Preparation, Characterization, and Photoluminescence Properties of Tb³⁺-, Ce³⁺-, and Ce³⁺/Tb³⁺-Activated RE₂Si₄N₆C (RE = Lu, Y, and Gd) Phosphors

Abstract

Photoluminescence properties of Tb3+ and Ce3+ singly doped and Ce3+/Tb3+-codoped RE2Si4N6C (RE = Lu, Y, and Gd) phosphors were investigated. Tb3+ shows similar luminescence properties in RE2Si4N6C (RE = Lu, Y, and Gd) host lattices and emits bright green light under UV excitation around 300 nm. The luminescence properties of Ce3+ in RE2Si4N6C host lattices are influenced by the size of the RE3+ ions (Lu2Si4N6C and Y2Si4N6C vs Gd2Si4N6C). Both Ce3+-activated Lu2Si4N6C and Y2Si4N6C phosphors exhibit a broad band emission in the wavelength range of 450−750 nm with peak center at about 540 nm, while Ce3+-activated Gd2Si4N6C shows a broad emission band in the wavelength range of 500−800 nm with peak center at about 610 nm. This difference is ascribed to the different site occupations of Ce3+ on the two crystallographic sites in Gd2Si4N6C as compared to the Y and Lu compounds. In Ce3+/Tb3+-codoped RE2Si4N6C (RE = Lu, Y, and Gd) phosphors, it is observed that energy transfer takes place from Ce3+ to Tb3+ in Ce3+/Tb3+-codoped Lu2Si4N6C and Y2Si4N6C but in the reversed direction from Tb3+ to Ce3+ in Ce3+/Tb3+-codoped Gd2Si4N6C, depending on the position of the 5d level of Ce3+ versus the 5D4 level of Tb3+. The potential applications of these phosphors are pointed out.

Nanosegregation and Neighbor‐Cation Control of Photoluminescence in Carbidonitridosilicate Phosphors

“…[14] Photoluminescence of Ce 3+ -and Tb 3+ -doped Y 2 Si 4 N 6 C materials, [18] and the underlying Ce 3+ -Tb 3+ energy transfer process, [19] have also been investigated, and Ln 1.99 Ce 0.01 Si 4 N 6 C for Ln=Gd and Lu have emission peaks of 610 nm and 540 nm. [19] Several studies have proposed that higher covalence is expected in the Y 2 Si 4 N 6 C network owing to the introduction of carbon, so that the thermal stability of photoluminescence in carbidonitridosilicates is expected to be better than that of corresponding SrYSi 4 N 7 type nitrides. [17,20,21] However, no studies of the evolution of phosphor properties within is surprising, as the progressive replacement of Sr 2+ and N 3− by Y 3+ and C 4− was expected to introduce more covalency into the materials and hence raise lattice rigidity and the quenching barrier height.…”

An Investigation of Self-Absorption and Corresponding Spectral Shift in Phosphors

“…Most LED phosphors -whether used in production or studied in research -are broadband and based on Ce 3+ (1)(2)(3)(4)(5)(6) or Eu 2+ (7)(8)(9)(10)(11)(12). The broad bands in these phosphors often lead to overlap between the absorption and emission profiles.…”

Synthesis and luminescence properties of novel Y2Si4N6C:Sm3+ carbonitride phosphor

“…Structurally, they are derived from the quaternary silicon nitride compounds, MRESi 4 N 7 (M¼ Ca, Sr, Ba; RE¼ Y, Yb), by formal substitutions of nitrogen by carbon and M 2 þ by RE 3 þ . The high structural stability of the carbonitride phosphors is expected due to the strong covalency of N 3 À and C 4 À in the host lattice [8]. In this paper, we report the luminescence properties and decay times of Y 2 Si 4 N 6 C:Sm 3 þ phosphor.…”