Preparation of Well Dispersed and Ultra-Fine Ce （Zr）O2 Mixed Oxide by Mechanochemical Processing

Ultra-fine CeO2-ZrO2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce2(CO3)3·8H2O, ZrOCl2·xH2O and ammonia were used as reactants. It is found that the crystalline Ce2(CO3)3·8H2O and ZrOCl2·xH2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce0.15Zr0.85O2 mixed oxide with pure tetragonal phase structure and medium particle size(D50)less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.     

Preparation of Compound Ultrafine CeO2 by Wet-Solid-Phase Mechanochemical Modification

To satisfy practical requirements from industrial applications, an alternate route for synthesis compound ultrafine CeO2 powders by wet-solid-phase mechanochemical modification using industrial grade hydrated cerium carbonate as raw material was proposed.The effect of modifier reaction percentage, reaction time, calcining temperature and modifier amount on particle size, density, suspensibility, and hardness of compound CeO2 powder was investigated.The phase evolutions of preparation process were characterized by XRD.SEM micrograph of the final product shows that compound CeO2 powders obtained are well-dispersed, spherically-shaped, uniformly-sized and submicron-sized particles.The method is readily available in raw material, low in cost, simple in process, and has great potential for industrialization.The compound CeO2 powders of different physical properties can be synthesized by controlling the above-mentioned influence factors in preparation process.     

Mechanochemical Reaction of Lanthanum Carbonate with Sodium Hydroxide and Preparation of Lanthanum Oxide Nanoparticle

Ｔｈｅｉｍｐｏｒｔａｎｃｅｏｆｎａｎｏｓｉｚｅｄｒａｒｅｅａｒｔｈｏｘｉｄｅｐｏｗｄｅｒｓｉｎｖａｒｉｏｕｓｔｅｃｈｎｉｃａｌａｐｐｌｉｃａｔｉｏｎｓｍａｋｅｓｔｈｅｉｒｐｒｅｐａｒａｔｉｏｎｔｅｃｈｎｏｌｏｇｙａｎｉｎｔｅｒｅｓｔ ｉｎｇｓｕｂｊｅｃｔｆｏｒｒｅｓｅａｒｃｈｗｏｒｋ[1 ] .Ｏｖｅｒｔｈｅｐａｓｔｄｅｃａｄｅｓ,ｍａｎｙｐｒｅｐａｒａｔｉｏｎｍｅｔｈｏｄｓｏｆｎａｎｏ ｓｉｚｅｄｒａｒｅｅａｒｔｈｏｘｉｄｅｓｈａｖｅｂｅｅｎｄｅｖｅｌｏｐｅｄ ,ｉｎｃｌｕｄｉｎｇｐｈｙｓｉｃａｌａｎｄ…     

机械力化学技术研究进展

金属和无机非金属粉末在高能球磨过程中受到强烈的机械力作用，组织不断细加、内部缺陷不断增加，导致材料体系自由能大幅度提高，在球与粉末颗粒碰撞的瞬间可以诱发固-固、固-液和固-气态化学反应。利用这种工艺被称之为机械力化学，可广泛用于制备纳米晶材料、复合纳米材料、纳米粒子、弥散强化材料、高分子聚合物以及进行矿物、废物处理和金属精炼。深入讨论了机械力化学过程的原理、特点及其应用。     

Citric Gel Synthesis and Luminescent Properties of Ce^3＋-Activated SrGa2O4 Phosphor

Ce^3＋-activated SrGa2O4 phosphor was synthesized by a method of citric gel,wherein citric acid served as a chelate agent,and the as-synthesized powder was calcined in a slightly reduced ambient.The crystallization characteristics of the sample varied with the calcining temperature.Compared with the phosphor prepared by the solid-state reaction,the phosphor synthesized by citric gel was calcined at a relatively lower temperature.Consequently,the volatilization of Ga2O3 during high-temperature calcining process was avoided.The typical double-peak emission of Ce^3＋ originated from 2D（5d）→4F5/2（4f）,and 2D（5d）→4F7/2（4f）was observed,and the intrinsic emission of SrGa2O4 host was much restricted.The emission intensity varied with the calcining temperature because the different crystallinity and the optimal concentration of Ce-dopant was determined at 3%.     

