X-ray-diffraction study of quasipseudomorphic ErSi1.7 layers formed by channeled ion-beam synthesis

ErSi1.7 layers with high crystalline quality (chi(min) of Er is 1.5%) have been formed by 90 keV Er ion implantation to a dose of 1.6X10(17)/cm(2) at 450 degrees C using channeled implantation. The perpendicular and parallel elastic strain e(perpendicular to)=-0.94%+/-0.02% and e(parallel to)=1.24%+/-0.08% of the heteroepitaxial erbium silicide layers have been measured with symmetric and asymmetric x-ray reflections using a double-crystal x-ray diffractometer. The deduced tetragonal distortion e(T(XRD))=e(parallel to)-e(perpendicular to)=2.18%+/-0.10%, which is consistent with the value e(T(RBS))2.14+/-0.17% deduced from the Rutherford backscattering and channeling measurements. The quasipseudomorphic growth of the epilayer and the stiffness along a and c axes of the epilayer deduced from the x-ray diffraction are discussed.

高能氩离子在钇铁石榴石中的电子能损效应研究

本文对国内外快重离子在固体材料中引起电子能损效应的研究工作的历史和现状作了简短回顾，重点列举了到目前为止在钇铁石榴石（YIG）电子能损效应研究中取得的主要结果以及几种主要的理论模型。详细叙述了在兰州重离子加速器上进行1GeV氢离子辐照YIG材料的实验过程。用倾斜样品X一射线衍射（STD）、穆斯堡尔谱、饱和磁化强度测量等方法研究了辐照前后YIG样品的微观结构和物理性质变化，分析结果表明晶胞常数a, 非晶相百分数Fp随电子能损Se和辐照剂量Φt的增加而变大，而饱和磁化强度4π Ms减小．验证了YIG完全非晶化的电子能损阈值为Se＝8.3 MeV/μm和临界剂量为Φt＝1x1014 ions/cm2,在总结本次实验和国内外文献结果的基础上，提出了一个关于Fp（Se, Φt）函数的经验性的数学模型，并在模型中将材料本身的性质和电子能损及辐照剂量联系起来。

Phase transformation in the surface region of zirconia and doped zirconia detected by UV Raman spectroscopy

The phase evolution of yttrium oxide and lanthanum oxide doped zirconia (Y2O3-ZrO2 and La2O3-ZrO2, respectively) from their tetragonal to monoclinic phase has been studied using UV Raman spectroscopy, visible Raman spectroscopy and XRD. UV Raman spectroscopy is found to be more sensitive at the surface region while visible Raman spectroscopy and XRD mainly give the bulk information. For Y2O3-ZrO2 and La2O3-ZrO2, the transformation of the bulk phase from the tetragonal to the monoclinic is significantly retarded by the presence of yttrium oxide and lanthanum oxide. However, the tetragonal phase in the surface region is difficult to stabilize, particularly when the stabilizer's content is low. The phase in the surface region can be more effectively stabilized by lanthanum oxide than yttrium oxide even though zirconia seemed to provide more enrichment in the surface region of the La2O3-ZrO2 sample than the Y2O3-ZrO2 sample, based on XPS analysis. The surface structural tension and the enrichment of the ZrO2, component in the surface region of ZrO2-Y2O3 and ZrO2-La2O3 might be the reasons for the striking difference between the phase change in the surface region and the bulk. Accordingly, the stabilized tetragonal surface region can significantly prevent the phase transition from developing into the bulk when the stabilizer's content is high.

The microstructure and mechanical properties of Mg-3Al-3RE alloys

The Mg-3Al-3RE alloys (RE, the cerium-rich or the yttrium-rich misch metal) were smelted in a resistance furnace under the protective flux from the Mg-RE master alloys and pure magnesium ingots. The microstructure and mechanical properties of samples prepared by steel mould casting method were investigated.

