Study of Precipitated Phases in Mn²⁺ Singly Doped KBr Crystals by Optical Spectroscopy and EPR

Abstract

The aggregation states of MnZ + in KBr : MnZ + doped crystals are investigated using optical techniques. Excitation and luminescence spectra as well as lifetimes are obtained as a function of temperature of different crystals. It is demonstrated that at least three different Mn2+ precipitates are formed inside the KBr. Two of them contain MnBrz-units with slightly distorted octahedral symmetries, while the third one involves two non-equivalent tetrahedral MnBr2-units. These centers exhibit a broad green luminescence band.Die Erscheinungsformen von Mn2+ in dotierten KBr : Mn2+-Kristallen werden mit optischen Methoden untersucht. Anregungs-und Lumineszenzspektren und Lebensdauern als Funktion der Temperatur wrrden an verschiedenen Kristallen gemessen. Es zeigt sich, da13 mindestens drei verschiedene Mr,?+-Aggregate im KBr auftreten. Zwei von ihnen enthalten MnBrz--Einheiten mit leicht gestorter oktaedrischer Symmetrie, das dritte ist mit zwei inaquivalenten tetraedrischen MnBr:--Einheiten verknupft. Diese Zentren zeigen ein breites, grunes Lumineszenzband.

Pressure-Induced Two-Color Photoluminescence inMnF2at Room Temperature

“…EdE is the density-of-states factor of the excitation and emission centers, respectively, ensuring energy conservation [32]. This equation justifies not only why RN !…”

“…For S-S, however, the overlap integral involves g emis S E and g exc S E and is therefore strongly reduced due to the large Stokes shift of 0.4 eV between S-emission and S-excitation bands (Fig. 2) [32]. The reduction of S !…”

Double-excitation transitions in the perovskiteNH4MnCl3studied by pressure techniques

“…This latter aspect was exploited to identify precipitates in Mn 2ϩ -doped alkali halides. [6][7][8] The effective spin-dependent mechanism governing the transition intensity in exchange coupled systems was first proposed, to our knowledge, by Tanabe 9 to explain the optical spectra of Mn-Mn dimers The effective transition moment is given by…”

NaCl(001) surfaces nanostructured by Suzuki precipitates: a scanning force microscopy study

“…However, also other metal impurity cations such as Mn 2+ [13,14], [16]- [19], [36], [40]- [42], [45]- [50], Mg 2+ [1,21,36,41,42], Fe 2+ [15,17,19,36,41,42,51], Ni 2+ [42,52], Co 2+ [53], Sr 2+ [42,54] and Pb 2+ [42,55] have been the subject of many investigations and discussions. In fact, the host lattice need not necessarily be NaCl: the Suzuki phase may exist also in NaBr (Mn 2+ [50]), KCl (Sm 2+ [57], Pb 2+ [58] and Eu 2+ [56,59]), KBr (Mn 2+ [60] and Eu 2+ [59,61,62]), LiF (Mg 2+ [11,63]) and AgCl (Pb 2+ [64]) and even in oxides (MgO:Mn 4+ [31], [65]- [67], NiO:Mn 4+ [67] and CuO:Pb 4+ [32,68]). Suzuki phases including two types of metal impurity cations have even been studied ...…”

“…Suzuki phases including two types of metal impurity cations have even been studied (NaCl:Pb, Eu 2+ [69] and NaCl:Cd, Pb 2+ [70]). The Suzuki phase has been characterized by many experimental methods like x-ray diffraction [10]- [12], [31,32], [34]- [36], [38,58,65,67], ionic conductivity or thermal current measurements [21,35,37,39,52,54,66], specific heat measurements [47], optical spectroscopy [46,50,53,56,59,60,62,65,67,69,70], Raman spectroscopy [12,40,52,53,55], laser spectroscopy [57], magnetic susceptibility measurements [41,48,65,67], electron paramagnetic resonance [45,46,60,64], neutron scattering [49], photoacoustic measurements …”