Mechanochemical synthesis of cerium orthophosphate

A facile, simple and rapid preparation method of cerium orthophosphate was presented. The synthesis of low-crystalline CePO₄ occurred upon mixing of cerium (III) nitrate and sodium phosphate, and was an exchange-type reaction. The phase composition of the obtained powder was checked by the XRD and FTIR methods, indicating the presence of cerium phosphate. Further investigations on thermal behavior of the synthesized cerium salt had shown that the obtained orthophosphate crystallized at first in rhabdophane-type structure. It converted to monazite (monoclinic symmetry) during heating at the temperatures of above 600 ºC. Oxidation of Ce³⁺ to Ce⁴⁺ was avoided during the syntheses, as confirmed by the XPS experiments.     

Preparation and Structure Characterization of Rare Earth Doped Alumina-Siloxane Gel and Its Modification on ER Effect

A series of samples of alumina-siloxane gel wrapped by poly (methyl methacrylate) and doped with rare earths such as lanthanum, praseodymium, yttrium, gadolinium and europium were prepared. The structure features were characterized by micrograph, X-ray fluorescence spectrum, X-ray diffraction spectrum, Fourier transform infrared spectrum and differential thermal analysis.Tests indicate that rare earths modify the electrorheological effects of the stable suspensions composed of samples stirred with silicon oil.     

Preparation of Rare Earth Doped Alumina-Siloxane Gel and Its ER Effect

Poly(methyl methacrylate) (PMMA) was used to wrap alumina-siloxane sol through emulsion polymerization. A kind of suspensions with notable ER effect was produced by fully mixing the prepared microcapsule with silicon oil. Meanwhile a series of PMMA wrapped alumina - siloxane gel doped with rare earths was obtained and its ER effect was tested, like viscosity of different rare earth ion doped samples in different powder concentrations and at different temperatures, at the same time, leak current density and dielectric constant were measured. Resuits show that the ER effect of this suspension is remarkable, and its stability is much better. The condition of emulsion polymerization and the mechanism of effect are discussed.     

ER Effect of PMMA Wrapped Alumina-Siloxane Gel Doped with Rare Earths

PMMA wrapped alumina-siloxane gel was obtained by using poly (methyl methacrylate) (PMMA) to wrap alumina-siloxane sol which was made from water glass, aluminum nitrate and a-methacrylic acid. Meanwhile, rare earth ions were used to dope in the course of reaction, and stable suspensions was produced by putting PMMA wrapped microcapsule powder doped with rare earths into methy-silicon oil. It is found that its electrorheologlcal (ER) effect improves strikingly after loading electric field. At a certain concentration, the immediate viscosity increases from 95 to 178 Pa‘s compared to the system without doping.     

Synthesis of YAG:Ce3+ Phosphor by Polyacrylamide Gel Method and Promoting Action of α-Al2O3 Seed Crystal on Phase Formation

YAG:Ce3 phosphor particles were prepared using polyacrylamide gel method. The structure evolution of powders during annealing process was followed by X-ray diffraction determination. It is found that some intermediate phases, including θ-Al2O3, YAM and YAP, are formed when calcining polyacrylamide gel, however, the pure YAG phase can be formed directly when calcining polyacrylamide gel with α-Al2O3 as seed crystal. These facts show that the existence of α-Al2O3 seed crystal can block the formation of θ-Al2O3, YAM and YAP, and accelerate its reaction with Y2O3 to form YAG phase directly at lower temperature. The emission peak of prepared YAG:Ce3 phosphor is wide with maximum at 550 nm and the exitation band has two peaks, the major one is around at 460 nm, which matches the blue emission of GaN LED and is suitable for the assemble of white LED. Some fluxes can enhance the photoluminescence intensity of phosphor particles, that can be attributed both to the improvement of crystallization processes of YAG and to the stabilization of trivalence cerium ion in YAG:Ce3 .     

