Carbon and hydrogen incorporation in ZnTe layers grown by metalorganic chemical vapor deposition

The metalorganic chemical vapor deposition growth of ZnTe has been performed at atmospheric pressure under helium and hydrogen carrier gases. Epitaxial growth was achieved on GaAs (100) substrates with the combination of diethylzinc and diethyltellurium as precursors. We have studied the incorporation of carbon and hydrogen in as-grown layers of ZnTe by secondary ion mass spectroscopy analysis and out-diffusion experiments with different carrier gases and growth temperatures. The amount of carbon and hydrogen incorporated in the ZnTe layers greatly depends on the nature of the gas considered. Under helium atmosphere, the amount of carbon and hydrogen incorporated are greater than under H₂ with an origin from organometallic precursors.     

Low‐Bandgap Methylammonium‐Rubidium Cation Sn‐Rich Perovskites for Efficient Ultraviolet–Visible–Near Infrared Photodetectors

Solution‐processed and low‐temperature Sn‐rich perovskites show their low bandgap of about 1.2 eV, enabling potential applications in next‐generation cost‐effective ultraviolet (UV)–visible (vis)–near infrared (NIR) photodetection. Particularly, the crystallization (crystallinity and orientation) and film (smooth and dense film) properties of Sn‐rich perovskites are critical for efficient photodetectors, but are limitedly studied. Here, controllable crystallization for growing high‐quality films with the improvements of increased crystallinity and strengthened preferred orientation through a introducing rubidium cation into the methylammonium Sn‐Pb perovskite system (65% Sn) is achieved. Fundamentally, the theoretical results show that rubidium incorporation causes lower surface energy of (110) plane, facilitating growth in the dominating plane and suppressing growth of other competing planes. Consequently, the methylammonium‐rubidium Sn‐Pb perovskite photodetectors simultaneously achieve larger photocurrent and lower noise current. Finally, highly efficient UV–vis–NIR (300–1100 nm) photodetectors with record‐high linear dynamic range of 110 and 3 dB cut‐off frequency reaching 1 MHz are demonstrated. This work contributes to enriching the cation selection in Sn‐Pb perovskite systems and offering a promising candidate for low‐cost UV–vis–NIR photodetection.     

Structural impact of nitrogen incorporation on properties of alkali germanophosphate glasses

The structure, atomic packing density, calorimetric glass transition, and hardness of mixed sodium–lithium germanophosphate oxynitride glasses with varying Ge/P and N/P ratios were investigated. The combined influences of nitridation and mixed network former effect (MNFE) on the glass structure were analyzed using Raman spectroscopy, X‐ray photoelectron spectroscopy (XPS), and ³¹P nuclear magnetic resonance (NMR) spectroscopy. Evidence for the existence of germanium in a higher coordination state, i.e., five‐ or sixfold coordination, was obtained by performing XPS analysis of the oxide glasses, with indication of conversion to tetrahedral coordination upon nitridation. Raman spectroscopy measurements implied that the germanate network was modified upon nitridation, including the removal of ring‐like germanate structures and P–O–Ge mixed linkages. The partial anionic N‐for‐O substitution gave rise to the linear dependence of the glass transition temperature (T_g) and hardness (H_V) on nitrogen content (expressed as N/P ratio), especially for lower Ge/P ratio. However, nitridation also caused an unexpected increase in liquid fragility and decrease in density. This suggests that the governing structural parameter for property evolution in such LiNaGePON glasses is not only the increased degree of cross‐linking of the phosphate chains, but rather the short‐ and intermediate‐range structural modifications within the germanate component of the oxynitride glasses.     

Structure modification of mordenite through isomorphous Ti substitution: Characterization and catalytic properties

The introduction of Ti atoms by means of TiCl₄ treatment and hydrothermal synthesis has been applied to mordenite zeolite with different structures from silicalite. The incorporation of Ti into the mordenite framework is demonstrated by XRD, FTIR,²⁹Si MAS NMR techniques, and tested with catalytic oxidation reactions. Ti-Al-mordenite catalyses the oxidation ofn-hexane, cyclohexane and benzene with hydrogen peroxide under very mild conditions. These reactions can be performed in methanol, acetonitrile and water as solvents. The rate of the reaction is strongly affected by the kind of solvent.     

Synthesis of titanium containing silica ZSM-48 (TS-48) using hexamethonium hydroxide as template

Titanium containing silica analog of ZSM-48 (TS-48) has been synthesized by a new method using hexamethonium hydroxide as a template. Titanium incorporation in the framework was evidenced from unit cell volume expansion, framework IR spectra and diffuse reflectance UV-Vis spectra.     

Incorporation of eicosapentaenoic and docosahexaenoic acids into groundnut oil by lipase-catalyzed ester interchange

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were incorporated into groundnut oil by interesterification with a 1,3-specific lipase fromMucor miehei. The resultant EPA and DHA concentrations of the groundnut oil were 9.5 and 8.0%, respectively.     

Incorporation of vanadium into the mordenite structure by direct hydrothermal crystallization and secondary synthesis

The substitution of vanadium atoms into the zeolite framework structure could be applied to the large pore zeolites by means of modified treatments as well as direct hydrothermal synthesis. The incorporation of vanadium into the mordenite framework was demonstrated by XRD, FTIR, UV-Vis techniques and tested with catalytic oxidation reactions. These vanadium-containing zeolites have selective catalytic properties in the various oxidation reactions as compared with vanadia-impregnated catalysts.     

金属离子与卟啉的嵌入反应动力学研究Ⅷ-- 丁二酸缓冲溶液中溴化间四(N-乙腈基-3-吡啶基)卟啉与Cu(Ⅱ)的配位反应

研究了在35士1℃,离子强度0.5 mol/L(KCl)条件下,丁二酸根催化Cu2+离子嵌入溴化间四(N-乙腈基-3-吡啶基)卟啉(H2T-β-ECNPyPBr4)的反应动力学及其机理.结果显示,在丁二酸缓冲体系中反应遵循阴离子催化卟啉变形机理;根据催化剂浓度、溶液的pH与反应速率间的关系,得到其反应动力学方程为d[CuP4+]/dt=5.81{(1.0+1.59×103)[B2]/1.0+1.92×10-5[H+]2}[Cu2+][P]T.     

Structure characterization of F-doped silica glass

Pure and fluorine-doped silica glass were fabricated by plasma chemical vapour deposition (PCVD) and characterized using Raman and infrared spectrum. The change in Raman intensity of 945 cm⁻¹ peak, relating to ≡Si—F stretching vibration, agrees with the change of F content. Compared with measured wavenumber in IR spectrum, the calculated absorption wavelength confirms the incorporation form of F into the glass, the detail of which is a tetrahedron with a Si atom in the center coupled with one F atom and three network O atoms. Such structure identification may be useful for explaining some properties of F-doping silica glass.