Mechanism of Phase Transformation and Formation of Barium Hexafer rite Doped with Rare-Earths in Sol-Gel Process

The phase-transformation in sol-gel preparation of barium hexaferrite and the formation of barium hexaferrite doped with La 3+ were studied by chemical p hase analysis, X-ray diffraction and infrared spectrometry analysis. The expe rimental results show that phase transformation reactions of FeCO 3, Fe 2O 3 and BaFe 2O 4, barium hexaferrite and γ-Fe 2O 3 take place in the heat tr eatment of gel. While the doping lanthanide ion replace barium ion, an equivalen t quantity of Fe 3+ are reduced to Fe 2+ to maintain the charge equili brium.

Oxidation of propane to acrylic acid and acetic acid over alkaline earth-doped Mo-V-Sb-O_x catalysts

Alkaline earth metal （Mg,Ca,Sr and Ba）-doped Mo-V-Sb-O x catalysts,prepared by a dry-up method,have been investigated for their catalytic performance in the oxidation of propane under different reaction conditions.The catalysts have been characterized by N2 adsorption-desorption,temperature-programmed desorption （TPD） of NH3,SEM and XRD.Influence of water vapor on the catalytic performance,particularly on the selectivities to acetic acid and acrylic acid,has also been studied.The selectivity to acrylic acid was improved significantly by the doping of alkaline earth metals to Mo-V-Sb-O x catalysts.The surface acidic sites of the catalyst decreased with the doping of the catalyst with alkaline earth metals,which ultimately was found to be beneficial for obtaining high selectivity to acrylic acid.The catalytic activity and product selectivities were found to be influenced by the reaction temperature,C3H8/O2 ratio and space velocity.A significant improvement in the selectivity to acrylic acid has also been observed by the addition of water vapor in the feed of propane and oxygen in the oxidation of propane.

Synthesis and Characterization of Rare Earth Complexes with Phthalanilic Acids and Amino Acids

The complexes with the general formula REP3A· H2O [P = 2- (COO ) C6H4CONHC6H4X, X=2-CI, 4-Br; A=Gly, Ala, Leu; RE=Pr3+, Nd3+] were synthesized and characlerized by elemental analysis, IR and reflectance electronic spectra and TG methods. The results show that rare earth ion in each complex is coordinated by three oxygen atoms. One is from the amido and the other two from the hydroxyl in the carboxylate and the amino acid respectively, and each complex contains one coordinate water molecule. Condon parameters Fk, Lande parameters(4f), Nephelanxetic ratio(β), percentage convalency parameter(δ) and bonding parameter(b ) of the chelates were calculated from the reflectance electronic spectra, indicating certain covalent character in the metalligand bond. The apparent decompose activation energies were evaluated and the decompose mechanism were discussed.

Recent Advances in New Band Rare-earth Doped Fiber Amplifiers

Broadband,high bit rate,long hauls and system intelligence are current trends in developing fiber optic communication systems.The ever-increasing traffic demands have made it urgent to develop new band optical fiber amplifier.Laser characteristics of various rare-earth ion including Er3+,Tm3+,Pr3+,Dy3+,Ho3+,and Nd3+ doped fiber are reviewed.Recent advances of rare-earth doped fiber amplifiers with wide-band and flat gain are also introduced.

Synthesis and Characterization of Titania and Rare Earth Doped Titania Nanoparticles by Sol-gel Process

Titania sol has been prepared by the sol-gel process with Ti（OC 4 H 9 ） 4 as precursor. TiO 2 gel was obtained through hydrolysis and condensation process. Rare earth such as La 2 O 3 , CeO 2 and Gd2O3 were introduced into the nanostructure TiO 2 . After TiO 2 and rare earth doped TiO 2 powders were calcined at 400℃, 500℃, 600℃, 700℃ and 800℃ respectively, the characteristic analyses of the TiO 2 samples were studied by UV-VIS, XRD and TEM etc. It was found that there are some stronger absorption peaks at 200-325 nm. The rare earth doping can increase the phase transition temperature converting anatase phase into rutile phase, can decrease the grain size of TiO 2 particles and can improve the anti-UV capacity of the coating fabrics.

Improvement strategy on thermophysical properties of A_(2)B_(2)O_(7)-type rare earth zirconates for thermal barrier coatings applications:A review

The A_(2)B_(2)O_(7)-type rare earth zirconate compounds have been considered as promising candidates for thermal barrier coating(TBC) materials because of their low sintering rate,improved phase stability,and reduced thermal conductivity in contrast with the currently used yttria-partially stabilized zirconia (YSZ) in high operating temperature environments.This review summarizes the recent progress on rare earth zirconates for TBCs that insulate high-temperature gas from hot-section components in gas turbines.Based on the first principles,molecular dynamics,and new data-driven calculation approaches,doping and high-entropy strategies have now been adopted in advanced TBC materials design.In this paper,the solid-state heat transfer mechanism of TBCs is explained from two aspects,including heat conduction over the full operating temperature range and thermal radiation at medium and high temperature.This paper also provides new insights into design considerations of adaptive TBC materials,and the challenges and potential breakthroughs are further highlighted for extreme environmental applications.Strategies for improving thermophysical performance are proposed in two approaches:defect engineering and material compositing.

