中国科学院广州能源研究所机构知识库

Novel spinel hollow nanofibers were synthesized by a convenient single-nozzle electrospinning technique. Based on the composition and morphology results by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), a 'gas-push' model was proposed to elucidate the formation mechanism of hollow nanofibers during calcination. Photoluminescence (PL) properties of calcined ZnAl2O4: xCr(3+) and MgAl2O4: xCr(3+) nanofibers were investigated systematically. Under an excitation of 400 nm or 530-550 nm ((4)A(2g)-> T-4(1g) or (4)A(2g ->)(4)T(2g) transitions of Cr3+ ions), an emission band at 675-725 nm including a sharp emission line (R-line) at similar to 687 nm with several vibrational sidebands was obtained. Compared with the spectroscopic properties of ZnAl2O4: xCr(3+) nanofibers, the emission band was broadened and the decay lifetime was shortened for MgAl2O4: xCr(3+) nanofibers. By calculation of crystal field strength, the value of D-q/B is estimated to be 3.25 and 2.72 for ZnAl2O4: xCr(3+) and MgAl2O4: xCr(3+) nanofibers, respectively. The difference of crystal field strength gives a good explanation of the spectroscopic and decay evolution between ZnAl2O4: xCr(3+) and MgAl2O4: xCr(3+) nanofibers.