Preparation of low-oxygen titanium powder by magnesiothermic reduction of TiO2 assisted by MgCl_(2)−HoCl_(3) molten salt

To reduce the production cost of titanium,a new method for direct preparation of low-oxygen titanium powder by the magnesiothermic reduction of TiO_(2) with the assistance of a MgCl_(2)−HoCl_(3) molten salt was proposed.Thermodynamic calculations showed that the magnesiothermic reduction of TiO_(2) was feasible.However,hindrance of the reduction reaction by the reduction by-product of MgO resulted in a considerably high O concentration in the titanium powder.The addition of HoCl_(3) to the system significantly reduces the activity of MgO to produce low-oxygen titanium powder.Thermochemical deoxidation and reduction experiments were conducted with MgCl_(2)−HoCl_(3) molten salt in the temperature range of 1023−1273 K.The results showed that titanium powder with oxygen concentration(mass fraction)below 5.00×10^(-4) can be prepared at the Mg−MgCl_(2)−HoOCl−HoCl_(3) equilibrium.

Interface and energy band manipulation of Bi2O3-Bi2S3 electrode enabling advanced magnesium-ion storage

Rechargeable magnesium-ion(Mg-ion)batteries have attracted wide attention for energy storage.However,magnesium anode is still limited by the irreversible Mg plating/stripping procedure.Herein,a well-designed binary Bi_(2)O_(3)-Bi_(2)S_(3)(BO-BS)heterostructure is fulfilled by virtue of the cooperative interface and energy band engineering targeted fast Mg-ion storage.The built-in electronic field resulting from the asymmetrical electron distribution at the interface of electron-rich S center at Bi_(2)S_(3) side and electron-poor O center at Bi_(2)O_(3) side effectively accelerates the electrochemical reaction kinetics in the Mg-ion battery system.Moreover,the as-designed heterogenous interface also benefits to maintaining the electrode integrity.With these advantages,the BO-BS electrode displays a remarkable capacity of 150.36 mAh g^(−1) at 0.67 A g^(-1) and a superior cycling stability.This investigation would offer novel insights into the rational design of functional heterogenous electrode materials targeted the fast reaction kinetics for energy storage systems.

Designing ultrastable P2/O3-type layered oxides for sodium ion batteries by regulating Na distribution and oxygen redox chemistry

P2/O3-type Ni/Mn-based layered oxides are promising cathode materials for sodium-ion batteries(SIBs)owing to their high energy density.However,exploring effective ways to enhance the synergy between the P2 and 03 phases remains a necessity.Herein,we design a P2/O3-type Na_(0.76)Ni_(0.31)Zn_(0.07)Mn_(0.50)Ti_(0.12)0_(2)(NNZMT)with high chemical/electrochemical stability by enhancing the coupling between the two phases.For the first time,a unique Na*extraction is observed from a Na-rich O3 phase by a Na-poor P2 phase and systematically investigated.This process is facilitated by Zn^(2+)/Ti^(4+)dual doping and calcination condition regulation,allowing a higher Na*content in the P2 phase with larger Na^(+)transport channels and enhancing Na transport kinetics.Because of reduced Na^(+)in the O3 phase,which increases the difficulty of H^(+)/Na^(+) exchange,the hydrostability of the O3 phase in NNZMT is considerably improved.Furthermore,Zn^(2+)/Ti^(4+)presence in NNZMT synergistically regulates oxygen redox chemistry,which effectively suppresses O_(2)/CO_(2) gas release and electrolyte decomposition,and completely inhibits phase transitions above 4.0 V.As a result,NNZMT achieves a high discharge capacity of 144.8 mA h g^(-1) with a median voltage of 3.42 V at 20 mA g^(-1) and exhibits excellent cycling performance with a capacity retention of 77.3% for 1000 cycles at 2000 mA g^(-1).This study provides an effective strategy and new insights into the design of high-performance layered-oxide cathode materials with enhanced structure/interface stability forSIBs.

