Luminescence of CNT coated LaPO_4:Tm phosphors and their field emission lamp application

摘要

When the phosphor LaPO_4:Tm was coated with carbon nanotubes (CNTs), carbon atoms were diffused into the phosphor lattice. Binding energy of La 3d and C 1s were not shifted by CNT coating, while that of 0 1s was lowered slightly as a result of the formation of C-O and C=O bonds on the phosphor surface. CNT coating increased the atomic concentrations of 0 and C by 27.4% and 9%, respectively. Photolumines-cence intensity decreased significantly, by 52%, when CNT concentration of 1.5 wt% was coated. This is attributed to covering the phosphor with black CNTs/carbons and the formation of C-O and C=O bonds on the phosphor surface. Conversely, cathodoluminescence (CL) intensity was improved by a factor of 3.86 when 1.25 wt% of CNTs was coated, attributing to improved conductivity, reduced charging, and increased CL excitation probability of the phosphor. The influence of CNT coating on the luminescence of LaPO_4:Tm was compared with that of LaPO_4:Eu phosphor. Blue CL was observed from LaPO_4:Tm, it is potential for field emission lamp application.