Numerical Simulation of Dopant Diffusion for Laser-Doped Crystalline Silicon

In this paper, the nonlinear numerical simulation of pulsed laser melting of crystalline silicon and phosphorus dopant liquid-phase diffusion has been established by the finite element method implemented in ANSYS. The melt front behavior as a function of time is described. The experimental SIMS work is intended to be used to validate the numerical model. The numerical simulation result is in good agreement with the corresponding experimental data.     

Promoting Photocatalytic Cleaning Efficiency of Textile Finishing Solutions with Nanoboron as a p-Type Dopant

Boron is a commonly used p-type dopant for semiconductor and photonic applications. In this study, standard photocatalytic titanium dioxide (TiO₂) particles were doped with nanosized boron particles and coated on textiles to bring the photocatalytic light intensity closer to the visible light range. Boron/titania nanoparticle composites were initially prepared in DI water solutions and studied for their photocatalytic response through a statistical central composite design. To determine the most effective titania and nanoboron particle blend for photocatalytic textile coating, absorbance and stain bleach analyses were performed by UV light exposure. The performance of the composite particles at the optimal concentration has also been evaluated in the finishing solution and compared with the performances of the pure titania particles. It was found that the textiles coated with 0.08 wt% anatase doped with 0.16 wt% nanoboron as a p-type dopant provided improvement in self-cleaning ability under the visible light range in the DI water environment. Energy band gap calculations further verified the nanoboron-doped titania blend to have a lower energy barrier as compared with the 0.1 wt% anatase in agreement with the photocatalytic activity improvements. Nanoboron is shown to be a strong candidate as a p-type dopant to titania for photocatalytic textile coatings.     

Highly enhanced dielectric loss of MgO-doped Ba0.67Sr0.33TiO3 ceramics prepared by a non-contamination DCC-HVCI method

MgO-doped Ba_0.67Sr_0.33TiO₃ (BST) ceramics with uniform microstructure and enhanced dielectric loss were prepared by direct coagulation casting via high valence counter ions (DCC-HVCI) method. MgO was utilized as acceptor dopant as well as coagulating agent to release Mg²⁺ solidifying ceramic suspensions. Effect of sintering temperature and MgO doping content on microstructure and dielectric properties of BST ceramics was investigated. It was found that the loss tangent value (tan δ) decreased remarkably from 0.025 to 0.004 with increasing MgO concentration from 0.5 to 1.5 mol%. The 1.5 mol% MgO-doped BST ceramics processed high density of 99.5% and tan δ of 0.004 which is improved by 150% compared with that of dry-pressed samples. This improvement can be attributed to the ubiquitous distribution of MgO in BST ceramic matrix leading to the enhanced inhibitive effect. This paper provides a novel facial route to prepare high-performance functional ceramics with high reliability and low cost.     

Spark plasma sintering of Al-doped ZrB2–SiC composite

This research presents the influence of Al addition on microstructure and mechanical behavior of ZrB₂–SiC ultra-high temperature ceramic matrix composite (UHTCMC) fabricated by spark plasma sintering (SPS). A 2.5?wt% Al-doped ZrB₂–20?vol% SiC UHTCMC was produced by SPS method at 1900?°C under a pressure of 40?MPa for 7?min. The microstructural and phase analysis of the composite showed that aluminum-containing compounds were formed in-situ during the SPS as a result of chemical reactions between Al and surface oxide films of the raw materials (i.e. ZrO₂ and SiO₂ on the surfaces of ZrB₂ and SiC particles, respectively). The Al dopant was completely consumed and converted to the intermetallic Al₃Zr and Al₄Si compounds as well as Al₂O₃ and Al₂SiO₅. A relative density of 99.8%, a hardness (HV5) of 21.5?GPa and a fracture toughness (indentation method) of 6.3?MPa?m^1/2 were estimated for the Al-doped ZrB₂–SiC composite. Crack bridging, branching, and deflection were identified as the main toughening mechanisms.     

