化学溶液沉积法制备Y2O3过渡层

为了满足YBa2Cu3O7(YBCO)超导带材生产实际的需要,在金属基带和YBCO超导薄膜之间制备一层合适的氧化物过渡层显得尤为重要。以乙酸钇为原料配制前驱体溶液,采用金属盐化学溶液沉积法在织构的Ni-5%W(质量分数)(Ni-5W)带上成功制备了Y_2O_3过渡层。结果显示,氮气氛下1050℃热处理1h后,所获得的Y_2O_3过渡层具有良好的晶体织构,晶体生长取向为(100),完全复制了Ni-5W带模板的结构,为YBCO生长提供了良好的模板。在Y_2O_3过渡层上制备的YBCO薄膜表现出良好的超导性能。     

硝酸盐法在Ni5W织构基带上外延生长La2Zr2O7过渡层的研究

采用硝酸盐为前驱盐制备涂层导体结构中的La2Zr2O7(LZO)过渡层.实验通过对前驱盐粉体热分解行为的分析,以及前驱盐溶液在铝酸镧(LAO)单晶和Ni5W合金基底上外延生长LZO膜层工艺的比较研究,经优化获得了采用硝酸盐为前驱盐,适用于Ni5W合金基底的低温两步热处理结合高温快速热处理制备LZO的工艺路线.研究发现,...     

GZO/Ag/GZO多层薄膜制备、结构与光电特性的研究

采用射频磁控溅射和离子束溅射联合设备在玻璃衬底上制备出了具有良好附着性、低电阻率和高透过率的GZO/Ag/GZO(ZnO掺杂Ga_2O_3简称GZO)多层薄膜.X射线衍射谱表明GZO/Ag/GZO多层薄膜是多晶膜,GZO层具有ZnO的六角纤锌矿结构,最佳取向为(002)方向;Ag层是立方结构,具有(111)取向.在GZO层厚度一定的情况下,研究了Ag层厚度的变化对多层膜结构以及光电特性的影响.研究发现,当Ag层厚度为10nm时,3层膜的电阻率为9×10~(-5)Ω·cm,在可见光范围内平均透过率达到89.7%,薄膜对应的品质因子数值为3.4×10~(-2)Ω~(-1).     

窄流道式MOCVD制备YGBCO超导层研究

金属有机化学气相沉积能连续、快速的沉积高温超导带材YBa_2Cu_3O_(7-x)(YBCO)超导层。但金属有机源的利用率与薄膜沉积速率以及沉积一致性难以兼顾,制备YBCO高温超导带材的成本居高不下。本文提出了一种新的窄流道式反应室以改进薄膜沉积的一致性。在200 mm长度腔体中沉积的280 nm厚的Y_(0.5)Gd_(0.5)Ba_2Cu_3O_(7-x)薄膜J_c分布在3.2～3.5 MA/cm~2(77 K,0 T),面外、面内半高宽值分别在1.39°～1.49°和1.88°～2.13°,表面平整致密。YBCO薄膜良好的一致性表明该窄流道反应室对制备YBa_2Cu_3O_(7-x)超导带材有好的实用性。     

稀土Dy和Ce共掺杂La2Zr2O7新型热障涂层用陶瓷材料

用化学沉淀法制备了稀土Dy和Ce共掺杂La2Zr2O7新型热障涂层用陶瓷粉末Lal.7Dy0.3(Zr0.8CeZr0.2)2-O7(LDCZ).通过X射线衍射、扫描电镜、高温膨胀仪、DSC和激光热导仪对粉末相结构、不同煅烧温度下的相组成、微观结构,高温相稳定性,热膨胀系数和导热系数进行了分析.结果表明,稀土共掺杂的La1.7Dy0.3(Zr0.8CeZr0.2)2O7保持了烧绿石结构,120℃时粉末为无定形的混合氧化物,900℃时转化为复合氧化物,1200℃时转变为单一的烧绿石相;高温下LDCZ无明显相变;添加Dy和Ce不仅可提高锆酸镧的热膨胀系数,使其高于8YSZ的热膨胀系数,并可使其导热系数较La2Zr2O7降低25%以上,达到1.28～1.07W/m.K.     

MgO缓冲层对PZT/AlGaN/GaN异质结构电学性能的影响

采用脉冲激光沉积(PLD)技术,以MgO作为缓冲层,在AlGaN/GaN半导体异质结构上沉积了Pb(Zr0.52T0.48) O3 (PZT)铁电薄膜,从而形成金属-铁电-介质-半导体结构(MFIS).XRD扫描结果表明,通过MgO缓冲层对界面结构的优化,实现了PZT薄膜沿(111)面择优取向生长.电流-电压(I-V ...     

