The free energy change for the reduction-diffusion reaction which was used to prepare the DyFe_2 D_y2 O_3(s) + 3Ca(g) + 4Fe(s) = 3C_aO(s) + 2D_yFe_2(s) intermetallic compound powder was calculated. The reduction-diffu...The free energy change for the reduction-diffusion reaction which was used to prepare the DyFe_2 D_y2 O_3(s) + 3Ca(g) + 4Fe(s) = 3C_aO(s) + 2D_yFe_2(s) intermetallic compound powder was calculated. The reduction-diffusion experiments were carried out at 1073, 1123. 1273 and 1373 K respectively using powders of D_y2O_3, iron, and calcium grains as raw materials. XRD and EDX analysis confirmed that D_yFe_2 was formed by the diffusion of Dy into Fe.展开更多
Nanocrystalline rare earth mixed oxides DyFe x Co 1- x O 3- δ were prepared by sol gel method and characterized by X ray diffraction (XRD), thermogravimetric analysis (TG DTA) and scanning elec...Nanocrystalline rare earth mixed oxides DyFe x Co 1- x O 3- δ were prepared by sol gel method and characterized by X ray diffraction (XRD), thermogravimetric analysis (TG DTA) and scanning electron microscope (SEM). The results show that DyFe x Co 1- x O 3- δ has the structure of perovskite type at 800 ℃ for 2 h calcination. The conductivity of the materials at different temperature was measured by four probe instrumentation and two pole method. The results show that the conductivity of mixed oxides DyFe x Co 1- x O 3- δ is higher than those of un mixed oxides DyFeO 3 and DyCoO 3 and the conductivity is the best at x =0.8 in the matter of DyFe x Co 1- x O 3- δ . The conductivity of these materials always increases with the temperature rising and there is an apparent change between 600 and 800 ℃. However, the spinodals are different with different ration of Fe 3+ and Co 3+ . This kind of oxide is a conductive pottery material.展开更多
The pure intermetallic compounds (Tb1-x;Dyx)Fe2 are super-magnetostriction materials, which were produced from DyFe2 and TbFe2 in this paper. The thermodynamic possibility and kinetic feasible conditions for DyFe2 and...The pure intermetallic compounds (Tb1-x;Dyx)Fe2 are super-magnetostriction materials, which were produced from DyFe2 and TbFe2 in this paper. The thermodynamic possibility and kinetic feasible conditions for DyFe2 and TbFe2 preparation by reduction-diffusion in Ca-Dy2O3-Fe and Ca-Tb4O7-Fe systems were analyzed and the products of DyFe2 and TbFe2 were confirmed by XRD. The contracting core model was applied to describe the reduction-diffusion process in which the diffusion is a rate-controlled step. The apparent activation energies of DyFe2 and TbFe2 processes are 45 and 39 kJ/mol respectively.展开更多
基金National Key Laboratory of the institute of Metal Corrosion and Proteation,Chinese Academy of Sciences.
文摘The free energy change for the reduction-diffusion reaction which was used to prepare the DyFe_2 D_y2 O_3(s) + 3Ca(g) + 4Fe(s) = 3C_aO(s) + 2D_yFe_2(s) intermetallic compound powder was calculated. The reduction-diffusion experiments were carried out at 1073, 1123. 1273 and 1373 K respectively using powders of D_y2O_3, iron, and calcium grains as raw materials. XRD and EDX analysis confirmed that D_yFe_2 was formed by the diffusion of Dy into Fe.
文摘Nanocrystalline rare earth mixed oxides DyFe x Co 1- x O 3- δ were prepared by sol gel method and characterized by X ray diffraction (XRD), thermogravimetric analysis (TG DTA) and scanning electron microscope (SEM). The results show that DyFe x Co 1- x O 3- δ has the structure of perovskite type at 800 ℃ for 2 h calcination. The conductivity of the materials at different temperature was measured by four probe instrumentation and two pole method. The results show that the conductivity of mixed oxides DyFe x Co 1- x O 3- δ is higher than those of un mixed oxides DyFeO 3 and DyCoO 3 and the conductivity is the best at x =0.8 in the matter of DyFe x Co 1- x O 3- δ . The conductivity of these materials always increases with the temperature rising and there is an apparent change between 600 and 800 ℃. However, the spinodals are different with different ration of Fe 3+ and Co 3+ . This kind of oxide is a conductive pottery material.
文摘The pure intermetallic compounds (Tb1-x;Dyx)Fe2 are super-magnetostriction materials, which were produced from DyFe2 and TbFe2 in this paper. The thermodynamic possibility and kinetic feasible conditions for DyFe2 and TbFe2 preparation by reduction-diffusion in Ca-Dy2O3-Fe and Ca-Tb4O7-Fe systems were analyzed and the products of DyFe2 and TbFe2 were confirmed by XRD. The contracting core model was applied to describe the reduction-diffusion process in which the diffusion is a rate-controlled step. The apparent activation energies of DyFe2 and TbFe2 processes are 45 and 39 kJ/mol respectively.
