A novel promising red phosphor Ca9LiBi0.667(PO4)7:Eu3+ with excellent responsiveness to phytochrome PFR for the indoor plant cultivation

Role of the Eu3+ Distribution on the Properties of β-Ca3(PO4)2 Phosphors: Structural, Luminescent, and 151Eu Mössbauer Spectroscopy Study of Ca9.5–1.5xMgEux(PO4)7

“…The β-TCP-type phosphors were characterized by trigonal crystal structures, which can be either polar [space group (SG) R 3 c ] or nonpolar (SG R 3̅ c ). The general formula, which reflects possible isomorphous substitution ( Z = 6), is Ca 10.5–0.5( x –2 y –3 z ) A + x B 2+ y R 3+ z (TO 4 ) 7 , where A + = alkaline cations (Li, Na, K), ,− B 2+ = divalent cations (Ca, Mg, Zn, Cd), − and R 3+ = trivalent RE elements (Y, Sc, Ln), Bi 3+ , In 3+ . − The β-Ca 3 (PO 4 ) 2 -type structure consists of five different crystallographic M1–M5 sites: the M1–M3 sites occupy 18b Wyckoff positions and are located at the centers of 8-vertex polyhedra; the M4 site occupies the 6a Wyckoff position and is located at the 3-fold axis at a 15-vertex polyhedron (which is usually half-occupied); the M5 site occupies the 6a Wyckoff position and is also located at the 3-fold axis at the center of a distorted octahedron. In the R 3̅ c structure, the M1 and M2 sites, P2O 4 and P3O 4 tetrahedra of the β-TCP-type structure, are equivalent, while the M5, M3 and P1 sites are situated at the center of symmetry.…”