Growth and morphology of neodymium or ytterbium doped calcium gadolinium yttrium oxoborate (Re∶Ca 4Gd x Y 1- x O(BO 3) 3(Re∶GdYCOB)Re =Nd,Yb; x =0-1)were systematically studied. Polycrystalline materials used for Re...Growth and morphology of neodymium or ytterbium doped calcium gadolinium yttrium oxoborate (Re∶Ca 4Gd x Y 1- x O(BO 3) 3(Re∶GdYCOB)Re =Nd,Yb; x =0-1)were systematically studied. Polycrystalline materials used for Re∶GdYCOB single crystals growth were synthesized by multistage solid phase reaction method.Re∶GdYCOB single crystals were grown by Czochralski technique.The pulling rates are 0.5-2mm/h and the rotation rates are 10-30r/min.Usually 65-75% polycrystalline materials can be transformed into good quality single crystals under our growth conditions. The structures of some as grown Re∶GdYCOB single crystals were measured by using a four circle diffractometer.The results measured show that the space group of the crystals is C 3 s Cm.The determined lattice constants of 8 at% Nd doped Ca 4YO(BO 3) 3 single crystal are a =0.8076nm, b =1.6020nm, c =0.3527nm , β =101.23°.展开更多
The effects of the addition of 0.6%Ca（mass fraction） on the as-cast microstructure and mechanical properties of the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc magnesium alloys were investigated and compared by optical...The effects of the addition of 0.6%Ca（mass fraction） on the as-cast microstructure and mechanical properties of the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc magnesium alloys were investigated and compared by optical microscopy and scanning electron microscopy,differential scanning calorimetry analysis,and tensile and creep tests.The results indicate that the addition of 0.6%Ca to the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys can refine the grains of the two alloys.At the same time,the addition of 0.6%Ca to the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys can effectively improve the tensile properties of the two alloys.In addition,the addition of 0.6%Ca can also improve the creep properties of the Mg-3Ce-1.2Mn-0.9Sc alloy but is not beneficial to the creep properties of the Mg-4Y-1.2Mn-0.9Sc alloy.The different effects of minor Ca on the creep properties of the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys are possibly related to the difference in the solid solubilities of Ce and Y in Mg.展开更多
The microstructural features of clacium rare earth(Ca RE) fluorocarbonate minerals from Southwest China were studied by using selected area electron diffraction(SAED) and high resolution transmission electron micros...The microstructural features of clacium rare earth(Ca RE) fluorocarbonate minerals from Southwest China were studied by using selected area electron diffraction(SAED) and high resolution transmission electron microscopy(HRTEM). Three new regularly mixed layer structures of B 8S 6 type with long period and different stacking sequence, i.e. B 8S 6 Ⅰ, B 8S 6 Ⅱ, and B 8S 6 Ⅲ, were found in the derived polycrystal of parisite, in which their structural symmetry, cell parameters, chemical formulas of crystal and stacking models of structural unit layer, etc. were determined. The results of this study also show that these new regularly mixed layer structrues were formed by order stacking unit layer of bastnaesite(B) and synchisite(S) in varying proportion along c axis. The observation under HRTEM reveals that in the three new regularly mixed layer structures there are different distribution modes of Ce F ion layers, CO 2- 3 ion groups between the Ce F ion layers, and CO 2- 3 ion groups between Ce F and Ca 2+ ion layers, and there are some heterogeneous textures, such as disorder interlayer and stacking fault. It further proves the complexity of the crystal structure of the Ca RE fluorocarbonate minerals.展开更多
文摘Growth and morphology of neodymium or ytterbium doped calcium gadolinium yttrium oxoborate (Re∶Ca 4Gd x Y 1- x O(BO 3) 3(Re∶GdYCOB)Re =Nd,Yb; x =0-1)were systematically studied. Polycrystalline materials used for Re∶GdYCOB single crystals growth were synthesized by multistage solid phase reaction method.Re∶GdYCOB single crystals were grown by Czochralski technique.The pulling rates are 0.5-2mm/h and the rotation rates are 10-30r/min.Usually 65-75% polycrystalline materials can be transformed into good quality single crystals under our growth conditions. The structures of some as grown Re∶GdYCOB single crystals were measured by using a four circle diffractometer.The results measured show that the space group of the crystals is C 3 s Cm.The determined lattice constants of 8 at% Nd doped Ca 4YO(BO 3) 3 single crystal are a =0.8076nm, b =1.6020nm, c =0.3527nm , β =101.23°.
基金Projects (CSTC2013jcyjC60001) supported by the Chongqing Science and Technology Commission of ChinaProject (KJ120834) supported by the Chongqing Education Commission of ChinaProject (CQUT1205) supported by the Open Funds from Key Laboratory of Manufacture and Test Techniques for Automobile Parts(Chongqing University of Technology),Ministry of Education,China
文摘The effects of the addition of 0.6%Ca（mass fraction） on the as-cast microstructure and mechanical properties of the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc magnesium alloys were investigated and compared by optical microscopy and scanning electron microscopy,differential scanning calorimetry analysis,and tensile and creep tests.The results indicate that the addition of 0.6%Ca to the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys can refine the grains of the two alloys.At the same time,the addition of 0.6%Ca to the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys can effectively improve the tensile properties of the two alloys.In addition,the addition of 0.6%Ca can also improve the creep properties of the Mg-3Ce-1.2Mn-0.9Sc alloy but is not beneficial to the creep properties of the Mg-4Y-1.2Mn-0.9Sc alloy.The different effects of minor Ca on the creep properties of the Mg-3Ce-1.2Mn-0.9Sc and Mg-4Y-1.2Mn-0.9Sc alloys are possibly related to the difference in the solid solubilities of Ce and Y in Mg.
文摘The microstructural features of clacium rare earth(Ca RE) fluorocarbonate minerals from Southwest China were studied by using selected area electron diffraction(SAED) and high resolution transmission electron microscopy(HRTEM). Three new regularly mixed layer structures of B 8S 6 type with long period and different stacking sequence, i.e. B 8S 6 Ⅰ, B 8S 6 Ⅱ, and B 8S 6 Ⅲ, were found in the derived polycrystal of parisite, in which their structural symmetry, cell parameters, chemical formulas of crystal and stacking models of structural unit layer, etc. were determined. The results of this study also show that these new regularly mixed layer structrues were formed by order stacking unit layer of bastnaesite(B) and synchisite(S) in varying proportion along c axis. The observation under HRTEM reveals that in the three new regularly mixed layer structures there are different distribution modes of Ce F ion layers, CO 2- 3 ion groups between the Ce F ion layers, and CO 2- 3 ion groups between Ce F and Ca 2+ ion layers, and there are some heterogeneous textures, such as disorder interlayer and stacking fault. It further proves the complexity of the crystal structure of the Ca RE fluorocarbonate minerals.
