This work reports the excellent dielectric properties of polyimide (PI) embedded with CaCu3Ti4O12(CCTO)/Ag nanoparticles (CCTO@Ag).

Using first-principles methods, we study the magnetic and electronic properties of three different spin configurations of the L1 0 phase of FePt and MnPt alloys. It is found that MnPt and FePt may be approximately considered as magnetic antipodes with opposite ferromagnetic ͑FM͒-antiferromagnetic ͑AFM͒ and in-plane/ out-of-plane magnetocrystalline anisotropy ͑MCA͒ relationships. In MnPt, the most stable phase is the AFM configuration with AFM chessboard spin coupling in the ͑001͒ plane, FM spin coupling between ͑001͒ planes, and all spin directions aligned in the ͑001͒ plane. Whereas in FePt, the most stable is the FM configuration with all spin directions aligned perpendicular to ͑001͒ plane. The out-of-plane MCA of MnPt is more than an order of magnitude less ͑ϳ0.1 meV͒ than that of FePt ͑ϳ2.9 meV͒ in their corresponding magnetic ground states. Our calculations indicate that an AFM state can be achieved in FePt by a small variation in tetragonality ratio ͑from 0.98 to 0.94͒. A pseudogap is observed at the Fermi energy for MnPt and just below the Fermi energy for FePt for the chessboard AFM model. This pseudogap may explain the ground-state magnetic configuration of MnPt.

The changes in value of CA and surface free energy (SFE) both reflect the changes of the leaf surface wettability, while the SFE value shows better in wettability characterizing. Obvious rice leaf wettability changes were found on different development stages, which may be beneficial for researches in agrochemical sprays wetting and spreading behavior. Factors influencing these alterations were discussed.

This work reports the high dielectric permittivity of polyimide (PI) embedded with CaCu3Ti4O12 (CCTO) nanoparticles. The dielectric behavior has been investigated over a frequency of 100 Hz-1 MHz. High dielectric permittivity (ε = 171) and low dielectric loss (tan δ = 0.45) at 100 Hz have been observed near the percolation threshold. The experimental results fit well with the Percolation theory. We suggest that the high dielectric permittivity originates from the large interface area and the remarkable Maxwell-Wagner-Sillars effect at percolation in which nomadic charge carriers are blocked at internal interfaces between CCTO nanoparticles and the polyimide matrix.

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High-quality Co-doped ZnO single crystalline films with a wide range of carrier concentration and good reproducibility have been grown by molecular beam epitaxy. After the systematic studies of the magnetic and transport properties of the films, we suggest that there are two distinct ferromagnetic mechanisms in different conductivity regimes. In the insulating regime, carriers tend to be localized, favoring the formation of bound magnetic polarons, which leads to ferromagnetism. In the metallic regime, however, most carriers are weakly localized and the free carrier-mediated exchange is dominant. Our experimental observations are well consistent with the recent theoretical description of magnetism in Co-doped ZnO and helpful for understanding the ferromagnetic mechanism in oxide-based diluted magnetic semiconductors.

Polycrystalline Si1−xMnx thin films codoped with boron have been fabricated by sputtering technique followed by postcrystallization processes. Structural, magnetic, and transport properties of the films were investigated. Magnetic property investigation indicated that the films consist of two ferromagnetic phases. The low Curie temperature ferromagnetic phase (TC∼50K) is due to the Mn4Si7 phase in the films as detected by x-ray diffraction, while the high temperature one (TC∼250K) is resulted from the incorporation of Mn into silicon. It has been found that, with carriers confirmed as p type, for the same effective concentration of Mn the saturation magnetization of the films with higher carrier concentration is higher than that of those with lower carrier concentration, which suggests a mechanism of hole-mediated ferromagnetism for Si-based diluted ferromagnetic semiconductors.

Low visible light absorption and high charge carrier recombination rate are two main disadvantages of TiO2 as a photocatalyst which severely limit its practical applications. To overcome the problems, Fe mono-doped and (Fe+Mo) co-doped TiO2 were synthesized and studied. It was found that (Fe+Mo) co-doping can further increase the visible absorption and improve the photocatalytic property of TiO2 compared with Fe mono-doping; Fe mono-doping improves the photocatalytic property of TiO2 only at very low doping level (Fe concentration less than 1.0%), while by co-doping a small amount of Mo with Fe, the effective doping concentration of Fe can be pushed to a higher level and the photocatalytic property of TiO2 can be further improved. Photoluminescence spectra indicated that Mo dopant may play a role in retarding the recombination process when co-doped into TiO2 with Fe. The mechanism behind was discussed. It was suggested that doping a small amount of Mo into Fe-TiO2 might be an efficient way to further improve the photocatalytic property of Fe-TiO2 without losing its photocatalytic specificity.