Nb2O5掺杂ZnO超高致密度陶瓷靶材的制备

采用传统的固相烧结技术制备了Nb2 O5掺杂ZnO陶瓷靶材,研究了不同烧结温度、Nb2 O5掺杂量对NZO靶材的电学性能、相对密度、抗弯强度的影响.结果表明:当烧结温度1200℃,Nb2 O5的掺杂量为0.4wt%时,其综合性能最佳,此时靶材电阻率为0.189Ω·cm,相对密度为99.46%,抗弯强度141.74 MPa.     

Al3+,Si4+对施主、受主掺杂高居里点BaTiO3基PTCR材料性能的影响

固相法合成 (Ba0 .6 Pb0 .4 )TiO3,固定外加TiO2 量 ,研究了Al3 、Si4 对施主Nb5 掺杂居里点Tc >3 2 0℃的 (Ba,Pb)TiO3材料室温电阻率的影响以及对施主Nb5 、受主Mn2 共掺时材料PTC效应等性能的影响。结果表明 ,添加物不影响材料基体的晶体结构 ,Al3 、Si4 可促进材料的烧结 ,适量的Al3 、Si4 可改善施受主掺杂的高居里点BaTiO3基PTCR陶瓷材料的性能     

高压LiNi0.5Mn1.5O4正极材料掺杂Nb离子改性研究

采用固相烧结法合成了Nb掺杂的LiNi0.5Mn1.5O4正极材料.通过XRD测试和充放电测试表征了材料的晶体结构和电化学性能.结果表明Nb掺杂容易产生LiNbO3杂质,并影响其放电能力,少量Nb掺杂获得的LiNi0.425Nb0.03Mn1.5O4展示出良好的大电流放电性能.     

锑掺杂PZSN压电陶瓷烧结工艺的研究

为制备大功率低损耗压电陶瓷材料，对改性锆钛酸铅压电陶瓷Pb0.9Ba0.05Sr0.05（Zn1／3Nb2／3）0.06（Sn1/3Nb2/3）0.05Ti0.44Zr0.44O3＋0．5％Mn（NO3）2（质量分数，下同）＋x％Sb2O3的烧结工艺进行比较研究，结果表明体系优化结工艺为以300℃／h的升温速率，在1250℃处保温3h，此时对0．1％～0．4％（质量分数）的Sb2O3掺杂，均可制备出综合性能优良的压电陶瓷。当掺杂量为0．1％（质量分数）时，其tanδ，Qm，Kp，d33和ε4分别为0．47％，2251，0.538，336pC／N和1897，可满足大功率应用的要求。     

放电等离子体烧结下Nb掺杂量对TiO2陶瓷靶材性能的影响

采用放电等离子体(SPS)烧结制备了Nb掺杂TiO2(NTO)陶瓷靶材,运用X射线衍射分析、扫描电子显微镜、四探针测试仪等对NTO陶瓷靶材样品的各性能进行表征.研究了在1100℃下不同Nb掺杂量对NTO陶瓷靶材相对密度、抗弯强度、电阻率、表面形貌与微观结构等性能的影响.实验结果表明:不同Nb掺杂量对NTO陶瓷靶材的性能有显著的影响,在1100℃烧结的NTO陶瓷靶材样品,随着Nb掺杂量的升高,相对密度、抗弯强度和电阻率先增大后逐渐降低,在5wt％掺杂量处均达到了最大值,且此时结晶完好、晶粒大小分布均匀.综合而言,5wt％Nb掺杂量的NTO陶瓷靶材的各项性能表现最优,其电阻率为13.23 mΩ·cm,抗弯强度为139.1 MPa,相对密度达到99.9％.     

溶胶–凝胶法制备(Na0.50+xK0.50-2xLix)Nb0.9Ta0.1O3无铅压电陶瓷及其性能

采用溶胶–凝胶法制备Li+取代(K0.5Na0.5)+及Ta5+取代Nb5+的(K0.5Na0.5)NbO3陶瓷粉体,采用无压烧结工艺制备(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3(x=0,0.02,0.04)陶瓷样品。研究了前驱体煅烧温度对陶瓷粉体物相组成的影响。分析了不同Li+掺杂量对样品物相组成、微观结构、体积密度及电学性能的影响。结果表明:前驱体的最佳煅烧温度为600℃,通过透射电子显微镜分析陶瓷粉体的粒径为49 nm;不同Li+掺杂量制备的(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3陶瓷样品均为正交相钙钛矿结构;随着Li+掺杂量的增加,(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3陶瓷的体积密度先增大后减小,介电常数逐渐升高,压电常数先降低再升高,剩余极化强度逐渐升高。Li+掺杂量x为0.04时样品的压电常数(d33=94 pC/N)、相对介电常数(εr=684.33)及剩余极化强度(Pr=98.27μC/cm2)较好。     