Mechanical behaviors of alumina ceramics doped with rare-earth oxides

The effects of three types of additives Y2O3, La2O3, and Sm2O3 on the sintering and mechanical behaviors of alumina ceramics were investigated. The bending strengths of alumina ceramics with Sm2O3 and Y2O3 additions were 455 and 439 MPa, respectively, higher than that with La2O3 addition. The fi＇acture toughness of the ceramics with Sm2O3 and Y2O3 were also higher than that with La2O3 addition. The fracture mode of rare earth oxides doped alumina ceramics exhibited obvious transgranular fractures as well as intergranular fracture. The results of research show that the improvement of bending strength and fracture toughness of alumina ceramics with rare earth oxides was achieved by refining the grain size and strengthening the grain boundary.

Rare Earth Elements-Doped LiCoO_2 Cathode Material for Lithium-Ion Batteries

Some compounds of LiCo 1- x RE x O 2 (RE=rare earth elements and x =0.01～0.03) were prepared by doping rare earth elements to LiCoO 2 via solid state synthesis. The microstructure characteristics of the LiCo 1- x RE x O 2 were investigated by XRD. It was found that the lattice parameters c are increased and the lattice volumes are enlarged compared to that of LiCoO 2. Moreover, the performance of LiCo 1- x RE x O 2 as the cathode material in lithium ion battery is improved, especially LiCo 1- x Y x O 2 and LiCo 1- x La x O 2. The initial charge/discharge capacities of LiCo 0.99 Y 0.01 O 2 and LiCo 0.99 La 0.01 O 2 are 174/154 (mAh·g -1 ) and 159/149 (mAh·g -1 ) respectively, while those for LiCoO 2 working in the same way are only 139/131 (mAh·g -1 ).

Study on rare earth/alkaline earth oxide-doped CeO_2 solid electrolyte

Five types of rare earth/alkaline earth oxide-doped CeO2 superfine-powders were synthesized by a low-temperature combustion technique. The relevant solid electrolyte materials were also sintered by pressureless sintering at different temperatures. The results of X-ray diffraction and transmission electron microscopy showed that the grain size of the powders was approximately 20-30 nm, and rare earth/alkaline earth oxides were completely dissolved into ceria-based solid solution with fluorite structure. The electrical conductivities of the SmzO3-CeO2 system were measured by the ac impedance technique in air at temperatures ranging from 513-900℃. The results indicated that the ionic conductivities of Srno.2oCe0.8Ol.875 solid electrolyte increase with increasing sintering temperature, and the relationship between the conductivities and measuring temperature obeys the An＇henius equation. Then the SmzO3-CeO2 material was further doped with other rare earth/alkaline earth oxide, and the conductivities improve with the effective index.

Rare earth doped CaCu_3Ti_4O_(12) electronic ceramics for high frequency applications

Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping....

Experimental and numerical investigation of mid-infrared laser in Pr^(3+)-doped chalcogenide fiber

We report on a chalcogenide glass fiber doped with Pr^(3+) that can be used for commercialized 1.5-μm and 2-μm laser excitations by emitting broadband 3 μm–5.5 μm fluorescence, which is extruded into a preform and then drawn into a step-index fiber. The spectroscopic properties of the fiber and glass are reported, and the mid-infrared fiber lasers are also numerically investigated. Cascade lasing is employed to increase the inversion population of the upper laser level. The particle swarm approach is applied to optimize the fiber laser parameters. The output power can reach 1.28 W at 4.89-μm wavelength, with a pump power of 5 W, excitation wavelength at 2.04 μm, Pr^(3+) ion concentration at 4.22 × 10^(25) ions/m^3,fiber length at 0.94 m, and fiber background loss at 3 dB/m.

Doped Organic Electroluminescence from a Novel Rare Earth Complex Tb(3-metho)_3phen

A novel rare earth complex Tb(3 metho) 3phen was synthesized and characterized. The complex was doped into PVK to improve the conductivity and film forming property of Tb(3 metho) 3phen. A device with a structure of ITO/PVK∶Tb(3 metho) 3phen /Al was fabricated to study the electroluminescent properties of Tb(3 metho) 3phen. And the optoluminescent and AFM properties of this device were also studied, which proved the existence of energy transfer from PVK to Tb(3 metho) 3phen. As a result, a pure green emission with sharp spectral band at 547.5 nm was observed.

Rare Earth Doped Optical Fibers for Temperature Sensing Utilizing Ratio-Based Technology

A new and practical fluorescence temperature detecting system based on fluorescence intensity ratio was proposed. The background theory of fluorescence intensity-ratio method was presented simply. And the characters of rare earth doped samples were detailed. The erbium-doped fiber was chosen as the sensing element. The energy levels of 2H11/2 and 4S3/2 are responsible for the emission of radiation at approximately 530 and 555 nm. The erbium-doped (960 ppm) fiber of length 20 cm and core diameter 3.2 μm was used as the sensing part. A silica photodiode transfers the fluorescence signal to electric signal, then the ratio of the average of the two different signals was calculated by the computer and the temperature was obtained. The ratio R of the intensity resulting from the transition between the two levels varies proportionly with temperature interval from 293 K to 373 K. The sensitivity of the sensor is approximately 0.05 K-1.