Structure and Luminescence Properties of Eu~(3+) Doped SiO_2 Glass Synthesized by Sol-Gel Process

Ａｍｏｎｇｌａｎｔｈａｎｉｄｅｉｏｎｓ ,Ｅｕ3 + ｉｏｎｐｏｓｓ ｅｓｅｓｇｏｏｄｌｕｍｉｎｅｓｃｅｎｔｃｈａｒａｃｔｅｒｉｓｔｉｃｓ ,ｈｉｇｈｃｏｌｏｒｐｕｒｉｔｙａｎｄｈｉｇｈｑｕａｎｔｕｍｅｆｆｉｃｉｅｎｃｙ .Ｅｕ3 + ｉｓｏｎｅｏｆｔｈｅｃｅｎｔｒａｌｉｏｎｓｆｉｒｓｔｓｅｌｅｃｔｅｄｆｏｒｔｈｅｐｒｅｐａｒａｔｉｏｎｏｆｒａｒｅｅａｒｔｈｉｏｎｓｄｏｐｅｄｌｕｍｉ ｎｅｓｃｅｎｔｍａｔｅｒｉａｌｓ .Ｄａｆｉｎｏｖａｅｔａｌ .[1] ｐｒｏｄｕｃｅｄＥｕ3 + ａｎｄＳＯ2 -4 ｄｏｐｅｄｔｕｎｇｓｔａ…     

Synthesis and Characterization of Cerium-Doped Lutetium Aluminum Garnet Phosphors by Nitrate-citrate Sol-Gel Combustion Process

Nanosized cerium-doped lutetium aluminum garnet （LuAG：Ce） phosphors were prepared by nitrate-citrate solgel combustion process using 1：1 ratio of the citrate：nitrate. The prepared LuAG：Ce phosphors were characterized by XRD, TEM, photoluminescence and radioluminescence spectra excited by UV and X-ray, respectively. The purified crystalline phase of LuAG：Ce was obtained at 900 ℃ by directly crystallizing from amorphous materials. The resultant Lu- AG：Ce phosphors were uniform and had good dispersivity with an average particle size of about 30 urn. Both photoluminescence and radioluminescence were well-known Ce^3＋ emissions located in the range of 470 -600 nm consisting of two emission bands because of the transition from the lowest 5d excited state （2D） to the 4f ground state of Ce^3＋, which matched well with the sensitivity curve of the Si-photodiode. There was a little red shift for the emission components from the UV-excited emission spectrum to the X-ray-excited emission spectrum. The fast scintillation decay component of 26 ns satisfies the requirements of fast scintillators.     

Preparing Process of Cerium Acetate and Rare Earth Acetate

Preparing process was presented and the influences of concentration of acetic acid, reaction temperature, the ratio of cerium carbonate and acetic acid, heat preservation time to the yield of cerium acetate were discussed.The crystalline cerium acetate and rare earth acetate such as ( La, Ce, Pr, Nd) (Ac) 3, ( Ce, Pr, Nd) (Ac) 3, ( Pr, Nd, Er,Y) (Ac) 3 and yttrium acetate were prepared under this condition.The shape, structure and composition of the crystals were determined by the methods of SEM, TG-DTA, X-ray diffraction and chemical analysis.The optimum prepared conditions of cerium acetate were described.This prepared process has characteristics such as simple process route, low cost, high yield, good quality, no pollution to environment, etc.     

稀土元素添加剂在泡沫铝合金制备中的应用

用稀土添加剂制取高强度稀土铝合金，相对抗拉强度σb相：1．07～1．32；延伸率δ：3．0％～7．5％；常压下添加合金增粘剂发泡剂后制得稀土泡沫合金，气孔率η：12．8％～33．5％。     

Structure evolution and thermal stability of La2O3-doped mullite fibers via sol-gel method

