Preparation and photoluminescence investigation of the LaPO₄:Eu³⁺ inverse opal structure

The inverse opal LaPO₄:Eu^{3 +} was successfully fabricated by the sol-gel method, and characterized by the scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), and photoluminescence investigations. The inverse opal LaPO₄:Eu^{3 +} sample has a different emission in comparison with the ordinary luminescence emission bands of Eu^{3 +} ion at 590, 615, and 695 nm. In the inverse opal structure, the strongest emission is the transition ⁵D₀→ ⁷F₄ at about 695 nm, which may be due to the fact that the emission in the plane decreases because of the photonic band structure and the corresponding emission in the vertical direction increases. For the emissions at 590 and 615 nm of the Eu^{3 +}, the results show that the emission ratio of 590 to 615 nm increases from 0.266 to 0.639 for the inverse opal sample in comparison with the ordinary sample, which means that the ratio increases about 2.4 times for the inverse opal sample.