Polypyride intercalation boosting the kinetics and stability of V_(3)O_(7)·H_(2)O cathodes for aqueous zinc-ion batteries

V_(3)O_(7)·H_(2)O(VO)is a high capacity cathode material in the field of aqueous zinc ion batteries(AZIBs),but it is limited by slow ion migration and low electrical conductivity.In this paper,polypyridine(PPyd)intercalated VO with nanoribbon structure was prepared by a simple in-situ pre-intercalation,which is noted VO-PPyd.The total density of states(TDOS)shows that after the pre-intercalation of PPyd,an intermediate energy level appears between the valence band and conduction band,which provides a step that can effectively reduce the band gap and enhance the electron conductivity.Furthermore,the density functional theory(DFT)results found that Zn^(2+)is more easily de-intercalated from the V-O skeleton,which proves that the embeddedness of PPyd improves the diffusion kinetics of Zn^(2+).Electrochemical studies have shown that VO-PPyd cathode materials exhibit excellent rate performance(high specific capacity of 465 and 192 mA h g^(-1)at 0.2 and 10 A g^(-1),respectively)and long-term cycling performance(92.7%capacity retention rate after 5300 cycles),due to their advantages in structure and composition.More importantly,the energy density of VO-PPyd//Zn at 581 and 5806 W kg^(-1)is 375 and 247 W h kg^(-1),respectively.VO-PPyd exhibits excellent electrochemical properties compared to previously reported vanadium based cathodes,which makes it highly competitive in the field of high-performance cathode materials of AZIBs.

Ba-Bi复合掺杂对Y_2O_3·2TiO_2微波介质陶瓷性能的影响

采用Ba-Bi复合掺杂对Y2O3·2TiO2微波介质陶瓷进行改性,以降低其烧结温度并改善其介电性能。在固定Bi2Ti2O7掺杂量为质量分数8%的基础上,研究了BaCO3掺杂量对陶瓷微结构、烧结性能和介电性能的影响。结果表明:当w(BaCO3)为1%时,在较低的烧结温度(约1280℃)下保温2h制备了一种新型中介电常数Y2O3·2TiO2微波介质陶瓷。该陶瓷具有较好的介电性能:在1MHz下,εr≈72.5,tanδ≈2.5×10-3;在微波频率(5.03GHz)下,εr=72.1,Q·f值为2241.0GHz。

纳米TiO_(2)对NH_(3)-H_(2)O-LiBr工质降膜吸收性能的影响

为了探讨纳米TiO_(2)对三元NH_(3)-H_(2)O-LiBr工质降膜吸收的影响,本文利用数值分析建立了三元工作流体薄膜吸收的连续方程、能量方程和组分质量平衡方程,采用Matlab软件进行编程和计算纳米流体的降膜吸收性能,将其与实验数据进行对比验证,并进一步分析了纳米TiO_(2)质量分数、初始氨浓度、初始温度、冷却水进口温度、吸收压力和下降薄膜管长度对薄膜吸收性能的影响。研究表明:添加纳米TiO_(2)可以增强降膜吸收的传质速率,主要原因为液膜中氨的扩散系数增加。当纳米TiO_(2)质量分数从0%增加到0.1%、0.3%和0.5%时,扩散系数分别增加了3.44倍、6.42倍和11.76倍。此外,增加初始氨浓度、降低初始温度、提高冷却水进口温度或降低吸收压力都可以提高最终溶液的饱和度。

Modification of Nano-α-Al2O3 and Its Influence on the Surface Properties of Waterborne Polyurethane Resin Composite Passivation Films

Silane coupling agent KH560 was used to modify the surface of nano-α-Al2O3 in ethanol-aqueous solution with different proportions. The particle size of nano-α-Al2O3 was determined by nano-particle size analyzer, and the effects of nano-α-Al2O3 content, ethanol-aqueous solution ratio and KH560 dosage on the dispersion and particle size of nano-α-Al2O3 were investigated. The material structure before and after modification was determined by Fourier transform infrared spectroscopy (FTIR). Aqueous polyurethane resin and inorganic components are combined with modified nano-α-Al2O3 dispersion to form chromium-free passivation solution. The solution is coated on the galvanized sheet, the adhesion and surface hardness are tested, the bonding strength of the coating and the surface hardness of the substrate are discussed. The corrosion resistance and surface morphology of the matrix were investigated by electrochemical test, neutral salt spray test and scanning electron microscope test. The chromium-free passivation film formed after the modification of nano-α-Al2O3 increases the surface hardness of galvanized sheet by about 85%. The corrosion resistance of the film is better than that of a single polyurethane film. The results show that the surface hardness and corrosion resistance of polyurethane resin composite passivation film are significantly improved by the introduction of nano-α-Al2O3.

