过量Na~+对(K_(0.5)Na_(0.5))NbO_3-LiNbO_3无铅压电陶瓷相组成及结构的影响

通过固相反应法预合成0.94(K0.5Na0.5)NbO3-0.06LiNbO3(KNLN6)无铅压电陶瓷粉体。采用X线衍射仪(XRD)、扫描电子显微镜/能谱仪(SEM/EDS)和高分辨透射电子显微镜(HRTEM)对KNLN6试样进行性能表征。结果表明:按化学计量配比合成的KNLN6粉体中含有K3Li2Nb5O15(KLN)第二相;Na2CO3摩尔分数过量5%时,可有效地消除第二相KLN,从而获得单一钙钛矿结构的KNLN6粉体,同时,粉体的预烧温度降低了50℃;在1070℃下烧结2 h制备的Na2CO3过量5%的无铅压电陶瓷中,KNLN6晶体具有A位无序的单一正交钙钛矿结构,晶粒呈立方体状,平均尺寸约为10μm。     

铌酸钾钙无铅压电陶瓷粉体的水热法制备

以KOH,Ca（OH）2和Nb2O5为原料,通过水热法合成了钙钛矿结构的（Ca,K）NbO3粉体。借助X射线衍射仪（XRD）对产物晶体结构进行表征,通过能量色散X射线荧光法（EDX）分析产物的化学组成,用扫描电子显微镜（SEM）观察产物粉体的表观形貌和粒径。研究了反应时间对产物形貌和晶体结构的影响。结果表明,在200℃,48h,浓度为6mol/L的碱性溶液条件下,可以合成出长2.0μm,宽0.2μm的长条状形貌的钙钛矿结构（Ca,K）NbO3粉体,此粉体有望用作钨青铜结构Ca2KNb5O15织构陶瓷的模板晶粒。     

微波水热温度对KNLNS粉体及陶瓷晶体结构与性能的影响

采用微波水热法制备了(K0.5005Na0.4275Li0.05)(Nb0.95Sb0.05)O3(KNLNS)无铅压电粉体,研究了不同微波水热温度条件下合成KNLNS粉体并以此粉体制备的陶瓷的晶体结构、显微形貌和介电性能.研究结果表明:当粉体合成温度为180℃时,粉体及陶瓷均不具有纯钙钛矿晶体结构,介电性能不佳;合成温度高于190℃,粉体及陶瓷均具有正交纯钙钛矿结构,粉体形貌呈立方状.合成温度高于200℃,对粉体及陶瓷的晶体结构和介电性能影响较小.     

水热法制备高结晶度分散性铌酸钾钠粉体

采用水热法制得纯钙钛矿相的(K_(0.5)Na_(0.5)NbO_3(KNN)超细粉体,并探索超声分散和水热反应时间对该无铅压电陶瓷KNN粉体颗粒大小以及颗粒相结构的影响。通过X射线衍射(XRD)和扫描电镜(SEM)对所得铌酸钾钠粉体的结构、颗粒大小进行了测试与表征。结果表明,经过750℃保温1h得到的粉体粒径细小,呈现纯钙钛矿结构;适当延长水热反应时间有利于结晶度的提高;超声处理有利于得到高分散性的粉体。     

微波水热法制备(1-x) K0.55Na0.45NbO3-xLiSbO3系无铅压电陶瓷

以分析纯NaOH,KOH,Li2CO3,Nb2O5,Sb2O3等为原料,采用微波水热法合成(1-x)K0.55Na0.45NbO3-xLiSbO3(KNNLS,x =0.03～0.07mol)粉体,分析了粉体的晶体结构与形貌.以该粉体制备压电陶瓷,系统研究了LiSbO3含量对压电陶瓷结构与性能的影响.研究结果表明:微波水热法在220℃下保温30min可以合成具有纯正交钙钛矿结构的KNNLS(x=0.03～0.07)粉体,粉体呈立方状,尺寸约0.5～1μm.利用该粉体制备的压电陶瓷结构致密,晶粒大小分布均匀.当x=0.05时,该组成陶瓷具有最佳的综合压电性能:压电常数d33=110 pC/N,平面机电耦合系数kp=0.29,介电常数εT33/ε0=466,介质损耗tanδ =1.4％以及机械品质因素Qm=107.     

