V掺杂对Bi_(3.25)La_(0.75)Ti_3O_(12)层状结构铁电陶瓷电性能的影响

用高温固相烧结法制备了V~(5+)掺杂的Bi_3.25La_0.75Ti_3O_(12)(BLT)层状结构铁电陶瓷.利用XRD对Bi_3.25La_0.75Ti_(3-x)VxO_(12+x/2)(BLTV-x)材料结构进行了晶相分析,结果表明所制备的陶瓷均具有单一的正交相结构.样品的介电常数温度谱显示:V~(5+)掺杂提高了材料的介电常数,x=0.03时介电常数最大,但样品的居里温度并没有发生大的变化.样品的介电损耗谱表明:由于V~(5+)掺入,由氧空位引起的样品介电损耗被极大的压制,在x=0.06时损耗最小.通过对材料的直流电导与温度关系的Arrhenius拟合,分析了样品的导电机理,结果显示V~(5+)的掺杂大大降低了材料中氧空位的浓度,使得陶瓷样品的电性能得到了很好的改善.     

添加玻璃料对BaSm_2Ti_4O_(12)微波介质陶瓷烧结行为和介电性能的影响

利用固相法制备BaSm_2Ti_4O_(12)(BST)微波介质陶瓷.研究了复合添加Li_2CO_3-B_2O_3-SiO_2-CaO-Al_2O_3(LBSCA)和BaO-B_2O_3-SiO_2(BBS) 玻璃料对BaSm_2Ti_4O_(12)微波介质陶瓷的烧结性能、介电性能、相组成和微观结构的影响.研究表明:复合掺杂10% LBSCA和2%～5% BBS可使烧结温度降至900 ℃.XRD分析表明复合掺杂两种玻璃料的BST陶瓷主晶相为BaSm_2Ti_4O_(12)相,玻璃料以玻璃相的形式存在陶瓷晶粒间.复合掺杂10% LBSCA+3%BBS玻璃料的BST陶瓷可在900 ℃、保温2 h条件下烧结致密,微波介电性能为:ε_r =55.63,Q_f = 4266 GHz,τ_f= -13.5×10~(-6)℃~(-1),这种陶瓷材料有望与纯Ag电极共烧,制作各种多层微波频率元器件.     

Ce掺杂0.9Bi_4Ti_3O_(12)-0.1K_(0.5)Na_(0.5)NbO_3铋层状压电陶瓷结构与性能研究（英文）

采用传统固相法制备了CeO_2掺杂0.9Bi_4Ti_3O_(12)-0.1K_(0.5)Na_(0.5)NbO_3(BTO-KNN)铋层状陶瓷材料。系统研究了CeO_2掺杂对BTO-KNN基陶瓷物相结构、微观结构以及电性能的影响。结果表明:所有陶瓷样品均为单一的铋层状结构:BTO-KNN基陶瓷的压电性能随着CeO_2的掺杂而显著提高,损耗明显降低。当CeO_2掺量为0.75%(质量分数)时,样品具有最佳的电性能:d_(33)=28 pC/N,介电损耗tanδ=0.29%,机械品质因数Q_m=2897,剩余极化强度P_r=11.83μC/cm~2,且居里温度T_c高达615℃;研究结果表明CeO_2掺杂0.9Bi_4Ti_3O_(12)-0.1K_(0.5)Na_(0.5)NbO_3铋层状陶瓷是一种潜在的高温陶瓷材料。     