Effect of Na_(2)O on formation of calcium aluminates in CaO-Al_(2)O_(3)-SiO_(2)system

The formation characteristics of calcium aluminates in the CaO-Al2O3-SiO2 system with sodium oxide was investigated by XRD, SEM-EDS and DSC-TG technologies. The main phases in the clinker after sintering at 1350 °C are 12CaO?7Al2O3, 2CaO?Al2O3?SiO2 and 2CaO?SiO2 when the mass ratio of Al2O3 to SiO2 is 3.0 and the molar ratio of CaO to Al2O3 is 1.0. The proportion of 12CaO?7Al2O3 increases with the increase of Na2O addition when the molar ratio of Na2O to Al2O3 is from 0 to 0.4, while the proportion of 2CaO?Al2O3?SiO2 decreases with the increase of Na2O addition. Na2O forms solid solution in 12CaO?7Al2O3, which increases the volume of elementary cell of 12CaO?7Al2O3. The formation temperature of 12CaO?7Al2O3 is decreased by 30 °C when the molar ratio of Na2O to Al2O3 increases from 0 to 0.4 determined by DSC. The alumina leaching property of clinker increases obviously with the increase of Na2O addition.

Synthesis of Li^+ adsorbent(H_2TiO_3) and its adsorption properties

H2TiO3 was obtained from the acid-modified adsorbent precursor Li2TiO3,which was synthesized by a solid-phase reaction between TiO2 and Li2CO3.The extraction ratio of Li＋ from Li2TiO3 was 98.86%,almost with no Ti4＋ extracted.The effects of lithium titanium ratio,calcining temperature and time were investigated on the synthesis of Li2TiO3.Li2TiO3,H2TiO3 and the adsorbed Li＋ adsorbent were characterized by XRD and SEM.The lithium adsorption properties were investigated by the adsorption kinetics and adsorption isotherm.The results indicate that H2TiO3 has an excellent adsorptive capacity for Li＋.Two simplified kinetic models including the pseudo-first-order and pseudo-second-order equations were selected to follow the adsorption processes.The rate constants of adsorption for these kinetic models were calculated.The results show that the adsorption process can be described by the pseudo-second-order equation,and the process is proved to be a chemical adsorption.The adsorption process that H2TiO3 adsorbs Li＋ in LiCl solution well fits the Langmuir equation with monolayer adsorption.

基于TiO_2-Y_2O_3粉体催化发光甲醇气体传感器的研究

发现当甲醇气体通过TiO2-Y2O3(质量比为3∶1)粉体表面时,可被空气中的O2催化氧化产生强烈的化学发光,基于此研制了一种新型的甲醇气体传感器.此传感器对甲醇的检测具有较高灵敏度和较强的选择性.在波长490nm处进行定量分析,催化发光强度与甲醇浓度在一定范围内呈良好的线性关系,其线性范围为25.74～12870mg/m3(r=0.9995,n=8);检出限为8.58mg/m3(信噪比=3).外来物质如正己烷、三氯甲烷、苯、无水乙醇、甲醛、丙酮、氨、甲苯与甲醇共存时,除了丙酮、乙醇和氨分别引起干扰外,苯与其它气体不干扰测定.该传感器工作时间可持续80h以上,是一种长寿命的、性能稳定的气体传感器,并成功地实现了对甲醇气体的实时在线检测.

Effects of silica additive on the NH_3-SCR activity and thermal stability of a V_2O_5/WO_3-TiO_2 catalyst

V2O5/WO3‐TiO2 and V2O5/WO3‐TiO2‐SiO2 catalysts were prepared by a wetness impregnation method, and both the catalysts were hydrothermally aged at 750℃ in 10 vol%H2O/air for 24 h. The catalysts were evaluated for NOx conversion using NH3 as the reductant. Hydrothermal ageing decreased the NOx conversion of V2O5/WO3‐TiO2 catalyst severely over the entire measured tem‐perature range. Interestingly, the NH3‐SCR activity of the silica‐modified catalyst at 220–480℃ is enhanced after ageing. The catalysts were characterized by X‐ray diffraction, nitrogen adsorption, X‐ray fluorescence, Raman spectroscopy, H2 temperature‐programmed reduction, and NH3 temper‐ature‐programmed desorption. The addition of silica inhibited the phase transition from anatase to rutile titania, growth of TiO2 crystallite size and shrinkage of catalyst surface area. Consequently, the vanadia species remained highly dispersed and the hydrothermal stability of the V2O5/WO3‐TiO2 catalyst was significantly improved.

