Preparation and thermoelectric properties of ternaryrare earth sulfide γ-Ce3-xEuxS4

The effect of Eu-substitution on the density and thermoelectric properties of ternary sulfide Ce3-xEuxS4 (0≤x≤0.8) compacts was investigated. Ce3-xEuxZ4 powders were prepared via the sulfurization of the oxide using CS2 gas at 1473 K. The pressureless sintered Ce3-xEuxS4 compacts in the atmosphere were crystallized in the γ-phase. The density of the Ce3-xEuxS4 compacts increased with the increas-ing of Eu-substitution. Eu-substitution yielded a higher Seebeck coefficient and lower electrical resistivity. The highest value of the thermoe-lectric power factor of 1.41×10-4 W/K2m was obtained for the Ce2.2Eu0.8S4 compact at 673 K. It indicated that Eu-substitution was effective for improving thermoelectric properties of Ce3-xEuxS4.     

Thermoelectric properties of Yb x Co_4 Sb_（12） system

Yb x Co 4 Sb 12 polycrystals were fabricated by vacuum melting combined with hot-press sintering.The effect of Yb-filling on thermoelectric property of unfilled skutterudite CoSb 3 was investigated,which indicated the enhancement of the power factor of the material.Transport properties of materials changed from semi-conductor to semi-metal during the measurement of electrical conductivity,which indicated the change of electronic band structure.The maximum value of electrical conductivity was about 190000 S/m at 300 K for all samples.On the basis of Yb-filling,power factor of Yb 0.2 Co 4 Sb 12 reached 5-6 mW/(m·K) during the measurement temperature.Thermal conductivity decreased with increase of Yb content,and the thermal conductivity of Yb 0.2 Co 4 Sb 12 reached 3.2 W/(m·K) at 600 K.The ZT value of Yb 0.2 Co 4 Sb 12 reached 1.16 at 700 K due to positive contribution from high power factor and low thermal conductivity.     

Preparation and luminescence properties of Ce3＋/Dy3＋-codoped fluorosilicate glass ceramics

The Ce3+and Dy3+ co-doped fluorosilicate glass and glass ceramics containing SrF2 or CeF3 nanocrystals were prepared under re-ducing atmosphere. The precipitated nano-crystalline phase shifted from cubic SrF2 to hexagonal CeF3 gradually with the heat treatment tem-perature increasing from 620 to 680 °C. The glass and glass ceramics emitted white light, deriving from a combination of the Ce3+ blue and the Dy3+ yellow light. The CIE coordinates could be tuned by adjusting the ratio of Ce3+/Dy3+ concentration. The luminescence could be en-hanced significantly by annealing the samples at the temperatures lower than 640 °C.     

Preparation and luminescence properties of BaWO4：yb3＋/Tm3＋ nano-crystal

This research investigated the effect of different contents of Tm3+and different concentration ratios of Yb/Tm on the lumi-nescent properties of BaWO4:Yb3+/Tm3+nano-crystal synthesized by the hydrother...     

Effects of the precursor size on the morphologies and properties of γ-Ce_2S_3 as a pigment

Ceria spheres with different sizes and sulfurized products with corresponding morphology were prepared by hydrothermal and gas-solid reaction method at 600–800 °C under CS2 atmosphere for a short time, respectively. Dimensional effect in preparation of γ-Ce2S3 was firstly investigated by means of techniques such as scanning electron microscopy(SEM), X-ray diffraction(XRD), thermal gravimetric analysis(TGA) and spectrophotometer. The results showed that when ceria nanoparticles with small size were used as precursors, the γ-Ce2S3 could be prepared at the lower temperature and the badly sintered products were obtained; when ceria nanoparticles with large size were employed as precursors, pure γ-Ce2S3 was difficultly obtained even if the temperature was up to 800 °C and the products tended to keep their original size. The heat-resistance property of the γ-Ce2S3 with large size was better than the smaller one, and the pure γ-Ce2S3 prepared from precursor with small size had a good pigmentary performance.     

Synthesis and luminescence properties of BaWO4：Pr^3＋ microcrystal

BaWO4:Pr3+ (hereafter BWO:Pr) microcrystals were prepared via a hydrothermal route, and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), photoluminescence excitation and emission spectra. The as-prepared products with different morphologies of egg-shape rod, olive-like, and quasi-sphere were obtained by the addition of the surfactants and chelating agents. The emis-sion spectra of BWO:Pr microcrystals showed the strong red emission (642 nm) assigned to the Pr3+ ions of 3P0→3F2 transition with blue ex-citation (484.6 nm, 3H4→3P0).     