Yb_2O_3和Sm_2O_3复合掺杂对锆钛酸钡陶瓷介电性能的影响

以碳酸钡、二氧化锆、二氧化钛等为原料,以Sm_2O_3为掺杂剂和掺杂量为0.5mol%Y_2O_3的锆钛酸钡陶瓷材料为研究对象,采用传统固相法分别于1250℃、1280℃、1300℃、1330℃下制备了陶瓷样品,研究Sm_2O_3加入物对体系介电性能和微观形貌的影响。结果表明,Sm~(3+)掺杂后的陶瓷样品主晶相不变,均为钙钛矿结构;掺杂能起到改善介电常数与介电损耗的作用,随着Sm_2O_3掺杂量的增加,陶瓷样品的介电常数最高至6623.49,而介电损耗最低至0.0145;掺杂还可以改变BZT陶瓷的介电性能,居里温度向室温方向移动,当Sm_2O_3掺杂量x=0.005 mol时,陶瓷样品的介电性能最好。     

倒车雷达用锆钛酸铅压电陶瓷材料的研究

对锆钛酸铅陶瓷材料进行了Nb2O5、SrCO3微量掺杂改性研究,观察了掺杂后陶瓷样品的显微结构,研究了其相对介电常数、压电常数、机电耦合系数及电容量变化率随测试温度变化的规律。实验结果表明:Nb2O5、SrCO3掺杂后,陶瓷结构致密,介电损耗减少,相对介电常数、压电常数、机电耦合系数明显提高,电容量变化率明显改善。当Nb2O5、SrCO3的添加量为0.6wt%时,制得的压电陶瓷材料具有最佳的压电性能:εr=2100,D33=450pC/N,Kp=0.81,ΔC/C10%(-55~85℃),可以满足高性能的汽车倒车雷达的应用要求。     

多种添加物联合作用对Mn-Zn铁氧体性能的影响

采用高温燃烧合成法制备Mn～Zn铁氧体粉体,并对多种添加物,如CaO,Nb2O5,SnO2和Ta2O5对Mn—Zn铁氧体性能的影响进行了深入地研究。结果表明：4种掺杂离子对Mn～Zn铁氧体性能的影响各不相同。掺入的部分Nb^5 和Sn^4 可溶于Mn—Zn铁氧体的晶格内,改变其品格大小,并使初始磁导率μ．与温度θ曲线上第2峰的位置向低温方向移动,但Nb^5 和Sn^4 对晶粒的生长影响较小。由于Ta^5 离子只存在于晶界处,所以对晶格常数和第2峰位置的影响均很小,但Ta^5 的存在有利于晶粒的生长,随Ta^5 的掺入量增加,铁氧体的晶粒尺寸增大,气孔率降低。此外,4种掺杂离子对Mn—Zn铁氧体性能的影响是相互关联的,当添加物的质量分数为CaCO30．05％,Nb2O50．024％,SnO20．15％,Ta2O50．024％时,初始磁导率,μi达到最大,功耗Pv达到最小。     

锰掺杂的二氧化钛光催化降解偶氮染料性能研究

采用超声分散法,以钛酸丁酯为前驱体,硫酸锰为掺杂剂,制备掺锰的纳米二氧化钛光催化剂。以甲基橙为目标降解物,对掺杂锰的二氧化钛粉体进行了光催化降解性能研究。结果表明：催化剂的最佳投加量为2 g/L,锰的掺杂量为10%[Mn占（Mn＋Ti）的摩尔分数]。焙烧温度为550℃,焙烧时间为2 h,锰掺杂的二氧化钛降解效果最佳。     

Colossal permittivity of (Gd + Nb) co-doped TiO2 ceramics induced by interface effects and defect cluster

Material with high dielectric constant plays an important role in energy storage elements. (Gd + Nb) co-doped TiO₂ (GNTO) ceramics with giant dielectric permittivity (>10⁴), low dielectric loss, good temperature and frequency stability in broad range of 30–150 °C and 10²–10⁶ Hz have been systematically characterized. Especially, a low dielectric loss of 0.027 and a giant dielectric permittivity of 5.63 × 10⁴ at 1 kHz are attained for the composition with x = 0.01. Results of complex impedance spectroscopy, I–V curve and frequency dependent dielectric constant under DC bias indicate that internal barrier layer capacitance (IBLC) effect, electrode effect and electron-pinned defect-dipole (EPDD) effect contribute to the colossal permittivity (CP) property simultaneously.     

