Co掺杂对（CeO2）0.92（Y2O3）0.06（La2O3）0.02电解质材料性能的影响

采用固相合成法合成CeO2基粉料(1-x)(CeO2)0.92(Y2O3)0.06(La2O3)0.02+xCoO1.5(x=0,0.5 mol%,1mol%和2mol%),并在不同温度下烧成。采用X射线衍射(X-ray diffraction,XRD)、Archimedes法、交流阻抗谱和热膨胀仪分别测试电解质材料的晶体结构、体积密度、离子电导率和热膨胀。结果表明:掺杂Co的试样经1500℃烧成后均为单一的立方萤石结构相,Co可以有效提高试样的烧结性能,降低烧结温度100℃;试样的晶界电导随着Co含量的增加而提高,当Co掺杂量为2mol%时,试样在700℃时表现出最高的离子电导率0.051s.cm-1。同时发现Co的掺杂对试样的热膨胀影响不大。     

MoO3掺杂对高纯Zr0.84Y0.16O1.92体系结构和电性能的影响

采用溶胶-凝胶法合成高纯(SiO2<50 mg/kg)Zr0.84Y0.16O1.92+x MoO3(0.00≤x≤0.07)固溶体,研究MoO3的掺杂量对Zr0.84Y0.16 O1.92体系结构和电性能的影响。通过X射线衍射(XRD)和场发射扫描电子显微镜(FE-SEM)对材料进行表征,交流阻抗谱(AC)测试材料的电性能。结果表明,掺入MoO3后,体系仍保持立方莹石型结构;MoO3掺杂于Zr0.84Y0.16O1.92固体电解质的最佳掺量为0.05%;MoO3具有降低体系烧结温度、促进晶粒生长和提高体系致密度的作用,掺入MoO3的Zr0.84Y0.16O1.92体系晶界电导率和总电导率提高。     

Y2O3和CeO2对镁砂烧结性能及显微结构的影响

以菱镁石于950℃制得的轻烧MgO粉(≤0.088 mm)为主要原料,分别加入质量分数为1%、2%、3%、4%的Y2O3和CeO2混匀,压制成型后于1 600℃煅烧3 h,冷却后测其体积密度和线收缩率,并利用XRD、SEM、EDS分析试样的物相组成及显微结构,以研究Y2O3和CeO2对镁砂烧结性能和显微结构的影响。结果表明:1)引入Y2O3和CeO2均有利于镁砂的烧结致密化,镁砂试样的体积密度和烧后线收缩率随其加入量的增加而增大;在加入量相同的情况下,加入Y2O3对镁砂的促烧结作用比加入CeO2的更明显。2)引入的Y2O3和CeO2都有部分固溶于方镁石晶体内,使MgO晶格发生畸变,有利于MgO晶粒发育良好,晶粒长大,晶界明显;Y2O3能与镁砂中的CaO、SiO2形成钇硅酸盐相分布在晶粒之间,而部分CeO2以游离形式存在于晶粒之间。3)与引入CeO2的试样相比,引入Y2O3的试样中气孔更加集中,晶界更加清晰,MgO晶粒尺寸较大,这是由于Y2O3和CeO2的性质差异造成稀土离子参与固溶体粒子取代程度不同的缘故。     

Y和Yb复合掺杂对BaCe_(0.5)Zr_(0.3)Y_(0.2-x)Yb_xO_(3-δ)的烧结性和电导率的影响

质子传导固体氧化物燃料电池具有广阔的应用前景,本文探索以BaCeO3为主体均相复合BaZrO3,采用ZnO为烧结助剂,制备了Y和Yb复合掺杂的BaZrO3-BaCeO3即BaCe0.5Zr0.3Y0.2-xYbxO3-δ(x=0、0.08、0.16)质子导体,重点研究了Y和Yb复合掺杂对质子导体材料烧结性、微观结构和电导率的影响。实验结果表明,x=0时,即BCZY-Z试样具有较好的性能,1350℃烧结6 h试样相对密度达到了97.1%,600℃电导率为6.3×10-3S/cm,700℃晶界电阻只有18Ω。     

