Ca8MgSm1–х(PO4)7:xEu3+, promising red phosphors for WLED application

Dina V. Deyneko, Ivan V. Nikiforov, Bogdan I. Lazoryak, Dmitry A. Spassky, Ivan I. Leonidov, Sergey Yu Stefanovich, Daria A. Petrova, Sergey M. Aksenov, Peter C. Burns

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)

Abstract

Novel red emitting phosphors Ca8MgSm1–х(PO4)7:xEu3+ with whitlockite-type structure were prepared by a high temperature solid-state reaction in air. Powder X-ray diffraction (PXRD), photoluminescence spectra, and fluorescence decay were used to characterize the structure and luminescence properties. All samples were found to have the expected rhombohedral structure with R3¯c space group. The non-polar space group is also confirmed by a photoluminescence study. This space group allows forbidden transitions for Eu3+. The presence of only one Shtark component in 5D07F0 confirms the presence of only one non-equivalent site containing Eu3+ ions. The high intensity of the transition ratio 5D07F2/5D07F1 establishes the strongly disordered environment of the Eu3+ ions. Thus, M1–M3 sites in the host matrix are occupied by Ca2+, Sm3+, and Eu3+ ions, whereas M5 is fully occupied by Mg2+. The optimal concentration was found with x = 0.75 in Ca8MgSm1–х(PO4)7:xEu3+ phosphors. The emitting of Sm3+ was depressed due to the high intensity of Eu3+ luminescence; however, the contribution of Sm3+ is manifested in the energy transfer process and shift of CIE coordinates. Furthermore, the CIE chromaticity coordinate of as-prepared Ca8MgSm0.25(PO4)7:0.75Eu3+ (x = 0.650; y = 0.345) is close to the standard red-emitting point (x = 0.67, y = 0.33). The experimental data indicate that Ca8MgSm1–х(PO4)7:xEu3+ upon excitation by near-UV radiation is a promising red phosphor for white-light-emitting diodes.

Original languageEnglish
Pages (from-to)897-903
Number of pages7
JournalJournal of Alloys and Compounds
Volume776
DOIs
Publication statusPublished - 5 Mar 2019
Externally publishedYes

Keywords

  • Eu
  • Red phosphors
  • Sm
  • Whitlockite-type structure
  • WLED

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