新型陶瓷材料的光激励发光性质研究

针对以往电子俘获光存储材料存在的问题，利用高温固相反应发制备了一种Eu^2 掺杂的氟氧化物玻璃陶瓷，研究表明在该材料中具有光激励发光(PSL)特性，并可用于电子俘获光存储。XRD分析表明该材料含有大量的BaF2微晶。根据其与BaF2相似的发光特性，推断玻璃陶瓷的PSL有可能来源于微晶中Eu^2 的5d-4f发射。但是决定光激励发光过程中的电子(空穴)陷阱的存在方式、电子迁移途径都有待进一步探讨的问题。与传统的BaFCl：Eu相比，这种材料的光激励发光衰减速度较慢。     

Thermal behaviour of amorphous Li2ZrO3 prepared by sol-gel technique

The results of the investigations of thermal behaviour of Li₂ZrO₃, prepared in the amorphous state by means of sol-gel technique are demonstrated. The thermal treatment was carried out in air under constant heating rate of 5 deg·min^–1 and cooling rate of 2.5 deg·min^–1. The methods of DTA, TG, Emanation Thermal Analysis (ETA) and dilatometry were used, for characterization of the thermal behaviour in dynamic conditions. The X-ray diffraction patterns were used for characterization of the phase changes observed by TA Methods.

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Zusammenfassung Ergebnisse aus Untersuchungen des thermischen Verhaltens von Li₂ZrO₃, hergestellt mittels einer Sol-Gel-Technik im amorphen Zustand werden dargelegt. Die thermische Behandlung wurde in Luft bei einer konstanten Aufheizgeschwindigkeit von 5 Grad·min^–1 und einer Abkühlgeschwindigkeit von 2,5Grad·min^–1 durchgeführt. Zur Beschreibung des thermischen Verhaltens unter dynamischen Verhältnissen wurden DTA, TG, Emanationsthermoanalyse und Dilatometrie angewendet. Zur näheren Charakterisierung der bei TG beobachteten Phasenumwandlungen wurde Röntgendiffraktion verwendet.

     

Shear and NMR experiments of materials with flow behaviour depending on the deformation history

Oxide ceramic masses react to simple shearing with hardening (peptisation: increase in the shear stress with the shear deformation). In the present study the correlation between the increase in the shear stress and the porosity, agglomeration processes and the type of flow are analysed. For this purpose oxide ceramic masses are tested in a shear device especially developed for pastes and analysed by rheometric experiments, NMR methods and particle size analysis. The results support the hypothesis that structural changes (hardening, increase in the mean porosity) of the material during the peptisation mainly depend on the magnitude and not on the kind of the energy input and thus of the type of flow. The fraction of bound (more generally, the immobilised) water increases with the shear displacement. Also crushing of primary particles could be observed. Both the crushing of solid particles causing an increased solid surface and the formation of a three-dimensional gel structure are microscopic effects capable of resulting in the binding or retaining water. On a macroscopic scale these phenomena cause hardening. Magnetic resonance imaging visualises flow-induced agglomerates, which form owing to the shear flow and increase the porosity averaged over the whole sample. After the shear experiment rolls of paste can be seen which indicate that the general assumption of a plane shear flow in the shear device is not warrantable. Received: 19 July 2001 Accepted: 25 October 2001     

Templated ceramic microstructures by using the breath-figure method

We describe the synthesis of two cyclobutadiene(cyclopentadienyl)cobalt-containing poly(p-phenylene ethynylene)s (PPEs) and their use as precursors for stable ceramic surface coatings. Organometallic PPEs were shaped into hexagonally ordered assemblies by using the breath-figure method. Such breath figures can be washed away with an appropriate solvent. Upon pyrolysis at 500 degrees C under either nitrogen or air, the bubble arrays persist as ceramics and are insoluble in organic solvents or water. The formed pyrolyzed bubble arrays were analyzed by optical and scanning electron microscopy, as well as energy dispersive X-ray microanalysis (EDX). The composition of the ceramic materials is discussed based on EDX and IR data.     

