A Mathematical-Physical Model for the Charge Transport in p-Type SrTiO3 Ceramics Under dc Load: Maxwell-Wagner Relaxation

A mathematical-physical model to describe the current response of p-type SrTiO₃ ceramics in the low-temperature regime upon dc voltage step was developed, utilizing the numerical class library DIFFPACK (Numerical Objects, Norway). The current response in the time domain shows the experimentally observed Maxwell-Wagner relaxation (space charge polarization), followed by leakage current, and, eventually, resistance degradation. The relaxation behavior is analyzed by means of the simulation results for the spatial profiles of the electrical potential and the respective point defects. The impact of bias voltage and grain boundaries on the relaxation time is investigated. The simulation results are compared with experimental data.     

Ab initio insights into the visible luminescent properties of ZnO

The luminescence spectrum of ZnO exhibits, besides a UV band-edge recombination line, a broad visible band around 2.2-2.4 eV whose origin has not been satisfactorily established. Recently, analysis of the luminescence of nanostructured materials with high surface-to-volume ratios has led some authors to suggest that the band could be related to surface states. This work presents a novel ab initio study of the most relevant ZnO surfaces and their intrinsic point defects. It reveals the existence of intragap surface states 0.5 eV above the valence band maximum. If additional bulk defect levels are considered, several bulk-to-surface transitions are compatible with the observed visible luminescence.     

冷轧变形纳米晶钴的X射线衍射研究

对冷轧变形前后纳米金属钴的微观应变。晶格常数以及晶粒尺寸的变化进行了研究，对X射线衍射图谱进行了分析计算，结果表明，变形过后晶体内部存有残余内应力并导致了微观应变，应变大小为ε=1．412×10q；对变形前后的晶格常数进行计算，得到变形后的晶格常数为a=0．25241nm；c=0．40782nm；透射电镜的观察和衍射谱线的计算表明变形后纳米金属钴的晶粒大小与形状基本未发生变化，平均晶粒尺寸为18．8nm。有可能是空位的活动降低了变形过程中的晶界迁移几率，使得变形后的晶粒尺寸基本没有发生变化。     

Electrical Conduction and Disorder in the Pyrochlore System (Gd1−xCax)2Sn2O7

Electrical conductivity measurements were made on the pyrochlore compounds (Gd₁–_xCa_x)₂Sn₂O₇ (x =0, 0.0036, 0.0057, 0.03) as a function of temperature, oxygen partial pressure and Ca doping concentration. An effective Frenkel constant and oxygen vacancy mobility were derived. Intrinsic anion disorder was found to be lower than the expected value based on the relative radii of the cations in the A and B sites (A₂B₂O₇). Low oxygen vacancy mobilities as well as low anion disorder resulted in considerably lower ionic conductivities in Gd_sSn₂O₇ relative to the previously studied Gd₂(Ti₁–_xZr_x)₂O₇ system. The temperature and composition dependence of the p-type electronic conductivity were evaluated and the oxidation enthalpy was derived.     

Na2Mo0.1S0.9O4(α)-In2(SO4)3体系的导电性、相关系与红外光谱研究

本文报道了应用Ｘ射线衍射，差热分析，ＩＲ光谱及电测量技术对Ｎａ２Ｍｏ０．１Ｓ０．９Ｏ４（α）－Ｉｎ２（ＳＯ４）３体系的研究结果，讨论Ｉｎ２（ＳＯ４）３对Ｎａ２Ｍｏ０．１Ｓ０．９Ｏ４的导电性及相存在形式的影响。     

微滤膜的污染与清洗保养

通过对电厂微滤清洗运行中的冲洗、保养、清洗的分析，提出了保证微滤正常运行的有效方案。     

Lattice Strain Due to an Atomic Vacancy

Volumetric strain can be divided into two parts: strain due to bond distance change and strain due to vacancy sources and sinks. In this paper, efforts are focused on studying the atomic lattice strain due to a vacancy in an FCC metal lattice with molecular dynamics simulation (MDS). The result has been compared with that from a continuum mechanics method. It is shown that using a continuum mechanics approach yields constitutive results similar to the ones obtained based purely on molecular dynamics considerations.     

空位对五唑阴离子盐Mn（N5）2冲击反应和损伤演化的影响

为探究微缺陷对五唑阴离子盐冲击响应、化学分解及损伤演化的影响,采用从头算分子动力学模拟方法研究了完美型Mn（N₅）₂晶体及含有3%空位浓度的Mn（N₅）₂晶体在不同速度（8,9,10,11,12 km·s^-1）c轴冲击波作用下的动力学演化和初始分解反应机理。冲击雨贡纽线的计算结果表明,含空位的Mn（N₅）₂体系比完美型体系在高压条件下表现出更大的体积压缩比。分子动力学模拟结果显示,当冲击波速v_shock<10 km·s^-1时,完美型及含有空位的体系在5000 fs内均未出现分解反应,而仅出现了不足10%的体积压缩;当v_shock=10 km·s^-1时,完美型体系于512.8 fs时刻开始在晶体内均匀地出现N—N键断裂的现象,而含空位体系的初始反应时间则提前至281.6 fs,并且N—N键的断裂集中发生在空位附近;当v_shock继续增加至11 km·s^-1和12 km·s^-1时,两种体系的初始反应时间不断提前,反应进程不断加快,但空位对体系冲击波感度的提升作用和对分解反应进程的加速作用随着冲击波速的提升而不断减弱。研究结果表明空位是热点的早期成核结构之一,空位的存在促进周围的五唑分子发生级联分解,使损伤不断演化成长和传播,进而引起含能材料的点火。     

智能建造产业链的核心产业筛选

智能建造是我国传统建筑业转型升级的必由之路,然而在企业转型实践过程中,部分企业对自身的发展定位不够明晰,企业转型难以取得突破性进展。其中一个重要原因在于国家层面缺少引领产业系统性发展的规划文件,企业本身也缺少对智能建造产业体系的深刻认识。因此,现阶段构建层次分明的智能建造产业体系就显得尤为重要。基于智能建造产业链,针对建筑业转型升级过程中存在的技术缺位,从225个智能建造相关产业中筛选出45个推动智能建造快速发展的核心产业,以期为构建智能建造产业体系、制定产业发展政策提供基础性建议。