Phase Behavior of BaLn2Mn2O7（Ln = Rare Earth） with a Layered Perovskite Structure

Many phases appear in BaLn2Mn2O7 family (Ln = rare earth) belonging to one of the Ruddlesden-Popper type compounds, depending upon the experimental conditions such as heating conditions when prepared and composition. Some of these phases were characterized by powder X-ray diffraction method using Rietveld analysis. These phases have only a little difference in crystal structure which has fundamentally K2NiF4 type stru,ture, although the X-ray diffraction patterns are clearly different : a little deformation or tilting of the oxygen oetahedron surrounding a central manganese ion composing the main frame of this structure induce these different diffraction patterns. Phase behavior of these compounds, mainly the detailed relation between various phases in BaTb2Mn2O7, was refined including the data of high temperature X-ray diffractometry.     

双层锰氧化物Nd1.2Sr1.8Mn2O7的相分离研究

通过固相反应法制备成了多晶样品Nd1.2Sr1.8Mn2O7,利用XRD和SQUID研究了样品的结构和磁性.研究结果表明,该样品的单相性很好,单相结构为Sr3Ti2O7四角形结构(14/mmm).磁性测量表明,温度高于居里温度(Tc=265K),样品呈现出顺磁性,随着温度的降低出现了顺磁-铁磁的转变,铁磁与反铁磁两相共存,温度低于50 K时铁磁逐渐消失,直到完全变为反铁磁.     

钙钛矿锰氧化物Y0.5Ca0.5Mn0.8Fe0.2O3的电子顺磁共振研究

用固相反应法制备了Y0．5Ca0．5Mn0．8Fe0．2O3多晶陶瓷材料，借助电子顺磁共振技术对多晶样品在150—300K温度范围内的顺磁共振行为进行了研究。结果表明样品的顺磁共振线宽△Hpp和g因子的值随着温度的降低是增加的。线宽的增加是由于随着温度的降低，样品进入一个长程的反铁磁态，体系的铁磁关联增强导致的。g因子随温度的降低而增加表明体系的轨道有序是逐渐增强的。     

Low Temperature Phase Transition Behavior of Ca-Doped Lanthanum Chromites

Phase transition of LaCrO3 and doped-LaCrO3 was studied by DSC, TG and XRD, and thermal expansion during the transition was analyzed. It is found that phase transition of LaCrO3 begins at about 240℃ and ends at about 265 ℃. Temperatures of phase transition rise obviously with increasing Ca^2＋ content. The transition of LaCrO3 and Ca-doped LaCrO3 from orthorhombic to rhombohedral is accompanied with endothermic reaction. No obvious change occurs in mass, but remarkable shrinkage occurs during phase transition.     

Synthesis and Structures of A Series of Novel Rare Earth Transition Metal Sulfates

Seven new rare earth transition metal sulfates were synthesized by hydrothermal reactions under conditions slightly above the critical point of water. Their crystal structures were determined from single crystal X-ray data. The compositions of the new compounds can be represented by two general formulae ： REM （OH） 3 （SO4） and RE2M （OH） 3 （SO4） 2F （H2O） with RE = Gd, Tb, Dy ; M = Ni, Cu. Three different crystal structure types were found for the formula REM （OH） 3 （SO4）. The structures of the new compounds all feature infinite chains of REOn coordination polyhedra, which are connected to chains of CuO6 or NiO6 octabedra. The limited size range of the rare earth cations observed in these compounds is most likely because of interactions between the octabedral chains and the chains of REOn polyhedra. The new compounds are closely related to the known yttrium transition metal sulfates.     

Sol-Gel Preparation and Phase Transition of RE Orthoborates

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Microstructures and Phase Transition Points of As-Cast Mg-Zn-Y System Alloys

As-east mierostruetures and their distribution of Mg-Zn-Y ternary alloy with high magnesium, low zinc and yttrium were examined using Nikon Epiphot optical microscopy （OM）, RigakuD/max-3C X- ray diffraetion （XRD）, and JEOL JSM-6700F scanning electron microscopy （SEM） equipped with an energydispersive X-ray spectroscopy （EDS）. In the as-east mierostructures, Yttrium and zinc tend to segregate at grain boundaries,     

