Strain facilitated small gas molecules sensing properties on Au doped SnSe2 monolayer

By the first-principles calculations, the sensitivity of CO, H₂O and NO adsorption on Au doped SnSe₂ monolayer surface is investigated. The results show that CO and H₂O molecules are physically adsorbed on Au doped SnSe₂ monolayer and act as donors to transfer 0.012 e and 0.044 e to the substrate, respectively. However, the NO molecule is chemically adsorbed on substrate and acts as an acceptor to obtain 0.116 e from the substrate. In addition, our results also show that the biaxial strain can effectively improve the adsorption energy and charge transfer of gas molecules adsorbed on the substrate surface. Also, the recovery time of desorbed gas molecules on the substrate surface is calculated, and the results indicate that the Au doped SnSe₂ is a perfect sensing material for detection and recovery of CO and NO under ?8% strain.     

Optical and thermal properties of poly(ethylene oxide) doped with MnCl2 salt

The optical and thermal properties of prepared poly(ethylene oxide)/MnCl₂ films were studied as a function of MnCl₂ concentration at room temperature. The observed optical energy gap (E_opt) and energy gap tail (ΔE) were determined from the measured absorption spectra. It was found that the optical energy gap decreases with MnCl₂ concentration, and the absorption coefficient reduces sharply at concentration of 5 wt% MnCl₂ compared with the neat PEO. Differential scanning calorimetry (DSC) measurement shows that the heat of fusion increases with the MnCl₂ concentration, while the melting point decreases. Correlation between the observed optical energy gap and heat of fusion is presented.     

镧和钴掺杂纳米TiO2的溶胶-凝胶法制备及其光催化性能

采用溶胶-凝胶法，制备了TiO2、Co^2＋／TiO2、La^3＋／TiO2＋,Co^2＋,La^3＋／TiO2光催化剂。通过考察掺杂离子的种类和用量对所得催化剂用于紫外光催化降解亚甲基蓝性能的影响，得出La^3＋／TiO2中La^3＋的适宜掺杂量为1.0％，Co^2＋，La^3＋／TiO2中，当La^3＋的掺杂量为1.0％时，Co^2＋的适宜掺杂量为0.2％，相应的脱色效率为99.83％、98.79％。当掺杂量适当时，四种催化剂用于紫外光催化降解亚甲基蓝的活性次序为：La^3＋／TiO2〉Co^2＋，La^3＋／TiO2〉TiO2〉Co^2＋／Ti02o XRD分析结果表明，所得光催化剂均为纳米粒子。     

Preparation of NaBiO3 and the electrochemical characteristic of manganese dioxide doped with NaBiO3

NaBiO₃ crystal of high purity has been synthesized through chemical oxidization. The morphology and thermal stability of NaBiO₃ were examined with scanning electron microscope (SEM) and thermogravimetry-differential scanning calorimetry (TG-DSC). The electrochemical properties of MnO₂ electrodes with and without doping NaBiO₃ were studied through galvanostatic charge/discharge and cyclic voltammetry. The results indicate that the MnO₂ electrode doped with NaBiO₃ possesses remarkably higher discharge voltage and capacity and better reversibility than the pure MnO₂ electrode and Bi₂O₃ doping MnO₂ electrode.     

Studies of structure and cycleability of LiMn2O4 and LiNd0.01Mn1.99O4 as cathode for Li-ion batteries

Lithium manganese oxides LiMn₂O₄ and rare earth elements doped LiNd_0.01Mn_1.99O₄ were synthesized by microwave method. The structure and the electrochemical performances of the samples were characterized. XRD data shows both samples exhibit the same pure spinel phase. But due to the introduction of Nd³⁺ ion into the unit cell, the lattice parameter of the Nd-doped spinel was larger than that of the undoped one. The two samples had a similar morphology including small particle size and homogeneous particle distribution as tested by SEM. The cyclic voltammmetry and constant-current charge-discharge tested that Nd-doped spinel displayed a better reversibility and cycleability.     

