The effects of rare-earth La_2O_3 addition on microstructures and electrical properties of SrTiO_3 ceramics were investigated. Semiconductor SrTiO_3-based voltage-sensing and dielectric dual functional ceramics was pr...The effects of rare-earth La_2O_3 addition on microstructures and electrical properties of SrTiO_3 ceramics were investigated. Semiconductor SrTiO_3-based voltage-sensing and dielectric dual functional ceramics was prepared by a single step sintering technology in this study, and the effects of the content of La_2O_3 on characteristics of the product were discussed in terms of microstructures and electrical properties of materials. The results show that SrTiO_3-based ceramics doped with La_2O_3 exhibits more homogeneous grain distribution, greater grain size, and excellent voltage sensing and dielectric characteristics than those without La_2O_3 doping. The samples doped with 1 1% La_2O_3 were sintered at 1420 ℃ in N_2+C weak reducing atmosphere. The average grain size of the samples doped with La_2O_3 is 40 μm, the breakdown voltage of 19.7 V·mm^(-1), the nonlinear exponent of 7.2, and dielectric constant of 22500. The results reveal that final products are suitable to use in low operating voltage.展开更多
Borosilicate glass with high rare earth content was fabricated by traditional method. The influence of glass compositions and rare earth content on absorption spectra was examined and discussed. With increasing Sm2O3 ...Borosilicate glass with high rare earth content was fabricated by traditional method. The influence of glass compositions and rare earth content on absorption spectra was examined and discussed. With increasing Sm2O3 content, the intensity of characteristic absorption peak is increased and the absorption peak is broadened. With increasing of the ratios of SiO2/B2O3 and Al2O3/SiO2, the broadening degree of absorption peak is increased. The experimental results provide basis for making special optical glasses which have the characteristics of high absorption for special wavelength laser and high transparence for visible light.展开更多
The effect of Eu-substitution on the density and thermoelectric properties of ternary sulfide Ce3-xEuxS4 （0≤x≤0.8） compacts was investigated. Ce3-xEuxS4 powders were prepared via the sulfurization of the oxide usi...The effect of Eu-substitution on the density and thermoelectric properties of ternary sulfide Ce3-xEuxS4 （0≤x≤0.8） compacts was investigated. Ce3-xEuxS4 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 T-phase. The density of the Ce3-xEuxS4 compacts increased with the increasing of Eu-substitution. Eu-substitution yielded a higher Seebeck coefficient and lower electrical resistivity. The highest value of the thermoelectric power factor of 1.41×10^-4 W/K^2m 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.展开更多
Nanocrystalline rare earth mixed oxides SmFe_(1-x)Co_xO_(3-delta) wereprepared by sol-gel method at 1 073 K for 2 h calcination and characterized by X-ray diffraction(XRD) and scanning electron microscope (SEM). The r...Nanocrystalline rare earth mixed oxides SmFe_(1-x)Co_xO_(3-delta) wereprepared by sol-gel method at 1 073 K for 2 h calcination and characterized by X-ray diffraction(XRD) and scanning electron microscope (SEM). The results show that SmFe_(1-x)Co_xO_(3-delta) hasthe structure of perovskite type. The conductivity of the materials increases with the temperaturerising and the maximum conductivity at 1 073 K is 2.6 S/cm with the best mole ratio of Fe^(3+) toCo^(3+) being 1: 4. This kind of oxide is a conductive ceramic material by means of conduction ofelectron and oxygen anion.展开更多
The refining effect of Al3Ti1B1RE master alloy on Al sheets used for pressure can manufacture and the behavior of mixed rare earths in master alloy were investigated with XRD, OM, SEM and EDAX. It is found that the r...The refining effect of Al3Ti1B1RE master alloy on Al sheets used for pressure can manufacture and the behavior of mixed rare earths in master alloy were investigated with XRD, OM, SEM and EDAX. It is found that the refining effect of the refiner on the material has superiority over foreign or domestic Al5Ti1B refiner, and the refiner still retains its refining ability for 6 h after adding it to molten Al, thus improving the strength and plasticity of the material remarkably. The excellent refining effect and stability of AlTiBRE refiner result from that RE can lower the surface energy of molten Al and improve the wetting characteristics of molten Al on refinement nuclei such as TiAl 3, TiB 2, etc., thus giving full play to the effect of heterogeneous nucleation and impeding the congregating tendency of TiB 2 phase in molten Al. At the same time, RE gathering in front of solid/liquid interface are also easy to cause composition supercooling in molten Al, thus impeding the growth of α Al grains and promoting α Al nucleation on refinement nuclei. In addition, RE also play certain role in purification and grain refinement, or modification, especially their effect of purification can improve the metallurgical quality of AlTiBRE master alloy.展开更多
