摘要
Un-doped and ZnAl_(x)O_(1.5x+1):0.1 mol%Tb^(3+)(ZAOT)nano-powders were synthesized via citrate sol-gel method.The AIx moles were varied in the range of 0.25≤x≤5.0.The X-ray powder diffraction(XRD)data reveal that for x<1.5,the prepared samples crystal structure consists of mixed phases of the cubic ZnAl_(2)O_(4) and hexagonal ZnO phases,while for x>1.5 the structure consists of single phase of cubic ZnAl_(2)O_(4).The Raman and Fourier-trans form infrared(FTIR)vibrational spectroscopy show the presence of vibrations emanating ZnAl_(2)O_(4) spinel.Scanning electron microscopy(SEM)and transmission electron microscopy(TEM)show the presence of irregular sphere at x>2.0 attributed to ZnAl_(2)O_(4).The photoluminescence(PL)spectroscopy reveals emissions from both the host and Tb^(3+)transitions.Emissions from Tb^(3+)are observed at 382,414,439,458 nm and 489,545,585,621 nm,which were attributed to the^(5)D_(3)→^(7)F_(6,5,4,2) and ^(5^)D_(4)→^(7)F_(6,5,4,3),respectively.The results confirm that the Tb^(3+)occupation site depends on the Alx moles.The International Commission on Illumination(CIE)colour chromaticity shows that the emission colour can be tuned from blue to green by varying the AIx moles.
基金
Project supported by the South African National Research Foundation(NRF)Thuthuka programme(UID 99266,113947)
NRF Incentive Funding for Rated Researchers(IPRR)(114924)
NRF Black Academics Advancement Programme(BAAP)(138233)。
