Ca0.85Bi0.10Cu3Ti4O12陶瓷的介电性能研究

利用固相反应法制备了Ca0.85Bi0.10Cu3Ti4O12 （BCCTO）高介电陶瓷材料.通过X射线衍射、介电频谱、阻抗谱和I-V特性曲线等测试,研究了不同烧结时间对BCCTO陶瓷结构和介电性能的影响.研究发现不同烧结温度的BCCTO陶瓷均为立方相钙钛矿结构,随烧结时间的延长其介电常数和非线性特性均有明显提高,样品表现出明显的Maxwell-Wagner （M-W）弛豫特征,表明样品中包含半导型的晶粒和绝缘层,这种IBLC结构对其介电和I-V特性都有重要贡献,延长烧结时间可以显著增强M-W弛豫特性.     

(Bi0.95Na0.75K0.2-xLix)0.5Ba0.05TiO3无铅压电陶瓷性质研究

采用溶胶-凝胶法制备了(Bi0.95Na0.75K0.2-xLix)0.5Ba0.05TiO3(NBT-KBT-BT xLi)微粉,并利用此微粉烧结出高密度无铅压电陶瓷.研究了陶瓷表面的显微结构,发现陶瓷主要组成为钙钛矿相结构,Li 的引入使陶瓷中产生呈针状的第二相.介电温谱表明该系列陶瓷是典型的弛豫型铁电体,居里温度在330℃附近.测量NBT-KBT-BT xLi陶瓷的压电常数,发现当x=0.05时,样品的压电常数d33高达197 pC/N,机电耦合系数kt为0.33,损耗tanδ为0.05,相对电容率rε为789.     

间苯二甲酰二茂铁二乙酰腙金属(Cu,Co,Ni)配位聚合物的高频介电性能

报道了用ＵＶ、ＩＲ及元素分析探讨了间苯二甲酰二茂铁二乙酰腙金属（Ｃｕ,Ｃｏ,Ｎｉ）配位聚合物的可能结构,以及在１０－１０００ＭＨｚ广泛频段下３种配位聚合物的介电常数－频率（ε′－ｆ）,介电损耗的正切－频率（ｔｕδ－ｆ）以及介电常数－温度（ε′－Ｔ）的关系。     

Bi掺杂的Ca3Co4O9的微结构和电输运性能

采用固相反应法制备了Bi掺杂的Ca3Co4O9热电材料。利用XRD和SEM等方法表征了样品的物相和微观组织,利用四线法测量了所有样品的电导率。研究结果表明：Bi掺杂的样品具有Ca3Co4O9单相,晶粒呈片状结构;随着Bi掺杂浓度的增加,样品的平均晶粒大小和致密度增加,电导率增大;电导率增加与样品的致密度,择优生长,晶粒大小密切相关。     

Bi4Ti3O12铁电薄膜溶胶—凝胶法制备过程中Bi—Ti溶胶的匀胶规律研究

介绍了Ｓｏｌｇｅｌ法制备Ｂｉ４Ｔｉ３Ｏ１２薄膜的工艺过程,研究了ＢｉＴｉ溶胶在Ｓｉ基片上的匀胶规律;用ＴＧＤＴＡ和ＴＥＭ技术研究了ＢｉＴｉ干凝胶的形态,并成功地在Ｐｔ／Ｔｉ／Ｓｉ基片上制备了ｃ轴取向的Ｂｉ４Ｔｉ３Ｏ１２薄膜．     

Structural and spectroscopic analysis of wurtzite (ZnO)1-x(Sb2O3)x composite semiconductor

The structural, vibrational and impedance analysis for(Zn O)1 x(Sb2O3)xcomposite synthesized by solid state reaction technique were carried out in the present investigation. X-ray diffraction(XRD) study showed that(Zn O)1 x(Sb2O3)xcomposite has hexagonal(wurtzite) crystal structure. Variation in lattice constants with Sb-doping indicated the proper incorporation of Sb dopant in Zn O host matrix. The results of Raman spectroscopy test suggested the signature of E2(high) and E1(TO) Raman modes, and verified the wurtzite structure of(Zn O)1 x(Sb2O3)x composite. Two additional phonon bands(671, 712) cm 1appeared in Raman spectra of composite samples due to the existence of the lattice defects caused by Sb doping or may be other intrinsic lattice defects formed during the synthesis of(Zn O)1 x(Sb2O3)xcomposite. The frequency dependent on the electrical characteristics, such as, impedance(Z), dielectric constant(ε) and AC conductivity(σ) have been studied in a range of frequencies for different Sb concentration at room temperature. The electrical measurement results showed that the impedance increased with Sb dopant concentration, while dielectric constant and AC conductivity decreased with Sb dopant concentration.     

