Premium
Bonding Scheme and Optical Properties in BiM 2 O 2 (PO 4 ) (M=Cd, Mg, Zn); Experimental and Theoretical Analysis
Author(s) -
Olchowka J.,
Mentré O.,
Kabbour H.,
Colmont M.,
Adlung M.,
Suta M.,
Wickleder C.
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201702373
Subject(s) - luminescence , lone pair , chemistry , excitation , band gap , crystal structure , spectroscopy , covalent bond , electronic structure , ion , emission spectrum , crystallography , atomic physics , materials science , analytical chemistry (journal) , computational chemistry , spectral line , molecule , physics , optoelectronics , organic chemistry , chromatography , quantum mechanics , astronomy
Luminescence properties of the Bi(M,M′) 2 PO 6 (M=Mg, Zn, Cd) series have been rationalized as a function of the M element using optical spectroscopy, as well as empirical and first principles calculations. The latter yielded indirect band gaps for all compounds with energies between 2.64 and 3.62 eV, whereas luminescence measurements exhibit bright warm white emission luminescence even at room temperature assigned to Bi 3+ transitions with, for example, 22.8 % quantum yield for M=Mg. The energies of the excitation maxima are shifted with the covalent character of the Bi−O bond by inductive effects of the neighboring M−O bonds. This is discussed on the basis of empirical and electronic structure calculations. Strikingly, in all the investigated compounds, an excitation process occurring at energies higher than the band gaps is observed, which seems to be intrinsic to the s 2 →sp electronic transitions of the Bi 3+ ions. Concerning the emission process, a direct correlation between the lone pair (LP) activity and the emission energy upon change of the lattice parameters was established governing the LP stereo‐activity in the BiMg 2‐ x Cd x PO 6 system. As a result, the possibility for tunable optical properties appears realistic in the Bi 2 O 3 ‐MO‐X 2 O 5 (X=P, V, As, etc.) systems taking into account the diversity of reported or novel crystal structures that can be designed using well‐established rules of crystal chemistry.