Ba₃Ga₃N₅—A Novel Host Lattice for Eu²⁺-Doped Luminescent Materials with Unexpected Nitridogallate Substructure

Abstract

ABSTRACT:The alkaline earth nitridogallate Ba 3 Ga 3 N 5 was synthesized from the elements in a sodium flux at 760°C utilizing weld shut tantalum ampules. The crystal structure was solved and refined on the basis of single-crystal X-ray diffraction data. Ba 3 Ga 3 N 5 (space group C2/c (No. 15), a = 16.801(3), b = 8.3301(2), c = 11.623(2) Å, β = 109.92(3)°, Z = 8) contains a hitherto unknown structural motif in nitridogallates, namely, infinite strands made up of GaN 4 tetrahedra, each sharing two edges and at least one corner with neighboring GaN 4 units. There are three Ba 2+ sites with coordination numbers six or eight, respectively, and one Ba 2+ position exhibiting a low coordination number 4 corresponding to a distorted tetrahedron. Eu 2+ -doped samples show red luminescence when excited by UV irradiation at room temperature. Luminescence investigations revealed a maximum emission intensity at 638 nm (FWHM =2123 cm ). Ba 3 Ga 3 N 5 is the first nitridogallate for which parity allowed broadband emission due to Eu 2+ -doping has been found. The electronic structure of both Ba 3 Ga 3 N 5 as well as isoelectronic but not isostructural Sr 3 Ga 3 N 5 was investigated by DFT methods. The calculations revealed a band gap of 1.53 eV for Sr 3 Ga 3 N 5 and 1.46 eV for Ba 3 Ga 3 N 5 .

Narrow-Band Green-Emitting Phosphor Ba2LiSi7AlN12:Eu2+ with High Thermal Stability Discovered by a Single Particle Diagnosis Approach

“…One is to investigate known crystal structures that are suitable for luminescent center doping and are not studied to be host crystals. [1][2][3][4] The other is to find new host materials by analyzing single crystals [5][6][7]11,[13][14][15][16][17][18] or powder products 12,19,20 . In the single crystal analysis, a large-size crystal (typically larger than 100 μm in all dimensions) is necessary to determine the crystal structure.…”

Color‐Tunable Luminescence of Y4Si2N2O7:Ce3+, Tb3+, Dy3+ Phosphors Prepared by the Soft‐Chemical Ammonolysis Method

“…With the extrapolation of the linear region between 240 and 250 nm, the band gap was determined as 4.37 eV (234 nm). This value is larger than the calculated band gap (3.67 eV) due to the insufficient description of the exchange correlation potential in the DFT calculations 17…”

Defect‐Related Luminescence in ­Nitridoborate Nitride, Mg3Ga(BN2)N2

“…In most host materials comprising alkaline‐earth metals, Eu 2+ ions are supposed to occupy the alkaline‐earth sites 27,28. However, the ionic radius of Mg 2+ is much too small to allow incorporation of Eu 2+ in a Mg 2+ site without a major site expansion.…”