氧化锑掺杂贫Ti钛酸锶钡陶瓷的介电性能及缺陷行为（英文）

采用固相法制备Sb_2O_3掺杂的贫Ti钛酸锶钡陶瓷,通过SEM、XRD和LCR测试系统研究其显微结构及介电性能随非化学计量比及Sb_2O_3含量的变化。结果表明:随着δ值增大,(Ba_(0.75)Sr_(0.25))Ti_(1-δ)O_(3-2δ)陶瓷由典型立方钙钛矿结构单相固溶体转变为多相化合物,而(Ba_(0.75)Sr_(0.25))Ti_(0.998)O_(2.996)陶瓷随Sb_2O_3掺杂量增加始终为单相固溶体。由V_(Ti)~(″″)及V_O~(··)引起的ABO_3型钙钛矿晶胞畸变导致(Ba_(0.75)Sr_(0.25))Ti_(1-δ)O_(3-2δ)陶瓷随δ值增大居里温度降低且相对介电常数增高。弹性偶极子V_O~(··)的定向引起畴壁钉扎而导致其介电损耗降低。(Ba_(0.75)Sr_(0.25))Ti_(0.998)O_(2.996)陶瓷的相对介电常数、介电常数最大值及居里温度均随着Sb_2O_3掺杂量增加显著降低而其介电损耗却随Sb_2O_3掺杂量的增加而增大。     

Tb4O7掺杂Cr2O3-TiO2基高发射率涂层结构及辐射性能研究

目的提高Cr_2O_3-TiO_2基陶瓷涂层的辐射性能。方法以Cr_2O_3、TiO_2、NiO、Tb_4O_7为原料,经喷雾干燥及高温烧结致密化处理,制备成具有尖晶石和钙钛矿混合结构的Cr_2O_3-TiO_2基复合团聚型粉体,利用大气等离子喷涂法在TC4钛合金表面制备Tb_4O_7掺杂型Cr_2O_3-TiO_2基陶瓷涂层。采用扫描电子显微镜、X射线衍射仪、IRE-2红外辐射测试仪,分别对样品的显微组织结构、物相组成及辐射性能进行了表征。结果团聚造粒后,复合粉体的球形度和流动性较好,可满足等离子喷涂连续使用。所制备的Cr_2O_3-TiO_2基陶瓷涂层的熔化状态较好,扁平化程度较高,涂层中掺杂的Tb元素分布均匀。Tb~(4+)、Tb~(3+)等稀土元素离子,取代NiCr_2O_4尖晶石结构中半径相近的Ni~(2+)、Cr~(3+),导致单一晶体结构的整齐度被破坏,晶胞体积的变化引起晶体结构产生畸变,辐射条带显著加强和宽化。随着Tb_4O_7掺杂量的增多,涂层发射率逐渐上升,当掺杂量达到7.5%时,涂层在600℃的法向全发射率达到0.91。结论 Tb_4O_7稀土氧化物的加入可以有效提高Cr_2O_3-TiO_2基陶瓷涂层的发射率,稀土掺杂诱发尖晶石晶体结构畸变,从而改善涂层的辐射性能。     

K改性的BNT-BZT压电陶瓷制备与性能研究

无铅压电陶瓷是压电材料中一个重要的研究方向，为了能够取代目前广泛应用的含铅材料，需要进一步提高无铅陶瓷材料的各项性能，尤其是压电性能。BNT-BZT系陶瓷是钛酸铋钠（BNT）和锆钛酸钡（BZT）两相形成的固溶体，在BNT-BZT陶瓷体系中，富BNT和低Zr含量的区域存在准同型相界，在相界附近可以得到性能优良的无铅压电陶瓷，其性能以3大约150pC/N，居里温度在240℃左右，介电常数大约900。在BNT-BZT相界点处掺杂K离子，研究了K改性的BNT-BZT体系陶瓷的微观结构与性能。实验结果表明，以3达到165pC／N；居里温度达到270℃；烧结中出现了玻璃相，预烧温度和烧结温度相对于原体系都有适当降低。     

铬掺杂PMS-PZT压电材料的研究

采用固相法制备铬掺杂PMSZT压电陶瓷,研究了在不同烧结温度下铬掺杂Pb1.04(Mn1/3Sb2/3)0 05ZrxTi0.95-xO3+z%(质量分数)Cr2O3陶瓷的介电和压电性能,分析讨论了Cr2O3掺杂量以及烧结温度与相组成,显微结构和电性能的关系.结果表明,Cr2O3掺杂0.6%(质量分数),烧结温度1260℃时,PMSZT压电陶瓷的居里温度最低且电性能优良,ε33T/ε0=1650,tan δ=0.006,d33=328pC/N,Kp=0.63,Qm=2300.     

烧结工艺对Sr_(0.3)Ba_(0.7)Bi_(3.7)La_(0.3)Ti_4O_(15)陶瓷显微结构及介电性能的影响

采用传统高温直接烧结和低温保温的两步烧结工艺制备铋层结构铁电陶瓷Sr0.3Ba0.7Bi3.7La0.3Ti4O15,获得结构致密、均匀、粒径介于1～3μm的陶瓷材料.结合XRD和SEM分析研究烧结工艺对陶瓷的晶相、显微结构和介电性能的影响.研究表明:采用两步烧结法使铋挥发和氧空位浓度降低,从而显著减弱了陶瓷的高温低频耗散.随着保温时间的增加,晶格畸变减少,居里温度降低了60℃左右.高温绝缘性也得到明显改善,高温电导率随保温时间的增加显著降低,保温15 h所得陶瓷样品的电导率降低了一个数量级,在280℃时为5.2×10-9S·m-1.     

CuO掺杂(Ba0.7Ca0.3)TiO3-Ba(Zr0.2Ti0.8)O3无铅压电陶瓷的研究

用传统固相反应法在不同温度下烧结制备了不同含量CuO掺杂的0.45(Ba0.7Ca0.3)TiO3-0.55Ba(Zr0.2Ti0.8)O3(BCZT45)无铅压电陶瓷,研究了CuO掺杂对BCZT45陶瓷微观形貌、相结构、介电和压电性能的影响。X射线衍射(XRD)结果表明所有陶瓷均形成了钙钛矿结构,Cu2+固溶进入BCZT45晶格,Cu2+部分取代Ti4+引起晶格畸变。加入CuO改善了BCZT45陶瓷的烧结性能,降低了烧结温度,使陶瓷在1350℃即可烧结,提高了陶瓷密度。随着CuO含量的增加,陶瓷的介温曲线向低温方向移动。掺杂少量CuO后,BCZT45陶瓷的压电常数增大,随着CuO掺杂量的增加又急剧降低。掺杂CuO含量为0.25mol%的BCZT45陶瓷具有最好的电学性能:压电常数d33=340pC/N,室温介电常数εr=3147,介电损耗tanδ=0.025。     

(1-x)K0.44Na0.52Li0.04Nb0.86Ta0.10Sb0.04O3-xSrTiO3无铅压电陶瓷性能研究

采用传统固相法对(1-x)K0.44Na0.52Li0.04Nb0.86Ta0.10Sb0.04O3-xSrTiO3压电陶瓷进行了钛酸锶掺杂改性研究.使用XRD并结合常规压电陶瓷性能测试手段对该体系的显微结构、压电、介电性能等进行表征.研究结果表明,随着SrTiO3加入量的增大,材料的居里温度和压电性能逐渐下降,材料的介电温度峰形逐渐变宽,出现弛豫现象;陶瓷烧结性能改善.致密度增加.     

氧化铝掺杂对Ba0.6Sr0.4(Zr0.2Ti0.8)O3陶瓷介电性能的影响

Zr4+取代Ti4+的Ba0.6Sr0.4(Zr0.2Ti0.8)O3固溶体在降低介电常数的同时,保持了BST固溶体优异的可调性。为降低BST材料的介电损耗和介电常数,以氧化铝为改性剂对Ba0.6Sr0.4(Zr0.2Ti0.8)O3材料(BSZT材料)进行了掺杂。随着氧化铝掺杂质量分数从1%到10%增加,BSZT材料的介电常数从5000降低到了1550(100kHz),介电损耗降低到0.001(100kHz)以下,而材料的介电可调性保持在35%左右(1.5kV/mm)。X射线衍射图谱表明,烧结后得到的BSZT材料具有典型的钙钛矿结构。扫描电子显微镜观察表明,氧化铝的掺杂使得陶瓷致密度较高,晶粒均匀。     

