Synthesis of Tb$^{3+}$ ion doped ZnWO$_4$ phosphors and investigation of their photoluminescence properties: concentration effect

[摘要] In this paper, the effects of Tb$^{3+}$ ion concentration on the structural and photoluminescence properties of ZnWO$_4$:Tb$^{3+}$ have been reported. X-ray diffraction studies indicated that the monoclinic structure of the samples and thecrystallinity were found to decrease with the increase of Tb$^{3+}$ ion concentration due to the distortion in the crystal lattice. The formation of the monoclinic structure was further supported by high resolution transmission electron microscopy and Fourier transform infrared analyses. The transmission electron microscopy image of ZnWO$_4$:Tb$^{3+}$ (7%) showed a spherical morphology with crystallite sizes in the range of $\sim$8–12 nm. The excitation spectrum showed a strong broad band originated from the electronic transition within the WO$^{6−}_6$ group. Upon excitation at 270 nm, the prepared ZnWO$_4$:Tb$^{3+}$ phosphors exhibited sharp and narrow emission peaks, characteristic of the f–f transitions of Tb$^{3+}$ ions besides a broad band with themaximum at around 460 nm due to the host lattice. The intensity of the broad emission band was found to decrease gradually with the increase of Tb$^{3+}$ ion concentration and reached minimum at 7 at%. The decay time of the prepared phosphors was investigated in detail and the maximum average lifetime value is found to be 1.187 ms.

[学科分类] 材料工程

[关键词] ZnWO$_4$:Tb$^{3+}$;photoluminescence;concentration effect.