Acrylonitrile Butadiene Styrene (ABS) nanocomposites were developed using Material Extrusion (MEX) Additive Manufacturing (AM) and Fused Filament Fabrication (FFF) methods. A range of mechanical tests was conducted on the produced 3D-printed structures to investigate the effect of Titanium Nitride (TiN) nanoparticles on the mechanical response of thermoplastic polymers. Detailed morphological characterization of the produced filaments and 3D-printed specimens was carried out using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). High-magnification images revealed a direct impact of the TiN concentration on the surface characteristics of the nanocomposites, indicating a strong correlation with their mechanical performance. The chemical compositions of the raw and nanocomposite materials were thoroughly investigated by conducting Raman and Energy Dispersive Spectroscopy (EDS) measurements. Most of the mechanical properties were improved with the inclusion of TiN nanoparticles with a content of 6 wt. % to reach the optimum mechanical response overall. ABS/TiN 6 wt. % exhibits remarkable increases in flexural modulus of elasticity (42.3%) and toughness (54.0%) in comparison with pure ABS. The development of ABS/TiN nanocomposites with reinforced mechanical properties is a successful example that validates the feasibility and powerful abilities of MEX 3D printing in AM.

Semiconducting quaternary chalcogenides with A₂ZnBQ₄ stoichiometry, where A and B are monovalent and tetravalent metal ions and Q is a chalcogen (e.g. Cu₂ZnSnS₄ or CZTS) have recently attracted attention as potential solar-cell absorbers made from abundant and non-toxic elements. Unfortunately, they exhibit relatively poor sunlight conversion efficiencies, which has been linked to site disorder within the tetrahedral cation sub-lattice. In order to gain a better understanding of the factors controlling cation disorder in these chalcogenides, we have used powder neutron diffraction, coupled with Density Functional Theory (DFT) simulations, to investigate the detailed structure of A₂ZnBQ₄ phases, with A = Cu, Ag; B = Sn, Ge; and Q = S, Se. Both DFT calculations and powder neutron diffraction data demonstrate that the kesterite structure (space group: I) is adopted in preference to the higher-energy stannite structure (space group: I2m). The contrast between the constituent cations afforded by neutron diffraction reveals that copper and zinc cations are only partially ordered in the kesterites Cu₂ZnBQ₄ (B = Sn, Ge), whereas the silver-containing phases are fully ordered. The degree of cation order in the copper-containing phases shows a greater sensitivity to the identity of the B-cation than to the chalcogenide anion. DFT indicates that cation ordering minimises inter-planar Zn²⁺⋯Zn²⁺ electrostatic interactions, while there is an additional intra-planar energy contribution associated with size mismatch. The complete Ag/Zn order in Ag₂ZnBQ₄ (B = Sn, Ge) phases can thus be related to the anisotropic expansion of the unit cell on replacing Cu with Ag.

The shandite family of solids, with hexagonal structure and composition $A_3{M}_2{X}_2$ (A = Ni, Co, Rh, Pd; M = Pb, In, Sn, Tl; X = S, Se), has attracted recent research attention due to promising applications as thermoelectric materials. Herein we discuss the electron and phonon transport properties of shandite-structured ${\mathrm{Ni}}_3{\mathrm{Sn}}_2{\mathrm{S}}_2$, based on a combination of density functional theory, Boltzmann transport theory, and experimental measurements. ${\mathrm{Ni}}_3{\mathrm{Sn}}_2{\mathrm{S}}_2$ exhibits a metallic and nonmagnetic ground state with ${\mathrm{Ni}}^0$ oxidation state and very low charge on Sn and S atoms. Seebeck coefficients obtained from theoretical calculations are in excellent agreement with those measured experimentally between 100 and 600 K. From the calculation of the ratio $\sigma /\tau$ between the electronic conductivity and relaxation time, and the experimental determination of electron conductivity, we extract the variation of the scattering rate ($1/\tau$) with temperature between 300 and 600 K, which turns out to be almost linear, thus implying that the dominant electron-scattering mechanism in this temperature range is via phonons. The electronic thermal conductivity, which deviates only slightly from the Wiedemann-Franz law, provides the main contribution to thermal transport. The small lattice contribution to the thermal conductivity is calculated from the phonon structure and third-order force constants, and is only $\sim 2\mathrm{W}{\mathrm{m}}^{-1}{\mathrm{K}}^{-1}$ at 300 K (less than 10% of the total thermal conductivity), which is confirmed by experimental measurements. Overall, ${\mathrm{Ni}}_3{\mathrm{Sn}}_2{\mathrm{S}}_2$ is a poor thermoelectric material ($ZT\sim$ 0.01 at 300 K), principally due to the low absolute value of the Seebeck coefficient. However, the understanding of its transport properties will be useful for the rationalization of the thermoelectric behavior of other, more promising members of the shandite family.