水热法制备Na_(0.5)Bi_(0.5)TiO_3陶瓷及其性能

以五水硝酸铋(Bi(NO_3)_3·5H_2O)和二氧化钛(TiO_2)为原料,氢氧化钠(NaOH)为矿化剂,采用水热法合成了具有钙钛矿结构的钛酸铋钠Na_(0.5)Bi_(0.5)TiO_3(BNT)无铅压电陶瓷粉体和陶瓷。利用X射线衍射仪(XRD)对产物晶体结构进行表征,用扫描电镜(SEM)观察产物粉体的表观形貌和粒径,并测试了陶瓷的电性能。结果表明,在200℃反应4h,NaOH浓度为6 mol/L,可以水热合成出单一晶相,粒径约为200nm的BNT粉体,用此粉体在1130℃烧结的陶瓷的介电常数ε_r=385.26,压电系数d_(33)=98cP/N。     

(1-x)KNN-xNKBT无铅压电陶瓷的结构及其电性能研究

采用传统固相法制备了(1-x)K0.5Na0.5NbO3-x(Na0.8K0.2)0.5Bi0.5TiO3(x=0-5%)无铅压电陶瓷,研究了(Na0.8K0.2)0.5Bi0.5TiO3的不同引入量对其物相结构、显微形貌、介电性能以及压电性能的影响。结果表明:所有样品都具有钙钛矿结构;随着x的增加,室温下样品从正交相逐渐向四方相过渡并且居里温度向低温方向移动,样品的压电常数d33与机电耦合系数kp均先升高后降低。该体系多晶型转变PPT位于2%≤x≤3%,当x=3%时,样品的压电性能达到最佳,其中:d33=189pC/N,kp=41%,Qm=96,tanδ=0.028。     

BNKT-NKS压电陶瓷的制备及电学性能研究

以碳酸盐和氧化物为原料,无水乙醇为研磨介质,采用固相法合成压电陶瓷体系0.995Bi0.5(Na0.8K0.2)0.5Ti O3-0.005(Na1-xKx)Sb O3(BNKT-NKS),并对其微结构、表面形貌、电学性能进行了分析测试。结果表明,压电陶瓷样品都能形成单一钙钛矿固溶体结构,具有较好的电学性质:x=30%时,d33=149 p C/N,kp=0.315,Qm=139,tanδ=0.037;x=10%时,tanδ=0.037。     

BNKT-NKS压电陶瓷的制备及电学性能研究

以碳酸盐和氧化物为原料,无水乙醇为研磨介质,采用固相法合成压电陶瓷体系0.995Bi0.5(Na0.8K0.2)0.5Ti O3-0.005(Na1-xKx)Sb O3(BNKT-NKS),并对其微结构、表面形貌、电学性能进行了分析测试。结果表明,压电陶瓷样品都能形成单一钙钛矿固溶体结构,具有较好的电学性质:x=30%时,d33=149 p C/N,kp=0.315,Qm=139,tanδ=0.037;x=10%时,tanδ=0.037。     

新品研发辑要

水热法合成Na0.5Bi0.5TiO3纳米陶瓷粉体简介:无铅压电陶瓷的研究开发是功能陶瓷研究的重要内容之一。其中,钛酸铋钾(缩写为KBT)是无铅压电体系的重要候选材料之一,为钙钛矿结构铁电体,室温时为四方晶系,居里点380℃。目前,该体系的合成多采用传统固相法,得到的KBT粉体较粗(微米     

结晶法由硫辛酸厂含铝废水制备铵明矾

以硫辛酸厂含铝废水中的Al3+为原料,采用结晶法制备铵明矾,研究了时间、NH4+/Al3+摩尔比、SO42-/Al3+摩尔比、温度、搅拌速度对废水中铝去除率和铵明矾产量的影响,对所制铵明矾与商品铵明矾进行比较. 结果表明,两者具有几乎相同的晶体结构、形貌和化学组成,所得产品符合同类工业产品标准. 结晶法用硫辛酸厂含铝废水制备铵明矾的适宜条件为：反应时间8 h,NH4+/Al3+ 1.40,SO42-/Al3+ 2.90,温度5~15℃,搅拌速度35~55 r/min. 宏观反应动力学表明,在晶体生长期,Al3+在边界层扩散传质为反应控制步骤,液相主体Al3+浓度C随时间t的变化关系符合方程C=(C0-Ci)e-kt+Ci. 当搅拌速度较低时,铵明矾晶体平均粒径大,分布宽;搅拌速度增加,晶体平均粒径减小,粒径分布变窄.     

碱金属催化添加剂对PX液相氧化过程的影响

验证了K+,Na+类添加剂在对二甲苯(PX)液相氧化体系中的助催化活性。对添加不同浓度碱金属离子的助催化作用进行了多组动力学实验,考察了添加K+,Na+对体系主反应和燃烧副反应和TA固体产品中4-CBA含量的影响,获得了对PX氧化过程的影响规律。实验发现,碱金属离子的添加有不同程度的活化效果;添加w(K+)=(30~100)×10-6可有效地加速主反应,但过大时(>500×10-6)作用就变得不明显,甚至会产生抑制;与K+相比,Na+对主反应的助催化活性要低得多。     

超高压环境下离子液体微乳液预处理对水稻秸秆的影响

以水稻秸秆为原料,对比了中低温条件下单独超高压（UHP）、单独离子液体微乳液（ILM）和超高压环境下离子液体微乳液（ILM+UHP）3种预处理方法,系统分析了预处理前后样品的化学组成、晶体结构、表面形貌以及酶水解的变化规律。结果表明,采用1-乙基-3甲基咪唑醋酸盐/环己烷/TX-100/正丁醇微乳液处理水稻秸秆,在压强为500 MPa、温度为50℃下处理4 h后,样品中木质素去除率为61.5%,纤维素结晶度指数下降17.3%,微观表面粗糙多孔,酶水解48 h的还原糖产率达75.3%。     

锰氧化物锂离子筛的掺杂改性及吸附性能研究

以二氧化锰和氢氧化锂为原料,采用高温固相法合成了锂锰氧化物前驱体,再经离子交换技术制备了锰氧化物锂离子筛并用于溶液中Li ⁺的吸附。考察了Al ³⁺和La ³⁺掺杂对锂离子筛结构、形貌和吸锂性能的影响。用粉末X射线衍射（XRD）、扫描电子显微镜（SEM）、傅里叶红外光谱（FTIR）对制备产物进行了表征。结果表明,产物为尖晶石型锰氧化物锂离子筛,呈片状形貌,分散性较均匀。Al ³⁺和La ³⁺掺杂后产物仍然保持尖晶石结构,形貌有所变化,分别呈现出不规则的立方体和纳米颗粒。吸附结果表明,掺杂后锰氧化物锂离子筛的吸附容量有所提高。     

Plasma-modified multiwalled carbon nanotubes with polyaniline for glucose biosensor applications

Multiwalled carbon nanotube (MWCNT) was modified through plasma polymerization of aniline by applying different radio frequency (radio frequency (RF): 13.56?MHz) powers. The modified MWCNTs were investigated in terms of morphology, chemical structure, and thermal behaviors, indicating the formation of composites based on the surface modification of MWCNT with polyaniline (PANI). These composites were then used in amperometric glucose biosensor, which was constructed by immobilizing glucose oxidase on premodified Pt electrode with PANI/MWCNT composites. The biosensor based on the composite obtained under RF power of 60?W exhibited the high sensitivity of 54.91?µA mM^?1 cm^?2 to glucose.     

Synthesis and characterization of fluorine-containing poly-styrene-acrylate latex with core–shell structure using a reactive surfactant

Fluorine-containing poly-styrene-acrylate (PSA) latex with core–shell structure was successfully synthesized by seeded semicontinuous emulsion polymerization using fluorine monomer Actyflon-G₀₄ and reactive emulsifier DNS-86. The chemical composition, morphology of latex, and surface composition of the latex film were characterized by Fourier transform infrared spectra, transmission electron microscopy, and X-ray photoelectron spectroscopy, respectively. The stability properties of latex were tested by Ca²⁺, centrifugal and mechanical stability tests, and the latex film was studied by water contact angle, water absorption ratio, and thermo-gravimetric analysis. The results show that fluorine-containing PSA latex particles with crosslinked core and crosslinked shell structure have excellent stability properties, and the film of latex has excellent water repellency, thermal stability, and chemical resistance properties when the amount of fluorine monomer was only 8.0 wt%.     