Hollow fibers of yttria-stabilized zirconia (8YSZ) prepared by calcination of electrospun composite fibers

8YSZ fibers were synthesized by calcination of PVP/zirconium oxychloride/yttrium nitrate composite fibers (PVP-Precursor) obtained by electrospinning. Scanning electron microscopy (SEM) indicated that the 8YSZ fibers are hollow and the gas released during organic binder decomposition resulted in the formation of hollow center in fibers

Syntheses, structures and reactions of a series of beta-diketiminatoyttrium compounds

This paper describes the synthesis and selected reactions of a series of crystalline mono(beta-diiminato) yttrium chlorides 3a, 3b, 4a, 4b, 5a, 5b, 5c and 9. The X-ray structure of each has been determined, as well as of [YCl(L-4)(2)] (6), [Y(L-1)(2)OBut] (7) and [Y{CH(SiMe3)(2)}(thf)(mu-Cl)(2)Li(OEt2)(2)(mu-Cl)](2) (8).

Aging behavior and mechanical properties of Mg-Gd-Ho alloys

The Mg-8Gd-0.6Zr-xHo (x = 1, 3 and 5, mass%) alloys were prepared by casting technology, and structures, aging strengthening mechanism and mechanical properties of the alloys were investigated. The age behaviors and the mechanical properties are improved by adding Ho addition. The structures of the alloys are characterized by the present of rosette-shaped equiaxed grains. The peak hardness value of the Mg-8Gd-0.6Zr-3Ho alloy is 100 Hv, which is about 30% higher than that of Mg-8Gd-0.6Zr alloy.

The influence of mischmetal and tin on the microstructure and mechanical properties of Mg-6Zn-5Al-based alloys

The influence of the addition of mischmetal (MM) and tin (Sn) (total content of mischmetal and tin = 4 wt.%) on the microstructure, aging behavior and mechanical properties of Mg-6Zn-5Al-based alloys has been investigated. The microstructure of the as-cast alloys consists of alpha-Mg. Mg-32(Al,Zn)(49), Al2Mg5Zn2, Mg2Sn and Al2MMZn2 phases, and the morphology of these intermetallic phases varies with different MM and Sri additions.

Microstructure and mechanical property of Mg-8.31Gd-1.12Dy-0.38Zr alloy

The Mg-8.31Gd-1.12Dy-0.38Zr (mass%) alloy was prepared by casting technology, and the microstructure, age hardening behavior and mechanical property have been investigated. It is noted that the alpha-Mg and the different Mg-RE (RE = Gd/Dy) compounds are subsistent in the as-cast and annealed state samples. The age hardening behavior is observed during the investigated temperature range, and the alloy exhibits high Vickers hardness, excellent ultimate tensile strength and yield strength at peak hardness.

Microstructures and mechanical properties of as-cast Mg–5Al–0.4Mn–xNd (x=0, 1, 2 and 4) alloys

Mg-5Al-0.4Mn-xNd (x=0, 1, 2 and 4wt.%) alloys were prepared by metal mould casting method. The microstructures and mechanical properties were investigated. The results demonstrated that Al11Nd3 phase was formed and mainly aggregated along the grain boundaries with the addition of Nd. Meanwhile, the grain sizes were greatly reduced with the increasing Nd content.

An effective method for enhancing metal-ions' selectivity of ionic liquid-based extraction system: Adding water-soluble complexing agent

Selective extraction-separation of yttrium(Ill) from heavy lanthanides into 1-octyl-3-methylimidazolium hexafluorophosphate ([C(8)mim][PF6]) containing Cyanex 923 was achieved by adding a water-soluble complexing agent (EDTA) to aqueous phase. The simple and environmentally benign complexing method was proved to be an effective strategy for enhancing the selectivity of [C(n)mim] [PF6]/[Tf2N]-based extraction system without increasing the loss of [C(n)mim](+). (c) 2007 Elsevier B.V. All rights reserved.