Search

The development of advanced photoactive materials has aroused widespread interest, but is severely plagued by the inherent narrow photo-responsive range and rapid recombination of electrons and holes. In this study, the unconventional BiOBr nanosheets decorated with Bi0 and oxygen vacancies (OVs) are successfully synthesized through a facial one-pot hydrothermal method, followed by heat treatment. Cetyltrimethylammonium bromide and mannitol contribute to the selective exposure of (001) and (010) facets, respectively. The absence of the outermost Br atoms facilitates the simultaneous generation of OVs and Bi0 on the surface during heating, forming the Schottky junction. The synergy of SPR in the Bi0 metal, OVs and Schottky junction can effectively enhance the light absorption and charge separation. This work proposes and verifies a feasible approach to construct defects in-situ by regulating the crystal facets and manipulating the surface atomic arrangement and coordination. [Display omitted] • BiOBr nanosheets with tunable exposed facets and surface atoms were fabricated. • The in-situ simultaneous decoration of Bi0 and OVs is achieved by heat treatment. • Bi0 selectively form on (010) facets exposed surface synthesized with mannitol. • Partial absence of outermost Br atoms in (001) facets contribute to Bi0 and OVs. • Bi0, OVs and Schottky junction enhance the light absorption and charge separation. [ABSTRACT FROM AUTHOR]

Abstract Gilbert damping enhancement induced by the spin pumping effect is investigated in Y 3 Fe 5 O 12 (YIG)/heavy metal bilayers. Because its spin polarization is high and Gilbert damping is low, Co 2 FeAl 0.5 Si 0.5 (CFAS) is deemed a promising ferromagnetic material in spintronics devices. We studied microwave dynamic magnetizations in YIG/CFAS bilayers combined with ferromagnetic resonance measurement using a vector network analyzer to reveal a 5-fold giant damping enhancement compared with that for the YIG/Pt bilayers. This phenomenon was attributed to both the exchange coupling effect and spin pumping effect. By inserting a 10-nm Cu spacer, direct exchange coupling can be suppressed. A spin mixing conductance g e f f ↑ ↓ of 7.75 × 1018m−2 generated by spin pumping was obtained. The study provides an effective approach to tailor the damping in magnetic thin films. Highlights • The Gilbert damping in YIG capped by CFAS increased significantly. • The damping derived from exchange coupling and spin pumping effect between the YIG film and CFAS layer. • The spin inject efficiency in YIG/CFAS interface is higher than YIG/Pt bilayers. [ABSTRACT FROM AUTHOR]

C-rich hydrogenated amorphous silicon carbide (a-Si 1-x C x :H) thin films were grown from hydrogen diluted silane (SiH 4 ) and methane (CH 4 ) mixtures in a plasma-enhanced chemical vapor deposition (PE-CVD) system at different silane gas flow rates. The effects of Si content on the composition, microstructure and photoluminescence (PL) properties of the films have been systematically investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), ultraviolet–visible (UV–Vis) transmittance and PL spectra. The multiphase structure of the grown films is confirmed as graphite-like sp 2 -C rich clusters embedded in a Si-C/C-C random network, and the diameter of the spherical sp 2 -C clusters is about 20–60 nm. As Si atoms are gradually incorporated into the films, they replace some C atoms in the Si-C/C-C random network, which results in an increase of structure disorder and brings large band tail states and narrow E g . Furthermore, it is found that both the sp 3 Si-C/C-C random network and the sp 2 carbon clusters are the origin of the PL emission, and the PL properties can be tuned by changing the Si content and the sp 2 carbon clusters in the C-rich a-Si 1-x C x :H thin films. [ABSTRACT FROM AUTHOR]

Elastic modulus of magnetic materials tends to increase with temperature rising, as the result of gradual loss of magnetic order with approaching Curie point. In this work, the similar behavior was also observed in the directional solidified Fe 73 Ga 27 alloy along the <100> preferred orientation. However, unlike the previous theory, results of magnetic-temperature and thermal expansion measurements show the absence of magneto-volume effect. Such unusual behavior of Young's modulus could be attributed to the enrichment of diffusing atoms along the direction of lowest modulus during the phase transition of A2 → D0 3 . According to the analysis of in situ heating XRD and TEM, the structure transitions of A2 → D0 3 → A1 → L1 2 were identified in the temperature range 20–500 °C, which correspond exactly to the changes of Young's modulus in both as-cast and directional solidified samples. [ABSTRACT FROM AUTHOR]

Single crystalline Ge 1-x-y Sn x Pb y alloys were grown on Ge/Si(100) substrates by a sputtering epitaxy method. Cross-sectional transmission electron microscopy revealed that no segregation of Sn and Pb occurred in these high quality alloys. The maximum Pb content of 1.7% was achieved, indicating that the co-introduction of Sn and Pb was a viable strategy to increase the Pb content in the Ge matrix. The thermal stability of the Ge 1-x-y Sn x Pb y (x < 0.081, y < 0.017) alloys revealed that the critical temperature for surface segregation was affected by not only the Pb content but also the Sn content. The direct bandgaps of the Ge 1-x-y Sn x Pb y alloys were calculated by the fitting of the absorption coefficient and the theoretical prediction indicated that the alloys have great potential for the application in efficient silicon-based optoelectronic devices. • Novel Ge 1-x-y Sn x Pb y ternary alloys were first grown by sputtering epitaxy. • The structural and optical properties of Ge 1-x-y Sn x Pb y alloys were studied. • The Ge 1-x-y Sn x Pb y alloys showed promising application on Silicon photonics. [ABSTRACT FROM AUTHOR]

Mg 1-x Cd x Co 0.05 Fe 1.95 O 4 ferrites are proposed for high frequency radar antennas, where x varies with the value of 0.0, 0.2, 0.3 and 0.4. With 5 wt% Bi 2 O 3 added for low temperature co-fired ceramic (LTCC) application, the spinel ferrites synthesized at 930 °C reveal fairly excellent magnetic and dielectric properties. X-ray diffraction indicates the processed samples present normal spinel peaks and Bi 24 Fe 2 O 39 (BFO) peaks. The existing BFO tailors the real part of magnetic permeability ( ε ′) and dielectric permittivity ( μ ′) to be approximately equal (x = 0.4, ε '≈ μ '≈26) at a wide frequency range from 1 MHz to 100 MHz. Meanwhile, the LTCC-processed samples have ultra low dielectric loss tanδ ε and magnetic loss tan δ μ (tan δ ε ≈0.0008, tan δ μ ≈0.03, x = 0.3). In addition, the high saturation magnetization and appropriate coercivity mean enhanced magnetization. These eminent magneto-dielectric characteristics enable the materials to possess a farther study-worthy necessarity. [ABSTRACT FROM AUTHOR]

• Single-crystalline GePb strip on an insulator was synthesized via rapid melting growth. • The Si and Pb diffusion behavior along GePb strip was investigated. • The structural properties of GePb strip was characterized in detail. • The photodetector of GePb strip showed good optical properties. High-quality single crystalline germanium lead (GePb) alloys were successfully grown on Si 3 N 4 layer using Si seed by rapid melting growth. The strip composition distribution was studied by Raman spectroscopy and energy dispersive X-ray spectroscopy; the highest Pb content in the GePb strip was 2%. Cross-sectional transmission electron microscopy and selected-area electron diffraction analyses indicated that the GePb strip had a high crystal quality with no dislocations or stacking faults. The GePb strip photodetectors were fabricated and showed good optical properties, with underestimated responsivities of 107, 71, and 20 mA/W at 1310, 1550, and 1630 nm, respectively. Therefore, the rapid melting growth is an effective method for obtaining high Pb content GePb alloys. In addition, GePb devices show high potential for photodetection. [ABSTRACT FROM AUTHOR]