The lanthana-doped mullite fibers were prepared via a sol-gel method from the aluminum isopropoxide-aluminum nitrate-tetraethyl orthosilicate system. The structure evolution and thermal stability of the mullite fibers were investigated by means of X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and trans-mission electron microscopy (TEM). The results showed that the fibers obtained after calcination at 1000℃ was in the form of Al2O3-rich mullite, which tended to transform to stoichiometric mullite with the lanthana content increasing. The lattice parameter a exhibited a decline trend with the lanthana content increasing, while b showed an upward tendency. Correspondingly, the redshift of Si-O-Si bond from 1255 to 1245 cm-1 was observed. The grain growth was inhibited for the doped fibers, among which the 5% La2O3-doped sample presented a mini-mum crystallite size (17.2 nm) after calcination at 1000 ℃ for 1 h.     

Study on Separation of Lanthanum from Praseodymium Complexes with IMDA by Gel and Macroporous Anion Exchangers

Ｍａｎｙｓｔｕｄｉｅｓｈａｖｅｂｅｅｎｍａｄｅｏｎｔｈｅｓｅｐａｒａｔｉｏｎｏｆｒａｒｅｅａｒｔｈｅｌｅｍｅｎｔｓｕｓｉｎｇｓｏｌｖｅｎｔｅｘｔｒａｃｔｉｏｎａｎｄｉｏｎｅｘｃｈａｎｇｅ[1].Ｓｉｎｃｅｔｈｅａｆｆｉｎｉｔｙｓｅｒｉｅｓｏｆｒａｒｅｅａｒｔｈｅｌｅｍｅｎｔｓｆｏｒｃａｔｉｏｎ-ｅｘｃｈａｎｇｅｒｓａｒｅｖｅｒｙｓｉｍｉｌａｒ,ａｓｅｐａｒａｔｉｏｎｂｙｅｌｕｔｉｏｎｗｉｔｈｉｎｏｒｇａｎｉｃａｃｉｄｓｉｓａｌｍｏｓｔｉｍｐｏｓｓｉｂｌｅ.Ｈｏｗｅｖｅｒ,ｇｏｏｄｒｅｓｕｌｔｓｃａｎｂｅ…     

Reaction between Lanthanum and Phosphorus in Steel

P always causes low temperature emhrittlement and temper embrittlement owing to itsgrain boundary segregation[']. Garcia C I etal. [2) reported a complex compound containingLa, O I S and P, in which LaZOZS acted as anucleation site and Fe-P precipitated on thesurface of the oxysulfide. Nevertheless, thermodynamic calculation by Seah M P showedthat La could not react with P in steel unlesstemperature is lower than 1100 T, sinceGibbs free energy of formation of LaP is positive above thi…     

Luminescent and Thermal Properties of Sm^ 3＋ Complex with Salicylate and o-Phenanthroline Incorporated in Silica Matrix

A ternary Sm（ Ⅲ ） complex with salicylate （sal-） and o-phenanthroline （phen） was synthesized and incorporated in silica matrix by sol-gel method. The luminescence behavior of the complex in silica gel was studied compared with that of the pure complex by means of emission, excitation spectra and thermogravimetic analysis. The results indicate that the fluorescence intensity ratio of the ^4G5/2→^6H9/2 transition to the ^4G5/2→^6H5/2 transition in silica gel doped with Sm（sal）3 （phen） is lower than that of the pure Sm（sal）3（phen）. The thermal stability of Sm（sal）3（phen） is enhanced greatly by the introduction of the complex into silica matrix. An isolated and chemical inert environment of the complex appears to be responsible for the thermal stability enhancement in silica gel.     

稀土导电铝合金的铸态组织和相组成

本文利用光学显微镜、扫描电镜、Ｘ射线衍射仪等，研究了Ｌａ、Ｃｅ对工业纯铝铸态组织和相组成的影响。结果表明，Ｌａ、Ｃｅ能细化工业纯铝的铸态组织，并和Ｆｅ、Ｓｉ等元素结合生成了二元或三元稀土化合物相。     

富铕中钇矿稀土萃取分离新工艺流程的研究

在比较传统工艺的基础上，提出以三出口为主体的富铕中钇矿萃取大分组的工艺及特点。