Synthesis and luminescence properties of a novel red Sr3Bi（PO4）3：Sm^3＋ phosphor

A series of Sr3Bi1-x(PO4)3: xSm3+phosphors were prepared by solid state method at 1250 °C for 4 h. X-ray diffraction (XRD) indi-cated that the sample was of a pure phase of Sr3Bi(PO4)3. The main excitation peaks were located at 343 (6H5/2→4H9/2), 360 (6H5/2→4D3/2), 373 (6H5/2→6P7/2), 400 (6H5/2→4F7/2), 414 (6H5/2→6P5/2) and 467 nm (6H5/2→4I13/2). The main emission were located at 563 (4G5/2→6H5/2), 599 (4G5/2→6H7/2), 646 (4G5/2→6H9/2) and 708 nm (4G5/2→6H11/2). The intensest emission was excited by 400 nm. We studied the effect of differ-ent doping concentrations of Sm3+ activator on the luminescence properties and found that the luminescent intensity first increased with Sm3+ concentration increasing, and then decreased. The luminescent intensity had the best value when x=0.04. The chromaticity coordinates of the sample Sr3Bi0.96(PO4)3:0.04Sm3+ were (x=0.57, y=0.36), and the lifetime was 2.12 ms.     

Study on VUV and UV Excitation Spectrum of GdVO_4∶Eu~( 3 )

Ｔｈｅｍｅｒｃｕｒｙ ｆｒｅｅｆｌｕｏｒｅｓｃｅｎｔｔｕｂｅｓａｎｄｐｌａｓｍａｄｉｓｐｌａｙｐａｎｅｌｓｈａｖｅｕｒｇｅｎｔｒｅｑｕｉｒｅｍｅｎｔｔｏｔｈｅｈｉｇｈｌｙｅｆｆｉｃｉｅｎｔａｎｄｓｔａｂｌｅｐｈｏｓｐｈｏｒｆｏｒｅｘｃｉｔａｔｉｏｎｉｎｔｈｅｕｌｔｒａｖｉｏｌｅｔｓｐｅｃｔｒａｌｒｅｇｉｏｎ(ＶＵＶ ,Ｅ >50 0 0ｃｍ-1,λ <2 0 0ｎｍ ) .Ｔｈｅｘｅｎｏｎｄｉｍｅｒｄｉｓｃｈａｒｇｅｉｎｈｉｇｈｐｒｅｓｓｕｒｅｇｉｖｅｓｔｈｅｈｉｇｈｅｓｔｅｆｆｉｃｉｅｎｃｙｏｆａｌｌｎｏｂｌｅｇａｓｅ…     

Study on Luminescence Properties of High-Density Phosphors BiTaO_~(3+) and BiTaO_4

Theparticleenergydetectedbymodernaccelera torsisgettinghigherandhigher ,whichrequiresbetterperformanceforscintillators .Thehigherthedensityofscintillators ,thelargeritslinearattenuationcoeffi cient ,whichcanreducethevolumeofthedetectingcrystalsandcomplicatedandhugeequipmentsoutsideit ,thenreducetheequipmentcostofacceleratorsgreatly .Itsdetectingcrystalconsistsofthousandsup onthousandsofcrystalarrays .Currently ,becauseofitsprominentmeritsofhighdensity (thatis 8.2 9g·cm- 3) ,shortradiationleng…     

VUV Spectroscopy of GdPO_4∶Eu~(3 ) and GdBO_3∶Eu~(3 )

VUV Spectroscopy of GdPO_4∶Eu~(3 ) and GdBO_3∶Eu~(3 )@Zimmerer G$Institut für Experimentalphysik der Universitt Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany     

Synthesis of CaWO4：Eu3＋ phosphor powders via ethylene glycol route and its optical properties

Eu3+ doped CaWO4 with tetragonal system were prepared at comparatively low temperature (125 ?C) in ethylene glycol medium. The phosphor was further investigated by X-ray diffractometer (XRD), photoluminescence spectrophotometer (PL), Fourier transform infra red (FT-IR) spectroscopy and transmission electron microscopy (TEM). XRD analysis indicated a decrease in the unit cell volume of CaWO4 with increasing Eu3+ ion concentration. It indicated the homogeneous substitution of Ca2+ ions in CaWO4 by the Eu3+ ions. TEM images showed that the particle size ranged from 20 to 200 nm and it could extend the application of the nanoparticles. The photoluminescence study showed that the intensity of electric dipole transition (5D0→7F2) at 614 nm dominated over the magnetic dipole transition (5D0→7F1) at 592 nm. The optimum concentration of Eu3+ for the highest luminescence was found to be 20 at.%. The as prepared samples were found to be dis-persible in water and methanol.     