添加剂对3Y-TZP材料烧结行为及力学性能的影响

在3Y－TZP（tetragonal zirconia polycrystals stabilized,3% Y2O3，摩尔分数）中，采用CAS（CaO-Al2O3-SiO2)玻璃粉料为添加剂，使材料在较低的温度下烧结致密，并具有较好的力学性能，发现液相烧结是使试样的烧结温度显著降低的主要原因。探讨了添加剂对试样的烧结特性及力学性能的影响。与加入LAS添加剂的试样相比，CAS试样的抗弯强度好高，而断裂韧性要差，分析了造成这种力学性能的原因。     

纳米ZnO或纳米Y2O3对熔融石英陶瓷烧结性能的影响

以高纯熔融石英粉为原料,分别加入相对于熔融石英粉质量1%、2%和3%的纳米ZnO或纳米Y2O3,经50 MPa压力成型后,在还原气氛中,于1 300、1 350和1 400℃保温1 h煅烧后,测定试样的显气孔率和常温抗折强度,并采用SEM分析试样的断口形貌。结果表明:引入纳米ZnO或纳米Y2O3可以明显地促进熔融石英陶瓷的烧结,纳米ZnO可大大提高熔融石英陶瓷材料的抗折强度并显著降低其显气孔率,纳米Y2O3作为熔融石英陶瓷助烧结剂的最佳加入量(w)为2%。     

NaCl对BaZr0.63Ce0.27Y0.10O2.95/ZnO质子导体的烧结性与电化学性能的影响

采用机械混合和高温固相反应法,在2%(摩尔分数)ZnO掺杂BaZr0.63Ce0.27Y0.10O2.95的质子导体(BZCY-Z2)中添加0~15%(摩尔分数)NaCl,在1400℃保温4h,制备BaZr0.63Ce0.27Y0.10O2.95/ZnO/NaCl(BZCY-Z2-Cl)复相质子导体。结果显示,加入NaCl作为复相烧结助剂后,由于出现液相,降低了试样的烧结温度与保温时间,从而改善了试样的烧结性能;NaCl均匀分布于晶界,改善了晶界特性,提高了晶界质子导电性,质子导体于700℃时在湿氢气氛中总电导率达7.48×10–3S/cm;电解质支撑型单元电池测试结果表明,单电池在550、600、650和700℃下离子传导系数分别达到0.97、0.97、0.95和0.93,表明该电解层材料为良好的质子导体;700℃时功率密度为17 mW/cm2,由于电解层厚度较厚(0.9nm),导致输出功率相对较低。上述结果表明所制备的质子导体材料具有良好的电化学性能。     

MoO_3掺杂对高纯Zr_（0.84）Y_（0.16）O_（1.92）体系结构和电性能的影响

采用溶胶-凝胶法合成高纯（SiO2〈50 mg/kg）Zr0.84Y0.16O1.92＋x MoO3（0.00≤x≤0.07）固溶体,研究MoO3的掺杂量对Zr0.84Y0.16 O1.92体系结构和电性能的影响。通过X射线衍射（XRD）和场发射扫描电子显微镜（FE-SEM）对材料进行表征,交流阻抗谱（AC）测试材料的电性能。结果表明,掺入MoO3后,体系仍保持立方莹石型结构;MoO3掺杂于Zr0.84Y0.16O1.92固体电解质的最佳掺量为0.05%;MoO3具有降低体系烧结温度、促进晶粒生长和提高体系致密度的作用,掺入MoO3的Zr0.84Y0.16O1.92体系晶界电导率和总电导率提高。     