离子交换树脂光度法测定合金样中的稀土总量

离子交换树脂光度法可直接将被测化学组分同时浓集和选择性吸附于树脂上进行光度测定,不需预浓缩和分离,故具有比溶液光度法更高的灵敏度和选择性,同时简化了分析手段,可检测样品液中痕量金属离子的含量。研究了TBA-稀土络合物定量富集在强碱性的阴离子交换树脂上的最佳实验条件,并直接测定了合金样中的稀土总量。     

GdMn2Ge2化合物的磁性和磁相变的分子场理论研究

采用交换作用的分子场理论模型对金属间化合物CdMn2Ge2的磁性、磁结构和磁相变进行了研究。理论分析和计算结果表明，CdMn2Ge2中存在5种不同类型的磁结构，外磁场以及温度的变化导致CdMn2Ge2从一种磁结构到另一种磁结构的一级或二级磁相变。计算了不同温度时GdMn2Ge2单晶的磁化曲线，并给出了外磁场沿晶轴α和c方向时的H-T磁相图，估计了Gd-Gd，Gd-Mn，层面内及层面间Mn-Mn的交换耦合参数。结果显示，要描述GdMn2Ge2的磁性，必须考虑晶格常数和温度对层面间Mn-Mn交换相互作用的影响。     

复合相变技术在锅炉上的应用

针对沙钢220 t/h煤气锅炉目前存在低温受热面严重腐蚀、排烟温度高、损失明显的现状,应用复合相变换热技术进行节能工艺改造,实现壁面温度可控可调,并在保证受热面不结露的前提下降低排烟温度,有效提高设备的热效率和防腐能力。     

Rietveld法模拟测算稀土双相永磁合金中物相的含量

用Rietveld法模拟计算稀土双相永磁合金Nd2Fe14B／α-Fe的X射线衍射谱(XRD)，并根据多相体模型与无标定量相分析法确定各物相的含量。此外，通过结构精修也可以进一步提取诸如纳米晶尺寸等微结构信息。对一组快淬Nd2Fe14B合金经700℃和不同时间退火(晶化处理)的样品进行α-Fe含量的测定结果表明，实测结果与实际工艺相吻合。该法可以推广应用于其他稀土双相永磁合金如Pr2Fe14B／α-Fe(或Fe3B)的相含量测定与微结构分析。     

Magnetic Phase Transition and Magnetic Entropy Change in La0.8Pr0.2Fe11.4Si1.6 Compound

The magnetic properties and the phase transformation of the partial substitution of Pr for La in LaFe11.4Si1.6 have been investigated by the means of X-ray diffraction (XRD) and vibrating sample magnetic (VSM). The results indicated that the single phase NaZn13-type cubic structure is stabilized for the compound La0.8Pr0.2Fe11.4Si1.6 and large values of the isothermal magnetic entropy change △SM around the curie temperature Tc~194 K in relative low magnetic fields. The maximum value |△SM|max~37.07J/kg·K-1 under a field of 1.5 T. Such large MCEs are attributed to the sharp change of the magnetization at the Curie temperature, the field-induced IEM transition and a strong temperature dependence of the critical field BC.     

纳米尺度析出相透射电镜的统计分析技术探讨

纳米级析出相在钢中起到析出强化作用或者作为晶粒生长的抑制剂，来获得特定取向的织构，因此，对析出相进行系统分析非常重要。目前通过扫描电镜和透射电镜很难实现纳米尺度尤其是50 nm以下析出相的统计分析工作。实验通过将扫描电镜夹杂物统计的Feature软件包应用到透射电镜的能谱控制软件中，从而实现了透射电镜直接对钢中纳米尺度析出相的统计。同时对透射电镜进行析出相统计中的主要影响因素如样品制备方法、采集参数、分类方法和大面积统计方法等进行了深入研究。结果表明，实验最佳条件为采用新的复型方法制样，能谱单点采集时间为5 s,图像分辨率为2 048,连续采图统计，终止条件为析出相统计数量过100个，确定了析出相制定分类规则的具体实现方法。结合无取相电工钢W800和WH470的实验统计结果可知，其析出相种类有CuS₂和MnS+CuS₂的核壳复合析出，且实验方法能够统计分析的析出相最小尺寸为10 nm。     

RECl3-SrCl2-LiCl三元系相图计算

基于对9个侧边二元系RECl₃-SrCl₂、RECl₃-LiCl、SrCl₂-LiCl(其中RE:La、Ce、Pr、Nd)热力学数据和实验相图信息的优化、评估,以及三元系相关热力学性质的分析,计算并讨论了RECl₃-SrCl₂-LiCl系列4个三元系相图。     

