Nanosized rare earth solid superacid SO42/TiO2-Nd2O3 was prepared and was used as a catalyst for cyclohexand dehydration to form cyclohexene.The influence of various preparation parameters such as the concentration of...Nanosized rare earth solid superacid SO42/TiO2-Nd2O3 was prepared and was used as a catalyst for cyclohexand dehydration to form cyclohexene.The influence of various preparation parameters such as the concentration of Nd3+,the concentration of H2SO4 and the calcination temperature on the catalytic activity was studied.It indicates that SO42-/TiO2-Nd2O3 has fairly high catalytic activity on the dehydration of cyclohexand and the yield of cyclohexene can reach 79.73%.The SO42-/TiO2-Nd2O3 catalytic mechanism for cyclohexand dehydration and the Nd3+ effect on the catalytic activity was also disccused.展开更多
The present work aimed to explore a kind of microwave dielectric materials with middle-permittivity, high Qf, near-zero τf, and lower sintering temperature. A series of Y2Ti2O7 microwave dielectric ceramics were synt...The present work aimed to explore a kind of microwave dielectric materials with middle-permittivity, high Qf, near-zero τf, and lower sintering temperature. A series of Y2Ti2O7 microwave dielectric ceramics were synthesized by conventional solid-state method. For improving the dielectric properties of Y2Ti2O7 system, Bi2O3, Nd2O3 and Nb2O5 were added and their effects on phase composition, micro-structure, and dielectric properties at microwave frequencies were investigated by means of X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The queuing score method for multi-target orthogonal design was used to obtain the optimum prescription. The results showed that the Y2Ti2O7 ceramics with 8 wt.% Bi2O3 and 1 mol.% Nd2O3-Nb2O5 were well sintered at 1350 ℃, exhibiting excellent dielectric characteristics, i.e. εr≈76, Qf≈18980 GHz, τf =＋25.5 ppm/℃.展开更多
In this paper, the conductivities of BaPbO 3 and BaPbO 3-Nd 2O 3 system ceramics are studied. The experimental results show that the charge carriers in this system ceramics are donor electrons captured in oxygen v...In this paper, the conductivities of BaPbO 3 and BaPbO 3-Nd 2O 3 system ceramics are studied. The experimental results show that the charge carriers in this system ceramics are donor electrons captured in oxygen vacancies. The conductivity and the PTC characteristics of the BaPbO 3-Nd 2O 3 ceramics are obviously different from those of pure BaPbO ceramics.展开更多
文摘Nanosized rare earth solid superacid SO42/TiO2-Nd2O3 was prepared and was used as a catalyst for cyclohexand dehydration to form cyclohexene.The influence of various preparation parameters such as the concentration of Nd3+,the concentration of H2SO4 and the calcination temperature on the catalytic activity was studied.It indicates that SO42-/TiO2-Nd2O3 has fairly high catalytic activity on the dehydration of cyclohexand and the yield of cyclohexene can reach 79.73%.The SO42-/TiO2-Nd2O3 catalytic mechanism for cyclohexand dehydration and the Nd3+ effect on the catalytic activity was also disccused.
基金supported by the Key University Science Research of Jiangsu Province (08KJA430002)the Priority Academic Program D velopment of Jiangsu Higher Education Institute
文摘The present work aimed to explore a kind of microwave dielectric materials with middle-permittivity, high Qf, near-zero τf, and lower sintering temperature. A series of Y2Ti2O7 microwave dielectric ceramics were synthesized by conventional solid-state method. For improving the dielectric properties of Y2Ti2O7 system, Bi2O3, Nd2O3 and Nb2O5 were added and their effects on phase composition, micro-structure, and dielectric properties at microwave frequencies were investigated by means of X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The queuing score method for multi-target orthogonal design was used to obtain the optimum prescription. The results showed that the Y2Ti2O7 ceramics with 8 wt.% Bi2O3 and 1 mol.% Nd2O3-Nb2O5 were well sintered at 1350 ℃, exhibiting excellent dielectric characteristics, i.e. εr≈76, Qf≈18980 GHz, τf =＋25.5 ppm/℃.
文摘In this paper, the conductivities of BaPbO 3 and BaPbO 3-Nd 2O 3 system ceramics are studied. The experimental results show that the charge carriers in this system ceramics are donor electrons captured in oxygen vacancies. The conductivity and the PTC characteristics of the BaPbO 3-Nd 2O 3 ceramics are obviously different from those of pure BaPbO ceramics.