添加MgO对不同SiO2含量的ZrO2-Al2O3-SiO2陶瓷烧结的影响

以高纯石英砂、α-Al2O3、ZrO2为原料,MgO为添加剂(添加质量分数分别为0、1%、2%、3%),经研磨、造粒、成型,并在1 600℃烧结2 h后获得了SiO2含量(w)分别为4%、8%、12%的ZrO2-Al2O3-SiO2系陶瓷试样。采用XRD、SEM对试样进行物相和显微结构的分析。结果表明:1)所制备的ZrO2-Al2O3-SiO2陶瓷的主要物相是单斜氧化锆、莫来石和刚玉,随着SiO2含量(w)由4%增加到12%,SiO2与Al2O3反应生成的莫来石量增加,体积膨胀效应越发明显,导致烧结试样的致密度降低;2)添加MgO促进了ZrO2-Al2O3-SiO2陶瓷的烧结,在SiO2含量为4%(w)的陶瓷中加入1%(w)的MgO时,烧结试样的致密度最大,其相对密度达到90.49%,体积密度为3.90 g·cm-3。     

用于固体氧化物燃料电池的Zn掺杂BaZr0.7Pr0.1Y0.2O3-δ质子导体电解质的制备与性能

采用柠檬酸–硝酸盐燃烧法制备了质子导体固体氧化物燃料电池(SOFC)电解质材料BaZr0.7Pr0.1Y0.2O3–δ(BZPY)和BaZr0.7Pr0.1Y0.16Zn0.04O3–δ(BZPYZn)。研究了Zn掺杂对材料烧结、热膨胀系数和电性能的影响;利用X射线衍射仪和扫描电子显微镜对样品物相和微观结构进行了表征。结果表明:BZPYZn经1 100℃煅烧5h后呈单一的钙钛矿结构。随烧结温度的升高(从1 300℃到1400℃),BZPYZn陶瓷体的晶粒尺寸增大,而孔隙率减小;1350℃保温5h烧结的BZPYZn陶瓷样品的相对密度达到97.3%;500～800℃范围内,离子电导率介于10–3～10–2S/cm之间。室温至1 000℃范围内,样品的热膨胀系数为9.2×10–6/K,表明其与电极材料(Ni)的热匹配性好。预示BZPYZn有望成为良好的质子传导型中温SOFC电解质材料。     

ZnO掺杂量与烧结温度对SnO2–Ta2O5–ZnO压敏变阻材料性能的影响

以SnO2、Ta2O5和ZnO粉为原料,通过传统陶瓷固相反应烧结法制备了压敏变阻材料,实验中ZnO含量为0～2.00%(摩尔分数),烧结温度控制在1 300～1500℃并保温2 h。研究了ZnO掺杂量和烧结温度对材料的组成、微观结构和电学性能的影响。结果表明:在温度一定条件下,随着ZnO掺杂量的增加,材料的非线性系数、压敏电压先增大后减小;在ZnO含量一定时,随着烧结温度从1 300℃升至1 450℃,材料的非线性系数、压敏电压先增大后减小。ZnO掺杂量为0.50%时,在1450℃烧结得到的样品的非线性系数最高(6.2),漏电流最小(262μA/cm2),压敏电压较高(83V/mm)。     

添加Li_2O对YSZ电解质性能影响

8%（摩尔分数,下同）Y2O3稳定的ZrO2（8YSZ）是固体氧化物燃料电池（SOFC）中最常用的电解质材料,本文研究了在8YSZ基体中加入n%Li2O（n=0,0.25,0.50,1.00,1.50,1.70,2.00,2.50,3.00）后（记为n%Li2OYSZ）对其晶相结构、晶格常数、烧结性能、微观形貌、电导率及其作为SOFC电解质性能的影响。结果表明,Li2O中的Li＋可以固溶到YSZ的晶格内使其晶格常数减小;Li2O的加入量n〈1.70时,瓷体在烧结过程中不会发生相变。加入少量的Li2O（n=0.25,0.50）可以提高YSZ的致密度和电导率,0.25%Li2OYSZ和0.50%Li2OYSZ样品800℃的电导率分别高达0.030 2 S/cm和0.027 6 S/cm,分别是纯YSZ的1.35和1.24倍;当Li2O含量n≥1.00时,相同条件下烧结体致密度随Li2O加入量的增大而逐渐减小;当n≥1.70时,样品在烧结过程中虽然出现相变,但在高于1400℃可以烧结致密,并得到纯立方相YSZ。将1250℃烧结制得的0.25%Li2OYSZ和0.50%Li2OYSZ作为SOFC电解质的单电池,800℃时的开路电压高于1.0V,说明YSZ中没有出现电子电导,具有比纯YSZ为电解质的单电池更高的性能输出,表现出了良好的应用前景。     