Influence of Ga~(3 ) on Photoluminescence of Ce~(3 )

ＩｎｆｌｕｅｎｃｅｏｆＧａ３＋ｏｎＰｈｏｔｏｌｕｍｉｎｅｓｃｅｎｃｅｏｆＣｅ３＋ＸｕＣｈｕｎｘｉａｎｇ（徐春祥），ＬｏｕＺｈｉｄｏｎｇ（娄志东）（ＩｎｓｔｉｔｕｔｅｏｆＭａｔｅｒｉａｌＰｈｙｓｉｃｓ，ＴｉａｎｊｉｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎｏ...     

Preparation and Upconversion Luminescence of Y_3Al_5O_(12):Yb~(3+),Er~(3+)Transparent Ceramics

Crystalline Y3Al5O12(YAG) exists in the cubicform,having a garnet structure[1 ,2],and has excellentchemical stability ,good optical and high temperaturecreep chemical stability[3 ~5]. YAG single crystal hasdrawn considerable attention since the early 1960s ,asit isthei mportant crystal forfluorescent andsolid-statelasers . However ,it is hard to prepare large size sam-ples and dope high concentrationions in YAGcrystal .Conversely ,the fabrication of YAGtransparent ceram-ics is relatively…     

Growth and Spectral Properties of Crystal Er~(3 )∶Y_(0.5)Gd_(0.5)VO_4

Er∶YVO4andEr∶GdVO4lasercrystalshavebeen widelystudiedandusedinlaser diodepumpedsolid statelasersfortheirgoodlaserproperties[1～4].Howev er,thethermalconductivityofEr∶YVO4crystalislow andthecrystaliseasytodecompose.ThoughEr∶GdVO4lasercrystalhasanexcell     

Luminescence properties of Eu3＋ and Ho3＋ in SreTiO4

Eu3+ and Ho3+ doped Sr2TiO4 were synthesized by using solid-state reactions. Samples sintered at 1300 oC for 6 h could be indexed to Sr2TiO4 with a single phase. Eu3+ in Sr2TiO4 emitted orange light under the excitation at 365 nm in a broad band which was coupled well with the strongest emission of high pressure mercury vapor lamps. Ho3+ in Sr2TiO4 emitted yellow light under blue excitation from 450 to 460 nm which agreed well with the emission of blue InGaN-based light-emitting diodes. The present results indicated that Sr2TiO4 was a promising host for high pressure mercury vapor lamps or white light-emitting diodes.     

Nucleation undercooling,solidification structures and magnetic properties of Nd_9Fe_(85–x)Ti_4C_2B_x (x=10–15) magnetic alloys

Nd_9Fe_(85–x)Ti_4C_2B_x(x=10–15) magnetic alloys were investigated by differential thermal analysis and X-ray diffraction analysis. The results showed that with the B content increasing from 10 at.% to 15 at.%, the liquidus temperatures TL of the alloys decreased from 1498.5 to 1472.5 K; the solidus temperatures TS of them increased from 1353.2 to 1358.3 K; and the nucleation undercooling of the alloy melts cooled at the rate of 40 K/min decreased from 122.8 to 95.9 K, resulting in the solidification structures consisting of Nd_2Fe_(14)B, Fe_3B, α-Fe, Nd1.1Fe4B4 and TiC nanocrystallines. Furthermore, the Nd_9Fe_(85–x)Ti_4C_2B_x(x=11, 13, 15) bulk alloys in sheet form with the thickness of 0.7 mm were prepared by copper mold suction casting and their solidification characteristics and solidification structures under sub-rapidly cooling rate were investigated. The results showed that partially amorphous structures were obtained in the as-cast bulk alloys and the amount of amorphous decreased with the increase of the B content. By annealing the as-cast bulk alloys at 923 K for 10 min, the nanocomposite microstructures composed with Nd_2Fe_(14)B, Fe_3B and α-Fe nanocrystallines, which showed a single-phase hard magnetic behavior and enhanced magnetic properties, were achieved.     