Quantum light storage in rare-earth-ion-doped solids

The reversible transfer of unknown quantum states between light and matter is essential for constructing large-scale quantum networks. Over the last decade, various physical systems have been proposed to realize such quantum memory for light. The solid-state quantum memory based on rare-earth-ion-doped solids has the advantages of a reduced setup complexity and high robustness for scalable application. We describe the methods used to spectrally prepare the quantum memory and release the photonic excitation on-demand. We will review the state of the art experiments and discuss the perspective applications of this particular system in both quantum information science and fundamental tests of quantum physics.

Properties and Application of Double Alkali Earth Doped Ce_ (0.9)Ca_(0.1-x) Sr_xO_( 1.90)

A series of solid solution material based on ceria, Ce 0.9 Ca 0.1- x Sr x O 1.90 ( x =0, 0 04, 0 05, 0 06), were synthesized by a solid reaction method. Ceria doped with two alkali earth elements has cubic fluorite structure. The ionic conductivity of these materials at high temperature was studied by impedance spectra, and an increasing effect of ionic conductivity was found. A maximum conductivity is achieved when the effective ionic radius is near to the critical radius (0 1106 nm). Some fuel cells were made using these materials as electrolyte. The output power and current of the SOFC with the electrolyte of double doped ceria are better than those of YSZ and single doped ceria, and the open circuit voltage of the double doped ceria is also higher than that of the single doped ones.

Inhomogeneity of Rare Earth Doped Ⅲ-Ⅴ Compounds Grown by LPE

The processing of InP, GaAs and related compounds doped with rare earth metals, such as Er, Nd and Gd, grown by LPE is described. The inhomogeneity of rare earth heavily doped epi-layers is studied by SIMS, SEM and X-ray diffraction techniques.

THE CRYSTAL STRUCTURE OF RARE EARTH COMPLEX WITH AMINO ACIDS Ⅱ The Crystal Structure of Gtutamate Comptex of Erbium Perchtorate

The crystat structure of {[Er;（L—Glu）;（H;O）;]（ClO;）;·3H;O);has been studied by X-ray diffraction. The crystal is monoctinic with space group P2;and cell parameters a=19.987（3） , b=16.505（3） , c=11.040（2） , β=104.69（1）;, V=3538（1） , Z=2, Dc=2.29 g. cm;, μ=53.2 cm;, F（000）=2384. The asymmetric unit contains two complex motecules and four centre ions. Each erbium （Ⅲ） is coordinated by five oxygen donors from four different glutamates and four oxygen donors from the aqua ligand to form a nine coordination potyhedron. The mean distances of Er—0 （carboxylate） and Er—Ow are 2.439 and 2.41 respectivety. The finat R and Rw are 0.043 and 0. 058, respectivety.

Multiple Energy Transfers in Rare Earth Complex-Doped SiO_2 Spheres

Silica spheres doped with Eu （TTFA）3 and/or Sm（TTFA）3 were synthesized by using the modified Stober method. The transmission electron microscope image reveals that the hybrid spheres have smooth surfaces and an average diameter of about 210 nm. Fluorescence spectrometer was used to analyze the fluorescence properties of hybrid spheres. The results show that multiple energy transfer processes are simultaneously achieved in the same samples co-doped with Eu （TTFA）3 and Sm（TTFA）3, namely between the ligand and Eu^3＋ ion, the ligand and Sm^3＋ ion, and Sm^3＋ ion and Eu^3＋ ion. Energy transfer of Sm^3＋→Eu^3＋ in the hybrid spheres leads to fluorescence enhancement of Eu^3＋ emission by approximately an order of magnitude. The lifetimes of the hybrid spheres were also measured.

Synthesis and Characterization of Rare Earth Solid Complexes with Sodium 5-Aminosalicylate

Ten new rare earth solid complexes were synthesized by the reaction of sodium 5-aminosalicyliate with rare earth chloride. The structure character, physical and chemical properties of these complexes were studied by IR, UV, ()~1H NMR spectra, TG-DTA, fluorescence, elemental analyses, molar conductance and magnetic susceptibility. The ten rare earth complexes exist in dimeric form probably and the coordination number is seven. The antibacterial activity of the ligand and six complexes was also tested against Staphylococcus aureus, Escherichia coli and Bacillus subtilis, and the effect of Yb complex at 20 mg·ml^(-1) against Staphylococcus aureus is most significant.

The Radiation Damage Mechanism of Rare Earth Doped BaF_2 Crystals

The Discrete variation Xα（DV-Xα）method was used to calculate the energylevel of some rare earth doped BaF2 crystals.The results indicated that elements Eu,Dyand Yb will change their valence from +3 to +2 under irradiation and thus change theoptical properties of the crystals.The calculation using radiation damage model agreeswell with experiments.