Enhanced Sintering of Yttrium-Doped Barium Zirconate by Addition of ZnO

The influence of transition metal oxides additives, especially zinc oxide, on the densification and electrical properties of doped barium zirconate have been examined. With the use of zinc oxide as a sintering aid, BaZr_0.85Y_0.15O_3–δ was readily sintered to above 93% of theoretical density at 1300°C. Scanning electron microscopic investigations showed Zn accumulation in the intergranular regions. Thermogravimetric analysis of the material under flowing CO₂ showed ZnO-modified barium zirconate to exhibit excellent chemical stability. The conductivity, as measured by A.C. impedance spectroscopy under H₂O saturated nitrogen, was slightly lower than that of unmodified barium zirconate. Electromotive force measurements under fuel cell conditions revealed the total ionic transport number to be ∼0.9 at 600°C. The combination of electrical and chemical properties and good sinterability render ZnO-modified barium zirconate an excellent candidate for reduced temperature solid oxide fuel cell applications.     

新型陶瓷连接材料(Pr0.5Nd0.5)0.7Ca0.3CrO3–δ–Sm0.1Gd0.1Ce0.8O1.9的制备与性能

采用络合燃烧法制备(Pr0.5Nd0.5)0.7Ca0.3CrO3–δ(PNCC)–Sm0.1Gd0.1Ce0.8O2–δ(SGDC)复合陶瓷连接材料。利用X射线衍射仪和扫描电子显微镜对烧结体的物相和微观结构进行了表征,采用四端探针法测量电导率。结果表明:PNCC和SGDC在高温烧结时具有稳定的物相和良好的化学相容性,SGDC掺杂量为5%(质量分数)的样品,在1400℃烧结5h,相对密度高达97.1%;700℃时,烧结陶瓷体在空气和氢气气氛中的电导率分别为47S/cm和4S/cm;室温至1000℃范围内,样品的热膨胀系数为10.4×10–6K–1,与中温电解质的热膨胀系数接近,说明SGDC掺杂的PNCC体系有望成为良好的中温固体氧化物燃料电池复合连接材料。     

Effect of cerium on yttrium-doped barium zirconate with a ZnO sintering aid: Grain and grain boundary protonic conduction

The grain and grain boundary protonic transport of yttrium-doped barium zirconate has been investigated for various Ce-substituted concentrations, and the origins of blocking on the grain and grain boundary resistances are considered. Ba(Zr_1-xCe_x)_0.85Y_0.15O_3-δ samples (BZCY, x = 0, 0.05, 0.1, and 0.2) with a ZnO sintering aid have been prepared via conventional ceramic processing, and their grain and grain boundary resistances have been experimentally measured as a function of temperature under humid conditions using 2-probe AC impedance measurements. In the grain, a high-Ce-substituted sample with a large lattice volume is more conductive than a low-substituted specimen. The high-Ce-substituted sample also exhibits low resistance to the grain boundary. In the investigation of the origin of current blocking on the grain boundary, it is found that the space charge significantly affects grain boundary transport in the low-Ce-substituted sample. However, other mechanisms such as the charge-neutral effect (structural effect) of the grain boundary transport in the high-Ce-substituted samples are considered. In terms of the total conductivity (the summation of the grain and grain boundary components) of BZCY, it is found that the highest Ce-substituted barium zirconate (x = 0.2) exhibited the highest conductivity, demonstrating that it can potentially be utilized as a solid electrolyte in electrochemical devices such as solid oxide fuel cells.     

Effect of synthesis atmosphere on the proton conductivity of Y-doped barium zirconate solid electrolytes

Yttrium-doped barium zirconate ceramic powders were synthesized by the oxidant peroxide method in air and under controlled atmosphere of nitrogen inside a glove box. The powders were characterized by thermogravimetry, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. After uniaxial cold isostatic pressing, green pellets were sintered at 1600 °C for 4 h. The electrical conductivity behavior was accessed by electrochemical impedance spectroscopy. The results show that specimens synthesized under controlled atmosphere achieved higher electrical conductivity, two orders of magnitude higher than specimens prepared in laboratory air. The enhancement in electrochemical properties and increase in sintering ability is attributed to the less carbonate contamination as a result lower grain boundary density in the samples prepared under controlled atmosphere.     