热处理对立方织构Ni-5%(体积分数)W基带上Ag薄膜择优取向的影响

采用磁控溅射法在立方织构Ni-5%(原子分数,下同)W基底上沉积了Ag薄膜作为第二代高温超导带材--YBaCuO涂层导体的导电缓冲层,并通过后期在Ar气氛下热处理使Ag膜具有(200)择优取向.磁控溅射后Ag膜的择优取向为(111),随着热处理温度的升高,(200)择优取向强度增加.采用慢降温工艺即在900℃下恒温30min,然后以较慢的速率10℃/h降至800℃后样品随炉冷却,有利于Ag薄膜由(111)向(200)的择优生长转变.     

氧离子束辅助激光制备具有织构的YBCO薄膜

应用氧离子束辅助准分子脉冲激光沉积薄膜技术,先在NiCr合金(Hastelloy c-275)基底上在室温下淀积具有平面织构的钇稳锆(YSZ)缓冲层薄膜,再在YSZ/NiCr基底上在750℃下制备具有平面织构和高临界电流密度的YBa2Cu3O7-x(YBCO)薄膜.YSZ和YBCO薄膜都为c-轴取向和平面织构的,YSZ(202)和YBCO(103)的X射线扫描衍射峰的全宽半峰值分别为18°和11°.YBCO薄膜的临界温度和临界电流密度分别为90K(R=0)和7.9×105A/cm2(77K,零磁场).     

Al2O3缓冲层对以ZnO∶Al为阳极的有机电致发光器件性能的影响

采用直流磁控溅射法制备ZnO∶Al(AZO)透明导电薄膜,薄膜电阻率为5.3×10-4Ω.cm,可见光区平均透过率大于85%。采用施加缓冲层的方法,在AZO和NPB之间加入一层Al2O3绝缘薄膜,提高了AZO阳极有机电致发光器件的性能,分析了Al2O3缓冲层的作用机理。结果表明施加1.5 nm缓冲层后器件的电流效率是单纯AZO阳极器件的3.4倍,同时也高于传统ITO器件。     

强立方织构Ni-40%Cu-3%W及复合基带的制备

本工作采用轧制辅助双轴织构技术(RABiTS)制备了无铁磁性的Ni-40%Cu-3%W合金及Ni-40%Cu-3%W/Ni9W/Ni-40%Cu-3%W复合基带。采用X射线衍射技术(XRD)及背散射电子衍射技术(EBSD)对Ni-40%Cu-3%W合金基带再结晶热处理后的织构进行了表征,结果表明,对Ni-40%Cu-3%W合金基带进行再结晶退火后(1 050 ℃保温60 min),合金基带表面形成了锐利的立方织构。此外,采用粉末冶金技术制备出了Ni-40%Cu-3%W/Ni9W/Ni-40%Cu-3%W合金复合坯锭,并采用RABiTS技术制备出了无铁磁性的复合基带,其室温下的屈服强度为255 MPa,明显高于商业化生产的Ni5W合金基带的屈服强度,弥补了Ni5W合金基带在磁性能和力学性能上的不足。     

Comparison of the Electronic Structures of La2CuO4, Sr2CuO2Cl2, and Sr2CuO2F2

First-principles cluster calculations are reported of the local electronic structure of the three compounds: La₂CuO₄, Sr₂CuO₂Cl₂, and Sr₂CuO₂F₂. The copper and the planar oxygen 2p atomic orbitals exhibit a similar degree of covalency. The out-of-plane orbitals, however, are quite different with the atomic orbital lowered significantly in energy for chlorine and fluorine apical positions.     

MgO-Al2O3-SiO2-TiO2-Y2O3玻璃的弹性模量

根据硬盘基板用材料的要求，制备了MgO-Al2O3-SiO2-TiO2-Y2O3高弹性模量玻璃（120GPa)，玻璃的弹性模量随组成的变化服从Makishima-Mackenzie理论，MgO,Al2O3,TiO2,Y2O3等具有较高单位体积离解能的氧化物有利于提高玻璃的弹性模量，但玻璃弹性模量的理论计算值低于测试值，这是因为Makishima-Mackenzie理论没有考虑玻璃内阳离子的具体配位，对MgO,Y2O3堆积密度因子的堆导存在误差，因此利用Makishima-Mackenzie理论发展高弹性模量玻璃时应对MgO,Y2O3等氧化物的计算进行修正。     

Les phases SrLa2Al2O7 et SrGd2Al2O7

SrLa₂Al₂O₇ and SrGd₂Al₂O₇ belong to the structural type Sr₃Ti₂O₇. In SrGd₂Al₂O₇ strontium and gadolinium occupy respectively the 12 and 9 coordinated sites, whereas in SrLa₂Al₂O₇ the homologous cations are statistically distributed. The fluorescence spectra of both phases activated by Eu³⁺ ions show that the only possible position of Eu³⁺ is the 9 coordinated site.     