烧结温度对Sr_2Bi_4Ti_5O_(18)铁电陶瓷性能的影响

用固相合成方法制备了Sr_2Bi_4Ti_5O_(18)铁电陶瓷,研究了烧结温度对Sr_2Bi_4Ti_5O_(18)铁电陶瓷相结构、显微结构、铁电性能和介电性能的影响,分析了相关机理.结果表明,在1150C℃进行烧结,样品晶粒发育完全,晶粒α轴择优取向,铁电性能优良,剩余极化强度2P,达到15.3μC/cm2、矫顽场强2E_c为103kV/cm;在100kHz～1MHz频率范围内,介电常数为176～168,介电损耗为0.027～0.025,具有较好的频率稳定性.     

Dielectric Properties of Eu-Doped CaCu_3Ti_4O_(12) with Different Compensation Mechanisms

To get a better understanding of the influence of rare-earth element doping,CaCu_3Ti_4O_(12)(CCTO) samples with a partial substitution of Ca with Eu with different compensation mechanisms were designed and prepared by solid-state reaction.All the ceramics were single phase,while the dielectric constants and thermally activated energy values for dielectric relaxation in Eu-doped ceramics were both lower than those of CCTO.Ca_(0.875)Eu_(0.1)Cu_3Ti_4O_(12)(CECT1)exhibited a slight decrease in both the permittivity and electric resistance of grain boundaries compared with CCTO,while Ca_(0.85)Eu_(0.1)Cu_3Ti_4O_(12)(CECT2) underwent a sharp decrease in permittivity associated with an abnormally large resistance.The different dielectric behavior indicates that the dielectric properties of CCTO are sensitive to the valence states of cations and defects.The variation of permittivity is related to the localization of carriers,which,according to the XPS results,should be caused by the presence of oxygen vacancies.The formation of defect complexes between cations and oxygen vacancies leads to the increase in resistance and prevents the hopping between Cu~+ and Cu~(2+),which is an important source of the polarization in grain boundaries.     

Microstructure and microwave dielectric properties of ZnO-B2O3 added （Ca0.254Li0.19Sm0.14）TiO3 ceramics

The effects of ZnO-B2O3 (ZB2) on the sintering behavior and microwave dielectric properties of (Ca0.254Li0.19Sm0.14)TiO3 ceramics were investigated.The densities of the specimens reached the maximum value by adding 3 wt.% ZB2 and then decreased.The sintering temperature of the specimens was lowered from 1300 to 1100°C without degradation of the microwave dielectric properties.The (Ca0.254Li0.19Sm0.14)TiO3 + 3 wt.% ZB2 sintered at 1100°C for 3 h showed good microwave dielectric properties,εr = 108.2,Qf = 6545 GHz,and τf = 6.5 ppm/°C,respectively,indicating that ZB2 was an effective sintering aid to improve the densification and microwave dielectric properties of (Ca0.254Li0.19Sm0.14)TiO3 ceramics.     

Dependence of dielectric properties of manganese-doped strontium titanate ceramics on sintering atmosphere

It is shown in this paper that the microscopic mechanism of the dielectric relaxation in Mn-doped strontium titanate (SrTiO₃–ST) ceramics is associated with the off-center displacement of ions. This was accomplished by studying the dielectric properties and electron spin resonance spectroscopy in combination with X-ray powder diffractometry and scanning electron microscopy techniques in Sr_1−xMn_xTiO₃ ceramic samples sintered in different atmospheres (air, oxygen and nitrogen) at 1500 °C. First, it is shown that manganese is incorporated into the perovskite lattice of ST, preferably as Mn²⁺ at Sr sites. However, a small amount of Mn⁴⁺ at Ti sites is also observed when fired in air or oxygen flow. The concentration of is the highest for sintering in oxygen, but firing in a reducing atmosphere (nitrogen) results solely in the incorporation of Mn²⁺ at Sr sites. Correspondingly, the dielectric relaxation observed in Sr_1−xMn_xTiO₃ markedly increases in intensity and slightly shifts towards a higher temperature for ceramics sintered in nitrogen compared with those fired in air or oxygen. All these facts are consistent with a suggestion that the off-center displacement of Mn²⁺ ions at the Sr sites of the highly polarizable ST lattice is the source of the observed relaxation behavior.     