Substitution of tin by indium in shandite-type phases, A₃Sn₂S₂ with mixed Co/Fe occupancy of the A-sites is used to tune the Fermi level within a region of the density of states in which there are sharp, narrow bands of predominantly metal d-character. Materials of general formula Co_2.5+xFe_0.5–xSn_2–-yIn_yS₂ (x = 0, 0.167; 0.0 ≤ y ≤ 0.7) have been prepared by solid-state reaction and the products characterized by powder X-ray diffraction. Electrical-transport property data reveal that the progressive depopulation of the upper conduction band as tin is replaced by indium increases the electrical resistivity, and the weakly temperature-dependent ρ(T) becomes more semiconducting in character. Concomitant changes in the negative Seebeck coefficient, the temperature dependence of which becomes increasingly linear, suggests the more highly substituted materials are n-type degenerate semiconductors. The power factors of the substituted phases, while increased, exhibit a weak temperature dependence. The observed reductions in thermal conductivity are principally due to reductions in the charge-carrier contribution on hole doping. A maximum figure-of-merit of (ZT)_max = 0.29 is obtained for the composition Co_2.667Fe_0.333Sn_1.6In_0.4S₂ at 573 K: among the highest values for an n-type sulfide at this temperature.

A detailed account of the local atomic structure and disorder at 5 K across the phase diagram of the high-temperature superconductor ${\mathrm{K}}_x{\mathrm{Fe}}_{2-y}{\mathrm{Se}}_{2-z}{\mathrm{S}}_z$ $(0\le z\le 2)$ is obtained from neutron total scattering and associated atomic pair distribution function (PDF) approaches. Various model-independent and model-dependent aspects of the analysis reveal a high level of structural complexity on the nanometer length scale. Evidence is found for considerable disorder in the $c$-axis stacking of the ${\mathrm{FeSe}}_{1-x}{\mathrm{S}}_x$ slabs without observable signs of turbostratic character of the disorder. In contrast to the related FeCh (Ch = S, Se)-type superconductors, substantial Fe-vacancies are present in ${\mathrm{K}}_x{\mathrm{Fe}}_{2-y}{\mathrm{Se}}_{2-z}{\mathrm{S}}_z$, deemed detrimental for superconductivity when ordered. Our study suggests that the distribution of vacancies significantly modifies the iron-chalcogen bond-length distribution, in agreement with observed evolution of the PDF signal. A crossoverlike transition is observed at a composition of $z\approx 1$, from a correlated disorder state at the selenium end to a more vacancy-ordered (VO) state closer to the sulfur end of the phase diagram. The S-content-dependent measures of the local structure are found to exhibit distinct behavior on either side of this crossover, correlating well with the evolution of the superconducting state to that of a magnetic semiconductor toward the $z\approx 2$ end. The behavior reinforces the idea of the intimate relationship of correlated Fe-vacancy order in the local structure and the emergent electronic properties.