The extraction behavior of rare earths was studied by using paraffin with ceresin as a diluent containing 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5.In solid phase,the composition of complexes is REP_3.The equilib- rium...The extraction behavior of rare earths was studied by using paraffin with ceresin as a diluent containing 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5.In solid phase,the composition of complexes is REP_3.The equilib- rium extraction constants and pH_(1/2) values of solid-liquid extraction are higher than those of normal liquid-liquid extraction.The extraction efficiency tends to maximum when the ratio of phases is 1:1.When the extraction temperature is higher than the melting point of paraffin and the extraction time is over 10 min,the extraction efficiency keeps constant.Moreover,the relationship among separation factor,equilibrium extrac- tion constant,pH_(1/2) value and atomic number was obtained.The mechanism of solid-liquid extraction is analogous to that of liquid-liquid extraction.展开更多
The research on the mechanism of the roast reaction of Baotou concentrate of rare earth with 15% Na 2CO 3 additions was carried out through thermal, X ray diffraction and chemical analysis. Bastnaesite(RECO 3F) wa...The research on the mechanism of the roast reaction of Baotou concentrate of rare earth with 15% Na 2CO 3 additions was carried out through thermal, X ray diffraction and chemical analysis. Bastnaesite(RECO 3F) was first decomposed into REOF at 623～741 K, then Monazite(REPO 4) reacted with Na 2CO 3 was decomposed into RE 2O 3 and produced Ca 8Nd 2(PO 4) 6O 2 at 853～928 K. The kinetics parameters of the roast reaction were calculated. The results of the calculation were as follows: at 623～741 K, E =152 kJ·mol -1 , n =0 77, A =1 11×10 12 s -1 ·mol -1 , k =1 102( T =705 K), and at 853～928 K, E =232 kJ·mol -1 , n =1 16, A =1 11×10 9 s -1 ·mol -1 , k =1 07×10 -4 ( T =915 K). The equation of the mechanism of the roast reaction is F 1=-ln(1- α ) at 623～741 K and 853～928 K according to TG curves.展开更多
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...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.展开更多
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 inv...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....展开更多
The doping effects of rare earth oxides Ho_2O_3 and Er_2O_3 on dielectric properties of BaTiO_3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain si...The doping effects of rare earth oxides Ho_2O_3 and Er_2O_3 on dielectric properties of BaTiO_3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain size was reduced evidently which realized the fine-grained effect. In this system, the trivalent oxides Ho_2O_3 and Er_2O_3 were added to BaTiO_3 ceramics. The rare earth oxides do not enter into inner lattice totally to replace A or B sites. Some of additives can improve dielectric strength by forming nonferroelectric phases, and the rest maintained at grain boundaries controls overgrowth of grains. The dielectric constant at room temperature is increased up to 3000 and the curve of TCC becomes flat. Meanwhile, the dielectric strength E_b becomes higher.展开更多
The structure of LiSrY2（BO3）3 has been solved by single-crystal X-ray diffraction analysis at 298 and 113 K on different diffractometers.It crystallizes in trigonal with space group P-3m1（No.164）.The cell paramete...The structure of LiSrY2（BO3）3 has been solved by single-crystal X-ray diffraction analysis at 298 and 113 K on different diffractometers.It crystallizes in trigonal with space group P-3m1（No.164）.The cell parameters at room temperature are as follows：a = 10.3345（9）,c = 6.4049（11） ,V = 592.41（13） 3,Z = 3,Mr = 448.81,F（000） = 618,μ = 21.327 mm-1 and Dc = 3.774 g/cm3.The crystal structure consists of gear-like [BY6O33] groups which are linked together by corner-sharing to form a two-dimensional layer parallel to the ab plane.These layers are connected one after another by sharing oxygen atoms with B（2） atoms along the c direction to construct a three-dimensional framework.Li and Sr atoms just occupy the cavities formed by oxygen atoms.In addition,the vibrational spectroscopy of LiSrY2（BO3）3 and photoluminescence properties of the Eu3＋ doped LiSrY2（BO3）3 were also studied.展开更多
