Lead-free strontium-doped ferroelectric ceramics with the compositional formula Ba1-xSrxTiO3 (barium strontium titanate, BST) M (x = 0, 0.25, 0.3, and 0.35) are effectively synthesized through a solid-state reaction. The as-prepared samples are characterized by X-ray diffraction (XRD) and Raman spectroscopy. Further dielectric properties and impedance are examined in detail. XRD and Raman studies reveal that the lattice constant, unit cell volume along with tetragonality ratio change with the Sr concentration, Curie temperature (T-c), and dielectric constant along with dielectric loss factor decrease with increasing Sr2+ ions in BST. A stable dielectric constant is detected in a wide frequency range of 1-1000 kHz. Curie-Weiss law and theoretical estimations indicate a large difference in structural disorder in BaTiO3 (barium titanate, BT) ceramics. Consistent with applied temperature and frequency, a noteworthy change is observed in dielectric constant and loss tangent behavior between lowly and highly doped BT samples. Diffusivity decreases with the increase in Sr2+ amount up to x = 0.3. The relaxation response in BST ceramic is observed for higher values of x. Impedance spectroscopy reveals those oxygen vacancies (OVs) are responsible for conduction in BST ceramics. This study is a systematical investigation on the relationship among the structure, dielectric, and impedance properties of Sr2+ substituted BT ceramics.

针对现有催化燃烧式瓦斯传感器气体选择性差等不足,试制研发无铅压电式微天平传感器.但压电陶瓷固有的频率-温度系数特性,使其谐振频率出现漂移,影响精度.故依据压电陶瓷及器件结构特征,对其谐振频率特性进行补偿,以满足谐振器高精度、 高稳定性等实际需求.通过有限元分析与试验方法确定了NKBT无铅压电陶瓷典型谐振体在获得单一谐振频率时的主要尺寸比例关系;然后基于实验测试结果,建立了频率温度漂移量与温度的函数关系,计算出频率温度系数,并利用试验检测了其精确性;最终通过推导获得了无铅压电陶瓷NKBT的补偿算法,该算法可以对微天平测量系统进行补偿.结果表明,对于两种压电振子,线性函数关系具有较好的效果,补偿后径向伸缩振动和横向伸缩振动谐振频率的相对误差分别为5.5％和6.8％,补偿效果良好.

Porous 0.8Na(0.5)Bi(0.5)TiO(3)-0.2K(0.5)Bi(0.5)TiO(3) ceramics are fabricated via the pore-forming agent method with polymethyl methacrylate (PMMA) and stearic acid (SA) as pore forming agents, and microstructure observations demonstrate that the porosity, pore shape, and pore sizes can be controlled by the synthesis technology. The dielectric properties of porous ceramics are found not only correlated to the pore-matrix composite model, but also have a significant grain-size effect. Based on the Zener Theory, pining forces exerted by pores on the grain boundary are calculated, to explain the shape effect of pores on grain boundary migration. A phase-field simulation is carried out to investigate pore shape effect on the grain size regulation in porous polycrystalline, and simulation results are in good agreements with experiential results as well as theoretical calculations. Thus, a modified equation is proposed to predict the effective permittivity of the porous piezoelectric ceramics by considering effects of porosity, pore shape and grain size.

The large-scale and resourceful utilization of solid waste is one of the important ways of sustainable development. The big data brings hope for further development in all walks of life, because huge amounts of data insist on the principle of “turning waste into treasure”. The steel big data has been taken as the research object in this paper. Firstly, a big data collection and storage system has been set up based on the Hadoop platform. Secondly, the steel slag prediction model based on the convolution neural network (CNN) is established. The material data of steelmaking, the operation data of steelmaking process, and the data of steel slag composition are put into the model from the Hadoop platform, and the prediction of the slag composition is further realized. Then, the alternatives for resource recovery are obtained according to the predicted composition of the steel slag. And considering the three aspects of economic feasibility, resource suitability, and environmental acceptance, the comprehensive evaluation system based on AHP is established to realize the recommendation of the optimal resource approach. Finally, taking a steel plant in Hebei as an example, the alternatives according to the prediction of the composition of steel slag are blast furnace iron-making, recycling waste steel, and cement admixture. The comprehensive evaluation values of the three resources are 0.48, 0.57, and 0.76, respectively, and the optimized resource of the steel slag produced by the steel plant is used as the cement admixture.

At present, dye wastewater pollution and solid wastes storage become the main environmental issues in China. Thus, it is of great significance to develop low-cost and efficient technologies to remove dyes from aquatic environment. In this paper, the mixture of magnesium slag and steel slag were used as the raw materials, Na2SiO3 center dot 9H(2)O as alkali activator, silica fume as toughening agent, conductive carbon black as conductive medium, a novel conductive alkali-activated-steel-slag-magnesium-slag-based composite cementitious material (CACCM) was successfully prepared and applied to dye wastewater treatment. The results indicated that the compressive strength of the prepared specimens with carbon black was decreased, and the electrically conductive property was improved significantly with growing of carbon black content. When carbon black content reached 4.5 wt%, the stable conductivity was 0.3997 S/m for the curing period of 28 d. PL spectrum revealed that the photoluminescence intensities progressively decreased with increasing of carbon black content. The incorporation of carbon black could improve the photo catalytic degradation rate of the composite cementitious material, and the conductivity was positively correlated with the degradation rate. 4.5CB/CACCM specimen showed the best photo catalytic degradation activity and the degradation rate of malachite green dye could reach 90.58% at 80 min. The photo catalytic degradation reaction belongs to the second-order reaction kinetics.

采用液相沉积法在导电碳布表面原位生长Co-MOFs纳米片,制得了Co-MOFs/CF复合材料.通过红外光谱、X射线衍射、扫描电子显微镜、恒流充放电、循环伏安、电化学阻抗等手段对材料的组成、结构形貌和电化学性能进行了表征.结果表明:当用作无黏结剂型锂离子电池电极时,在50 mA/g电流密度下,Co-MOFs/CF的首次放电比容量为1621.3 mA·h/g,100次循环后,其放电比容量仍可达445.1 mA·h/g.相比于纯Co-MOFs,Co-MOFs/CF的首次Coulomb效率和循环性能均有明显改善,主要归因于Co-MOFs的二维片状结构与碳布良好导电性之间的协同作用,Co-MOFs/CF优异的电化学性能使其成为很好的锂离子电池电极候选材料.