Effect of Fe_2O_3 on non-isothermal crystallization of CaO-MgO-Al_2O_3-SiO_2 glass

The crystallization behavior and kinetics of CaO-MgO-Al2O3 SiO2（CMAS） glass with the Fe2O3 content ranging from zero to 5%were investigated by differential scanning calorimetry（DSC）.The structure and phase analyses were made by Fourier transform infrared spectroscopy（FT-IR） and X-ray diffraction（XRD）.The experiment results show that the endothermic peak temperature about 760℃ is associated with transition and the exothermic peak temperature about 1000℃ is associated with crystallization.The crystallization peak temperature decreases with increasing the Fe203 content.The crystallization mechanism is changed from two-dimensional crystallization to one-dimensional growth,and the intensity of diopside peaks becomes stronger gradually.There is a saltation for the crystallization temperature with the addition of 0.5%Fe2O3 due to the decomposition of Fe2O3.Si-O-Si,O-Si-O and T-O-T（T=Si,Fe,Al） linkages are observed in Fe2O3-CaO-MgO-Al2O3-SiO2 glass.

Mn-Y/TiO_2低温NH_3选择性催化还原NO性能研究

研究了稀土金属Y掺杂Mn/TiO2催化剂的低温NH3选择性催化还原NO性能。采用溶胶凝胶法制备Y掺杂的TiO2载体,负载前驱体硝酸锰构成了Y掺杂的Mn-Y/TiO2催化剂。考察Y的掺杂量,操作条件如反应温度、氧含量、进口NO浓度和空速等因素对其催化还原NO性能的影响。结果表明,Y与Ti的最佳摩尔比为1.5%,X射线衍射(X-raydiffraction,XRD)分析Y掺杂抑制了锐钛矿晶相的转移,有利于催化剂比表面积增大,从而提高催化剂的活性;在反应温度180℃、空速14000h-1、氧含量为3%、NO浓度0.06%及体积比φ(NH3)/φ(NO)为1的条件下,Mn负载量为5%,焙烧温度500℃下制备的MnTiY催化剂对NO的转化率达到93.5%。

Photocatalytic activity of TiO_2 supported SiO_2-Al_2O_3 aerogels prepared from industrial fly ash

A ternary composite of TiO2 and a SiO2-Al2O3 aerogel with good photocatalytic activity was prepared by a simple sol-gel method with TiO2 nanoparticles and SiO2-Al2O3 aerogels derived from industrial fly ash.The structural features of the TiO2/SiO2-Al2O3 aerogel composite were investigated by X-ray powder diffraction,Fourier transform infrared spectroscopy,transmission electron microscopy,gas adsorption measurements and diffuse reflectance UV-visible spectroscopy.The optimal conditions for photocatalytic degradation of 2-sec-butyl-4,6-dinitrophenol（DNBP],included an initial DNBP concentration of 0.167 mmol/L at pH = 4.86 with a catalyst concentration of 6 g/L,under visible light irradiation for 5 h.A plausible mechanism is proposed for the photocatalytic degradation of DNBP.Our composite showed higher photocatalytic activity for DNBP degradation than that of pure TiO2.This indicates that this material can serve as an efficient photocatalyst for degradation of hazardous organic pollutants in wastewater.

TiO_2/YFeO_3复合光催化剂的制备、表征及其对气相苯的降解(英文)

利用共沉淀法和柠檬酸法制备YFeO3,并以其为载体,将TiO2溶胶负载在其表面,制备了复合光催化剂TiO2/YFeO3.在紫外灯的照射下,考察对气相苯的降解效果并利用N2吸附、X射线衍射(XRD)、拉曼光谱、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、UV-Vis漫反射光谱等手段对催化剂进行了表征.结果表明,以共沉淀法制备的YFeO3为载体的复合催化剂,180min内苯的降解率达到44.7%,表现出更好的光催化活性.两种方法制备的YFeO3均为斜方晶相,TiO2分散在载体的表面,并与YFeO3存在一定的相互作用;两种复合催化剂均具有较窄的带隙能.

