Single crystal growth and characterization of LaLuO3

Wide shoulder and fast lateral growth are characteristics of LaLuO₃ during crystallization onto an iridium rod in Czochralski's configuration. Under careful temperature control, necking in and further low-speed pulling provided for single-crystal growth, but spontaneous separation of the growing crystal from the melt is a strongly limiting factor for production of large boules. Ce- and Pr-doped single crystals of up to 0.5 cm³ were obtained and used in measurements of the X-ray data, density, melting point and optical properties and in annealing studies.     

无机闪烁体CeF3的时间特性

本文用脉冲γ源方法实验测量了北京玻璃研究院生产的新型无机闪烁体CeF3的发光衰减常数，得出了该种闪烁体的两种发光成分：对于直径为45mm，厚度分别为14．5，10，4．5和3mm的4个闪烁体，其发光衰减时间的快成分在12．1－9．9ns，慢成分在34．0－30．7ns，等效衰减时间常数在26．2－20．8ns，随着闪烁体厚度的增加发光时间变慢。     

Cerium: a suitable green corrosion inhibitor for tinplate

In chloride solutions, tinplate exhibits localised corrosion processes due to the defects or imperfections of the outer Sn layer, which leaves the Sn-Fe alloyed layer exposed to aggressive solutions. The anodic character of the external Sn with respect to the internal alloyed layer, will lead to its dissolution acting as a sacrificial anode. The addition of cerium salts to the aggressive media decreases the pitting susceptibility of tinplate by means of cerium precipitation on the cathodic sites (bare Sn-Fe areas). This induces to a change of the controlling mechanism suggesting that cerium is a cathodic inhibitor for tinplate, which could be corroborated by removal selectively the outer Sn layer and leaving the Sn-Fe layer directly exposed to the solution. In these conditions, the corrosion process of the steel base will take place through the defects of the Sn-Fe layer, which presents a cathodic character in comparison to the base metal, inducing the precipitation of cerium on the alloyed layer.Scanning electron microscopy and energy dispersive spectroscopy analysis revealed that the location of cerium precipitates depend on the distribution of the cathodic areas that could lead either to a continuous layer covering the surface or to precipitates inside the mechanical failures.     

Cerium Distribution in Spheroidal Graphite of Cast Iron

Six thin sections of spheroidal graphites in cast iron have been investigated by TEM and SEM.Thespheroidal graphites consist of two or three layers and have nuclei which are composed of Ce_2O_2S and Ce_2O_3.Cerium is existed ont only in nuclei,but also in central layer and middle layer of graphite.     

Catalyst Synthesis Using Supercritical Carbon Dioxide: A Green Route to High Activity Materials

Catalysts are intrinsically considered to be a key part of green and sustainable technology. However, many catalysts require the use of non-green methodologies during their manufacture. With the increased focus on green issues that is now emerging, it is essential that some attention is focussed on synthesing catalysts using green approaches. However, it is critical that any material prepared using these new green methods has to exhibit key advantages over current technology, such as significantly enhanced performance, if they are o be adopted in this competitive industry. Here the use of supercritical carbon dioxide as an anti-solvent is discussed and two examples, namely the synthesis of vanadium phosphate and ceria-supported gold catalysts, are described using supercritical carbon dioxide in the preparation. Both of these examples demonstrate significant advantages with respect to higher activity when compared with catalysts prepared using standard methods.     

Utilization of carbon dioxide as soft oxidant for oxydehydrogenation of ethylbenzene to styrene over V2O5–CeO2/TiO2–ZrO2 catalyst

Vanadium oxide and cerium oxide doped titania–zirconia mixed oxides were explored for oxidative dehydrogenation of ethylbenzene to styrene utilizing carbon dioxide as a soft oxidant. The investigated TiO₂–ZrO₂ mixed oxide support with high specific surface area (207 m² g⁻¹) was synthesized by a coprecipitation method. Over the calcined support (550 °C), a monolayer equivalent (15 wt.%) of V₂O₅, CeO₂ or a combination of both were deposited by using wet-impregnation or co-impregnation methods to make the V₂O₅/TiO₂–ZrO₂, CeO₂/TiO₂–ZrO₂ and V₂O₅–CeO₂/TiO₂–ZrO₂ combination catalysts, respectively. These catalysts were characterized using X-ray diffraction (XRD), Raman, scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature preprogrammed reduction (TPR), CO₂ temperature preprogrammed desorption (TPD) and BET surface area methods. All characterization studies revealed that the deposited promoter oxides are in a highly dispersed form over the support, and the combined acid–base and redox properties of the catalysts play a major role in this reaction. The V₂O₅–CeO₂/TiO₂–ZrO₂ catalyst exhibited a better conversion and product selectivity than other combinations. In particular, the addition of CeO₂ to V₂O₅/TiO₂–ZrO₂ prevented catalyst deactivation and helped to maintain a high and stable catalytic activity.     

