Structure and photoluminescence characterization of Tb³⁺-doped LaPO₄ nanorods prepared via the microwave-assisted method

LaPO₄ nanopowders doped with 1, 2… 10, 11, 15 and 20 mol% Tb³⁺ have been prepared by the microwave-assisted method. Transmission electron microscope (TEM) images indicated that the nanopowders are composed of nanorods. X-ray diffraction (XRD) analysis showed that the prepared nanorods exhibit hexagonal crystal structure and the diffraction peaks were shifted towards the higher 2θ angle side with increasing Tb³⁺ dopant concentration. Raman scattering measurement found out that some of scattering lines were shifted and broadened to higher wavenumber side with increasing Tb³⁺ concentration. It is discovered that the photoluminescence (PL) of Tb³⁺ ions results from the radiative intra-configurational f–f transitions that occur from the ⁵D₄ exited state to the ⁷F_J (J=0,1–6) ground states; the photoluminescence excitation (PLE) of Tb³⁺ ions takes place from the ⁷F₆ ground state to the ⁵D_J (J=0,1–4), ⁵L₁₀, ⁵G_J (J=2–4), ⁵H_J and ⁵I_J exited states. It was observed that the photoluminescence intensity reached a maximum in the samples doped with 15 mol% Tb³⁺. Double-exponential decay of the ⁵D₄→⁷F₅ emission was observed with lifetimes of ~5 ns and 6.35 ms. - Highlights: • Hexagonal LaPO₄:Tb nanorods have been prepared by the microwave-assisted method. • XRD peaks were shifted to higher 2θ angle side with increasing Tb³⁺ concentration. • Some Raman peaks shifted and broadened to higher energy with rising Tb³⁺ content. • The ⁵D₄→⁷F₅ emission of Tb³⁺ ion exhibits a double-exponential decay