溶胶-凝胶法制备(Srx Ca1-x)3 Co4O9粉的工艺研究

采用溶胶-凝胶法,以乙二醇为溶剂,柠檬酸为螯合剂,由硝酸锶、硝酸钙、硝酸钴制备碱土金属锶掺杂的(SrxCa1-x)3Co4O9热电材料前驱粉.溶胶中加入添加剂,在70℃水浴环境下制备凝胶.干凝胶分别在500℃、750℃下煅烧1h、2h,制得了30nm左右的片状单晶(SrxCa1-x)3Co4O9粉.利用XRD、SEM等方法对样品进行分析、表征.     

溶胶-凝胶法制备Ca3Co4O9粉的工艺研究

采用溶胶-凝胶法制备了Ca3Co4O9粉,确定了适用于Ca3Co4O9粉制备的方法及工艺条件,并利用XRD、SEM 等方法分析表征样品.实验结果表明,以乙二醇为溶剂,柠檬酸为螯合剂,加入添加剂制得凝胶,干凝胶在750～900 ℃下烧结2 h,制得了20～30 nm的片状单晶Ca3Co4O9粉.     

溶胶-凝胶法制备Ca3Co4O9纳米粉的工艺研究

本文采用溶胶-凝胶法成功制备了Ca3Co4O9粉体。通过分析样品的显微结构与物相组成,优化了制备工艺。结果表明,溶胶-凝胶法制得的Ca3Co4O9为取向无规则的片状组织;750℃下预烧保温2h是本试验较合适的热处理条件。     

溶胶-凝胶微波加热合成Ca_(2.7)La_(0.3)Co_4O_9前驱粉

以硝酸钙、硝酸钴、硝酸镧和柠檬酸等为原料,用溶胶-凝胶法制备出凝胶,在100℃下烘干,然后用微波炉加热,合成了Ca2.7La0.3Co4O9前驱粉体。讨论了微波合成参数对粉体晶相和晶粒度的影响。用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对制备的粉体进行了测试。结果表明,溶胶-凝胶结合微波加热法可以在较短的时间内制得Ca2.7La0.3Co4O9粉体,且晶形发育比常规加热更完善。微波高火加热20min,可得到纯相的Ca2.7La0.3Co4O9前驱粉。     

BiFe_(1-x)Co_xO_3粉体的共沉淀-水热法制备与表征

以Bi(NO_3)_3·5H_2O、Fe(NO_3)_3·9H_2O、Co(NO_3)_2·6H_2O和KOH为原料,NH_3·H_2O为沉淀剂,采用共沉淀-水热法制备BiFe_(1-x)Co_xO_3粉体,借助XRD、SEM和VSM研究掺杂对晶体结构、形貌和磁学性能的影响。结果表明:在180℃和220℃保温4 h的条件下成功制备出Co掺杂BiFe_(1-x)Co_xO_3粉体,Co掺杂量x=0～0.1时,BiFe_(1-x)Co_xO_3粉体晶粒由100 nm类球形逐渐变成粒径为250 nm的立方体状,BiFe_(1-x)Co_xO_3粉体较未掺杂的BiFeO_3粉体磁性明显增大。     

Ca_2Co_2O_5氧化物热电陶瓷材料的制备研究

本文通过溶胶-凝胶法和固相合成法两种方法研究Ca_2Co_2O_5氧化物热电陶瓷材料的制备过程。湿法制备前驱体粉,以Ca(NO_3)_2·4H_2O和Co(NO3_)_2·6H_2O为原料,纯净水为溶剂,柠檬酸为络合剂。采用溶胶-凝胶法制备Ca_2Co_2O_5粉末,以Ca O和Co3O4为原料,采用固相合成法制备Ca_2Co_2O_5粉末,采用常压烧结的方法,在1000℃、950℃、900℃三种温度下进行烧结,并利用TG-DSC、XRD、SEM等手段对Ca_2Co_2O_5的热分解过程,物相组成和形貌进行表征。结果表明:干粉800℃热处理,湿法950℃烧结时,块体呈现致密的片层结构,相组成成分纯度高~([1~3])。     

不同粉体制备工艺对Ca3Co4O9陶瓷性能的影响

采用溶胶凝胶法和化学共沉淀法制备了Ca3Co4O9粉体,并烧结为纯相Ca3Co4O9陶瓷。利用XRD、SEM等方法对陶瓷样品的物相以及断面形貌进行了表征,利用四探针法测量了Ca3Co4O9陶瓷的电导率。试验结果表明化学共沉淀法与溶胶凝胶法粉体相比,制得的Ca3Co4O9陶瓷不仅具有更低的气孔率、线收缩率,而且具有更高的电导率,也是一种制备高性能热电材料粉体的有效方法。     

掺杂金属离子对Ca3Co4O9的热电性能的影响

采用溶胶-凝胶法,在常压空气中,经850℃烧结4h制备了Ca3Co4O9掺杂不同金属离子M(Na ,Ag ,La2 )的(Ca1-xMx)3Co4O9热电材料.通过X射线衍射、扫描电镜等对材料的微结构进行了表征,重点考察了掺杂不同金属离子对Ca3Co4O9中温热电性能参数Seebeck系数、电导率和功率因子的影响.结果表明:金属掺杂的(Ca1-xMx)3Co4O9热电材料具有致密的内部结构,并能够明显改善Ca3Co4O9的热电性能,尤其是掺杂Na 样品的热电性能有较为明显的提高,并且掺杂离子浓度对改善热电性能也有一定影响,组成为(Ca0.90Na0.10)3Co4O9时的功率因子提高最明显.     

