Unraveling the Preferable Occupation and Luminescent Properties of Ce³⁺-Doped Ca₉Nd(PO₄)₇

Abstract

Various Ce 3+ -doped Ca 9 Nd(PO 4 ) 7 (denotes as CNP: xCe 3+ ) samples were synthesized through a conventional high-temperature solid-state reaction. The CNP: Ce 3+ has a similar lattice with β-Ca 3 (PO 4 ) 2 . Both X-ray diffraction (XRD) analyses and the corresponding Rietveld refinement showed the phase purity of CNP:xCe 3+ and a preferable site occupation of Ce. The luminescent properties of CNP:xCe 3+ have been investigated. Factors that lead to concentration quenching were determined as the dipoledipole interaction by fitting the emission spectra of these samples. The structural variation upon different dopant concentrations was also studied by theoretical simulation based on density functional theory, which also reveals a large band gap of the CNP host to accommodate luminescent centers. Charge density difference reveals the changes in the local environment after Ce 3+ /Ca 2+ replacements. The work provides a thorough case study of a Ce 3+ doped material to give insight into further site engineering.