Preparation Of Nano-Rare-Earth Oxides And Nano-Rare-Earth/Rubber Composites

Rare earth materials for the special electron structure have been applied widely in many fields for example, optics, electrics, magnetics and radial shielding. Nano-rare earth materials can exhibit lots of special properties including small size effect, high specific surface effect, quantum effect, high optical, electronic, magnetical properties, superconductive property and high reactivity, which can improve the properties of nano-materials at a large extent. Therefore, the preparation of rare earth nano-materials attracts more and more concern.In this thesis, three methods were used to prepare nano-rare-earth material. In the first method, ammonia as precipitator was added to rare earth chloride solution and the rare earth hydroxid emusion could be gained. Then, the rare earth hydroxid emusion was sprayed to prepare superfine precursor. Finally, nano-rare-earth compound could be obtained through calcining the precursor. In the second method, the rare earth hydroxid emusion prepared in method one was filtered and washed for several times before spray drying. In the third method (salt-assisted spray drying method), sodium chloride as precipitator instead of ammonia, and other processes were similar with the first method. Rare earth/rubber nano-composites were prepared by mixing nano-rare-earth compound and nitrile-butadiene rubber(NBR).TGA, XRD, SEM, TEM, X-Ray tests were used to characterize the nano-rare-arth compound and rare earth/rubber nano-composites. The results are as follow.(1) Preparation of Gd2O3 nanoparticles:Cubic Gd2O3 with the size of about 100nm was gained through calcining the precursor at 900℃in the first method. Monoclinic Gd2O3 of sheet structure with thickness of about 100nm was obtained through calcining the precursor at 900℃in the second method. Monoclinic Gd2O3 of sheet structure with thickness of about 20nm was obtained after washing the product prepared by calcining the precursor at 700℃in the third method.(2) Preparation of the La(Ce, Sm) nanometer particles:In the samples prepared by the first method, tetragonal LaOCl of discal structure with thickness of about 200nm was gained through calcining the precursor at 950℃. Cubic CeO2 with the size of about 100nm was gained through calcining the precursor at 700℃. Cubic and monoclinic Sm2O3 with the size of about 100nm were obtained simultaneously through calcining the precursor at 950℃. In the samples prepared by salt-assisted spray drying method, tetragonal LaOCl of sheet structure with thickness of about 20nm was obtained after washing the product prepared by calcining the precursor at 700℃. Cubic CeO2 of spherical structure with size of about 30nm was obtained after washing the product prepared by calcining the precursor at 700℃. tetragonal SmOCl and monoclinic Sm2O3 of sheet structure with thickness of about 50nm were obtained after washing the product prepared by calcining the precursor at 700℃.(3) Preparation of Sm-Gd mixed oxides:Sm-Gd mixed oxides were prepared in the first method. The size of products was about 100nm. The results indicated that the mixed oxides could be formed by Gd2O3 and Sm2O3 oxides with same crystal structure in the final products.(4) Preparation of different nano-Gd2O3/NBR composites:First, simple mixing method was used to prepare Gd2O3/NBR composites, in which the Gd2O3 was prepared by method 1. the size of Gd2O3 particles in the Gd2O3/NBR composite was in the range of 100-500nm. Second, Gd2O3/NBR composites were prepared by co-coagulation method. The nano Gd2O3 prepared by salt-assisted spray drying method was mixed with NBR latex. Gd2O3 nanoparticles dispersed finely in the Gd2O3/NBR composite. Compared with micro-Gd2O3/NBR composites, the tensile strength and the shielding property of nano-Gd2O3/NBR composites increased significantly. With the increase of nano-Gd2O3 concentration, the tensile strength and the shielding property of the nano-Gd2O3/NBR composite also increased linearly.