Optical response of the assembled Tb(OH)
nanospheres and the resulting luminescence change. (a) Top view and (b) lateral SEM images of assembled Tb(OH)3/SiO2 nanospheres. (c) Transmittance spectrum of (a). (d) CL spectrum of randomly dispersed Tb(OH)3/SiO2 (dotted line) and CL spectrum of assembled Tb(OH)3/SiO2 PCs (solid line), both were taken at an electron acceleration voltage of 15 kV.