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The demand for cheap and green energy as a replacement for fossil fuels has never been greater, and perovskite solar cells (PSCs) are among the leading means of meeting it. The surface properties of metal halide perovskite layers play crucial roles in the performance and durability of such cells. Consequently, a wide range of engineering processes for surface modification of perovskite layers has been investigated and among them is atmospheric pressure plasma (APP). Nevertheless, knowledge of the interaction between plasma and perovskite layers is still far from complete. In this work, CH3NH3PbI3 films were subjected to APP generated by a portable plasma source. A detailed understanding of band energy after plasma treatment is crucial to the investigation of the behavior of the perovskite layer. This study demonstrates a remarkable shift in the valence and conduction bands of a perovskite layer after plasma treatment, while band gap energy remains relatively constant. We found that short plasma treatment of perovskite layers resulted in higher performance and stability of PSCs.

Small-punch and nano-indentation tests were used for the first time to probe strength of 500 mu m thin Ni50Ti50 shape memory platelets in their hydrogen-free and hydrogen-doped states. Results show excellent reproducibility and suggest that hydrogen penetrates the alloy more efficiently during the cathodic charging at ambient temperatures as compared to heat treatments in a controlled hydrogen atmosphere. Hydrogen content exceeding 100 wtppm results in a retransformation from the B19' martensite to the R lattice and causes a systematic drop of the rupture strength. The retransformation events in thin surface lamellae were documented by the transmission electron microscopy. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

In the present work, nanocomposite Mo-B-C coatings were deposited on high speed steel and hard metal substrates by magnetron sputtering of three targets. These coatings were subjected to annealing to final temperatures in the range from 500 °C to 1000 °C. It was found that the as deposited Mo-B-C coatings exhibited hardness of ∼20 GPa, nanocomposite microstructure with very fine grains (∼2 nm) and low degree of crystallinity. The X-ray diffraction and transmission electron microscopy together with selective area electron diffraction were used to study the temperature induced changes of the microstructure of the coating and its crystallinity. The annealing process significantly improved the hardness (from ∼20 GPa to ∼30 GPa) and effective elastic modulus (from initial 330 GPa–500 GPa) of coatings while their resistance to fracture was kept sufficiently high.

Several amorphous Mo–B–C coatings with wide range of compositions were subjected to thermal annealing to a final temperature of 1000 °C in UHV conditions. The nature of the induced recrystallization depended mostly on the Mo content in the coating. A higher Mo content resulted in a nanocrystalline Mo2C phase, a lower Mo content in a nanocrystalline Mo2BC phase and Mo content in-between resulted only in a near-amorphous microstructure. In all cases, the hardness and effective elastic modulus increased significantly after annealing up to values of ∼29 GPa and 500 GPa, respectively. The cobalt diffusion from the WC-Co substrates affected the lower parts of coatings forming a MoCoB interface.