Abstract
Ca9–xPbxEu(PO4)7 (0 ≤ x ≤ 1) solid solutions with a whitlockite-type (or β-Ca3(PO4)2-type) structure (sp.gr. R3c) were prepared by a standard solid-state method in air. Their luminescent properties under near-ultraviolet (n-UV) light were investigated. Excitation spectra of Ca9–xPbxEu(PO4)7 showed the strongest absorption at about 395 nm, which matches well with commercially available n-UV-emitting GaN-based LED chips. Emission spectra indicated an intense red emission due to the 5D0 → 7F2 transition of Eu3+, with a maximum in the intensity for Ca8.5Pb0.5Eu(PO4)7. The emission intensity of Ca8.5Pb0.5Eu(PO4)7 was about 1.8 times higher than that of a Ca9Eu(PO4)7 phosphor. We suggest that the introduction of Pb2+ is an efficient approach to enhance luminescence properties of such phosphors. We clarified the influence of the Ca2+ → Pb2+ substitution on intensities of three bands for the 5D0 → 7F0 transition in excitation spectra of Ca9–xPbxEu(PO4)7. In addition, we found a reversible first-order phase transition from R3≿ to R3¯≿ symmetry by second-harmonic generation in the range from 753 K (x = 1) to 846 K (x = 0).
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
