Ba3Ca1+xNb2?xO9?δ复合钙钛矿型固体电解质性能研究

高温质子导体固体电解质Ba₃Ca_1+xNb_2?xO_9?δ化学性质稳定,中低温电导率较高,具有较好的应用前景。采用固相合成法制备得到了复合钙钛矿相的Ba₃Ca_1+xNb_2?xO_9?δ（x=0、0.10、0.18、0.30）材料。随着Ca掺杂量的增加Ba₃Ca_1+xNb_2?xO_9?δ样品的电导率先增加后降低,x=0.18的样品电导率最高。Ba₃Ca_1+xNb_2?xO_9?δ材料在含氢中的电子空穴迁移数较低,当温度低于750 ℃时,材料中质子导电为主;当温度达800 ℃后,材料中氧离子导电为主。x=0.10的样品质子迁移数最高,随着掺杂量的增加样品氧离子迁移数逐渐增大,质子迁移数逐渐降低。      

Investigation on pumping oxygen characteristics of （Bi2O3）0.73（Y2O3）0.27 solid electrolyte

（Bi2O3）0.73（Y2O3）0.27 fine powders prepared by wet chemical precipitation method were cold isostatically pressed to form solid electrolyte tubes, and sintered at 900 ℃ for 10 h in the air. Their pumping oxygen characteristics in non-dehydrated Ar gas were investigated, where a ZrO2 （Y2O3 stabilized） oxygen sensor was used to measure the oxygen partial pressure Po2. The results showed that the Po2 value reached magnitudes of 1×10^-2-1×10^-10 Pa at the applied pumping oxygen voltage of 0.5 V, 1×10^-37-1×10^-27 Pa at 1.0 V and 1×10^-53-1×10^47 Pa at 2.0 V within the temperature range from 550 to 650 ℃. Moreover, no cracks were found in the tested solid electrolyte tubes. Thus, the Bi2O3-Y2O3 system might be used in solid electrolyte oxygen pump for purifying gases.     

电渣重熔过程渣池流场数值模拟

采用商业软件ANSYS和FLUENT建立了电渣重熔过程渣池流场数学模型,分析了电渣重熔过程电磁力和热浮力共同作用下渣池流动行为,以及典型电渣重熔工艺参数(电极形貌、插入深度、填充比和电流强度)对电渣重熔过程渣池内流场的影响规律.结果表明:电磁力有利于渣池内产生逆时针涡流,浮力有利于渣池产生顺时针涡流.电极端部形貌对渣池流动影响较大,当电渣重熔电流均为5 000 A,频率为50 Hz时,平头电极所在渣池内同时存在逆时针涡流和顺时针涡流,锥形电极所在渣池内只存在逆时针涡流.电极填充比和电流都对渣池内流动行为影响较大,减小电极填充比和增大电流强度都会使渣池内逆时针涡流增加.     

成型压力和掺杂对Na1.4Co2O4基材料性能的影响

采用溶胶-凝胶法制备了Na位掺杂Sr和Li(掺杂量分别为0.1,0.2,0.3和0.4)的Nal.4Co2O4基热电材料,研究了成型压力和掺杂对Nal.4Co2O4基材料电导率、Seebeck系数和功率因子等热电性能的影响.采用XRD分析了NaxCo2O4基热电材料的相组成.研究结果表明:掺杂Sr和Li制备的Nal.4Co2O4基材料的主晶相均为γ-Nal.4Co2O4;增加成型压力及掺杂Li均可明显提高材料的电导率、Seebeck系数和功率因子;当Li掺杂量为0.4时,在310MPa下制备的Nal.4Co2O4基材料的功率因子为7.44mw·m-1·K-2,明显高于未掺杂试样;适量掺杂Sr也可一定程度上提高材料的热电性能.     

热电材料的研究现状及发展

随着能源的日益紧缺以及环境污染问题的日趋严重,热电材料作为一种热能和电能相互转换的功能材料受到人们的重视.系统阐述了传统热电材料和新型热电材料的研究现状,介绍了各系列热电材料的热电性能及适用范围等,指出了其今后的发展方向.     

