Effects of Nd, Sm, Gd, Dy, Er Dopant on Electrical Properties of BaTiO3 Ceramics

BaTiO3 ceramics doped with various quantities of Nd2O3, Sm2O3, Gd2O3, Dy2O3 and Er2O3 were prepared respectively ( the adulterate concentrations were 0. 001,0. 002, 0. 003, 0.005, 0. 007 mol fraction) through a sol-gel method and their electrical properties were researched. It is found that each adulteration of Nd2O3, Sm2O3 Gd2O3,Dy2O3 and Er2O3 all can make the resistivity of BaTiO3 ceramics decline , especially Sm2O3 and Gd2O3. When the addition of Sm2O3 is 0. 001 mol, the resistivity is the smallest, declining from 4.0 × 1012 to 6.5 × 103 Ω different kind of rare earth exhibits different regularity. The grain resistance of BaTiO3 ceramics doped with Sm2O3 or Gd2O3 exhibits a NTC effect, at the same time the grain boundary resistance has a PTC effect, and the grain boundary resistance is much larger than the grain resistance, so the PTC effects of BaTiO3 ceramics doped with Sm2O3 or Gd2O3 originate from the grain boundary. The additions of Nd2O3 , Gd2O3 or Er2O3 make the dielectric constant and the dielectric loss of BaTiO3 ceramics change evidently, especially Nd2O3. The dielectric constant is larger than that of pure BaTiO3 ceramics, on the other hand, the dielectric loss is much lower, which is useful in capacitor fields.     

Er and Gd Co-Doped Ceria-Based Electrolyte Materials for IT-SOFCs Prepared by the Cellulose-Templating Method

Ce_0.9?x Gd_0.1Er _x O_1.9?x/2 (0 ≤ x ≤ 0.1) (EGDC) powders were successfully synthesized with a fast and facile cellulose-templating method for the first time and characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The samples were calcined at a relatively low calcination temperature of 773 K (500 °C). The sintering behavior of the calcined EGDC powders was also investigated at 1673 K (1400 °C) for 6 hours. Calcined Ce_0.9?x Gd_0.1Er _x O_1.9?x/2 (0 ≤ x ≤ 0.1) powders and sintered Ce_0.9?x Gd_0.1Er _x O_1.9?x/2 (0 ≤ x ≤ 0.1) pellets crystallized in the cubic fluorite structure. It was found that the relative densities of the sintered EGDC pellets were over 95 pct for all the Er contents studied. Moreover, the effect of Er content on the ionic conductivity of the gadolinium-doped ceria (GDC, Ce_0.9Gd_0.1O_1.90) was investigated. The highest ionic conductivity value was found to be 3.57 × 10^?2 S cm^?1 at 1073 K (800 °C) for the sintered Ce_0.82Gd_0.1Er_0.08O_1.91 at 1673 K (1400 °C) for 6 hours.     

钆对烧结钕铁硼磁体磁性能和相结构的影响

通过电弧炉冶炼合金,采用球磨制粉,在磁场下取向成型,真空烧结和热处理制备了Nd17-xRxFe76.5B6.5磁体,研究了在钕铁硼永磁体中用稀土Gd部分地代替钕时对永磁体的磁性能随Gd含量的变化。实验结果表明:在一定的烧结及热处理工艺条件下,Nd17-xRxFe76.5B6.5磁体在Gd含量小于5%(原子分数)时,Gd对磁体的剩磁和内禀矫顽力影响相对较小,当Gd含量5%时,磁体磁性能急剧下降。显微成分分析表明,在合金铸态下,Gd可抑制合金的α-Fe相的析出;在磁体中,Gd进入主相是降低磁体矫顽力的主要原因。     

稀土氧化物LnO1.5掺杂CeO2-δ固体电解质的缺陷与电导率

利用缺陷化学的知识,对定量求解稀土氧化物LnO1.5掺杂CeO2-δ固体电解质中氧离子空位的浓度进行了初步探讨.在此基础上,推导出了该固体电解质的离子电导率和电子电导率的表达式.并且得出了计算CeO2基固体电解质临界氧分压P*O2的公式,利用该公式对两个问题进行了简单分析.     

Gd2O3掺杂ZrO2电解质材料的制备和电性能的研究

用溶胶-凝胶法制备了含10mol％Gd2O3的水合ZrO2,通过喷雾低温干燥、高温煅烧获得10GdSZ粉体,经喷雾制粒得到球状、不团聚、流动性好的粉体。在15MPa压力下压制成陶瓷片。坯片在1350—1600℃温度下烧结,烧结密度达到理论密度的98％。用两探针法测定电解质的电导率。结果表明,制备的10GdSZ电解质材料的电导率,在700℃下达到6．8×10^-1S·cm^-1,适于制作中温固体电解质材料。     

Er或Nd组合着色的新型陶瓷变色颜料的研究

用高温固相反应合成出了新型陶瓷光致变色颜料 ,此陶瓷颜料主要用 Er与 Nd作发色剂 ,并添加其它金属氧化物组合着色而成。     

Study on Rare Earth Electrolyte of Ce_(0.9)RE_(0.1)O_(2-δ) (RE=Pr, Nd, Sm, Gd, Dy)

Thesolidelectrolyteisakeycomponentofsolidoxidefuelcell (SOFC) .Dopedceriaisoneofpromis inghigh conductingsolidelectrolyteinSOFC[1,2 ] .Butitiswell knownthatitisdifficulttosinterdopedceriabysolidstatereactioninair .TheCe0 .9RE0 .1O2 -δelectrolytematerialswerepreparedbythesol gelmethod .Thesinteringtemperatureofthesamplescandecreasetoabout 4 0 0K .Theionicconductivityandlinearthermalexpansionpropertiesofsol gelpreparedCe0 .9RE0 .1O2 -δinawidetemperaturerangewerein vestigated .Thepowder…     