Stability of phases in （Ba,Gd）MnO3 solid solution system

The existing phases in BaxGd1-xMnO3 solid solution system （0≤x≤ 1） were studied by analyzing the detailed crystal structure of each composition from the results of the Rietveld method using powder X-ray diffraction data. For a small substitution of Ba for Gd （0≤x〈0. 1）, the orthorhombic phase with a perovskite type structure （Pnma space group） was stably formed and this fact was supported by the electron diffraction data. There existed an intermediate phase of Ba0.33Gd0.67MnO3, which was characterized as the tetragonal phase with perovskite structure. The composition range of this phase was narrow and almost line compound. Between the regions of these phases, there existed two-phase region. There was also a two-phase region between the intermediate tetragonal phase and BaMnO3. Measurement of electrical conductivities of these orthorhombic solid solutions and tetragonal phases showed semiconducting behaviors for both phases and the existence of the phase transition at high temperature for the orthorhombic phase, The transition temperature decreased as the Ba content increased.     

卷取温度对纳米析出高强钢中析出相的影响

以新型热轧纳米析出强化钢为研究对象,利用透射电子显微镜分析了不同卷取温度下纳米析出相的形貌特征及尺寸分布。分析结果表明,当卷取温度小于650℃时,纳米析出颗粒尺寸小,但数量较少,对高强钢力学性能的贡献有限;当卷取温度高于650℃时,纳米析出颗粒逐渐长大并粗化,这也不利于提高材料的强度;只有当卷取温度为650℃时,钢中纳米析出颗粒无论是数量还是尺寸,均更有利于纳米析出高强钢获得优异的力学性能。     

奥氏体不锈钢物相的精细结构表征

以热轧态316L不锈钢为研究对象,首先利用X射线衍射仪(XRD)对其主要物相进行标定,进而利用透射电镜(TEM)的选区电子衍射和高分辨像功能确认了χ相的存在。然后利用透射电子背散射衍射技术(t-EBSD)对所有物相的分布进行表征,与常规电子背散射衍射(EBSD)的结果进行比较,准确显示了χ相的分布特征。结果表明,组织中以奥氏体基体相和带状组织为主,带状组织中主要含有σ相,还有少量的铁素体相和奥氏体相,χ相不仅存在于带状组织中,还存在于奥氏体基体中,且χ相和σ相中都富含Fe、Cr、Mo元素。     

Electrical and Magnetic Properties of Bilayer Manganites La1.4Sr1.6Mn1.96TE0.04O7 （TE = Mn, Fe, Ti, Nb）

The electrical and magnetic properties of bilayer manganites La1.4Sr1.6Mn1.96TE0.04O7（TE = Mn, Fe, Ti, Nb） were investigated. Doping caused obvious changes in electrical and magnetic behaviors such as decrease of insulator-metal transition and magnetic transition temperatures, increase of peak resistivity, and different magnetoresistance effect. These changes had a significant degree of correlation with the valence of doped ions. From Fe, Ti to Nb doping, the effect was doubly stronger. The results could be well understood by considering the different destructions on double-exchange interaction and different influences on lattice distortion caused by Fe, Ti and Nb doping. The temperature dependence of magnetization measured at high field showed that the influence of doping was greatest near three-dimensional magnetic transition temperature of parent phase.     

冷却制度对包钢钢渣物相演变的影响

文章通过将充分熔融后的转炉渣以水淬、热泼、空冷和炉冷4种不同的冷却方式冷却,来研究不同冷速下转炉渣物相演变规律,以了解包钢钢渣基础物相规律。研究表明,以相同的冷却方式处理后,不同钢渣中的矿物相种类大致相同。对于同一种转炉渣,冷却速度越缓慢,析出的矿物相种类越复杂,且分布形态更杂乱,但含铁相却有进一步富集的趋势。     

Gd_5Si_(1.8)Ge_(1.8)Sn_(0.4)合金的高温相变

为认识合金的高温相变,采用热分析技术对Gd5Si1.8Ge1.8Sn0.4合金可能的高温相变进行了定性研究,并利用高温XRD研究了合金在200～400℃之间的相结构。研究结果表明:升温过程中,Gd5Si1.8Ge1.8Sn0.4合金在200～300℃之间发生了由Gd5Si2Ge2-型单斜结构向Gd5Si4-型正交结构的转变。从而为探索材料方便快捷的制备工艺提供技术支持。