Ferroelectric, dielectric, and optical properties of Nd-substituted Bi4Ti3O12 nanoparticles synthesized by sol-gel method

This paper reports the synthesis of neodymium substituted bismuth titanate nanoparticles(BNdT) for ferroelectric random access memory(Fe RAM) based applications using sol-gel route. X-ray diffraction pattern showed that the BNdT nanoparticles exhibited perovskite structure with orthorhombic phase. The microstructure of the BNdT nanoparticles showed that the grains were in spherical structure with a bi-modal distribution of spheres. Dielectric constant and dielectric loss of BNdT nanoparticles were measured in the frequency range 100 Hz to 100 kHz. Nd-substituted BNdT nanoparticles showed the high remanent polarization(P_r=33.2 μC/cm~2, Ec=62.5 kV/cm) than pure bismuth titanate(BT)(P_r=14.6 μC/cm~2, Ec=182.8 kV/cm) ideal for FeRAM based applications. The occurrence of red shift in photoluminescence(PL) spectrum is considered to be due to the isomerisation that may occur from the heating of samples.     

锰、钴掺杂PBSZT压电陶瓷性能的研究

为制备大功率低损耗压电陶瓷材料,对铅基压电陶瓷材料Pb0.9Ba0.05Sr0.05(Sn1/3Nb2/3)0.06(Zn1/3Nb2/3)0.06Ti0.44Zr0.44O3 0.5wt%Sb2O3(质量分数,下同)进行掺杂改性研究,结果表明钴最好的掺杂量为0.3wt%~1.0wt%,此时陶瓷可得到较好的综合性能。0.5wt%锰掺杂可得性能为介电损耗tanδ=0.47%、机械品质因素Qm=2065、机电耦合系数Kp=0.515、压电常数d33=322、介电常数εr=1470。在适量的钴和锰同时掺杂时可得到更低的介电损耗(0.45%)和较好的压电性能,表明同时掺杂可最优地降低介电损耗。     

Evaluation of Ca3(Co,M)2O6 (M=Co, Fe, Mn, Ni) as new cathode materials for solid-oxide fuel cells

Series compounds Ca_3(Co_(0.9)M_(0.1))_2O_6(M = Co,Fe,Mn,Ni) with hexagonal crystal structure were prepared by sol-gel route as the cathode materials for solid oxide fuel cells(SOFCs).Effects of the varied atomic compositions on the structure,electrical conductivity,thermal expansion and electrochemical performance were systematically evaluated.Experimental results showed that the lattice parameters of Ca_3(Co_(0.9)Fe_(0.1))_2O_6and Ca_3(Co_(0.9)Mn_(0.1))_2O_6 were both expanded to certain degree.Electron-doping and hole-doping effects were expected in Ca_3(Co_(0.9)Mn_(0.1))_2O_6and Ca_3(Co_(0.9)Ni_(0.1))_2O_6 respectively according to the chemical states of constituent elements and thermal-activated behavior of electrical conductivity.Thermal expansion coefficients(TEC) of Ca_3(Co_(0.9)M_(0.1))_2O_6 were measured to be distributed around 16×10~(-6)K~(-1) and compositional elements of Fe,Mn,and Ni were especially beneficial for alleviation of the thermal expansion problem of cathode materials.By using Ca_3(Co_(0.9)M_(0.1))_2O_6 as the cathodes operated at 800 ℃,the interfacial area-specific resistance varied in the order of M = Co M = Fe M = Ni M = Mn,and the over-potential increased in the order of M = Fe ≈ M = Co M = Mn M = Ni.Among all of these compounds,Ca_3(Co_(0.9)Fe_(0.1))_2O_6 showed the best electrochemical performance and the power density as high as ca.500 mW cm~(-2) at800 ℃ achieved in the single cell with La_(0.8)Sr_(0.2)Ga_(0.83)Mg_(0.17)O_(2.815) as electrolyte and Ni-Ce_(0.8)Sm_(0.2)O_(1.9) as anode.Ca_3(Co_(0.9)M_(0.1))_2O_6(M = Co,Fe,Mn,Ni) can be used as the cost-effective cathode materials for SOFCs.     

