Bonding Scheme and Optical Properties in BiM2O2(PO4) (M=Cd, Mg, Zn); Experimental and Theoretical Analysis. Issue 62 (16th October 2017)

• Record Type: Journal Article
• Authors: Olchowka, J.; Mentré, O.; Kabbour, H.; Colmont, M.; Adlung, M.; Suta, M.; Wickleder, C.
• Is Part Of: Chemistry. Volume 23:Issue 62(2017)
• Page Start: 15694
• Page End: 15703
• Publication Date: 2017-10-16
• Subjects: anion centered tetrahedra -- bismuth luminescence -- lone pair -- optical properties; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201702373
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: Luminescence properties of the Bi(M, M′)2 PO6 (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 BiMg2‐ x Cd x PO6 system. As a result, the possibility for tunable optical properties appears realistic in the Bi2 O3 ‐MO‐X2 O5 (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. Abstract : Lone pair excitation : Luminescence properties of the Bi(M, M′)2 PO6 (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.