Effect of unsaturation in bicarboxylic acid dopants for solid‐state synthesis of polyaniline

Conjugation in the polymeric backbone leads to an electrical conducting nature for conducting polymers, and organic acids can be used as dopants to manipulate the electroactive behaviour. The present investigation deals with the effect of unsaturation in bicarboxylic acid dopant structures on the properties of polyaniline (PAni). PAni was synthesized via solvent‐free solid‐state polymerization. Oxalic acid, fumaric acid and trans,trans‐muconic acid containing 0, 1 and 2 double bonds, respectively, in their molecular structures were used as dopants. Fine particles directionally agglomerate to form nanowires. The use of a conjugated dopant results in highly crystalline PAni. With an increase in the number of double bonds in the dopant structure, the conductivity at room temperature increases, whereas the activation energy, hopping range, optical band gap and supercapacitive performance reduce. The inter‐chain hopping is expected to be favoured by the presence of unsaturation, and even more by conjugation in the dopant structure. © 2016 Society of Chemical Industry     

MOS Capacitance-Voltage Characteristics Ⅱ.Sensitivity of Electronic Trapping at Dopant Impurity from Parameter Variations

Low-frequency and high-frequency Capacitance-Voltage（C-V） curves of Metal-Oxide-Semiconductor Capacitors（MOSC）,including electron and hole trapping at the dopant donor and acceptor impurities,are presented to illustrate giant trapping capacitances,from>0.01C_ox to>10C_ox.Five device and materials parameters are varied for fundamental trapping parameter characterization,and electrical and optical signal processing applications.Parameters include spatially constant concentration of the dopant-donor-impurity electron trap,N_DD,the ground state electron trapping energy level depth measured from the conduction band edge, E_C—E_D,the degeneracy of the trapped electron at the ground state,g_D,the device temperature,T,and the gate oxide thickness,x_OX.     

添加锂微量掺杂物对锰掺杂ZnO铁磁性能的提高

利用溶胶-凝胶法制备了Mn掺杂和Mn,Li共掺ZnO室温铁磁性半导体,分别采用X射线衍射(XRD),X光电子能谱(XPS),紫外-可见分光光度计(UV-VIS)和振动样品磁强计(VSM)研究了添加Li微鼍掺杂物对Mn掺杂ZnO的晶体结构、电子价态、能带宽度和铁磁特性的影响.结果表明:添加Li微量掺杂物明硅提高了Mn掺杂ZnO的铁磁特性,使Mn掺杂ZnO的饱和磁化强度提高了31.52%;Li+存在于Mn掺杂ZnO晶体结构的间隙位置,晶胞参数a和c略有增加,晶粒尺寸减小;Mn离子均以+2价存在,没有Li和Mn氧化物杂质相的存在;同时,添加Li微量掺杂物使Mn掺杂ZnO的能带宽度减小了0.144 eV,载流子发生变化.铁磁性的提高归因于Li的引入导致ZnO晶格中的间隙电子掺杂和间隙缺陷的产生及载流子的变化,以及Mn2+-Mn2+间接铁磁性交换耦合的增强.     

高磁性能SrFe_(12-x)Cr_xO_(19)铁氧体制备和表征

用传统陶瓷工艺制备了M型Sr Fe12-xCrxO19(x=0~0.6)铁氧体,利用X射线衍射、扫描电子显微镜和B-H分析仪对样品的结构与磁性能进行了表征。研究了铬含量、烧结温度和复合添加剂对磁体性能的影响。结果表明,适量的铬取代和复合添加可以提高锶铁氧体的综合磁性能;当x=0.2时,在相对低的温度(1135~1165℃)烧结,其磁性能达到TDK的FB6H性能水平。其中,最佳磁性能可达到Br=401.7m T、Hcb=300.5k A/m、Hcj=353.1k A/m和(BH)max=31.4k J/m3。     

Thermal behaviour of strontium tartrate single crystals grown in gel

Thermal behaviour of strontium tartrate crystals grown with the aid of sodium metasilicate gel is investigated using thermogravimetry (TG) and differential thermal analysis (DTA). Effect of magnetic field and dopant (Pb)²⁺ on the crystal stability is also studied using thermal analysis. This study reveals that water molecules are locked up in the lattice with different strengths in the grown crystals.