助剂对铁系CO变换催化剂结构和稳定性影响的X—射线衍射研究

采用Ｘ－射线衍射法测定加入助剂Ｃｒ２Ｏ３，Ｂｉ２Ｏ３，ＣｅＯ２的γ－Ｆｅ２Ｏ３催化剂还原前后的物相及氧化铁晶胞参数和晶粒度，结果表明，Ｃｒ２Ｏ３，Ｂｉ２Ｏ３，ＣｅＯ２都没有取代Ｆｅ２Ｏ３晶胞中的铁原子，但它们在催化剂中的作用是不同的。Ｃｒ２Ｏ３和Ｂｉ２Ｏ３进入Ｆｅ２Ｏ３的晶格中，能抑制氧化铁晶粒的长大，提高了催化剂活性和稳定性；     

助剂对铁系CO变换催化剂结构和稳定性影响的X-射线衍射研究

采用Ｘ－射线衍射法（ＸＲＤ） 测定加入助剂Ｃｒ２Ｏ３、Ｂｉ２Ｏ３、ＣｅＯ２ 的γ－Ｆｅ２Ｏ３ 催化剂还原前后的物相及氧化铁晶胞参数和晶粒度, 结果表明, Ｃｒ２Ｏ３、Ｂｉ２Ｏ３、ＣｅＯ２ 都没有取代Ｆｅ２Ｏ３ 晶胞中的铁原子, 但它们在催化剂中的作用是不同的。Ｃｒ２Ｏ３ 和Ｂｉ２Ｏ３ 进入Ｆｅ２Ｏ３ 的晶格中, 能抑制氧化铁晶粒的长大, 提高了催化剂的活性和稳定性; 而ＣｅＯ２ 则堆积在氧化铁表面, 它对氧化铁晶粒的长大作用不大, 它使催化剂活性大大提高必定有其它因素起作用。     

Bi2O_3－Fe_2O_3系陶瓷材料的气－湿－温多功能特性

利用Ｘ射线衍射（ＸＲＤ）分析了烧结温度及Ｂｉ／Ｆｅ比对Ｂｉ２Ｏ３－Ｆｅ２Ｏ３系物相组成的影响。初步探讨了材料的导电类型、气敏性能及阻－湿特性，结果表明Ｂｉ２Ｏ３－Ｆｅ２Ｏ３系有可能作为一种气－湿－温多功能敏感材料体系     

Cr_2O_3对PbO－Bi_2O_3－B_2O_3玻璃颜色及析晶性能的影响

Ｃｒ_２Ｏ_３对ＰｂＯ－Ｂｉ_２Ｏ_３－Ｂ_２Ｏ_３玻璃颜色及析晶性能的影响郝德生（齐齐哈尔轻工学院１６１００６）ＥｆｆｅｃｔｓｏｆＴｒａｃｅＣｒ２Ｏ３ｏｎＣｏｌｏｒａｔｉｏｎａｎｄＮｕｃｌｅａｔｉｏｎｏｆＰｂＯ－Ｂｉ２Ｏ３－Ｂ２Ｏ３ＧｌａｓｓＳｙｓｔｅｍ...     

Bi2O3—Fe2O3系陶瓷材料的气—湿—温多功能特性

利用Ｘ射线衍射（ＸＲＤ）分析了烧结温度及Ｂｉ／Ｆｅ比对Ｂｉ２ｏ３－Ｆｅ２Ｏ３系组成的影响。初步了材料的导电类型、气敏性能及阻－湿特性，结果表明Ｂｉ２Ｏ３－Ｆｅ２Ｏ３系有可能作为一种气－湿－温多功能敏感材料体系。     

SOL—GEL法制备新型复合磁粉

本文产次报导用ＳＯＬ－ＧＥＬ法制备钡铁本泡覆纺锤形α－Ｆｅ２ｏ３粉末。ＢＦ－α－Ｆｅ２Ｏ３可以在３８０℃，还原气氛下制成包钡铁氧体的γ－Ｆｅ２Ｏ３复合磁粉。     

MgO—B2O3—SiO2三元系1100℃等温截面的应用

采用粉末烧结方法制备ＭｇＯ－Ｂ２Ｏ３－ＳｉＯ２三元系不同组成的样品，用Ｘ－射线衍射、岩相和化学分析方法结合研究了１１００℃４０≤ＭｇＯ％〈６０组成范围内的相关系，结果表明可用３ＭｇＯ．Ｂ２Ｏ３－２ＭｇＯ．ＳｉＯ２－２ＭｇＯ．Ｂ２Ｏ３，２ＭｇＯ．Ｂ２Ｏ３－２ＭｇＯ．ＳｉＯ２－ＭｇＯ．ＳｉＯ２，２ＭｇＯ．Ｂ２Ｏ３－ＭｇＯ．ＳｉＯ２－ＳｉＯ２三个三角形表示各平衡相的相关系。应用重心规则计算平衡相量与组成     

