Rare-earth-free white emitting Ba₂TiP₂O₉ phosphor: revealing its crystal structure and photoluminescence properties

Abstract

A high intensity bluish-white emitting Ba2TiP2O9 phosphor was synthesized by a conventional solid-state reaction method and the precise crystal structure was investigated for the first time by Rietveld refinement analysis. Ba2TiP2O9 has a monoclinic crystal structure with a space group C2/c (no. 15), which is built out of PO4 tetrahedra and TiO5 pyramidal polyhedra connected to form a chain structure along the c-axis. The emission of Ba2TiP2O9 is due to a charge transfer transition between Ti(4+)-O(2-) in the pyramidal TiO5. The obtained Ba2TiP2O9 was excited efficiently by UV and VUV and displayed a bright bluish-white luminescence.

Photoluminescence mechanism of self-activated titanate phosphors investigated by x-ray absorption spectroscopy under UV irradiation

“…The intensities of the observed and calculated patterns were normalized to unity. The crystal parameters obtained from our Rietveld analysis are listed in table 1, which are comparable to the reported values [9,19,20]. The corresponding crystal structures are illustrated as insets in each panel of figure 1, highlighting the TiO 5 polyhedra.…”

“…Both 3d transition-metal ions and rare-earth elements can act as color center dopants [2][3][4]. Recently, several self-activated titanate phosphors have been reported [5][6][7][8][9][10]. One significant advantage of these materials is that they are free of dopants, enabling 1 Author to whom any correspondence should be be addressed.…”

Synthesis, structure, and luminescence of Eu3+‐activated La4Ti3O12nanoparticles with layered perovskite structure

“…The sample shows a bluish‐white emission band centered at 520 nm (2.38 eV) and with a full width at half‐maximum (FWHM) of 167 nm. According to the references for TiO 6 ‐containing phosphor such as Ba 2 TiP 2 O 9 , BaTiO 3 , BaTiSi 3 O 9 , and BaTi(PO 4 ) 2 etc., the self‐activated luminescence of La 4 Ti 3 O 12 could be assigned to CT transition from O2p to 3d orbital in TiO 6 octahedra. The Stokes shift was estimated to be 18.3 × 10 3 cm −1 , which is bigger than that of the reported titanates such as BaTi(PO 4 ) 2 (11 × 10 3 ), BaTiSi 3 O 9 (13.9 × 10 3 ), NaYTiO 4 (14.5 × 10 3 ) etc.…”

New Structural Design Strategy: Optical Center VO4-Activated Broadband Yellow Phosphate Phosphors for High-Color-Rendering WLEDs

“…anionic groups usually show self-activated emission properties . Thus, some vanadate, tungstate, titanate, and niobate exhibit luminescence originating from the charge-transfer (CT) transition from the central cation to the ligand, without introducing an activator. − The VO 4 group, as one of the anionic-group optical centers, usually shows an impressive broadband emission covering the spectrum range of 400–700 nm, which, as a result of two distinct transitions of 3 T 2 – 1 A 1 and 3 T 1 – 1 A 1 of VO 4 units, − make VO 4 -activated luminescent materials potential candidates for high-color-rendering-index (CRI) WLEDs. Unfortunately, most VO 4 -activated phosphors merely exist in vanadates, rendering a limited number of VO 4 -activated phosphors.…”