Nanocrystallization of SrBi2Nb2O9 from glasses in the system Li2B4O7---SrO---Bi2O3---Nb2O5

Transparent glasses in the system (100−x)Li₂B₄O₇–x(SrO---Bi₂O₃---Nb₂O₅) (10≤x≤60) (in molar ratio) were fabricated by a conventional melt-quenching technique. Amorphous and glassy characteristics of the as-quenched samples were established via X-ray powder diffraction (XRD) and differential thermal analyses (DTA) respectively. Glass–ceramics embedded with strontium bismuth niobate, SrBi₂Nb₂O₉ (SBN) nanocrystals were produced by heat-treating the as-quenched glasses at temperatures higher than 500 °C. Perovskite SBN phase formation through an intermediate fluorite phase in the glass matrix was confirmed by XRD and transmission electron microscopy (TEM). Infrared and Raman spectroscopic studies corroborate the observation of fluorite phase formation. The dielectric constant (_r) and the loss factor (D) for the lithium borate, Li₂B₄O₇ (LBO) glass comprising randomly oriented SBN nanocrystals were determined and compared with those predicted based on the various dielectric mixture rule formalism. The dielectric constant was found to increase with increasing SBN content in LBO glass matrix.     

La2O3在MgO-Al2O3-SiO2-TiO2微晶玻璃中的作用

在MgO-Al2O3-SiO2-TiO2玻璃中添加不同数量的氧化镧，采用差热分析，X射线衍射及电子显微镜等技术研究了氧化镧对玻璃析晶过程与力学性能的影响。氧化镧的加入使玻璃中析出α－堇青石相的温度降低，同时避免了高膨胀方石英相的析出。随着氧化镧加入量的增加，玻璃整体析晶能力下降，微晶玻璃中晶相含量减少，晶粒尺寸增大，微晶玻璃的弹性模量与硬度减小，断裂韧性增加，体现出大尺寸长柱状金红石晶粒的增韧作用。     

Phase relations of the Li2O-Ta2O5-B2O3 and Li2O-WO3-B2O3 systems and promising nonlinear optical compounds in K2O-Ta2O5-B2O3 system

The subsolidus phase equilibria of the Li₂O-Ta₂O₅-B₂O₃, K₂O-Ta₂O₅-B₂O₃ and Li₂O-WO₃-B₂O₃ systems have been investigated mainly by means of the powder X-ray diffraction method. Two ternary compounds, KTaB₂O₆ and K₃Ta₃B₂O₁₂ were confirmed in the system K₂O-Ta₂O₅-B₂O₃. Crystal structure of compound KTaB₂O₆ has been refined from X-ray powder diffraction data using the Rietveld method. The compound crystallizes in the orthorhombic, space group Pmn2₁ (No. 31), with lattice parameters a = 7.3253(4) Å, b = 3.8402(2) Å, c = 9.3040(5) Å, z = 2 and D_calc = 4.283 g/cm³. The powder second harmonic generation (SHG) coefficients of KTaB₂O₆ and K₃Ta₃B₂O₁₂ were five times and two times as large as that of KH₂PO₄ (KDP), respectively.     

Subsolidus phase equilibria in the Al2O3-CeO2-PbO and Al2O3-CeO2-RuO2 systems

The subsolidus phase equilibria in air for the Al₂O₃-CeO₂-PbO and Al₂O₃-CeO₂-RuO₂ systems were studied with the aim of obtaining information on possible interactions between a CeO₂-based solid electrolyte in solid-oxide fuel cells (SOFCs) and other oxides. No ternary compound was found in either of the systems. The tie line in the Al₂O₃-PbO-CeO₂ system is between Al₂Pb₂O₅ and the CeO₂.     

Na2O-B2O3-SiO2-SnO2系统的分相与析晶

对Na2O-B2O3-SiO2-SnO2四元系统的分相与析晶进行了探讨．通过对不同组成点在热处理、化学处理各阶段的试样进行能谱分析、XRD分析及SEM分析，确认了SnO2分布在分相结构中的富硼碱相中；在该系统中SnO2晶体的析出有赖于分相过程；分相结构尺度限制了SnO2的析晶尺寸．试验结果表明，通过控制分相结构得到了负载于多孔富硅载体的纳米尺寸的SnO2材料．该材料具有较高的CO氧化催化活性．     

Quasiparticle dispersion of Sr2CuO2Cl2

Recent angle resolved photoemission (ARPES) measurements for the insulating cuprate Sr₂CuO₂Cl₂ have provided the first experimental data which can be directly compared to the (theoretically) well-studied problem of a single hole propagating in an antiferromagnet. Some discrepancies withthe familiar 2D t— J model were observed. Here we discuss a comparison between the ARPES results and the quasiparticle dispersion of both (i) the extended t— t— J Hamiltonian and (ii) the three-band Hubbard model.     

High-pressure substitutions for Cd In Cd2Nb2O7 and Cd2Ta2O7

Substitutions into cadmium niobate of the type Cd_2?xA_xNb₂O₇ (x≤0.5) have been carried out at 58 kbars and 1100°C. The substituting A cations were Mg, Mn, Fe, Co, Ni, Cu, and Zn which are all smaller than Cd. Rhombohedral or triclinic distortions derived from cubic Cd₂Nb₂O₇ were achieved at values of x as low as 0.05. All the substituted phases appear to be centric at room temperature. Analogous substitutions into Cd₂Ta₂O₇ were also made.