Dy_2O_3掺杂对BaTiO_3陶瓷结构与性能的影响

对水热法合成的BaTiO3粉体进行稀土氧化物Dy2O3掺杂改性,利用扫描电镜、X射线衍射及电气性能测试等手段,分析了离子取代行为和晶格参数与固溶度之间的关系,重点研究了Dy2O3掺杂量对BaTiO3陶瓷的晶粒尺寸、介电性能的影响规律.结果表明,Dy2O3在陶瓷的烧结过程中可抑制晶粒生长,使晶粒尺寸变小,提高了陶瓷的致密度.当掺杂量w(Dy2O3)为0.6%时,陶瓷晶粒的晶格常数达到最大值,此时晶粒内部缺位浓度最低,常温介电常数提高到4100,在-15～100℃范围内,介电常数随温度变化率为±10%,交流击穿场强为3 2kV/mm.

低量Yb^(3+)掺杂的TiO_2复合纳米粉体的制备及光催化活性

利用酸催化的溶胶-凝胶法制备了纯TiO2和低量Yb3+(w=0.125%)掺杂的TiO2复合纳米粉体,采用XRD,BET,XPS,DRS和SPS等技术进行了表征,以亚甲基蓝(MB)的光催化降解为探针反应,评价了其光催化活性,探讨了低量Yb3+掺杂对TiO2纳米粒子光催化活性的影响机制.研究结果表明,0.125%Yb3+掺杂可以显著提高TiO2纳米粒子的光催化活性.低量Yb3+掺杂可以抑制TiO2由锐钛矿相向金红石相的转变,阻碍TiO2晶粒的生长,改善粉体的表面织构特性,提高高温组织稳定性.XPS分析表明,Yb3+掺杂可以导致粉体的表面羟基含量增加.SPS分析表明,Yb3+掺杂能够抑制光生e-/h+复合,改善粒子表面的光吸收性能.与纯TiO2相比,Yb3+掺杂TiO2纳米粒子光催化氧化活性的提高应归因于Yb3+掺杂抑制了e-/h+复合,增加了表面羟基含量,增大了比表面积,增强了样品表面的光吸收能力.

掺杂Y^(3+)的纳米TiO_2微粒的制备及其光催化性能

在Sol-Gel法制备纳米TiO2微粒的最佳制备条件的基础上,制备了掺杂稀土离子钇(Y3+)的纳米TiO2复合粒子,并对这二者进行了XRD,TEM和DRS表征及光催化活性检验。结果表明,未经掺杂的TiO2与掺杂稀土Y3+的TiO2均为锐钛和金红石的混合晶型,锐钛和金红石的比例约为3?1;掺杂抑制了TiO2晶粒的生长,使得TiO2粒径明显变小,其颗粒大小为10nm左右。用DRS表征微粒的光吸收能力和光吸收带边移动情况,发现掺杂导致了TiO2光吸收能力增强及吸收带边红移。通过对苯酚的光催化氧化降解研究,发现当Y3+掺杂量(按质量)为1.5%时,TiO2光催化活性最高,与未掺杂的TiO2相比,其光催化活性提高约20%。

B_2O_3蒸汽掺杂的中低温烧结Y-BaTiO_3及其PTCR特性研究

通过B_2O_3蒸汽掺杂,Y-BaTiO_3陶瓷的烧结温度大幅度降低。B_2O_3蒸汽掺杂后的样品,室温电阻率下降,升阻比提高,通过对氧化硼蒸汽掺杂样品的XRD分析研究表明,硼间隙可以在钛酸钡晶格中存在,硼间隙和/或相关缺陷络合物可以形成电子捕获中心,从而提高PTCR效应。

Morphology and Frictional Characteristics Under Electrical Currents of Al_2O_3/Cu Composites Prepared by Internal Oxidation

Two Al2O3/Cu composites containing 0.24 wt.% Al2O3 and 0.60 wt.% Al2O3 separately are prepared by internal oxidation. Effects of sliding speed and pressure on the frictional characteristics of the composites and copper against brass are investigated and compared. The changes in morphology of the sliding surface and subsurface are examined with scanning electron microscope （SEM） and energy dispersive X-ray spectrum （EDS）. The results show that the wear resistance of the Al2O3/Cu composites is superior to that of copper under the same conditions, Under a given electrical current, the wear rate of Al2O3/Cu composites decreases as the Al2O3-content increases, However, the wear rates of the Al2O3/Cu composites and copper increase as the sliding speed and pressure increase under dry sliding condition. The main wear mechanisms for Al2O3/Cu composites are of abrasion and adhesion; for copper, it is adhesion, although wear by oxidation and electrical erosion can also be observed as the speed and pressure rise.