Co掺杂量对(CeO2)0.92(Y2O3)0.06(Sm2O3)0.02电解质材料性能的影响

采用固相反应法合成CeO2基电解质材料(1-x)(CeO2)0.92(Y2O3)0.06(Sm2O3)0.02+xCoO1.5(x=0、0.5％、1％和2％),并在不同温度下烧成.结果表明,添加Co的试样经1 500℃烧成之后合成了单一的立方萤石结构相,Co可以有效促进试样的烧结,降低烧结温度约100℃;其中Co的添加量为0.5％时,试样表现出最高的离子电导率和最低的活化能.同时发现Co的添加对试样的热膨胀系数影响不大.     

PbO对Pb(Zr0.52Ti0.48)O3压电陶瓷性能的影响

采用固相反应的方法制备了Pb(Zr0.52Ti0.48)O3(PZT)压电陶瓷,研究了过量PbO对Pb(Zr0.52Ti0.48)O3压电陶瓷性能的影响。通过XRD和SEM研究了PbO过量对Pb(Zr0.52Ti0.48)O3压电陶瓷的晶相结构及显微形貌的影响,研究结果表明PbO过量不会影响Pb(Zr0.52Ti0.48)O3材料的相结构(均为钙钛矿结构),但是PbO过量太多,会出现过烧现象及气孔等,PbO过量为5%mol时结晶最好。测量了样品的密度、电阻率、压电系数以及介电性能,对这些测量结果的研究表明采用850℃预烧、1 250℃终烧的烧结工艺,PbO过量为5%mol的Pb(Zr0.52Ti0.48)O3压电陶瓷致密性好,密度最大,且具有良好的介电与压电性能,其压电系数最大为322 pC/N。     

Nd(Fe1-xCox)9Si2Cy化合物的穆斯堡尔谱研究

利用真空熔炼法制备了 Ba Cd11结构的 Nd(Fe1-x Cox) 9Si2 Cy 化合物 ,X射线衍射的结果表明 C原子加入后 ,单胞体积膨胀 .室温下测量了样品的穆斯堡尔谱 ,发现随着 Co含量的增加 ,化合物中 Fe的平均超精细场先增大后减小 .而 C原子的加入 ,则使 Fe的平均超精细增加 ,同质异能移减小     

0.94(Bi0.5Na0.5)TiO3-0.06Ba(Zr0.25Ti0.75)O3陶瓷的制备、表征与热释电性能

以BaCO3、Na2CO3、TiO2、ZrO2和Bi2O3为原料,通过固相反应法合成了铁电粉末材料0.96(Bi0.5Na0.5)TiO3-0.04Ba(Zr,Ti)O3(BNT-BZT),采用常压烧结法制备了BNT-BZT陶瓷片.考察压力和烧结温度对陶瓷致密性的影响,并对BNT-BZT粉末和陶瓷片的结构、形貌和成分进...     

溶胶法制备粒状合金固体Fe_(0.10)Co_(0.05)-(SiO2)_(0.85)的研究

首次用溶胶法制备出了Fe0．10Co0．05－（SiO2）0．85粒状合金固体。这种粒状合金固体是一种纳米复合材料，由嵌在SiO2母体中的Fe－Co合金颗粒构成。本文报告这种材料的基本制备方法以及还原温度对其磁学性质的影响。     

Elastic anomalies near phase transitions of lead-free （Na,Bi）TiO3 and （Ba,Zr）TiO3 ferroelectric ceramics

We have investigated the temperature dependence of elastic modulus for various ferroelectric ceramics in the temperature range of 20–90°C.The Na0.5Bi0.5TiO3(NBT)ceramics has a phase transition at 200°C,thus exhibits minimal change in elastic modulus up to 90°C,while the elastic modulus of the BaZr0.07Ti0.93O3(BZT-7)shows 12.5%change at the phase transition temperature of70°C and that of the BaZr0.15Ti0.85O3(BZT-15)ceramics shows 34.6%change at the phase transition temperature of60°C.The variations of elastic modulus will affect the temperature stability of devices made by these lead-free ferroelectric ceramics.     