细晶结构掺杂石墨的抗氧化行为研究

通过球磨分散方法制备了具有优良热，机械性能的细晶掺杂石墨材料。采用热分析仪考察了掺杂不同粒径陶瓷粒子的复合材料在1500℃温度范围内抗氧化行为；利用扫描电镜样品在800℃，1200℃和1400℃恒温氧化后的表面形貌。研究结果表明；结晶掺杂石墨在氧化温度高于800℃时有优良的抗氧化性能。     

Growth and characterization of Si doped vapor phase epitaxial GaAs for mesfet

This paper describes the Si-doping of GaAs that was grown using the AsCl₃:H₂:GaAs, Ga Chemical vapor deposition process. The doping sources were AsCl₃:SiCl₄ liquid solutions which proved to be highly reproducible for Si doping within the range, 1×1O¹⁶ to 2×10¹⁹ cm^?3. Incorporation of Si into the GaAs apparently occurs under near equilibrium conditions. This point is considered in detail and the consequences experimentally utilized to grow n, n+ bilayers using a single AsCl₃:SiCl₄ doping solution. Si impurity profiles based upon differential capacitance and SIMS data are presented. These can be very abrupt for n, n⁺ structures with order of magnitude changes occurring within 500 Å. For the 1×10₁₆ to 8×l0¹⁸ cm^?3 doped samples the mobilities at 78 and 298°K are comparable to the higher values reported for GaAs thin films grown by CVD. Power FET devices made from this material have demonstrated an output density of 0.86 watts/mm at 10 GHz.     

Synthesis and Characterization of Sm_xGd_yCe_(1-x-y)O_(2-δ) Nanopowders

SmxGdyCe1-x-yO2-δ (x+y=0.2 and x=0, 0.04, 0.08, 0.12, 0.16, 0.2) nanopowders were prepared by a copre-cipitation method. The zeta potential and sedimentation volume of Ce(OH)4 aqueous dispersions at different pH values were measured. The isoelectric point (IEP) of Ce(OH)4 suspensions is 7.0. The maximum potential value of -18.5 mV and maximum sedimentation volume of 19 ml are reached at pH=10. The evolution behaviors of the xSm(OH)3·yGd(OH)3·(1-x-y)Ce(OH)4 dried powders in the heating process was characterized by DTA/TG and XRO. The powders decompose to ceria based solid solution at a temperature below 300℃ and forms cubic fluorite structure ceria at about 650℃. The properties of SmxGdyCe1-x-yO2-δ solid solutions were characterized by XRD, TEM and BET. The lattice parameter of doped Ce02 increases linearly with increasing Sm3+ substitution (or decreasing Gd3+ substitution). The particle size of the doped ceria powders is from 5 nm to 10 nm.     

Rare earth element cerium substituted Ca–Si–Mg system bioceramics: From mechanism to mechanical and degradation properties

Cerium (Ce)-substituted diopsides (CaMgSi₂O₆) with enhanced mechanical strength and bioactivity were fabricated by precipitation method, followed by annealing at 1000 °C for 4 h. The mineralogical, morphological, in vitro biomineralization, degradation, and mechanical properties were investigated in order to assess the factors and mechanisms affecting the resultant properties. The X-ray diffractometer results showed that the onset of substitutional solid solubility in 0.25 mol Ce would result in new phase formation (cerium dioxide [CeO₂], and magnesium silicate [MgSiO₃]) further causing lattice instability. With increasing Ce dopant levels to 1.00 mol, the initial CaMgSi₂O₆ phase was completely replaced by new phases. The field-emission scanning electron microscopy results indicated that the 0.25 mol Ce had the best biomineralization performance in vitro, while less hydroxyapatite precipitates were found with further increasing Ce dopant levels, suggesting the new phases led to the hindrance of precipitates. The weight loss values indicated that the high dissolution rate of ions in the matrix was observed in the pure sample, while the high readsorption rate of ions in the simulated body fluid (SBF) occurred with increasing Ce dopant levels. The pH value and the inductively coupled plasma-mass spectrometer results suggested that the release of Ca and Mg ions controlled the pH value. The mechanical strength of matrices before SBF immersion was related to the phase transformation, the elastic modulus of CeO₂ and CaMgSi₂O₆, and the release of Mg ions, while the mechanical strength of matrices after SBF immersion was dominated by the structure of matrices.     

Influence of micro- and nanoparticles of zirconium oxides on the dielectric properties of CaCu3Ti4O12

This work presents the results of Zr oxide doping of a CaCu₃Ti₄O₁₂ (CCTO) ceramic prepared by a solid-state reaction. Different stoichiometries (ZrO and ZrO₂) and grain sizes (micro- and nanoparticles) were added as dopants at concentrations of 0.5 and 1.0 wt%. Zr-doping controls the grain size growth, leading to a reduction of the grain size as observed by scanning electron microscopy. For both dopant concentrations, all of the samples exhibited lower dielectric loss and a smaller dielectric constant than those of undoped CCTO. The sample doped with 0.5% of the non-stoichiometric ZrO exhibits a dielectric constant over 3200 and a dissipation factor of 0.02 at 1 kHz. The impedance spectroscopy analysis confirms that the decrease of dielectric loss is mainly due to an increase in resistivity at grain boundaries, which is attributed to the suppression of oxygen-loss promoted by dopants.