双掺杂Bi_2O_3电解质的合成及其电性能测试

通过双掺杂氧化镝和氧化钨于氧化铋中,合成电解质并对其导电性进行测试。通过差热-热重来分析其热性能,确定其合成的烧结温度;并利用粉末X射线衍射对合成材料进行相分析,利用交流阻抗谱方法测试、计算试样的电导率。结果表明,烧结温度800℃时可得到具有高电导率相的立方相萤石结构的粉体,并无其它晶型出现。经计算,掺杂后的氧化铋电解质在700℃时电导率达18.7 S/m,比目前使用最普遍的电解质材料YSZ电导率在500℃时高1~2个数量级。     

溶胶–凝胶法制备(Na0.50+xK0.50-2xLix)Nb0.9Ta0.1O3无铅压电陶瓷及其性能

采用溶胶–凝胶法制备Li+取代(K0.5Na0.5)+及Ta5+取代Nb5+的(K0.5Na0.5)NbO3陶瓷粉体,采用无压烧结工艺制备(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3(x=0,0.02,0.04)陶瓷样品。研究了前驱体煅烧温度对陶瓷粉体物相组成的影响。分析了不同Li+掺杂量对样品物相组成、微观结构、体积密度及电学性能的影响。结果表明:前驱体的最佳煅烧温度为600℃,通过透射电子显微镜分析陶瓷粉体的粒径为49 nm;不同Li+掺杂量制备的(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3陶瓷样品均为正交相钙钛矿结构;随着Li+掺杂量的增加,(Na0.50+xK0.50–2xLix)Nb0.9Ta0.1O3陶瓷的体积密度先增大后减小,介电常数逐渐升高,压电常数先降低再升高,剩余极化强度逐渐升高。Li+掺杂量x为0.04时样品的压电常数(d33=94 pC/N)、相对介电常数(εr=684.33)及剩余极化强度(Pr=98.27μC/cm2)较好。     

Influences of ZnO on the Properties of SrZr0.9Y0.1O2.95 Protonic Conductor

The effects of ZnO additive on the microstructure, phase formation, and electrical conduction of yttrium-doped strontium zirconate were investigated. The sintering temperature of SrZr_0.9Y_0.1O_2.95 can be lowered to 1350°C by addition of ZnO. The electrical conduction is found to be strongly correlated with the ZnO contents. When the ZnO content is <5 mol%, the electrical conductivity increased with an increase in the ZnO contents. Electromotive force measurements under fuel cell conditions indicated a pure ionic conduction over this range of ZnO contents. However, it had a detrimental effect on the electrical conduction when the ZnO content was more than 6 mol%. The main reason for this is discussed according to the defect chemistry and microstructure.     

Properties of barium zirconate sintered from different barium and zirconium sources

In this study, barium zirconate powder was prepared by a solid-state reaction using different barium and zirconium sources. Thermal analysis and phase identification demonstrated that barium zirconate could be synthesized from barium hydroxide at a lower temperature than from barium carbonate. Copper oxide was used as a dopant to improve the sintering performance of the barium zirconate; sintered samples with 2 mol% copper oxide exhibited relatively superior comprehensive performance. The mechanical properties and thermal stability of barium zirconate were characterized; the internal composition structure of the samples prepared with basic zirconium carbonate was uneven, resulting in somewhat reduced performance. The samples maintained a high elastic modulus and strength before and after thermal shock. It was observed under an electron microscope that a liquid phase was generated inside the samples after thermal shock, and numerous barium zirconate whiskers were formed. The whiskers ensured that the sample could withstand greater thermal stress, thus exhibiting excellent thermal shock stability. This work demonstrates the promising potential of barium zirconate in the field of high-temperature materials.