基金Project supported by Science and Technology Foundation of Yunnan Province (2002GG-09)
文摘The effects of rare-earth La_2O_3 addition on microstructures and electrical properties of SrTiO_3 ceramics were investigated. Semiconductor SrTiO_3-based voltage-sensing and dielectric dual functional ceramics was prepared by a single step sintering technology in this study, and the effects of the content of La_2O_3 on characteristics of the product were discussed in terms of microstructures and electrical properties of materials. The results show that SrTiO_3-based ceramics doped with La_2O_3 exhibits more homogeneous grain distribution, greater grain size, and excellent voltage sensing and dielectric characteristics than those without La_2O_3 doping. The samples doped with 1 1% La_2O_3 were sintered at 1420 ℃ in N_2+C weak reducing atmosphere. The average grain size of the samples doped with La_2O_3 is 40 μm, the breakdown voltage of 19.7 V·mm^(-1), the nonlinear exponent of 7.2, and dielectric constant of 22500. The results reveal that final products are suitable to use in low operating voltage.
文摘Borosilicate glass with high rare earth content was fabricated by traditional method. The influence of glass compositions and rare earth content on absorption spectra was examined and discussed. With increasing Sm2O3 content, the intensity of characteristic absorption peak is increased and the absorption peak is broadened. With increasing of the ratios of SiO2/B2O3 and Al2O3/SiO2, the broadening degree of absorption peak is increased. The experimental results provide basis for making special optical glasses which have the characteristics of high absorption for special wavelength laser and high transparence for visible light.
基金supported by the National Natural Science Foundation of China (20501023)the National "863" Project Foundation of China (2004AA001340)the Nature Science Foundation of Guangdong for Doctorial Training base (5300527)
文摘The effect of Eu-substitution on the density and thermoelectric properties of ternary sulfide Ce3-xEuxS4 （0≤x≤0.8） compacts was investigated. Ce3-xEuxS4 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 T-phase. The density of the Ce3-xEuxS4 compacts increased with the increasing of Eu-substitution. Eu-substitution yielded a higher Seebeck coefficient and lower electrical resistivity. The highest value of the thermoelectric power factor of 1.41×10^-4 W/K^2m 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.
文摘Nanocrystalline rare earth mixed oxides SmFe_(1-x)Co_xO_(3-delta) wereprepared by sol-gel method at 1 073 K for 2 h calcination and characterized by X-ray diffraction(XRD) and scanning electron microscope (SEM). The results show that SmFe_(1-x)Co_xO_(3-delta) hasthe structure of perovskite type. The conductivity of the materials increases with the temperaturerising and the maximum conductivity at 1 073 K is 2.6 S/cm with the best mole ratio of Fe^(3+) toCo^(3+) being 1: 4. This kind of oxide is a conductive ceramic material by means of conduction ofelectron and oxygen anion.
文摘The refining effect of Al3Ti1B1RE master alloy on Al sheets used for pressure can manufacture and the behavior of mixed rare earths in master alloy were investigated with XRD, OM, SEM and EDAX. It is found that the refining effect of the refiner on the material has superiority over foreign or domestic Al5Ti1B refiner, and the refiner still retains its refining ability for 6 h after adding it to molten Al, thus improving the strength and plasticity of the material remarkably. The excellent refining effect and stability of AlTiBRE refiner result from that RE can lower the surface energy of molten Al and improve the wetting characteristics of molten Al on refinement nuclei such as TiAl 3, TiB 2, etc., thus giving full play to the effect of heterogeneous nucleation and impeding the congregating tendency of TiB 2 phase in molten Al. At the same time, RE gathering in front of solid/liquid interface are also easy to cause composition supercooling in molten Al, thus impeding the growth of α Al grains and promoting α Al nucleation on refinement nuclei. In addition, RE also play certain role in purification and grain refinement, or modification, especially their effect of purification can improve the metallurgical quality of AlTiBRE master alloy.