热电氧化物(Ca_3Co_2O_6)_(1-x)(Ca_3Co_4O_9)_x的制备和表征

热电氧化物Ca3Co2O6和Ca3Co4O9是Ca-Co-O体系中两个确定的态,其热电性质显著不同.我们采用“快速加热法”制备了(Ca3Co2O6)1-x(Ca3Co4O9)x(x=0,0.2,0.4,0.6,0.8,1),并利用XRD、SEM等实验方法分析表征样品,系统研究了热电氧化物从Ca3Co2O6到Ca3Co4O9的转化过程.从SEM图中可知Ca3Co2O6为无规取向棒状结构,Ca3Co4O9为法向取向与表面近似垂直的片状结构,XRD结果显示x=0.4之前的样品Ca3Co2O6和Ca3Co4O9两相衍射峰并存,x=0.6以后的样品是Ca3Co4O9单相.     

半金属 Bi（111）表面上的单分子磁体 Fe4

单分子磁体具有独特的磁学性质,如磁化强度的量子隧穿和量子相干振荡.该实验利用了STM针尖沉积方法,把单分子磁体Fe4沉积到比较惰性的半金属Bi(111)表面,并利用低温扫描隧道显微镜(LT-STM)观察了分子的形貌,发现分子的结构完整;还利用扫描隧道谱(STS)技术测量了分子的态密度分布和HOMO-LUMO能隙,为单分子磁体Fe4的应用提供了一定的参考意义.     

Influence of Cr2O3 additive and sintering temperature on the structural characteristics and piezoelectric properties of Bi4Ti2.95W0.05O12.05 Aurivillius ceramics

In this paper, Cr_2O_3(0–0.4 wt%) as an additive was added into Bi_4Ti_(2.95)W_(0.05)O_(12.05)(BITW) for preparing a kind of W/Cr co-doped BIT(BITW-yCr) Aurivillius ceramics, both W~(6+) and Cr~(3+) are considered to substitute Ti~(4+) in the [TiO_6] octahedron of BIT. Besides the orthorhombic Bi_4Ti_3O_(12) as the major phase, BITW-yCr ceramics also contain the cubic Bi_2Ti_2O_7 as the second phase which was formed due to the doping effect of WO_3, but its formation could be depressed by the addition of less Cr_2O_3. Additionally, the cell parameters of BITW ceramics are also changed by the incorporation of Cr_2O_3, as the distortion degree of the orthorhombic structure(a/b)increases firstly and then decreases with its addtional amount(y). On the other hand, the grain growth of BITWyCr ceramics is mainly controlled by the sintering process, there a higher sintering temperature results in a larger grain size. In comparison to BIT ceramics, BITW-yCr ceramics with less Cr-addition(y=0–0.2) require a higher sintering temperature to attain the best dense state, moreover, as y increases, the sintering temperature to gain the highest piezoelectric activity also increases. Finally, BITW-0.2Cr which was sintered at 1150 °C exhibits a higher piezoelectric activity than the others, which could be attributed to its larger orthorhombic distortion and larger grain size, its ideal piezoelectric constant(d_(33)=28pC/N) provides it with great applying potentiality.     

(La,Sr)(Co,Fe)O_3与(La,Sr)MnO_3阴极材料的表征与性能

采用氨水沉淀法分别制备La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF)与La0.8Sr0.2MnO3-δ(LSM)两种阴极材料,并用X射线衍射(XRD)、场发射扫描电子显微镜(FESEM)和比表面积(BET)对所制备材料的结构、晶粒大小、形貌及比表面积进行表征.结果表明,LSCF和LSM前驱体分别在900℃和1200℃煅烧5h后产物均形成单一正交的钙钛矿结构,但LSCF具有较小的粒径和较大的比表面积.电化学性能测试结果表明,LSCF阴极比LSM阴极的过电位低,且LSCF为阴极单电池的输出功率较高.     

LaMO3（M=Fe,Co,Ni）氧吸附性能与CO氧化催化活性

以ＸＰＳ表征了ＬａＭＯ３（Ｍ＝Ｆｅ，Ｃｏ，Ｎｉ）晶体表面氧的性质，区分了ＸＰＳ谱中二种Ｏ１ｓ峰．由Ｏ吸峰的相对强度获得了ＬａＭＯ３表面吸附Ｏ２性能的变化规律，并得到了Ｏ２吸附量（脉冲法）实验结果的映证．ＣＯ氧化反应活性测定发现：３００℃下，ＬａＭＯ３活性顺序为ＬａＣｏＯ３＞ＬａＮｉＯ３＞ＬａＦｅＯ３，与其Ｏ２吸附量大小顺序相一致．