Ca3Co4O9陶瓷的制备与表征

本实验采用溶胶-凝胶法制备了Ca3Co4O9陶瓷,寻求了其合适的制备工艺,并对陶瓷的显微结构、物相组成、元素组成等进行了表征测试.实验结果表明:煅烧温度为800～900 ℃时均能得到纯相Ca3Co4O9;Ca3Co4O9为取向无规则层片状组织,颗粒尺寸均匀,为2 μm左右;样品的致密度不高,气孔率相对较大.     

(1-x)BaTiO3-xLiNbO3陶瓷的制备及性能研究

采用复合溶胶凝胶法制粉技术结合传统陶瓷制备工艺，制备了（1-x）BaTiO3-xLiNbO3陶瓷，并对其晶相特征、介电及压电、铁电性能进行了研究。在1250℃下烧结的陶瓷形成了单一相的钙钛矿结构固溶体，该固溶体在20-40℃之间存在二级相变，介电常数及介电损耗出现异常变化。陶瓷的铁电、压电性能随LiNbO3的加入得到显著提高。LiNbO3加入量为0．005mol的陶瓷压电常数d33为121pC／N，剩余极化强度为2．8μC／cm^2。     

(Ba_(1-α)Sr_α)_(4.8)(Sm_(0.7)La_(0.3))_(8.8)Ti_(18)O_(54)陶瓷的微波介电性能

采用固相合成法制备了(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54(α=0.1～0.5)系陶瓷,表征了该陶瓷的相组成和显微结构,测试了微波介电性能.结果表明:α=0.3时,(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54系陶瓷为单相的新钨青铜结构固溶体.α>0.3时,相继出现了第二相BaLa2Ti4O12和La0.66TiO2.993.随α的增加,(Ba(1-α)Srα)4.8(Sm0.7La0.3)8.8Ti18O54系陶瓷的相对介电常数(εr)先增大后有所波动,品质因数(Qf)先增大后减小,谐振频率温度系数(τf)单调减小.α=0.3时,在1 350℃烧结的陶瓷的微波介电性能最佳:εr=98.77,Qf=5184GHz,τf=10.9×10-6/℃,优于不掺杂的BaO-Sm2O3-TiO2陶瓷的.     

Fe~(3 )、Zn~(2 )、Mn~(2 )、Cu~(2 )、Ca~(2 )、Mg~(2 )等离子共存体系中Ca~(2 )、Mg~(2 )的测定

叙述了Fe3 、Zn2 、Mn2 、Cu2 、Ca2 、Mg2 等离子共存体系中采用六次甲基四胺 -铜试剂沉淀除去Fe3 、Zn2 、Mn2 、Cu2 等干扰离子 ,用EDTA滴定钙镁的方法 ,该方法钙的回收率在 99.7%～ 10 0 .3 % ;镁的回收率在 10 0 .0 %～ 10 0 .4% ,标准偏差为 0 .0 2 2。     

Adhesion of calcium phosphate coatings on polyethylene (PE), polystyrene (PS), poly(tetrafluoroethylene) (PTFE), poly(dimethylsiloxane) (PDMS) and poly-L-lactic acid (PLLA)

Calcium phosphate (CaP) coatings can be applied to improve the biological performance of polymeric medical implants. For clinical applications, a strong adhesion of the coating to the polymeric substrate is important. Therefore, the adhesion of rf magnetron-sputter-deposited CaP coatings on five polymers was studied: polyethylene (PE), polystyrene (PS), poly(tetrafluoroethylene) (PTFE), poly-L-lactic acid (PLLA) and poly(dimethylsiloxane) (PDMS). To influence the adhesion, the interface was varied in six different ways, e. g. by a plasma or ion-beam pretreatment, or by using a Ti interlayer. The adhesion was determined by using scratch, tensile and 180^° bend tests. Especially the polymers PE and PS needed a bombardment by energetic particles prior to or during coating deposition, to enable the formation of chemical bonds between the coating and the polymer, which gave adhesion. On PLLA and PDMS, being oxygen containing polymers, it was easier to establish a strong interface. An overtreatment of the polymeric substrates gave worse adhesion, probably due to the formation of weak low molecular weight (LMW) layers on the polymer. On PTFE, the use of a Ti interlayer was necessary to prevent the PTFE from UV degradation during coating deposition, as this caused cohesive failure within the PTFE. The results showed that each polymer requires a different approach for obtaining optimal adhesion. The observed adhesion could often be explained in the terms of processes occurred during the pretreatment of the polymers or the deposition of the coating.     

