Fabrication And Properties Of Rare Earth-doped Lanthanum Dioxymonocyanamides Nanostructures

Rare earth dioxymonocyanamides have become one of the important matrixes for lanthanide cations-doped phosphors owing to their unique structure and properties. Nowadays, the fabrication of rare earth dioxymonocyanamides nanostructures is not found in the literatures except for rare earth dioxymonocyanamides powders. Electrospinning has been proved to be one of the best methods to fabricate low-dimensional nanomaterials owing to its simple operation, high efficiency and reproducibility. Hence, fabrication of rare earth ions-doped rare earth dioxymonocyanamides one-dimensional nanomaterials via electrospinning remains an important and meaningful subject of study.In this dissertation, PVP/rare earth nitrates composite nanostructures were fabricated by electrospinning, and then La2O3, La2O3:RE3+(RE=Eu,Tb) nanofibers and nanobelts and La2O3:RE3+(RE=Er, Yb/Er) nanofibers were prepared through calcining the as-obtained composite nanofibers and nanobelts. For the first time, La2O2CN2, La2O2CN2:RE3+(RE=Eu,Tb) nanofibers and nanobelts and La2O2CN2:RE3+(RE=Er,Yb/Er) upconversion luminescent nanofibers were successfully synthesized via cyanamidation of the above-prepared respective La2O3,La2O3:RE3+nanofibers and nanobelts and La2O3:RE3+(RE=Er, Yb/Er) nanofibers.The samples were systematically characterized by modern measurement techniques, including XRD, SEM, EDX, TEM, PL and BET method. The results show that La2O2CN2:RE3+(RE=Eu, Tb, Er, Yb/Er) nanostructures are pure tetragonal structure with space group I4/mmm. The mean diameter of La2O2CN2:RE3+nanofibers are about120-280nm and the width of La2O2CN2:RE3+nannobelts is ca.1-4μm. La2O2CN2nanomaterials exhibit excellent photocatalytic activity in photodegradation of rhodamine B (RhB) aqueous solution under ultraviolet light irradiation, and the nanofibers have higher photocatalytic ability than nanobelts under the same experimental conditions. La2O2CN2:RE3+nanostructures possess excellent fluorescent performances. Possible formation mechanisms of rare earth dioxymonocyanamides nanofibers and nanobelts are also presented, and some meaningful results are obtained. These new findings have paved the way for the future study of luminescence of rare earth ions-doped rare earth dioxymonocyanamides low-dimensional nanomaterials.