The luminescence of some oxidic bismuth and lead compounds

Abstract

The luminescence properties of the bismuth compounds BizGe309, BiuMOrO (M = Ge, Ti), and Bi2A1409 and of the lead compounds PbGe,O, and PbM204 (M = Al, Ga) are reported and discussed. BilZMOZO and probably PbGe307 show semiconductor-type luminescence. For Bi&fOr,, blue and red emission bands are reported which both are ascribed to radiative recombination at (deep) defect centre levels in the band gap. The blue emission originates probably from surface defects. The other compounds show broad emission and excitation bands with large Stokes shifts. The transitions occur on one and the same B?+(Pb*+) ion. From decay time measurements it is found that the energy difference between the two lowest excited levels is very small for all compounds. The large Stokes shifts and small trap depths are discussed in terms of the asymmetrical coordination of the 6sz ions in the compounds under discussion. It is concluded that asymmetrically surrounded Bi3+ ions give rise to luminescence which is characterized by a broad emission band which shows a very large Stokes shift (22 eV).

Infrared luminescence in Bi-doped Ge–S and As–Ge–S chalcogenide glasses and fibers

“…Formation energy estimations based on the calculated total energies of corresponding unit cells show that Bi 3+ centers are favorable. Calculated wavelengths of the absorption bands of such Bi 3+ and Bi 2+ centers in GeS 2 network agree well with the experimental data available on the spectral properties of similar Bi-related centers in several hosts [18][19][20][21][22]. These centers are not related to IR luminescence and are of no interest for our investigation, since both the absorption and luminescence bands of the centers fall in the host self-absorption range.…”

The luminescence of mercury-like ions in and the crystal structure of SrLaBO4

“…4 is the energy difference between levels 2 and 3 and rJ the purely radiative decay time of the level 3PJ. The results are well in line with those observed for Pb*+ and Bi3+ in off-center position (2).…”

“…The Pb2+ luminescence shows a large Stokes shift and high efficiency at room temperature. In view of earlier work on luminescences of this type in this laboratory (2), this seemed to be a tempting case to investigate in more Ref. (I).…”

Luminescence of s2 ions in CsCdBr3 and CsMgCl3

“…This is not observed, since the Stokes shift is about 1.4 eV. A large Stokes shift suggests off-center position for Bi3+ (12). Therefore we assume that the Bi3+ ion is associated with a MgZ+-vacancy, so that the Bi3+ ion shifts alongside the chain direction toward the vacancy.…”

“…For the decay-time measurements on CsMgC13-Bi3+ a photon-counting system (EG&G) was used. Details of this system have been described elsewhere (12). The emission wavelength was selected by a double monochromator (Jobin Yvon, HRD l), equipped with a photomultiplier tube (RCA C3 1034).…”