Adsorption and desorption properties of D151 resin for Ce(Ⅲ)

The present research is aimed at the development of D151 resin as an adsorbent that it can be used in the adsorption of Ce(Ⅲ) ions.The adsorption and desorption behaviors of Ce(Ⅲ) on D151 resin have been investigated by chemistry analysis.The influence of operational conditions such as contact time,initial concentration of Ce(Ⅲ),initial pH of solution and temperature on the adsorption of Ce(Ⅲ) had also been examined.The results show that the optimal adsorption condition of D151 for Ce(Ⅲ) was achieved at pH=6.50 in HAc-NaAc medium.The maximum uptake capacity of Ce(Ⅲ) was 392 mg/g resin at 298 K.The adsorption of Ce(Ⅲ) followed both the Langmuir isotherm and Freundlich isotherm,and the correlation coefficients had been evaluated.Even kinetics on the adsorption of Ce(Ⅲ) had been studied.The adsorption rate constant k298 K valued was 1.3×10-5 s-1.The calculation data of thermodynamic parameters which ΔS0 value of 91.34 and ΔH0 value of 7.07 kJ/mol indicate the endothermic nature of the adsorption process.While,a decrease of Gibb’s free energy(ΔG0) with increasing temperature indicated the spontaneous nature of the adsorption process.Finally,Ce(Ⅲ) could be eluted by using 0.5 mol/L HCl solution and the elution percentage was as high as 100%.Adsorption mechanism was also proposed for the adsorption of Ce(Ⅲ) ions onto D151 resin using infrared spectroscopy technique.     

Preparation and Luminescence Properties of the New Long Phosphorescent Phosphors Ba_(1-x)Ca_xAl_2O_4∶Eu ~(2 ), Dy~(3 )

Inrecentyears ,SrAl2 O4 ∶Eu2 ,Dy3 ,CaAl2 O4 ∶Eu2 ,Nd3 [1～ 8] andBaAl2 O4 ∶Eu2 ,Dy3 [9]havebeenconsideredasusefulblueandgreenphos phorsbytheirlongdurationphosphorescence .Howev er ,toourknowledge ,thephosphorBa1-xCaxAl2 O4 ∶Eu2 ,Dy3 hasnotbeeninvestigated .TheluminescenceofEu2 isverystronglydepen dentonthehostlattice ,whichcanoccurfromtheul traviolettotheredregionoftheelectromagneticspec trum .Itiswellknownthatthepersistentluminescenceisduetothetrappingofenergyinthed…     

Nanoscratch behaviors of La_(0.7)Sr_(0.3)MnO_(3 δ) thin films

The nanoscratch behaviors of La0.7Sr0.3MnO3 δ films, which were deposited with ratio of O2/(O2 Ar), ranging from 4.4% to 45.6%, by DC magnetron sputter, were investigated by a nanoindentation technique. The results indicated that the friction coefficient between the films and the diamond tip depended on the loading critical load. The friction coefficient was about 0.08–0.12 when the loading normal load was less than the loading critical load. The films displayed excellent elastic recovery after unloading. When the loading load was larger than the loading critical load, plastic deformation and ploughing appeared for the films. The friction coefficient was about 0.43 when the film was damaged completely. The suitable decrease in ratio of O2/(O2 Ar) could improve the nanoscratch resistance of the films. The film deposited with O2/(O2 Ar)=25% possessed better scratch resistance due to good elastic recovery, high nanohardness, and critical load. The loading critical load of the film was larger than 80 mN.     

Synthesis, X-ray structure and luminescent properties of Sm~(3+) ternary complex with novel heterocyclic β-diketone and 1,10-phenanthroline (Phen)

A new neutral ternary samarium complex Sm(Phen)HL3 in which Phen is 1,10-phenanthroline and HL is (1,3-bis(1,3-dimethyl-1H-pyrazol-4-yl)-1,3-propanedione) was synthesized. Molecular structure of this complex was determined by X-ray diffraction. Under UV-light this complex is demonstrated bright red luminescence (λmax=647 nm), which was corresponding to the electric dipole 4G5/2→6H9/2 transition in Sm3+ ion. UV-absorption, excitation and emission spectra of the title compound were investigated.