新型CuO-ZnO-Al2O3复合金属氧化物的制备及其结构研究

采用自行研制的成核晶化隔离法制备了不同Cu²⁺、Zn²⁺和Al³⁺物质的量比的层状双金属氢氧化物(LDHs)。通过X射线衍射(XRD)、红外光谱(FT-IR)、热重-差热分析(TG-DTA)、程序升温还原(TPR)及X光电子能谱(XPS)等研究手段对LDHs及其在500 ℃焙烧产物的组成、结构和表面化学状态进行了分析。结果表明,在焙烧产物中均存在一定形式相互作用的CuO-ZnO-Al₂O₃复合金属氧化物,Cu²⁺、Zn²⁺和Al³⁺之间的配比影响LDHs结构和热稳定性及其焙烧产物的组成和还原性能。     

生物质碳气凝胶/MnO2复合电极对 Rb+、Cs+的电吸附行为

以柚子皮为主要原料,采用低温水热碳化-真空冷冻干燥-高温碳化相结合的方法,制备了生物质碳气凝胶（PCA）,并将其用于制备PCA单一和PCA@MnO2（MPCA）复合电吸附电极,利用SEM、XRD、FT-IR、BET及电化学工作站对电极材料的形貌、结构和电化学性质进行了表征,并考察了两种电极对Rb+、Cs+的电吸附行为。结果表明,自制PCA为三维多孔结构,利于吸附质扩散;电极比电容大,循环性能好。电极的组成对电吸附行为具有较大的影响,二氧化锰的加入改变了电极对离子的吸附选择性,MPCA［m（二氧化锰）∶m（PCA）=4∶1］复合电极对铷的吸附量明显优于铯,平衡吸附量分别可以达到85 μmol/g和64 μmol/g,优于PCA电极,且具有良好的循环再生性能。     

Electrodeposition and characterization of Cu-Ni-Zn and Cu-Ni-Cd alloys

The electrodeposition of ternary Cu-Ni-Zn and Cu-Ni-Cd alloys was investigated in acidic sulphate electrolytes. The influence of Zn²⁺ and Cd²⁺ ions concentrations as well as the effect of current density on the surface appearance and the deposits’ composition was examined. Sodium dithiolate (NaS)₂CC(CN)₂·3H₂O was used as surface active substance (SAS), and the effect of the SAS on the alloys composition and surface morphology was also investigated. No significant effect of SAS on the alloy composition, however, apparently effect on the deposits surface morphology was observed. It was also noticed that on increasing Zn²⁺ (or Cd²⁺) concentration in the bath, a depletion in the nickel content in the deposit occurred. Deposits obtained were characterized from the structural and morphological points of view. It was found that the structure and morphology of the deposited alloys are mainly controlled by both the applied current densities and the bath composition.     

Chemical vapor deposition derived ultralong SiC nanofibers: structural characterization and growth mechanism

In this study, the ultralong SiC nanofibers (SiC NFs) were synthesized through the sol–gel method assisted the chemical vapor deposition technique. The scanning electron microscope, transmission electron microscopy, X-ray diffraction, Raman, Fourier transform infrared, and X-ray photoelectron spectroscopy techniques were systematically employed to investigate the microstructure, morphology, and phase composition of the as-prepared products. The results demonstrated that the as-obtained products were β-SiC nanofibers with face-centered cubic crystal structure. Meanwhile, the ultralong SiC NFs present an average diameter of about 18 nm and a length up to several hundreds of micrometers and grew along the [1 1 1] direction with a planar stacking faults. In addition, we also investigated the formation mechanism and growth process of the ultralong SiC NFs. The successful preparation of such ultralong SiC NFs provides new idea for fabricating of other silicon-based ultralong nanofibers.