CaO－Al_2O_3－SiO_2玻璃表面上晶体生长动力学和分相影响

ＣａＯ－Ａｌ＿２Ｏ＿３－ＳｉＯ＿２玻璃表面上晶体生长动力学和分相影响杨晓晶，李家治（中国科学院上海硅酸盐研究所２０００５０）许淑惠（西北轻工业学院７１２０８１）ＳｕｒｆａｃｅＣｒｙｓｔａｌＧｒｏｗｔｈＫｉｎｅｔｉｃｓｉｎＣａＯ－Ａｌ＿２Ｏ＿３－ＳｉＯ...     

CeO2基电解质材料的扫描电镜观察

用Ｓｍ２Ｏ３和Ｇｄ２Ｏ３共同掺杂ＣｅＯ２基电解质组分（ＣｅＯ２）０．９（Ｓｍ２Ｏ３）０．０５（Ｇｄ２Ｏ３）０．０５随着烧结温度的提高，晶粒持续长大，由１４００℃烧结时的２－３μｍ长大到１６００℃烧结时的１０－１２μｍ，单位尺寸内的晶界数量减少；各温度烧结样品的断口都呈穿晶断裂。     

溶胶—凝胶法合成了BaAl2Si2O8超细粉末的研究

以Ｂａ（ＯＨ）２．８Ｈ２Ｏ，Ａｌ（ＮＯ３）３．９Ｈ２Ｏ，ＴＥＯＳ为原料，采用溶胶－凝胶法制备ＢａＯ－Ａｌ２Ｏ３－ＳｉＯ２三元系粉末，研究了不同因素对生成稳定溶胶和胶化时间的影响，用ＴＧ－ＤＴＡ，ＸＲＤ研究了溶胶－凝胶的热处理过程，用ＴＥＭ观察了粉体的粒径。     

Crystallographic Properties of Hydrothermal Barium Titanate Crystallites

The crystallographic properties and defects of hydrothermally grown barium titanate crystallites are reported. When a precursor with a Ba:Ti molar ratio of 1.0 was used, cubic barium titanate crystallites were formed. However, when the precursor Ba:Ti molar ratio was 3.0, the product was tetragonal. The defect concentration (including OH defects and barium vacancies) was higher in cubic crystallites than in tetragonal crystallites. Because of the defects in the crystallites, the displacement of Ba²⁺ cations and the deformation of the Ti-O₆ octahedrons was suppressed; thus, no phase transition from cubic to tetragonal occurred at the Curie point. When the defects were eliminated by thermal treatment, the normal crystallographic properties were obtained. A high reaction temperature and a high Ba:Ti molar ratio in the precursor were beneficial to limiting defect dormation in the crystallites; thus, tetragonal crystallites were obtained.     

Electrical resistivity of porous carbon materials, “Woodceramics” at low temperatures

Woodceramics obtained by carbonizing woody materials are new carbon materials recently developed for industrial use. They are porous, light, hard and cheap to produce and have heat and corrosion resistance. They are being considered for applications in various fields. We investigated the dependence of the electrical resistivity of Woodceramics at temperatures between 100 K and 300 K, and considered the conduction mechanism of Woodceramics which are porous conductors. The electrical resistivity of Woodceramics decreases as sintering temperature increases. It varies over a wide range. And the resistivity dependence on the temperature of Woodceramics is similar to that of a semiconductor. We propose that the semiconducting behavior is caused by an energy gap decrease which depends on the sintering temperature, as a result of change in size of the graphite micro-crystallites in glassy carbon which is present in Woodceramics.     

The Sintering of Supported Metal Catalysts

Metal catalysts are commonly employed in the form of metal dispersed as small crystallites on high surface area supports. The use of these supported metal catalysts increases the utilization of the metal as a catalyst since a large fraction of the metal atoms are at the surface of the small metal crystallites. Another important function of the support is to physically separate the small metal crystallites and thereby hinder the agglomeration of the small metal crystallites into larger crystallites. This agglomeration would decrease the number of surface metal atoms per unit mass of metal, and thereby decrease the utilization of the metal and the activity of the catalyst.     

