低温烧结NaBi(WO4)2陶瓷的介电性能

采用固相合成法制备了（WO₄）₂（NBW）陶瓷，研究了NBW陶瓷的相结构、形貌、烧结特性和微波介电性能。NBW陶瓷在625~800℃烧结1~4 h能够致密化。X射线衍射表明在625~800℃烧结2 h的NBW陶瓷均为四方晶系白钨矿结构的单相陶瓷。随着烧结温度的提高，NBW陶瓷的介电常数、品质因数（Qf值）先增加后降低，谐振频率温度系数逐渐降低。经650℃烧结2 h获得的NBW陶瓷的介电常数为14.36，Qf值为16 503 GHz，谐振频率温度系数为-1.055×10-5℃^-1。NBW陶瓷与银共烧反应生成Ag₂W₂O₇相，而与Au、Al共烧具备化学兼容性。     

溶胶-凝胶法制备(Ba0.85Ca0.15)(Ti0.9Zr0.1)O3无铅压电陶瓷研究

锆钛酸钡钙基无铅压电陶瓷由于具有较好的压铁电性能且环境友好而备受研究者关注,但其存在烧结温度高(>1450℃)、居里温度低等缺点。为降低锆钛酸钡钙基压电陶瓷的预烧及烧结温度,并优化其电学性能,本研究采用溶胶-凝胶法成功合成了(Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃无铅压电陶瓷的前驱粉体,并在预烧温度为1000℃、烧结温度为1420℃时成功制备了(Ba_0.85Ca_0.15)(Ti_0.9Zr_0.1)O₃陶瓷,相较于传统固相法,陶瓷的预烧温度降低了250℃,烧结温度降低了30℃,成功改善了陶瓷的烧结行为,得到了铁电性能、介电性能和压电性能优良且致密性良好的低温烧结陶瓷。     

Cu2+离子A位取代对MgTiO3陶瓷结构及介电性能的影响

采用固相反应制备了Mg_1-xCu_x TiO₃(0.00≤x≤0.20)微波介电陶瓷,研究CuO烧结助剂对MgTiO₃陶瓷的微观结构和微波介电性能的影响。实验结果表明,CuO中的Cu²⁺离子会进入到MgTiO₃晶格中并取代Mg²⁺,形成Mg_1-xCu_x TiO₃固溶体。由于液相效应,适量的CuO可以促进MgTiO₃陶瓷的致密化烧结,降低其烧结温度。Cu²⁺离子的A位取代会改变样品的TiO₆八面体扭曲度。随着Cu²⁺离子含量的增加,会使MgTiO₃陶瓷的结构稳定性降低。随着CuO含量的增加,晶粒的不均匀生长和液相的出现导致样品的品质因数(Qf)下降。同时,Mg_1-xCu_x TiO₃陶瓷的相对密度、结构...     

A位取代对(Ca0.61Nd0.26)TiO3陶瓷烧结特性和介电性能的影响

采用常规固相反应法,以(Ca0.61Nd0.26)TiO3体系为基体成分,研究了A位取代对(Ca0.61Nd0.26)TiO3陶瓷的烧结特性和介电性能的影响规律。结果表明:Zn,Mg的A位取代,促使(Ca0.61Nd0.26)TiO3陶瓷烧结温度从1350℃降至1250℃。Zn,Mg在一定范围内A位取代(Ca0.61Nd0.26)TiO3中的Ca可形成钙钛矿结构的固溶体,Zn、Mg最大固溶度(x(Zn),y(Mg))分别不超过0.1和0.15mol。当取代量超过固溶度后,分别形成Ca2Zn4Ti15O36和MgTi2O5第二相。随Zn和Mg取代量的增加,陶瓷介电常数(εr)和谐振频率温度系数(τf)减小。陶瓷品质因数(Qf)值随Zn取代量先增后减,而随Mg取代量增加,其Qf值一直增大。Zn,Mg最佳取代分别为x(Zn)=0.15和y(Mg)=0.25,在1250℃烧结2h,[(Ca0.85Zn0.15)0.61Nd0.26]TiO3的介电性能:εr=93.60,Qf=12454GHz,τf= 150.3ppm·℃-1,[(Ca0.75Mg0.25)0.61Nd0.26]TiO3的介电性能:εr=72.48,Qf=14622GHz,τf= 108ppm·℃-1。     

B2O3-Bi2O3-ZnO-Al2O3玻璃助烧剂对BaTiO3陶瓷烧结条件、晶体结构和介电性能的影响

通过调节B₂O₃-Bi₂O₃-ZnO-Al₂O₃(BBZA)玻璃的添加量研究其对钛酸钡(BaTiO₃)陶瓷烧结条件、晶体结构和介电性能的影响。结果表明：添加适量的BBZA玻璃能够有效地将BaTiO₃陶瓷烧结温度由1 350℃降至950℃,并使其致密化。同时,添加BBZA玻璃后,BaTiO₃的晶体结构随着烧结温度的升高而发生转变(立方相→四方相)。另外,BBZA玻璃的引入使BaTiO₃陶瓷的居里峰得到了有效的抑制和拓宽。陶瓷微观形貌显示,玻璃相均匀分布在BaTiO₃晶粒表面。优化的BaTiO₃陶瓷制备条件如下：BBZA添加量(质量分数)为2.0%,烧结温度为950℃。在该条件下制备的BaTiO₃陶瓷介电常数达到1 364,介电损耗低至1.2%。     

Li2O-Na2O-B2O3-SiO2烧结助剂对BaAl2Si2O8陶瓷结构与介电性能的影响

采用传统固相反应工艺,按化学计量比合成BaO-Al_2O3-SiO_2(BAS)-x%(w/w) Li_2O-Na_2O-B_2O3-SiO_2(LNBS)(x=0,1,2,3,4)陶瓷。研究不同LNBS烧结助剂添加量对BAS系微波介质陶瓷的结构和介电性能的影响。通过Clausius-Mossotti公式计算讨论了BAS理论与实验介电常数(εr)的差异。研究结果表明:LNBS烧结助剂中Li+进入钡长石Al3+位或单四元环(S4R)间隙,并产生了O_2-空位或Ba2+空位,从而促进BAS六方相向单斜相的转变。添加适量的LNBS烧结助剂后,BAS陶瓷的烧结温度从1 400℃降低到1 325℃,同时BAS陶瓷样品密度、品质因数(Qf)值以及频率温度系数(τf)得到改善。当x=1,烧结温度为1 325℃时,可获得综合性能相对较好的BAS陶瓷,其介电性能:Qf=35 199 GHz,εr=6.37,τf=-1.613×10-5℃-1。     

锂盐及制备工艺对固态电解质Li7La3Zr2O12成相的影响研究

石榴石型Li₇La₃Zr₂O₁₂(LLZO)离子导电性高,在全固态锂离子电池中具有潜在的应用价值。但目前报道的LLZO制备工艺烧结温度范围宽,稳定性差,不利于宏量制备。本文以烧结产物物相结构和结晶度为考察指标,系统研究了锂源及用量、烧结温度、烧结时间等因素对LLZO成相的影响。结果表明,当以分解温度较低的锂盐(LiNO₃)为原料时,在800℃下得到四方相LLZO,900℃时呈立方相LLZO;当以分解温度较高的锂盐(Li₂CO₃)为原料时,900℃才能形成四方相LLZO。烧结时间的延长和温度升高均会导致锂的挥发损失,影响LLZO物相的形成。通过增加锂盐用量、改变烧结前驱体聚集特性与烧结时间可抑制锂的挥发。当以过量10%的Li₂CO₃为原料时,900℃烧结6h可稳定的得到立方相LLZO。该研究较为系统地分析了制备工艺对LLZO成相的影响,可为LLZO宏量稳定制备提供借鉴。     

新型电解质材料CaZr0.1Ti0.9O3的制备与电性能研究

采用溶胶-燃烧法合成了可用于固体氧化物燃料电池(SOFC)的新型固体电解质材料CaZr_0.1Ti_0.9O₃。通过XRD、交流复阻抗等电化学方法对样品的结构、电导性能进行了表征,并考察了材料的烧结性能。结果表明,溶胶-燃烧法可以成功制备出具有良好烧结性能的CaZr_0.1Ti_0.9O₃电解质粉末,1400℃下得到的烧结体的相对密度可达到95%。电性能测试表明CaZr_0.1Ti_0.9O₃烧结体在中温范围内具有较高的氧离子电导率（σ^_800℃＝2.24×10^-3 S/cm）、低的电导活化能（0.89 eV）;样品的导电性能受烧结温度的影响,合理的控制烧结温度对于获得导电性能优良的CaZr_0.1Ti_0.9O₃电解质材料具有重要作用。     

含氟CaO-P2O5-SiO2-Na2O-B2O3玻璃陶瓷的制备及性能表征

采用溶胶-凝胶法制备CaO-P₂O₅-SiO₂-Na₂O-B₂O₃体系前驱体粉末,用CaF₂替代部分CaO再次制备前驱体粉末。 通过TG-DSC分析确定结晶温度为865 ℃,经过热处理获得主晶相为Na₆Ca₃Si₆O₁₈的玻璃陶瓷。 通过X射线衍射(XRD)、傅里叶红外光谱(FTIR)、扫描电子显微镜(SEM)等技术手段及体外生物活性实验分析玻璃陶瓷的显微结构及性能。 结果表明,CaF₂的加入能提高玻璃陶瓷的体积密度、抗折强度和弹性模量,并且不会破坏玻璃陶瓷的生物活性。     

烧结(Pr,Nd,Dy)32.2Co13Cu0.4FebalB0.98磁体磁性能和微观组织的研究

以烧结Nd-Fe-B磁体为基,复合添加了Cu,Co和重稀土Dy,成功制备了具有优良温度稳定性的磁体,磁体最高使用温度T_w≈210℃,剩磁温度系数α=-0.053%·℃^-1。研究发现,所制备磁体中存在着大量块状富稀土晶界相,而严重缺乏薄层富稀土晶界相,即使经过二级回火,薄层富稀土晶界相数量也没有明显增加。在块状富稀土晶界相中有贫Co相和富Co相同时存在的现象。TEM观察发现在富Co相中有RE₂(Fe,Co)₁₇相的存在,这不利于矫顽力的提升。研究表明：晶界处Cu和Co是对立分布的,经过合理的回火工艺后,Cu在晶界的分布更为均匀,Co则主要分布在晶界角落。此外,在一级回火水淬态磁体中的富Co相区域内,发现了RE(Fe,Co)₂ Laves相。     

Conversion of NO in NO/N2, NO/O2/N2, NO/C2H4/N2 and NO/C2H4/O2/N2 Systems by Dielectric Barrier Discharge Plasmas

An experimental study on the conversion of NO in the NO/N₂, NO/O₂/N₂, NO/C₂H₄/N₂ and NO/C₂H₄/O₂/N₂ systems has been carried out using dielectric barrier discharge (DBD) plasmas at atmospheric pressure. In the NO/N₂ system, NO decomposition to N₂ and O₂ is the dominating reaction; NO conversion to NO₂ is less significant. O₂ produced from NO decomposition was detected by an on-line mass spectrometer. With the increase of NO initial concentration, the concentration of O₂ produced decreases at 298 K, but slightly increases at 523 K. In the NO/O₂/N₂ system, NO is mainly oxidized to NO₂, but NO conversion becomes very low at 523 K and over 1.6% of O₂. In the NO/C₂H₄/N₂ system, NO is reduced to N₂ with about the same NO conversion as that in the NO/N₂ system but without NO₂ formation. In the NO/C₂H₄/O₂/N₂ system, the oxidation of NO to NO₂ is dramatically promoted. At 523 K, with the increase of the energy density, NO conversion increases rapidly first, and then almost stabilizes at 93–91% of NO conversion with 61–55% of NO₂ selectivity in the energy density range of 317–550 J L⁻¹. It finally decreases gradually at high energy density. A negligible amount of N₂O is formed in the above four systems. Of the four systems studied, NO conversion and NO₂ selectivity of the NO/C₂H₄/O₂/N₂ system are the highest, and NO/O₂/C₂H₄/N₂ system has the lowest electrical energy consumption per NO molecule converted.     

Nd2O3添加量对BaTiO3陶瓷介电性能的影响

BaTiO₃ ceramics doped with Nd₂O₃(the additive content was respectively 0.001,0.002,0.003,0.005,0.01,0.03mol)were prepared by Sol-Gel method. Effects of Nd₂O₃ contents on the dielectric constant (ε), the dielectric loss (tanδ) ,the Curie-temperature (T_C) and the resistivity (ρ) of BaTiO₃ ceramic were studied. When Nd₂O₃ content was 0.001mol and 0.002mol, the dielectric constant was increased obviously, but the dielectric loss was also increased. When Nd₂O₃ content was 0.003mol, the dielectric constant was increased, and the dielectric loss was decreased, which was suitable for application in condenser. The resistivity was decreased obviously with the increasing of Nd₂O₃ contents, the resistivity was the smallest when Nd₂O₃ content was 0.001mol. The Curie-temperature was also decreased with the increasing of Nd₂O₃ contents.     

