The transport properties of CrN thin films deposited on sapphire have been tailored through structural modifications induced by cumulative argon implantation. As-grown samples experience the typical structural transition in CrN films from orthorhombic at low temperature to cubic above the N & eacute;el temperature (approximate to 280 K) and exhibit a metallic-like conduction in both phases. With increasing implantation dose, the conduction mode shifts to a semiconductor-like behavior in both phases, albeit at different damage levels. Analysis of the results suggests that hopping conduction becomes dominant beyond a given damage threshold. The results highlight a promising correlation between defect engineering and conduction mechanisms, offering valuable insights into the versatile electrical properties of CrN films. These implantation-induced defects scatter carriers, leading to a decrease in their mobility. As the implantation dose increases, the defect landscape evolves, modifying the density of states. However, up to a dose of 0.050 dpa, no significant influence on phonon scattering is observed. This approach demonstrates that ion implantation enables precise tuning of CrN's electrical properties without affecting thermal conductivity, offering valuable insights into defect engineering in transition metal nitrides and underscoring its potential for transport properties decorrelation.

The influence of heavy atom incorporation (in this case, tungsten, W) into scandium nitride is examined to assess its impact on the electronic structure and associated thermoelectric properties. Incorporating W, with its 5d valence electrons, is expected to shift the Fermi level into the conduction band. A solid solution of Sc1−x​Wx​Ny​ system is also expected to form as ScN exhibits the largest unit cell among the early 3d transition metal nitrides. However, phase separation is initiated at x = 0.10 and results in Sc- and W-rich regions occurring through conventional nucleation and growth. High-temperature nitrogen substoichiometry (at ∼800 °C) and formation of secondary phase is governed by inducing N vacancies in the crystal system. The N/W ratio alters the occupancy of the nonbonding t2g states in the valence band and results in phase instability. The Sc1−x​Wx​Ny​ system is found to be less covalent than a ScN reference sample indicating the presence of ionic and metallic bonds as observed through spectroscopic studies. A unique combination of a metal-like Seebeck coefficient with increased electrical resistivity is found for the Sc1−x​Wx​Ny​ system compared to the ScN reference. This study aims to elucidate the structural, microstructural, and electronic properties of the Sc1-xWxNy system and establishing a correlation with thermoelectric properties, through a combined experimental and theoretical approach.

Fiber-textured and epitaxial NiO thin films were deposited on Si(100), c-Al₂O₃, and muscovite mica(001) sub-strates using reactive magnetron sputtering at substrate temperatures of 300 °C and 400 °C, to investigate theeffect of film thickness and substrate temperature on epitaxial growth of NiO films. The as-deposited filmsexhibited a face-centered cubic structure with a larger lattice constant, attributed to strain induced during thesputtering process. With an increase in substrate temperature to 400 °C, the d-spacing decreased due to strainrelease, approaching the NiO bulk value for the thickest film. The NiO film grown on Si(100) displayed fibertexture. On c-plane sapphire, NiO thin films exhibited twin domains and three-fold symmetry, consistent withexpected crystallographic orientation relationship for NaCl-structured materials onsapphire: (111)_NiO ‖ (0001)_Al2O3 and [011]_NiO ‖ [1010]_Al2O3, [011]_NiO ‖[1010]_Al2O3. On muscovite mica(001)substrates, the observed epitaxial shows that the mechanism is conventional epitaxy, rather than van der Waalsepitaxy, consistent with the epitaxial growth of the non-layered non-van-der-Waals compound NiO. The epitaxialrelationship was identified as of (111)_NiO‖(001)_Mica and [011]_NiO ‖[010]_Mica, [011]_NiO ‖[010]_Mica.

CrN-based thin films are emerging as thermoelectric materials for energy harvesting. Their thermoelectric properties depend on phase composition and stoichiometry, necessitating control over the nitrogen content and how it affects the phase composition. Here, the effect of high-temperature ammonia annealing on the thermoelectric properties as well as crystal structure of thin films of Cr-N on c-plane sapphire (Al2O3(0001)) was investigated. Single-phase (cubic CrN) and mix-phase (cubic CrN + hexagonal-Cr2N) Cr-N films were annealed in ammonia, converting any secondary phase of hexagonal Cr2N to cubic CrN. The thermoelectric properties of the films that contained a secondary phase of hexagonal (CrN)-N-2 greatly improved upon annealing, with an increase of 900% to 0.5 x 10-3 W m(-1) K-2 for the film annealed at 800 degrees C for 2 h. Annealing of single-phase films of cubic CrN resulted in films with near-insulating electrical properties. For the thermoelectric applications of CrN, ammonia annealing can be beneficial over meticulous deposition control.

We report results from a study of the local structure of hydrated nanocrystalline 2 �m films of the well known proton conductor BaZr1-xScxO3-x/2 with x = 0.45, 0.54 and 0.64, using infrared (IR) spectroscopy. The films were prepared by magnetron sputtering. Analysis of the IR spectra focused on the O–H stretching region (2000—3700 cm-1), which reveals the presence of several distinct O–H stretching bands for which the intensity and frequency of each band vary in an unsystematic manner with Sc concentration. The spectra for the two higher Sc concentrations, x = 0.54 and 0.64, exhibit a distinct, highly intense O–H stretching band centered at around 3400–3500 cm-1, which is assigned to relatively symmetric, weakly hydrogen-bonding, proton configurations. The spectrum for the lower Sc concentration, x = 0.45, does not feature such a band but a broader, weaker, O–H stretching band between approximately 2500 and 3700 cm-1, suggesting that the protons are more homogeneously distributed over a range of different local proton coordinations in this relatively weakly doped material. A comparison to the IR spectra of powder samples of similar compositions suggests that for x = 0.45, the spectra and proton coordination of films and powder samples are similar, whereas for x = 0.54 and 0.64, a larger fraction of protons seems to be located in weakly hydrogen-bonding proton configurations in the films compared to the respective powder samples.

High-entropy materials, an exciting new class of structural materials involvingfive or more elements, are emerging as unexplored ground forsuperconductors. Here, the effects of nitrogen stoichiometry are investigatedon local chemical structure of TiZrNbTa-based thin films by variousX-ray-based techniques. Lattice distortion and short-range order of a set ofTiZrNbTaNxsamples, including bond lengths of different atomic pairs andcoordination numbers of substituting atoms are quantitatively studied. Themaximum superconducting transition temperature Tcis found at 10 K for anear-stoichiometric (TiZrNbTa)N1.08film, which is>8 K measured for ametallic TiZrNbTa film. The underlying electronic structure and chemicalbonding in these high entropy nitrides thus influence the superconductingmacroscopic properties.

Phase formation, morphology, and optical properties of Ti(O,N) thin films with varied oxygen-to- nitrogen ration content were investigated. The films were deposited by magnetron sputtering at 500 & DEG;C on Si(100) and c-plane sapphire substrate. A competition between a NaCl B1 structure TiN1-xOx, a rhombohedral structure Ti-2(O1-yNy)(3), and an anatase structure Ti(O1-zNz)(2) phase was observed. While the N-rich films were composed of a NaCl B1 TiN1-xOx phase, an increase of oxygen in the films yields the growth of rhombohedral Ti-2(O1-yNy)(3) phase and the oxygen-rich films are comprised of a mixture of the rhombohedral Ti-2(O1-yNy)(3) phase and anatase Ti(O1-zNz)(2) phase. The optical properties of the films were correlated to the phase composition and the observation of abrupt changes in terms of refractive index and absorption coefficient. The oxide film became relatively transparent in the visible range while the addition of nitrogen into films increases the absorption. The oxygen rich-samples have bandgap values below 3.75 eV, which is higher than the value for pure TiO2, and lower than the optical bandgap of pure TiN. The optical properties characterizations revealed the possibility of adjusting the band gap and the absorption coefficient depending on the N-content, because of the phases constituting the films combined with anionic substitution.

Thin films of BaZr1-xScxO3-x/2, (0 ≤ x ≤ 0.64), well known as proton conducting solid electrolytes for intermediatetemperature solid oxide fuel cell, were deposited by magnetron sputtering. X-ray diffraction analysis of theas deposited films reveals the presence of single-phase perovskite structure. The films were deposited on fourdifferent substrates (c-Al2O3, LaAlO3〈100〉, LaAlO3〈110〉, LaAlO3〈111〉) yielding random, (110)- or (100)-orientedfilms. The stability of the as-deposited films was assessed by annealing in air at 600 ◦C for 2 h. Theannealing treatment revealed instabilities of the perovskite structure for the (110) and randomly oriented films,but not for (100) oriented film. The instability of the coating under heat treatment was attributed to the lowoxygen content in the film (understoichiometry) prior annealing combined with the surface energy and atomiclayers stacking along the growth direction. An understoichiometric (100) oriented perovskite films showedhigher stability of the structure under an annealing in air at 600 ◦C.

Chromium-based nitrides are used in hard, resilient coatings and show promise for thermoelectric applications due to their combination of structural, thermal, and electronic properties. Here, we investigate the electronic structures and chemical bonding correlated to the thermoelectric properties of epitaxially grown chromium-based multicomponent nitride Cr(Mo,V)Nx thin films. The small amount of N vacancies causes Cr 3d and N 2p states to appear at the Fermi level and reduces the band gap in Cr0.51N0.49. Incorporating holes by alloying of V in N-deficient CrN results in an enhanced thermoelectric power factor with marginal change in the charge transfer of Cr to N compared with Cr0.51N0.49. Further alloying of Mo, isoelectronic to Cr, increases the density of states at the Fermi level due to hybridization of the (Cr, V) 3d and Mo 4d-N 2p states in Cr(Mo,V)Nx. This hybridization and N off-stoichiometry result in more metal-like electrical resistivity and reduction in Seebeck coefficient. The N deficiency in Cr(Mo,V)Nx also depicts a critical role in reduction of the charge transfer from metal to N site compared with Cr0.51N0.49 and Cr0.50V0.03N0.47. In this paper, we envisage ways for enhancing thermoelectric properties through electronic band engineering by alloying and competing effects of N vacancies.

Corrosion resistance and catalytic activity toward the oxygen reduction reaction (ORR) in an alkaline environment are two key properties for water recombination applications. In this work, CoCrFexNi (0 <= x <= 0.7) thin films were deposited by magnetron sputtering on polished steel substrates. The native passive layer was 2-4 nm thick and coherent to the columnar grains determined by transmission electron microscopy. The effect of Fe on the corrosion properties in 0.1 M NaCl and 1 M KOH and the catalytic activity of the films toward ORR were investigated. Electrochemical impedance spectroscopy and potentiodynamic polarization measurements indicate that CoCrFe0.7Ni and CoCrFe0.3Ni have the highest corrosion resistance of the studied films in NaCl and KOH, respectively. The high corrosion resistance of the CoCrFe0.7Ni film in NaCl was attributed to the smaller overall grain size, which leads to a more homogeneous film with a stronger passive layer. For CoCrFe0.3Ni in KOH, it was attributed to a lower Fe dissolution into the electrolyte and the build-up of a thick and protective hydroxide layer. Scanning Kelvin probe force microscopy showed no potential differences globally in any of the films, but locally, a potential gradient between the top of the columns and grain boundaries was observed. Corrosion of the films was likely initiated at the top of the columns where the potential was lowest. It was concluded that Fe is essential for the electrochemical activation of the surfaces and the catalytic activity toward ORR in an alkaline medium. The highest catalytic activity was recorded for high Fe-content films (x >= 0.5) and was attributed to the formation of platelet-like oxide particles on the film surface upon anodization. The study showed that the combination of corrosion resistance and catalytic activity toward ORR is possible for CoCrFexNi, making this material system a suitable candidate for water recombination in an alkaline environment.