductor” has been published in Computational Materials Science and “Thermoelectric properties of BiSbTe alloy nanofilms produced by DC sputtering: experiments and modeling” has been published in Journal of Materials Science.

In the first one, we investigate a new 2D material with BC₁₀N₂ stoichiometry based on the molecular structure of diboron porphyrin. Ab-initio molecular dynamics simulations indicate mechanical stability up to 4000 K. Electronic structure calculations based on density functional theory predict a 0.6 eV direct band gap. Non-equilibrium molecular dynamics simulations predict anisotropic lattice thermal conductivities of 160 and 115  W/m–K along perpendicular in-plane directions at room temperature. Overall the results indicate that, in spite of its interesting anisotropic transport properties, diboron porphyrin monolayers are not suitable candidates for thermoelectric applications.

In the second one, we analyze the deposition of BiSbTe films and the effect of a thermal treatment on their thermoelectric properties. We produced sputtering targets from decommissioned commercial thermoelectric modules, exploring an environmentally responsible destination for discarded devices. Films deposited by DC sputtering presented an improvement in thermoelectric efficiency as the annealing temperature was increased from 423 K to 623 K. We modeled the effect of the annealing temperature on thermal conductivity, electrical resistivity, and Seebeck coefficient with the theory of q-deformed algebra, and related the q-factor to structural properties of the films. This work could pave the way for modeling experimental measurements via the formalism of q-deformation algebra.

Both publications result from collaboration with colleagues at Universidade Federal do Rio Grande do Norte, Universidade Federal da Paraíba and Universidade Federal de Campina Grande.

I must be getting closer to becoming a real materials scientist now.

Our third publication of 2019 “Outstanding strength, optical characteristics and thermal conductivity of graphene-like BC₃ and BC₆N semiconductors” has just been accepted for publication in Carbon.

Carbon-based 2D materials with honeycomb lattices, such as graphene, polyaniline carbon-nitride, and boron-carbide exhibit exceptional physical properties. Here, we propose two novel graphene-like materials with BC₆N stoichiometry. We employ first-principles calculations to explore mechanical, optical and thermal transport characteristics of graphene-like BC₃ and BC₆N monolayers. The absence of imaginary phonon frequencies confirm the dynamical stability of BC₃ and BC₆N monolayers. First principles results also reveal that BC₃ and BC₆N present high elastic moduli and tensile strengths. Electronic structure calculations show that BC₃ and BC₆N monolayers are indirect and direct bandgap semiconductors, respectively. An analysis of their optical absorption spectra reveals absorption peaks for in-plane polarization in the visible range. Finally, ab-initio based anharmonic lattice dynamics calculations predict room temperature lattice thermal conductivities of 410 and 1710  W/-K, respectively. Notably, the thermal conductivity of BC₆N is one of the highest among 2D materials. Our results indicate that those new BC₆N monolayers are promising candidates for the design of novel nanodevices.

This work is our most recent collaboration with Dr. Bohayra Mortazavi and Prof. Timon Rabczuk at Bauhaus-Universität Weimar.