纳米CaMgSi2O6粉体的低温合成与微波介电性能

以硝酸锂、偏钒酸铵、硝酸钙、硝酸镁、正硅酸乙酯为原料，采用溶胶-凝胶法低温合成纳米CaMgSi₂O₆微波介质陶瓷粉体，研究了不同粒径粉体的烧结行为与微波介电性能。结果表明，通过在钙镁硅溶胶中引入锂钒烧结助剂可大大降低陶瓷粉体的晶相合成温度，干凝胶在750 ℃煅烧后可获得主晶相为CaMgSi₂O₆、分散性良好、粒径为78～98 nm的陶瓷粉体，可满足微型片式元器件用超薄陶瓷介质层的制备要求;该粉体在890 ℃烧结后获得致密结构的陶瓷，具有良好的微波介电性能:介电常数为7.68，品质因数为24 542 GHz，频率温度系数为-57.25×10^-6 ℃^-1。     

溶胶凝胶法制备Nd2O3改性钛酸钡陶瓷的研究

The technological condition for the preparation of BaTiO₃ ceramics doped with Nd₂O₃ by Sol-Gel was deter-mined through orthogonal experiment. When n_Ba(Ac)2∶n_Ti(OC4H9)4∶n_Nd2O3∶n_{CH3(CH2)2CH2OH}∶n_H2O=1.00∶1.00∶0.003∶7.30∶37.04, pH=3.5,T=25℃,the light-yellow-transparent-stable solution and thorough transparent gel was generat-ed, the transforming time of solution to gel was 25h. The crystal structure and particle size of BaTiO₃ ceramics doped with Nd₂O₃ were studied by SEM and X-ray respectively, the type of the crystal was tetragonal, the particle size was about 24.7nm. The dielectric constant (ε) and dielectric loss (tanδ) of BaTiO₃ ceramics doped with Nd₂O₃ were determined between 10⁴～10⁶Hz, and the results showed that the dielectric constant was increased obviously, the dielectric loss was decreased clear and the resistivity (ρ_V) was also decreased noticeably.     

熔盐法制备Ca0.9La0.2/3Cu3Ti4O12陶瓷粉体及其介电性能研究

以CaCO3,CuO,TiO2,La2O3为反应物,NaCl,KCl为熔盐,通过熔盐法分别在700、750、800、850℃条件下合成Ca0.9La0.2/3Cu3Ti4O12陶瓷粉体。利用XRD和SEM分别对陶瓷粉体的物相结构和微观形貌进行了分析,并对其介电性能进行了测试。实验结果表明,随着合成温度的升高,陶瓷粉体的钙钛矿相含量逐渐增大,与传统固相法相比,熔盐法制备的粉体无团聚现象,耗时少。Ca0.9La0.2/3Cu3Ti4O12粉体制备的陶瓷在1 000℃烧结、测试频率在100 Hz~10 kHz时,获得优良的介电性能:介电常数大大超过104,介电损耗在0.1~0.47之间。     

Non-centrosymmetric Ba3Ti3O6(BO3)2

The compound previously reported as Ba₂Ti₂B₂O₉ has been reformulated as Ba₃Ti₃B₂O₁₂, or Ba₃Ti₃O₆(BO₃)₂, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO₃:BaTiB₂O₆ (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric space group, a=8.7377(11) Å, c=3.9147(8) Å, Z=1, wR(F²)=0.039 for 504 unique reflections. Ba₃Ti₃O₆(BO₃)₂ is isostructural with K₃Ta₃O₆(BO₃)₂. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba₃Ti₃O₆(BO₃)₂ is equal to 95% of that of LiNbO₃.     

Cr2(WO4)3和Cr2(MoO4)3的负热膨胀特性研究

用液相反应-前驱物烧结法制备了Cr₂(WO₄)₃和Cr₂(MoO₄)₃粉体。298～1 073 K的原位粉末X射线衍射数据表明Cr₂(WO₄)₃和Cr₂(MoO₄)₃的晶胞体积随温度的升高而增大, 本征线热膨胀系数分别为(1.274±0.003)×10^-6 K^-1和(1.612±0.003)×10^-6 K^-1。用热膨胀仪研究了Cr₂(WO₄)₃和Cr₂(MoO₄)₃在静态空气中298～1 073 K范围内热膨胀行为，即开始表现为正热膨胀，随后在相转变点达到最大值，最后表现为负热膨胀，其负热膨胀系数分别为(-7.033±0.014)×10^-6 K^-1和(-9.282±0.019)×10^-6 K^-1。     

Bi_2O_3掺杂对Ag(Nb_(0.8)Ta_(0.2))O_3陶瓷结构和介电性能的影响(英文)

本文研究了Bi2O3掺杂对Ag(Nb0.8Ta0.2)O3陶瓷的结构和介电性能的影响。X射线衍射(XRD)结果表明,Bi2O3的掺杂可以使陶瓷中Ag+被还原并析出,且银析出的量随Bi2O3掺杂量的增加而不断增加,这可能源自于Bi3+对Ag+的取代。在一定范围内增大Bi2O3掺杂量可提高Ag(Nb0.8Ta0.2)O3陶瓷的室温介电常数,降低介电损耗,并使温度系数向负值方向移动。当Bi2O3的掺杂量约为3.5wt%时,样品具有较大的介电常数(ε=672)和较小的介电损耗(tanδ=7.3×10-4)。