Na_(1.4)Co_2O_4基热电材料的溶胶-凝胶法制备及表征

采用溶胶-凝胶法制备了掺杂Sr, Li和Cu的Na_1.4Co₂O₄基热电材料, 采用XRD分析了Na_1.4Co₂O₄基热电材料的相组成.通过DTA-TG曲线确定材料的预烧结和终烧结温度分别为450和850 ℃. 研究了掺杂量对Na_1.4Co₂O₄基材料电阻率、Seebeck系数和功率因子等热电性能的影响. 结果表明, 掺杂Li可降低Na_1.4Co₂O₄的电阻率, 掺杂 Sr和Cu使材料的电阻率增加; 掺杂Li和Cu可大幅度提高Na_1.4Co₂O₄的Seebeck系数和功率因子; 掺杂Sr的改善效果不显著, 掺杂Li的效果最好; 当Li掺杂量为0.40, Na_1.4Co₂O₄基热电材料的功率因子在15℃时达到最大值 7444.73 μW?m^-1?K^-2.     

Preparation and sintering properties of zirconia-mullite-corundum composites using fly ash and zircon

Zirconia-mullite-corundum composites were successfully prepared from fly ash,zircon and alumina powder by a reaction sintering process.The phase and microstructure evolutions of the composite synthesized at desired temperatures of 1 400,1 500 and 1 600°C for 4 h were characterized by X-ray diffractometry and scanning electronic microscopy,respectively.The influences of sintering temperature on shrinkage ratio,apparent porosity and bulk density of the synthesized composite were investigated.The formation process of the composites was discussed in detail.The results show that the zirconia-mullite-corundum composites with good sintering properties can be prepared at 1 600°C for 4 h.Zirconia particles can be homogeneously distributed in mullite matrix,and the zirconia particles are around 5μm.The formation process of zirconia-mullite-corundum composites consists of decomposition of zircon and mullitization process.     

Zr_(0.92)Mg_(0.08)O_(1.92)和Zr_(0.92)Y_(0.08)O_(1.96)固体电解质的制备及性能

采用固相合成法在1 650℃分别合成了Zr0.92Mg0.08O1.92和Zr0.92Y0.08O1.962种固体电解质,其相对密度分别为96.19%和95.12%。XRD分析表明在Zr0.92Mg0.08O1.92和Zr0.92Y0.08O1.96固体电解质中均含有立方固溶体相,SEM分析表明2种材料微观结构致密。采用交流阻抗法分别测定了Zr0.92Mg0.08O1.92及Zr0.92Y0.08O1.96固体电解质在1 000~1 600℃的电导率。结果表明:随着温度的升高,Zr0.92Mg0.08O1.92固体电解质的电导率不断增大,但Zr0.92Y0.08O1.96的电导率在1 400℃时达到最大值(7.24×10—2 S/cm),随后降低;在1 000~1 450℃,Zr0.92Y0.08O1.96的电导率高于Zr0.92Mg0.08O1.92,在1 500~1 600℃,Zr0.92Mg0.08O1.92的电导率高于Zr0.92Y0.08O1.96。分析得到Zr0.92Mg0.08O1.92和Zr0.92Y0.08O1.96在1 000~1 450℃温度区间的电导激活能分别为1.61和0.20eV,在1 450~1 600℃温度区间的电导激活能分别为0.55和0.85eV。     

CaZr_(1-x)In_xO_(3-α)(x=0,0.05,0.10,0.15)质子导体的电学性能

采用固相反应法在1400℃合成了CaZr1-xInxO3-α(x=0,0.05,0.10,0.15)陶瓷粉体,在空气中1550℃,10 h对材料进行二次烧结.XRD物相分析结果确定合成后的样品中有CaZrO3和微量CaIn2O4存在.实验在600～850℃含水氩气中测量了样品的交流阻抗谱,计算出其电导率随温度变化的规律和电导激活能.在800℃时,CaZr1-xInxO3-α的电导率分别为4.64×10-7 S/cm(x=0)、3.06×10-4 S/cm(x=0.05)、3.89×10-4 S/cm(x=0.10)、3.93×10-4 S/cm(x=0.15).研究结果表明:对CaZrO3掺In能显著提高材料的电导率,降低电导激活能,掺杂量x0.1时,电导率增加变缓,并且电导率随温度的升高而增大.研究得到CaZr1-xInxO3-α的电导率与掺杂量的关系式.