Co-doping effects of A-site Y3+ and B-site Al3+ on the microstructures and dielectric properties of CaCu3Ti4O12 ceramics

Different doping elements have been used to reduce the dielectric losses of CaCu₃Ti₄O₁₂ ceramics, but their dielectric constants usually are undesirably decreased. This work intends to reduce their dielectric losses and simultaneously enhance their dielectric constants by co-doping Y³⁺ as a donor at A site and Al³⁺ as an acceptor at B site for substituting Ca²⁺ and Ti⁴⁺, respectively. Samples with different doping concentrations x = 0, 0.01, 0.02, 0.03, 0.05 and 0.07 have been prepared. It has been shown that their dielectric losses are generally reduced and their dielectric constants are simultaneously enhanced across the frequency range up to 1 MHz. The doped sample with x = 0.05 exhibits the highest dielectric constant, which is well over 10⁴ for frequency up to 1 MHz and is about 20% higher than the undoped sample. Impedance spectra indicate that the doped samples have much higher grain boundary resistance than the undoped one.     

Ternary doping of Na+, Bi3+ and La3+ to improve piezoelectric constant and electrical resistivity simultaneously in calcium bismuth niobate ceramics

High Curie-temperature layer-structured calcium bismuth niobate (CaBi₂Nb₂O₉) piezoelectric ceramics are promising for important application in high-temperature vibration sensors. However, such application is currently limited due to not only poor high-temperature piezoelectric constant (d₃₃), which is attributable to spontaneous polarization along a-b plane and high coercive fields, but also inferior high-temperature electrical resistivity, which results from volatilization of Bi₂O₃ during the sintering process that increases defect concentration of oxygen vacancies. Herein, we report a Na⁺, Bi³⁺ and La³⁺ ternary-doping-strategy to obtain Ca_0.8(Na_0.5La_0.3Bi_0.2)_0.2Bi₂Nb₂O₉ ceramics, which exhibited higher piezoelectric constant and larger electrical resistivity as accompanied by a better thermal stability at high-temperatures. The piezoelectric constant was enhanced from 8.8 pC/N in pristine CaBi₂Nb₂O₉ to 13.4 pC/N in Ca_0.8(Na_0.5La_0.3Bi_0.2)_0.2Bi₂Nb₂O₉ ceramics, which is ascribed to the presence of pseudo-tetragonal structural distortion after La³⁺ doping. In addition, the electrical resistivity at 600 °C was increased by more than one-order of magnitude from 3.7 × 10⁴ Ω cm in pristine CaBi₂Nb₂O₉ to 1.4 × 10⁶ Ω cm in Ca_0.8(Na_0.5La_0.3Bi_0.2)_0.2Bi₂Nb₂O₉ ceramics. Such significant improvement in electrical resistivity results from the reduction in oxygen vacancies due to ternary doping of Na⁺, Bi³⁺ and La³⁺ and stronger binding interaction between La³⁺ dopants and O^2? in (Bi₂O₂)²⁺ layers in Ca_0.8(Na_0.5La_0.3Bi_0.2)_0.2Bi₂Nb₂O₉ ceramics. This work demonstrates an important way of employing chemical doping to improve piezoelectric constant and electrical resistivity simultaneously at high-temperatures to tune structural distortion in bismuth-layered structural CaBi₂Nb₂O₉ ceramics.     

硫酸介质中D2EHPA萃取In~(3+)与Fe~(3+)的动力学

采用恒界面池法研究了从硫酸介质中萃取In3+和Fe3+的动力学,考察了搅拌速度、界面面积、温度、萃取剂浓度、氢离子活度及硫酸根浓度对In3+,Fe3+萃取速率的影响.结果表明,在温度25℃、搅拌转速70～240 r/min条件下,In3+以三价离子形式被萃取,萃取活化能为17.54 k J/mol,萃取过程为扩散控制;Fe3+以Fe SO4+形式被萃取,萃取活化能为52.87 k J/mol,萃取过程为界面化学反应控制.增加D2EHPA浓度可增大正向反应动力,提高萃取速率.萃取过程为阳离子交换,氢离子活度增加会导致萃取速率降低,硫酸根与金属离子的络合效应会降低萃取速率.通过动力学研究得到In3+萃取的正向速率方程为-d CIn3+/dt=10-0.378[In3+](aq)[H+](aq)-0.376[H2A2](org)0.158,Fe3+萃取的正向速率方程为-d CFe3+/dt=10-2.413[Fe3+](aq)[H+](aq)-1.526[H2A2](org)0.600.     

一种含席夫碱结构的表面活性剂与Cu2+配合的稳定性及抗菌性

用可见分光光度法测定了一种含席夫碱结构的表面活性剂及其Cu2+配合物的吸收光谱,其配位稳定常数β在25℃、0.01mol/L硼砂作缓冲溶液时为1.91×108;合成了配合物并用浓度稀释法研究了该配合物的抗菌性.实验结果说明该表面活性剂具有较强的络合铜离子能力,并形成稳定的配合物.该铜配合物对大肠杆菌、金黄色葡萄球菌和白色念珠菌都有一定的抗菌能力.     