(K_(0.485)Na_(0.485)Li_(0.03))NbO_3-Pb(Zr_(0.53)Ti_(0.47))O_3压电陶瓷的压电性能与微观结构

采用传统电子陶瓷制备技术和工业原料制备了新型(1-x)(K0.485Na0.485>Li0.03)NbO3-Pb(Zr0.53Ti0.47)O3少铅压电陶瓷,研究了该体系陶瓷的压电性能及微观结构.X射线衍射分析表明:在1250℃烧结3h的条件下,所有陶瓷样品都具有纯的钙钛矿结构和高致密性,并且在室温下形成了正交相和四方相共存的结构.x=0.75时,陶瓷的压电性能达到最佳:压电常数d33=363 pC/N,机电耦合系数kp=63%,相对介电常数εr=1 590,介质损耗tanδ=1.70%.     

Ternary Complexes of cis-(NH(3))(2)PtCl(2) (cis-DDP) With Guanosine (guo), Cytidine (cyd) and the Aminoacids Glycine (gly), L-Alanine (ala), L-2-Aminobutyric Acid (2-aba), L-Norvaline (nval) and L-Norleucine (nleu)

The ternary complexes of formulae cis-[(NH(3))(2)Pt(nucl)(amac)]NO(3), where nucl = guo and cyd (guanosine and cytidine) and amac = the deprotonated aminoacids glycine (gly), L-alanine (ala), L-2-aminobutyric acid (2-aba), L-norvaline (nval) and L-norleucine (nleu), were prepared from the reactions of the binary chelated ones cis-[(NH(3))(2)Pt(nucl)(amac)]NO(3) with the nucleosides.They were characterized by (1)H, (13)C and (195)Pt NMR and IR spectra, together with elemental analysis and conductivity measurements. The aminoacids coordinate with Pt(II) in the ternary complexes with their terminal -NH(2) groups, guo through N(7) and cyd through N(3). Ligand-ligand hydrophobic interactions were also observed in the ternary complexes and were stronger with longer aliphatic chains of the aminoacids. The (3)E sugar conformation increased by 5-7% in the ternary systems, as compared to the free nucleosides, while the percentage of the gg conformation remained almost constant and the one of the anti conformation of the sugar increased also slightly. Finally, the h conformer around the C(alpha)-C(beta) bonds of the aminoacids reached a maximum in the binary systems and decreased again considerably in the ternary ones.     

Ba(Zr_(0.055)Ti_(0.945))O_3含量对[(Na_(0.80)K_(0.16)Li_(0.04))_(0.5)Bi_(0.5)]TiO_3陶瓷性能的影响

系统研究(1-y)[(Na0.80K0.16Li0.04)0.5Bi0.5]TiO3-yBa(Zr0.055Ti0.945)O3无铅压电陶瓷,获得压电应变常数高达185pC/N的0.94[(Na0.80K0.16Li0.04)0.5Bi0.5]-TiO3-0.06Ba(Zr0.055Ti0.945)O3压电陶瓷。样品的晶体结构为三方相、四方相共存,处于准同型相界(morphotropic phase boundary,MPB)附近。该类陶瓷室温MPB的摩尔(下同)含量为0.050y0.065。样品y=0.060在40°左右的(003)、(021)双峰与46.5°左右的(002)、(200)双峰分裂最明显。随着Ba(Zr0.055Ti0.945)O3含量的增加,铁电相-反铁电相相变温度(θd)升高、反铁电相-顺电相相变温度(θm)降低;θd和θm的温差越来越小,材料的弛豫性逐渐降低。     

La掺杂(Na_(0.5)Bi_(0.5))_(0.82)(K_(0.5)Bi_(0.5))_(0.18)TiO_3系统无铅压电陶瓷的制备工艺探讨

采用传统陶瓷工艺,研究了制备[(Na0.5Bi0.5)0.82(K0.5Bi0.5)0.18]1-xLaxTiO3(x=0.00,0.01,0.03,0.05,0.10)无铅压电陶瓷的工艺条件对陶瓷的物相组成、显微结构和压电性能的影响。利用XRD、SEM等技术分析结果表明,合成温度的提高有利于主晶相的形成,且此系统烧成温度范围较窄,故需控制在合适的烧成温度下才能得到高致密度的陶瓷。同时,研究了极化工艺条件对材料压电性能的影响,结果表明,提高极化电场强度、控制适当的极化温度有利于提高材料的压电性能。     

Photopyroelectric Spectroscopic Studies of ZnO-MnO(2)-Co(3)O(4)-V(2)O(5) Ceramics

Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO(2) + 0.4Co(3)O(4) + xV(2)O(5)), x = 0-1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300-800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (E(g)) was 2.11 eV for 0.3 mol% V(2)O(5) at a sintering temperature of 1025 °C as determined from the plot (ρhυ)(2)versushυ. With a further increase in V(2)O(5), the value of E(g) was found to be 2.59 eV. Steepness factor 'σ(A)' and 'σ(B)', which characterize the slope of exponential optical absorption, is discussed with reference to the variation of E(g). XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively.