Fe68Zr20B12 amorphous alloy was prepared by mechanical alloying（MA） method and annealed at different temperatures. Microstructures and magnetic properties of Fe68Zr20B12 alloys as-milled and annealed at 693, 843, 94...Fe68Zr20B12 amorphous alloy was prepared by mechanical alloying（MA） method and annealed at different temperatures. Microstructures and magnetic properties of Fe68Zr20B12 alloys as-milled and annealed at 693, 843, 943 and 993 K were studied. The raw powders（Fe, Zr, B） formed b. c. c. α-Fe solid solution at early stages of MA and then transformed into amorphous alloy. Grain size（D） of Fe68Zr20B12 alloys increases with increasing annealing temperature and keeps at nanometer level. The specific saturation magnetization（σs） increases with increasing annealing temperature from 300 K to 943 K, and then decreases with annealing temperature at 993 K because of the precipitation of Fe3B.展开更多
Commercial nanosized alumina and titania particles were selected as raw materials to prepare the blended slurry with composition of A1203-13%TiO2 （mass fraction）, which were reconstituted into micrometer-sized granu...Commercial nanosized alumina and titania particles were selected as raw materials to prepare the blended slurry with composition of A1203-13%TiO2 （mass fraction）, which were reconstituted into micrometer-sized granules by spray drying, subsequently sintering at different temperatures to form nanostructured feedstock for thermal spraying, and then A1203-13%TiO2 nanocoatings were deposited by plasma spraying. The evolution of morphology, microstructure, and phase transformation of the agglomerated powder and as-sprayed coatings were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results show that A1203 retains the same a phase as the raw material during sintering, while TiO2 changes from anatase to futile. During plasma spraying, some a-A1203 phases solidify to form metastable y-A1203, and the volume fraction of a-A1203 decreases as CPSP increases. However, peaks of the TiO2 phase are not observed from the as-sprayed coatings except for the coatings sprayed at the lower CPSP. As the CPSP increases, nanostructured TiO2 is dissolved easily in y-A1203 or z-A1203＇TiO2 phase. After heat treatment, y-A1203 in the coatings transforms to a-A1203, and rutile is precipitated.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
ZnSe∶Mn nanocrystals were grown by chemical vapour transport method using the matrix of SiO2 aerogels. The cubic structure of the nanocrystals was confirmed by powder X-ray diffraction (XRD) and electron diffraction ...ZnSe∶Mn nanocrystals were grown by chemical vapour transport method using the matrix of SiO2 aerogels. The cubic structure of the nanocrystals was confirmed by powder X-ray diffraction (XRD) and electron diffraction (ED) studies. The size of the crystals was observed using transmission electron microscope (TEM). The oxidation state of Mn in ZnSe nanocrystal was found using electron spin resonance (ESR) spectrum. The room temperature luminescence measurements show the peaks corresponding to both bandgap of the material and Mn in ZnSe.展开更多
基金Funded by the Science and Technology Development Project of Jilin Province (No. 20040506-3)
文摘Fe68Zr20B12 amorphous alloy was prepared by mechanical alloying（MA） method and annealed at different temperatures. Microstructures and magnetic properties of Fe68Zr20B12 alloys as-milled and annealed at 693, 843, 943 and 993 K were studied. The raw powders（Fe, Zr, B） formed b. c. c. α-Fe solid solution at early stages of MA and then transformed into amorphous alloy. Grain size（D） of Fe68Zr20B12 alloys increases with increasing annealing temperature and keeps at nanometer level. The specific saturation magnetization（σs） increases with increasing annealing temperature from 300 K to 943 K, and then decreases with annealing temperature at 993 K because of the precipitation of Fe3B.
基金Projects(51072045,51102074)supported by the National Natural Science Foundation of China
文摘Commercial nanosized alumina and titania particles were selected as raw materials to prepare the blended slurry with composition of A1203-13%TiO2 （mass fraction）, which were reconstituted into micrometer-sized granules by spray drying, subsequently sintering at different temperatures to form nanostructured feedstock for thermal spraying, and then A1203-13%TiO2 nanocoatings were deposited by plasma spraying. The evolution of morphology, microstructure, and phase transformation of the agglomerated powder and as-sprayed coatings were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The results show that A1203 retains the same a phase as the raw material during sintering, while TiO2 changes from anatase to futile. During plasma spraying, some a-A1203 phases solidify to form metastable y-A1203, and the volume fraction of a-A1203 decreases as CPSP increases. However, peaks of the TiO2 phase are not observed from the as-sprayed coatings except for the coatings sprayed at the lower CPSP. As the CPSP increases, nanostructured TiO2 is dissolved easily in y-A1203 or z-A1203＇TiO2 phase. After heat treatment, y-A1203 in the coatings transforms to a-A1203, and rutile is precipitated.
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ZnSe∶Mn nanocrystals were grown by chemical vapour transport method using the matrix of SiO2 aerogels. The cubic structure of the nanocrystals was confirmed by powder X-ray diffraction (XRD) and electron diffraction (ED) studies. The size of the crystals was observed using transmission electron microscope (TEM). The oxidation state of Mn in ZnSe nanocrystal was found using electron spin resonance (ESR) spectrum. The room temperature luminescence measurements show the peaks corresponding to both bandgap of the material and Mn in ZnSe.