An investigation into the self-propagating high temperature synthesis (SHS) of superconducting ceramics by thermal methods

The SHS route is based on the well-known thermite reaction, in which a strongly exothermic reaction can sustain itself and propagate in the form of a combustion wave until the reactants have been completely consumed. The successful application of the method to the synthesis of superconducting ceramics of stoichiometry RBa₂Cu₃O_y (R=Y, Er, Yb) is reported. The 123 phase was obtained when pellets of R₂O₃, BaO₂ and Cu metal in the correct proportions were dropped into a heater held at 800°C in an oxygen atmosphere and left there for only 10 minutes. Thermal methods (DSC and DTA) are excellent techniques with which to investigate the dependence of the reaction on heating rate, atmosphere and starting composition.     

成骨肿瘤细胞在纳米氧化钛陶瓷表面的生物活性研究

以羟基磷灰石和氧化镁为晶粒生长抑制剂制备的纳米氧化钛陶瓷为研究对象, 采用体外成骨细胞Ros17/28与材料复合培养的方法, 通过MTT法、荧光染色法和SEM细胞形貌观察等手段综合判断细胞在材料表面的活性, 以此评价纳米氧化钛陶瓷的生物活性. 结果表明, 以羟基磷灰石为晶粒生长抑制剂的氧化钛陶瓷晶体颗粒尺寸达到纳米级, 其生物活性超出了以氧化镁为晶粒生长抑制剂的氧化钛陶瓷和纯羟基磷灰石陶瓷, 具有优异的生物相容性, 是生物活性陶瓷.     

碳酸盐前驱物制备Y2O3超细粉及透明陶瓷

以Y(NO3)3和NH4HCO3为原料,通过向Y(NO3)3溶液中滴加NH4HCO3的方式制备了化学组成为Y2(CO3)3·2H2O的先驱沉淀物。研究了先驱沉淀物煅烧过程中的物相变化。先驱沉淀物1100℃煅烧4h后得到了平均粒径为60nm的无团聚Y2O3超细粉体。所得粉体不添加任何添加剂,在1700℃下真空烧结4h得到了透明Y2O3陶瓷。     

The investigation of ancient pottery

Summary Ancient ceramic samples (single fragments and different parts of pots, unbroken and repaired; total about 180 samples) dated from the transitional period of late Bronze to early Iron Age (VIII-VI centuries BC) and early Iron Age (VII-IV centuries BC) were investigated by thermal analysis, X-ray powder diffraction, petrography, and scanning electron microscopy equipped with the energy-dispersive X-ray analyzer. In addition to that, to identify the clay sources for the ceramic manufacturing, about 15 samples of clays and soils found near archeological digs and taken from the mineralogical museum were investigated. We found out that the calcite content of ceramics is a very informative parameter for the identification of the clay source for the pottery manufactured at low technological level (low-temperature firing).     

ZnVSb基压敏陶瓷中尖晶石相形成机理的研究

ZnO压敏电阻陶瓷是一种典型的“晶界特性”功能陶瓷材料，材料的宏观电学特性与陶瓷的显微组织结构有密切联系。由于ZnSb尖晶石相在使ZnO基压敏电阻陶瓷显微形貌细化和均匀化方面有明显促进作用，自ZnO基压敏电阻发明以来．ZnSb尖晶石在其中的形成机理就成为该陶瓷研究领域的热点。     

AES investigations on starting powders for high performance ceramics

AES depth profiles on ceramic powders (untreated/hydrolyzed/oxidized/ (Al, Y)₂O₃ coated Si₃N₄, [BaO, SiO₂] coated Al₂O₃) are feasible on thin, homogeneous layers or m sized agglomerations prepared on an Au foil. By means of the depth profiles one can qualitatively characterize the coating around the particles. Factor analysis of the depth profiles on the differently treated Si₃N₄ powders suggests the existence of an Si₂N₂O phase on the oxidized sample.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday