Photoactive bismuth vanadate (BiVO4) thin films were deposited by reactive co-magnetron sputtering from metallic Bi and V targets. The effects of the V-to-Bi ratio, molybdenum doping and post-annealing on the crystallographic and photoelectrochemical (PEC) properties of the BiVO4 films were investigated. Phase-pure monoclinic BiVO4 films, which are more photoactive than the tetragonal BiVO4 phase, were obtained under slightly vanadium-rich conditions. After annealing of the Mo-doped BiVO4 films, the photocurrent increased 2.6 times compared to undoped films. After optimization of the BiVO4 film thickness, the photocurrent densities (without a catalyst or a blocking layer or a hole scavenger) exceeded 1.2 mA/cm2 at a potential of 1.23 VRHE under solar AM1.5 irradiation. The surprisingly high injection efficiency of holes into the electrolyte is attributed to the highly porous film morphology. This co-magnetron sputtering preparation route for photoactive BiVO4 films opens new possibilities for the fabrication of large-scale devices for water splitting.

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Highly (001)‐textured tungsten diselenide WSe2 thin films have been prepared by a two‐step process on quartz glass and TiN metallic back contacts, respectively. At first, X‐ray amorphous, selenium‐rich WSe2+x films were deposited by reactive magnetron sputtering at room temperature onto a thin metal promoter film (Ni or Pd) and afterwards annealed in an H2Se/Ar atmosphere. X‐ray diffraction and scanning electron microscopy show that highly (001)‐oriented WSe2 films can be grown, which is caused by the formation of liquid promoter‐metal selenide droplets which dissolve tungsten or tungsten selenide at temperatures, higher than the eutectic temperature in the promoter metal–selenium system, followed by oversaturation and eventually crystallization of WSe2 platelets. Time‐resolved microwave conductivity measurements show that the films are photoactive. The sum of the carrier mobilities of the best films µe + µh is in the range of 1–7 cm2 V−1 s−1.

The thermal expansion properties of Mn3Zn1−xSnxN (x=0.1, 0.2, 0.3, 0.5, 0.8, 1.0) compounds were investigated by variable temperature X‐ray powder diffraction. With increasing Sn content, the thermal expansion behavior of Mn3Zn1−xSnxN changes from positive to negative and returns to positive near the magnetic transition temperature range. Moreover, the magnetic transition temperature increases from 185 to 495 K. It is interesting that the abnormal thermal expansion behavior of Mn3Zn1−xSnxN is related to the number of valence electrons on Zn site and the equivalent effect with three valence electrons is beneficial for displaying negative thermal expansion. In addition, the antiferromagnetic order state gradually canted with the increasing Sn content due to the increase of Mn–Mn distance.

The negative thermal expansion (NTE) and correlated magnetic and electrical transport properties of Mn3GaxSi1−xN were investigated. For pure Mn3GaN, there is a large NTE effect corresponding to the antiferromagnetic to paramagnetic transition. Very interestingly, when partial Ga was replaced by Si, the NTE properties around the magnetic transition were changed. The NTE temperature range was broadened to ΔT=148 K for Mn3Ga0.75Si0.25N and the linear thermal expansion coefficient was estimated as β=−1.4 × 10−5 K−1 (272–420 K). Accordingly, the resistivity also showed a decrease from 327 to 395 K with temperature. With a further increasing Si content to x=0.5, the magnetic transition still occured, but the NTE effect did not appear. After careful observation, an anomaly was found at around 350 K in a–T, ρ–T, and DSC curves of Mn3Ga0.5Si0.5N, respectively. This phenomenon strongly implies the close correlation among lattice, spin, and charge in this series materials.