Effect of additive on corrosion resistance of NiFe2O4 ceramics as inert anodes

In order to improve the corrosion resistance of NiFe2O4 ceramics as inert anode, additive V2O5 was added to raw materials NiO and Fe2O3. The inert anodes of nickel-ferrite ceramics were prepared by powder metaUurgic method and the static corrosion rate in Na3AlF6-Al2O3 was determined by mass loss measurement. The effect of V2O5 on sintering property and corrosion resistance was studied. The results show that V2O5 can promote the grain to develop completely and improve sintering property. EDS results show the reaction product Ni2FeVO6 distributes along the grain boundary. The corrosion tests show that V2O5 is beneficial to improving corrosion resistance remarkably. The reasons that V2O5 can improve the corrosion resistance must be V2O5 promoting the gains to develop completely and Ni2FeVO6 distributes along the grain boundary. The stable structure can control the chemical dissolution of ceramics anode and the reinforced grain boundary can control the grain-boundary corrosion rate.     

Effect of MnO2 Addition on Sintering Properties of 18NiO-NiFe2O4 Composite Ceramics: Preliminary Results

NiFe₂O₄ samples with small amounts of MnO₂ were prepared via ball-milling process and two-step sintering process from commercial powders. Sintered density, average grain size, and microstructure of Mn-doped 18NiO-NiFe₂O₄ composite ceramics have been investigated by means of x-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. Bending strength was measured by three-point method. The results show that the crystalline structures of the ceramic matrix are still NiFe₂O₄ spinel structure and Mn ions homogeneously distribute in both the grains interiors and the grain boundaries. When 1 wt.% MnO₂ was added, the values of relative density and bending strength of composite ceramics reached their respective maximum of 93.6% and 38.75 MPa, respectively. It is preliminarily found that MnO₂ can reduce the sintering temperature obviously because of partial substitution of Fe³⁺ with Mn⁴⁺ in NiFe₂O₄ lattice.     

轴向压力对Na0.5Bi4.5Ti4O15铋层结构铁电陶瓷取向性的影响

采用烧结时在陶瓷坯体上施加一个较小的轴向压力方法实现了铋层结构Na0.5Bi4.5Ti4O15铁电陶瓷的织构化。实验表明,随压力增加,陶瓷的横向延伸率上升,材料密度略有降低。同时,XRD分析表明,轴向压力提高了平行压力方向和垂直压力方向上晶粒取向度的差异,表明施加压力有助于提高陶瓷的织构化程度。同时,电学性能测试表明,随着压力增加,压力方向上的陶瓷介电常数和损耗均随之下降。在NBT体系的烧结过程中,低熔点的Bi2O3等低熔点物质会首先熔融,形成局部液态;NBT晶粒具有片状结构,在外力和高温熔体的共同作用下,发生倾斜和滑移,产生定向排列的趋势;随后,这些局部定向的大晶粒作为模板,促进了NBT陶瓷的晶粒定向和织构化。     

烧结温度对WO_3系电容-压敏复合陶瓷电性能的影响(英文)

研究了烧结温度对WO_3系电容-压敏复合陶瓷显微结构、非线性电学性能及介电性能的影响.随着烧结温度从1050 ℃到1200 ℃的升高,WO_3陶瓷的晶粒尺寸增大,压敏电压随之降低.在1150 ℃烧结条件下,掺杂0.8 mol% Y_2O_3 的WO_3 压敏陶瓷样品表现出优良的综合电性能,其非线性系数为3.5,相对介电常数为1.13×10~4.然而,过高的烧结温度,不利于样品的非线性电学性能.WO_3系电容-压敏复合陶瓷较适合的烧结温度为1150 ℃,这是因为,在此温度下最有利于样品的晶界势垒结构的形成.