Controlled growth of Bi-Functional La doped CeO2 nanorods for photocatalytic H2 production and supercapacitor applications

The rapid increase in energy consumption has severely rehabilitated human life urging to develop reliable and environmental friendly energy storage devices. Target oriented, systematic approach has been adopted to synthesis La doped CeO₂ nanostructures with percentage as La_xCe_1-xO₂ (X = 0,1,3,5,7) for potential super capacitors applications. Morphological doping impact on H₂ production, electrochemical and optical properties are thoroughly investigated. XRD studies revealed the crystalline phase purity and attained approximately 35 nm average crystallite size. The SEM images exposed that primary morphology nano-particles has been tuned into nanorods by increasing the La concentration in CeO₂ with size range 40～60 nm. CV graphs depicted that the prepared electrodes obey the pseudo capacitive faradaic reactions behavior in nature. Maximum capacitance (925 F g^-1) has been achieved by La_0·05Ce_0·95O₂ which is better than numerous reported materials. The La_0·05Ce_0·95O₂ also exhibited excellent GCD stability with 87.8% retention exhibiting it suitability for supercapacitor applications. Furthermore, the La_0·05Ce_0·95O₂ showed the significantly higher H₂ (9 μmol h^?1g^?1) production rate as compared to undoped CeO₂ and La_0·01Ce_0·99O_2, La_0·03Ce_0·97O₂ samples. This higher production is attributed to the recombination rate and have strong substantial correlation with optical characteristics.     

Electric field-assisted synthesis/sintering cerium oxide: 5 wt.% gadolinium oxide

Gadolinium oxide ceramic powders were mixed to cerium oxide ceramic powders, pressed to pellets, and sintered either at 1450 °C or applying 200 V cm⁻¹ electric field at 800 °C, 900 °C and 1000 °C. The structural phases and the microstructure of the sintered pellets were analyzed by X-ray diffraction and scanning electron microscopy, respectively. The formation of substitutional solid solution was followed by monitoring the increase of the electrical conductivity by impedance spectroscopy and X-ray diffraction. The main results show that Joule heating due to the flow through the pellets of the electric current, which was produced by the application of the electric field, allows for promoting partial solid solution as well as partial sintering the ceria-gadolinia pellets. Moreover, grain growth that occurred in the high temperature sintered pellets was inhibited in the electric field-assisted synthesized/sintered pellets, being an alternative technique for producing cerium oxide-gadolinium oxide solid solutions.     

Photoluminescence and decay characteristics of cerium,gallium and vanadium - containing borate-based bioactive glass powders for bioimaging applications

Biomaterials having photoluminescent properties play a crucial role in real-time bioimaging after in vivo implantation. In this study, photoluminescence properties and decay characteristics of the borate-based 13–93B3 glasses containing different concentrations of cerium, gallium, and vanadium oxides were investigated for biomedical applications. The borate-based bioactive glass powders were prepared using melt-quench technique and size reduction was performed through planetary ball milling. Bioactivity of the prepared powders was investigated in simulated body fluid at 37 °C under static conditions. The photoluminescent properties and decay kinetics of the as-prepared and the SBF-treated bioactive glass powders were analyzed by steady-state and time-resolved photoluminescence measurements. Results revealed that the cerium activated glasses exhibited an intense luminescence centered at 538 nm. Broad-band emission of the gallium and vanadium doped samples was centered at 440 and 572 nm, respectively. All of the SBF-treated glasses exhibited enhanced lifetimes and bi-exponential decays both in nanosecond and microsecond regime measurements. It was concluded that depending on the dopant concentration, bioactive glass particles prepared in the study showed remarkable photoluminescence and have potential to be used in bioimaging applications.     

Advanced visible-light photocatalytic property of biologically structured carbon/ceria hybrid multilayer membranes prepared by bamboo leaves

Biologically structured carbon/cerium dioxide materials are synthesized by biological templates. The microscopic morphology, structure and the effects of different oxidation temperatures on materials are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) ultraviolet-visible light spectrum (UV–Vis) and X-ray Photoelectron Spectroscopy (XPS). Moreover, by splitting water under visible light irradiation, the hydrogen production is measured to test the photocatalytic property of these materials. The results show that materials made with bamboo biological templates which are immersed in 0.1 mol L^?1 of cerium nitrate solution, then carbonizated in nitrogen (700 °C) and oxidized in air (500–600 °C), can obtain the biological structure of bamboo leaves. The product is in the composition of hybrid multilayer membrane, which one is carbon membrane form plant cell carbonation and another is ceria membrane by nanoparticle self assembly. The best oxidation temperature is 550 °C and the band gap of carbon/cerium dioxide materials synthesized at this optimum oxidation temperature could be reduced to 2.75 eV. After exposure to visible light for 6 h, the optimal hydrogen production is about 302 μmol g^?1, which is much higher than that of pure CeO₂.