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Mn+1AXn (MAX) phases are novel structural and functional materials with a layered crystal structure. Their unique properties such as good machinability, high electrical conductivity, low friction, and corrosion resistance are appealing for many engineering applications. Herein, Ti2AlC and Ti3AlC2 MAX thin films are synthesized by magnetron sputtering and subsequent thermal annealing. A multilayer approach is used to deposit single‐element nanolayers of titanium, aluminum, and carbon onto silicon substrates with a double‐layer‐diffusion barrier of SiO2 and SixNy. Ti2AlC and Ti3AlC2 thin films (thickness ≈500 nm) are formed via rapid thermal annealing and verified by X‐Ray diffraction. Nanoindentation tests show hardness values of about 11.6 and 5.3 GPa for Ti2AlC and Ti3AlC2, respectively. The tribological behavior of the Ti2AlC and Ti3AlC2 thin films against AISI 52100 steel balls under dry sliding conditions is studied using ball‐on‐flat tribometry. The resulting coefficient of friction (CoF) for Ti2AlC and Ti3AlC2 ranges between 0.21–0.42 and 0.64–0.91, respectively. The better tribological behavior observed for Ti2AlC thin films is ascribed to its smaller grain size, reduced surface roughness, and higher hardness. [ABSTRACT FROM AUTHOR]

The selective metallization of nonconductive polymer materials has broad applications in the fields of integrated circuit technology and metallized patterns. This work discusses a methodology to pattern metal tracks on polybutylene terephthalate substrates. The process consists of three steps: 1) surface patterning with picosecond laser pulses (1030 nm) in air, 2) Pd seeding via treatment in PdCl2 solution, and 3) selective metallization via electroless copper deposition. Picosecond laser irradiation promotes not only surface roughening but also chemical modification to enable Pd seeding as the polymer surface acquires the ability to reduce Pd(II)‐chloride species to metallic Pd. The laser parameters, as well as the PdCl2 concentration and seeding temperature, have an influence on the polymer surface morphology, the concentration and distribution of metallic Pd, and the copper layer properties. Homogeneous copper layers with well‐defined geometries, good coating‐substrate adhesion, and high electrical conductivity can be obtained. This is ascribed to the synergistic effect of the chemical surface activation and roughness development (from 0.13 to ≈1.6 μm). As the patterning and surface activation are performed in air, directly on the as‐received polymer substrate, this methodology shows great potential for metallization of electronic devices with 3D complex geometries. [ABSTRACT FROM AUTHOR]

Adobe bricks, or mud bricks, are construction elements which have defined major architectural traditions in the Andes over thousands of years. From Moche pyramids and the ancient city of Chan Chan in pre-Hispanic times, to Spanish casonas of the colonial period and rural houses in contemporary South America, adobe has been a central component in Andean architecture. Discovery of the remains of an early monumental building constructed primarily of adobes at Los Morteros (lower Chao Valley, north coast of Peru) places the invention of adobe architecture before 5,100 calendar years B.P. The unique composition, internal structure, and chronology of the adobes from Los Morteros show the beginnings of this architectural technique, which is associated with El Ni~no rainfall and the construction of the earliest adobe monumental building in the Americas. We propose that adobe architecture became a major Andean tradition after a long period of technical evolution and experimentation with both shape and composition. [ABSTRACT FROM AUTHOR]

The photoelectrochemical (PEC) properties of sputtered aluminum doped hydrogenated amorphous silicon carbide thin films grown on p-type crystalline silicon substrates were investigated in 1 M solution under chopped light illumination. Optical and structural properties of the top absorber layer were systematically assessed after post-deposition isochronical annealing treatments. Samples exhibited a noticeable improvement of the opto-electronic properties after thermal treatments. In addition, an abrupt enhancement of the photocurrent was observed reaching a saturation value of 17 mA cm−2 at −1.75 V vs. Ag/AgCl (3.5 M KCl). In this research we propose that this enhancement effect is associated to a charge transfer kinetic mechanism influenced by surface states and the p-type substrate. The latter most likely due to the space charge region extending beyond the absorber layer reaching the substrate. Current density-potential and electrochemical impedance spectroscopy measurements in dark revealed a reduction of the native layer at cathodic potentials higher than −1 V vs. Ag/AgCl (3.5 M KCl), which contributes to the high charge transfer kinetic of the system. We believe that these results will contribute to understand the substrate influence in the PEC performance of top absorber layers in multilayer structures for solar water splitting. [ABSTRACT FROM AUTHOR]

Ph y s. 54 (2021) 26960 1 (3pp) ht tps://doi.or g/1 0.1 088/1 361-6463/abef ee Er r at um: Anal y sis of the ph y sical and phot oelectr oc hemical pr oper ties of c-Si(p)/a-SiC:H(p) phot ocathodes f or solar w at er split ting (2021 J. Ph y s. D: Appl. J our nal of Ph y sics D: Applied Ph y sics J. Ph y s. D: Appl. Erratum: Analysis of the physical and photoelectrochemical properties of c-Si(p)/a-SiC:H(p) photocathodes for solar water splitting (2021 J. Phys. [Extracted from the article]

AlxGa1-xN solid solutions were heteroepitaxially grown on 3C-SiC(111)/Si(111) pseudo substrates fabricated by low pressure chemical vapour deposition. Free standing doubly-clamped resonator bars and cantilevers were fabricated from these AlxGa1-xN layers. The resonance frequencies of the microelectromechanical structures were measured using electrostatic excitation and vibrometry at ambient conditions. The obtained resonance frequencies allowed a self consistent determination of the Young's modulus of the AlxGa1-xN layers and the residual strain in the free standing structures. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

MAX phase coating could have interesting technical applications in many fields. This paper describes the synthesis of the M n+1AX n phase Ti3SiC2 by a rapid thermal annealing process of physical vapor deposited TiCSi multilayer thin films on Si (100) and SiO2 substrates. Annealing temperatures of 800-1000 °C affected the solid state reaction of titanium, carbon and silicon creating titanium-carbides, -silicides, and Ti3SiC2. The film structures and chemical compositions were observed by grazing incidence X-ray diffraction, transmission electron microscopy, and glow discharge optical emission spectroscopy. Analysis after the rapid thermal processing revealed the formation of the polycrystalline M n+1AX n phase Ti3SiC2 in coexistence with TiSi2, TiC and Ti5Si3, even within a 0 s annealing process. This synthesis method has a high potential for the formation of MAX phases as a high temperature electrical contact material. [ABSTRACT FROM AUTHOR]