文摘The extraction behavior of rare earths was studied by using paraffin with ceresin as a diluent containing 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5.In solid phase,the composition of complexes is REP_3.The equilib- rium extraction constants and pH_(1/2) values of solid-liquid extraction are higher than those of normal liquid-liquid extraction.The extraction efficiency tends to maximum when the ratio of phases is 1:1.When the extraction temperature is higher than the melting point of paraffin and the extraction time is over 10 min,the extraction efficiency keeps constant.Moreover,the relationship among separation factor,equilibrium extrac- tion constant,pH_(1/2) value and atomic number was obtained.The mechanism of solid-liquid extraction is analogous to that of liquid-liquid extraction.
文摘The research on the mechanism of the roast reaction of Baotou concentrate of rare earth with 15% Na 2CO 3 additions was carried out through thermal, X ray diffraction and chemical analysis. Bastnaesite(RECO 3F) was first decomposed into REOF at 623～741 K, then Monazite(REPO 4) reacted with Na 2CO 3 was decomposed into RE 2O 3 and produced Ca 8Nd 2(PO 4) 6O 2 at 853～928 K. The kinetics parameters of the roast reaction were calculated. The results of the calculation were as follows: at 623～741 K, E =152 kJ·mol -1 , n =0 77, A =1 11×10 12 s -1 ·mol -1 , k =1 102( T =705 K), and at 853～928 K, E =232 kJ·mol -1 , n =1 16, A =1 11×10 9 s -1 ·mol -1 , k =1 07×10 -4 ( T =915 K). The equation of the mechanism of the roast reaction is F 1=-ln(1- α ) at 623～741 K and 853～928 K according to TG curves.
文摘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.
基金supported by the National Basic Research Program of China (973) (2007CB31407)Foundation for Innovative Research Groups of the NSFC (60721001)+1 种基金the Young Fund of Sichuan Province (08ZQ026-013)the National Natural Science Foundation of China (50972023, 50872078)
文摘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....
文摘The doping effects of rare earth oxides Ho_2O_3 and Er_2O_3 on dielectric properties of BaTiO_3-based ceramics were studied. After adding rare earth elements, grain growth in this system was inhibited and the grain size was reduced evidently which realized the fine-grained effect. In this system, the trivalent oxides Ho_2O_3 and Er_2O_3 were added to BaTiO_3 ceramics. The rare earth oxides do not enter into inner lattice totally to replace A or B sites. Some of additives can improve dielectric strength by forming nonferroelectric phases, and the rest maintained at grain boundaries controls overgrowth of grains. The dielectric constant at room temperature is increased up to 3000 and the curve of TCC becomes flat. Meanwhile, the dielectric strength E_b becomes higher.
基金supported by the Major Research Project of Xi’an University of Arts and Science (No.zd200906)the Special Fund of Education Committee of Shaanxi Province (No.09JK743)
文摘The structure of LiSrY2（BO3）3 has been solved by single-crystal X-ray diffraction analysis at 298 and 113 K on different diffractometers.It crystallizes in trigonal with space group P-3m1（No.164）.The cell parameters at room temperature are as follows：a = 10.3345（9）,c = 6.4049（11） ,V = 592.41（13） 3,Z = 3,Mr = 448.81,F（000） = 618,μ = 21.327 mm-1 and Dc = 3.774 g/cm3.The crystal structure consists of gear-like [BY6O33] groups which are linked together by corner-sharing to form a two-dimensional layer parallel to the ab plane.These layers are connected one after another by sharing oxygen atoms with B（2） atoms along the c direction to construct a three-dimensional framework.Li and Sr atoms just occupy the cavities formed by oxygen atoms.In addition,the vibrational spectroscopy of LiSrY2（BO3）3 and photoluminescence properties of the Eu3＋ doped LiSrY2（BO3）3 were also studied.