Dynamic mechanical analysis of fibers. II. Estimation of fiber orientation and characterization of heat set PET yarns

A drawn PET yarn was heat set (annealed) at temperatures between 110°C and 245°C in an unconstrained mode and the samples characterized by dynamic mechanical analysis (DMA). A method for estimating the fiber orientation factor (α) is proposed using DMA and shown to be more sensitive than the crystalline orientation (x-ray diffraction) or total orientation (birefringence) measurements of the heat set yarns. The extension/shrinkage behavior of the heat set yarns has been discussed in the light of morphological changes, e.g., degree of orientation and the micro-crystallite formation. Unlike in the unconstrained mode, heat setting under constraint does not lead to the formation of micro-crystallites as revealed by differential scanning calorimetry. As a consequence, although the modulus and degree of orientation increase upon constrained annealing, the thermal stability, i.e., loss of orientation (reflected by shrinkage) could not be improved.     

Crystallization and melting behavior in syndiotactic polypropylene: Origin of multiple melting phenomenon

The melting behavior of syndiotactic polypropylene (s‐PP) after isothermal crystallization from the melt state was studied using differential scanning calorimetry (DSC) and wide‐angle X‐ray diffraction (WAXD) techniques. Three melting endotherms were observed for isothermal crystallization at high degrees of undercooling. The minor endotherm, located closed to the corresponding crystallization temperature, was postulated to be the melting of the secondary crystallites formed at the crystallization temperature. The low‐temperature melting peak was found to be the melting of the primary crystallites formed, and the high‐temperature melting peak was a result of the melting of the crystallites recrystallized during a heating scan. The triple‐melting behavior observed in subsequent melting endotherms of s‐PP was therefore described as contributions from melting of the secondary crystallites and their recrystallization, partial melting of the less stable fraction of the primary crystallites and their recrystallization, melting of the primary crystallites, and remelting of the recrystallized crystallites formed during the heating scan. In addition, determination of the equilibrium melting temperature for this s‐PP resin according to the linear and nonlinear Hoffman–Weeks extrapolations provided values of 143.1 and 185.6°C, respectively. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1083–1097, 2001     

水热法制备氧化锌陶瓷粉体中的形态调制

水热条件下制备超细微晶是一个晶体生长的过程。本文根据晶粒形态与水热介质碱度强弱之间的关系,揭示了不同形态的ＺｎＯ的形成机理,实现了水热法氧化锌陶瓷微晶制备过程中的形态调控。     

纳米CdSe_xS_(1-x)微晶玻璃的光吸收性能

半导体纳米微晶掺杂滤光玻璃由于具有优异光学性质 ,近年来已成为光电子材料科学与技术关注的焦点之一。以硼硅酸盐玻璃为基质 ,通过对掺杂微晶组成、结构的设计以及颗粒尺寸的控制 ,系统的研究了纳米微晶的组成、结构以及纳米颗粒尺寸效应等因素对玻璃光吸收性能的影响。结果表明 ,玻璃吸收曲线的截止波长位置以及截止吸收系数主要取决于半导体纳米CdSexS1-x微晶的组成 ,吸收曲线的斜率取决于纳米微晶的颗粒尺寸分布     

Bimodal crystalline orientation in polypropylene: Mechanism of formation

Melt-spun polypropylene fibers have two sets of crystallites, each with a different preferred orientation. A probable kinetic mechanism of nucleation and growth of the two sets of crystallites, based on an analysis of crystallization in oriented polymers, is proposed. Experimental data on the fractions of these two sets of crystallites in as-spun fibers and the effect of subsequent drawing or thermal annealing on the relative amounts of these two sets are presented.     

超细水杨酸的制备

采用晶体生长抑制剂技术,制备了超细水杨酸晶体。以相对分子质量为600的聚乙二醇为水杨酸晶体生长抑制剂时,制备的水杨酸针状体的直径范围为100nm~5μm。当聚乙二醇的相对分子质量为2000时,制备的水杨酸针状体的直径范围为500nm~5μm。在水杨酸晶体生长过程中,通过聚乙二醇的羟基与水杨酸的羧基的相互作用控制了水杨酸晶体的大小。用季戊四醇为水杨酸晶体生长抑制剂时,制备出了平均直径为8μm的棒状水杨酸晶体。     

Hydrothermal synthesis and characterization of multiferroic Bi1−xLaxFeO3 crystallites

Bi_1?xLa_xFeO₃ (BLFO, x = 0.0–0.2) crystallites were synthesized by the hydrothermal route. X-ray diffraction results indicate that pure BLFO crystallites could be obtained for x ≤ 0.1, and the phase purity was sensitive to the PH value of precursor solutions. Transmission electron microscope observation reveals that needle like BLFO crystallites were formed for x = 0.1. The coexistence of ferroelectric and magnetic transition is detected by using differential thermal analysis, indicating the multiferroic characteristics of BLFO crystallites. The Néel temperature of BLFO crystallites for x = 0.1 shifts upwards, whereas the Curie temperature shifts downwards, compared with those of BFO crystallites without La substitution. Weak ferromagnetic property of BLFO crystallites was induced and enhanced with increasing the La content.