Growth and Spectral Properties of Crystal Er3+:Y0.5Gd0.5VO4

Er3 :Y0.5Gd0.5VO4 crystal with good optical quality was grown by Czochraski method. The structure of the crystal was determined by X-ray powder diffraction method. The segregation coefficient of Er3 ions in the crystal was measured by the ICP method. The absorption and emission spectra were also measured. On the basis of the spectra, the absorption cross-sections, emission spectrum FWHM and fluorescence lifetime of the crystal were calculated. From the properties mentioned above.     

添加Gd、Ho对烧结Nd-Fe-B磁体微结构与性能的影响

在Nd-Fe-B合金中添加Gd、Ho元素,可促进Nd2Fe14B柱状晶的生长,使富Nd相分布均匀,细化磁体的晶粒。添加Ho对磁体内禀矫顽力提高较好,添加Gd对磁体J-H退磁曲线的方形度提高较好,但磁体的剩磁与磁能积会降低。Gd、Ho的添加可以降低磁体的开路磁通不可逆损失,使得磁体具有较好的热稳定性。     

Er对5083合金微观组织及力学性能的影响

采用传统的铸锭冶金法制备实验合金,利用拉伸试验、金相组织观察、SEM扫描以及TEM透射等实验方法,研究了稀土元素Er对5083合金微观组织及力学性能的影响。结果表明,稀土元素Er的加入,在结晶过程中形成了一种粗大化合物,这种粗大化合物对合金的力学性能不利。     

C对Gd的磁热性能和显微硬度的影响

研究了Gd1-xCx(x≤0.05)合金的磁性、磁热性能、显微硬度。结果表明,当x≤0.05,与纯Gd比较,Gd1-xCx合金的显微硬度明显得到提高,同时居里温度,磁热性能的变化不大。含微量C的Gd1-xCx合金作制冷工质优于纯金属Gd。     

Synthesis and Spectral Properties of Nd3+:Gd3Ga5O12 Nanopowder for Transparent Laser Ceramics

Nd3 :Gd3Ga5O12 (Nd:GGG) nanopowder for transparent laser ceramics was synthesized using sol-gel method. XRD, SEM, and fluorescence spectrum were used to study the properties of Nd3 :Gd3Ga5O12 nanopowder. XRD patterns of samples show that it has a cubic structure. Meanwhile, pure Nd:GGG crystals were obtained at 1000 ℃ for 12 h. SEM photographs show that dispersed, uniform, ball-like Nd:GGG nanopowder is obtained. Both XRD and SEM results show that the crystallization degree and the grain size increase with the increase in calcining temperature. Analysis of fluorescence spectrum shows that fluorescence emission occurs at 1062.7 nm, which is the result of Nd3 (4F3/2→4I11/2) transition. Homogenous Nd:GGG nanopowder with a small grain size synthesized using the sol-gel method is favorable for sintering the transparent ceramic, which proves that the nanopowder obtained is suitable as a precursor for preparing GGG transparent ceramics.     

Mg~(2+)对硫酸锰电解液理化性质的影响

控制试验溶液中Mn~(2+)浓度18.75g/L、(NH_4)_2SO_4浓度100g/L,研究Mg~(2+)浓度对硫酸锰电解液理化性质的影响。结果表明,随着Mg~(2+)浓度的增加,不同温度梯度下硫酸锰电解液的密度、电导率以及黏度均呈上升趋势,而表面张力逐渐下降。当Mg~(2+)浓度一定时,随着温度的升高,硫酸锰电解液的密度、黏度及表面张力呈下降趋势,而电导率逐渐增加。     

稀土Nd对铸造铝硅合金变质作用的长效性及重熔性研究

以稀土元素Nd为变质剂,采用金属型铸造工艺制备铸造铝硅合金ZL101,并通过金相显微镜、扫描电镜、布氏硬度计和电子万能试验机研究变质时间及重熔次数对合金显微组织和力学性能的影响.结果表明,稀土Nd对合金具有较好的变质作用,并具有长效性和重熔性,变质6h及重熔4次后合金中的共晶硅组织仍呈小片状的变质状态,且合金硬度及拉伸性能均未受明显影响.变质不同时间及重熔不同次数的合金拉伸试样均为解理断裂.     

Effect of Ceria on Structure and Thermostability of Copper-Iron-Oxide Catalyst

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氧化铈稳定纳米氧化锆高温性能的研究

等离子喷涂热障涂层技术广泛应用于航空发动机热端部件的高温防护。应用大气等离子喷涂法成功制备了纳米氧化铈氧化钇稳定的氧化锆(CYSZ)涂层,并与常规氧化钇稳定氧化锆(YSZ)涂层在1300℃下热处理10小时,研究高温对两种涂层性能的影响,与常规的YSZ涂层相比,CeO2的掺杂使涂层具有更高的稳定性。经过高温处理,CYSZ涂层的相结构没有发生明显变化。显微形貌结果表明,CYSZ涂层没有产生裂纹缺陷,涂层中纳米区域晶粒度随着温度的升高略有增大,这表明了纳米结构的CYSZ涂层具有更优异的高温稳定性。热循环氧化实验结果证明,CYSZ涂层具有更长的热循环寿命以及优异的高温抗氧化性能。