Extraction relationship of Li+ and H+ using tributyl phosphate in the presence of Fe(III)

ABSTRACT

During the extraction of lithium from high Mg-containing salt lake brines by tributyl phosphate (TBP) in the presence of Fe(III), H⁺ is used to stabilize Fe(III). However, the distribution ratio of H⁺ (D_H) is 4–6 times higher than that of Li⁺ (D_Li), which affects the extraction of Li⁺ significantly. In this study, the competition mechanism between H⁺ and Li⁺ was investigated by spectral analysis and thermodynamic equilibrium. The extracted species are determined as HFeCl₄ · 2TBP and LiFeCl₄ · 2TBP for H⁺ and Li⁺, respectively. The apparent equilibrium constants are K_H = 799.8 and K_Li = 120.6, respectively. Both equilibrium constants and the distribution ratios for H⁺ and Li⁺ extraction show that extraction of H⁺ is stronger than Li⁺.     

Electrochemically deposited Ni + WC composite coatings obtained under constant and pulsating current regimes

A series of Ni + WC composite coatings were obtained by electrodeposition on a rotating disc electrode (RDE) from a commercially available Watts bath containing additives for brightness and smoothing and insoluble WC particles, using either constant or pulsating current. It was shown that the amount of WC embedded in the coating could vary from a few percent to over 80% depending on the rotation rate and the current density of deposition. Higher amounts (over 50 mass%) of embedded WC particles could be obtained only at rotation rates higher than 2000 rpm. It was also shown that the concentration of insoluble WC particles in the Watts bath has no significant influence on the amount of WC embedded in the coating, enabling the use of dilute mixtures (2 mass% of WC in the solution). At higher amounts of embedded WC particles, rough deposits were obtained with the WC particles being mostly incorporated in agglomerates of different sizes (from about 50 m to about 100 m). It was also shown that under the same conditions of electrodeposition, higher amounts of embedded WC particles could be obtained from solutions containing smaller particles.     

羧甲基纤维素钠螯合Cu(Ⅱ)的稳定常数测定及螯合效果分析

为了考察羧甲基纤维素钠(CMC)对重金属离子 的螯合能力,利用紫外分光光度法测定了不同c(Cu²⁺)/c(-COO^-)浓度比下CMC与 形成螯合物的吸收光谱,探讨了螯合物的组成,并计算其稳定常数。结果表明:CMC对 有螯合作用,当c(Cu²⁺)/c(-COO^-)小于0.6,螯合物在237 nm处出现最大吸收峰,-COO^-为主要配体,与 按物质的量比为2:1进行螯合,此时,螯合物稳定常数为1.88×10¹⁰;c(Cu²⁺)/c(-COO^-)为0.6～1.0时,214、237 nm处出现最大吸收峰,-COO^-、-OH都参与螯合反应并形成新的螯合物;c(Cu²⁺)/ c(-COO^-)大于1.0时,214 nm存在最大吸收峰,-OH为主要配体。考察了利用CMC螯合去除溶液中 的效果,实验表明,CMC-Cu螯合物可在溶液中直接析出,析出物为絮状沉淀。当c(Cu²⁺)/c(-COO^-)等于0.5时为最佳CMC用量,此时上清液中 去除率可以达到96%以上。     

Improved dielectric and non-ohmic properties of (Zn + Zr) codoped CaCu3Ti4O12 thin films

The good dielectric and non-ohmic properties of CaCu₃Ti₄O₁₂ and CaCu_2.95Zn_0.05Ti_4-xZr_xO₁₂ (x?=?0, 0.05 and 0.10) thin films prepared by a sol-gel method were determined. The enhanced dielectric properties, with a dielectric constant of ${\epsilon }^{\text{'}}$ ≈ 4357 and a dielectric loss of tan δ?≈?0.019, of the CaCu_2.95Zn_0.05Ti_3.95Zr_0.05O₁₂ (ZnZr05) thin film at 1?kHz and room temperature were investigated. The XPS spectrum showed that the ZnZr05 film can produce copper vacancies V_Cu” and mixed valence structures for Cu⁺/Cu²⁺ and Ti³⁺/Ti⁴⁺ inside the crystal. The ZnZr05 film maintained a high dielectric constant due to the large grain sizes and the presence of the mixed valence structures, while its low tan δ was attributed to an increase in the V_Cu” concentration. At the same time, the enhanced nonlinear coefficient (4.2) and low leakage current (193?μA) of the ZnZr05 film were explained in detail.