Cr4+ and Mn5+ active centers for new solid state laser materials

and luminescence in glass ceramic silica

“…The characteristic infrared emissions of Cr-doped inorganic crystals are presently associated with tetrahedrally coordinated Cr 4þ that has the electron structure Arð3d 2 Þ. Cr 4þ -doped materials present wide bands and the emission can be assign to spin allowed transition ð 3 T 2 ! 3 A 2 Þ [3,6]. The Cr 4þ -doped compounds correspond to weak-field situations for which Dq=B ¼ 1:221:6, whereas the Mn 5þ and Fe 6þ ones correspond to situations for which Dq=B ¼ 1:922:2.…”

“…The energy-level scheme of Cr 4þ ion with 3d 2 configuration can be described with the TSD [7]. Moreover, the optically active Cr 4þ center occupies the tetrahedrally coordinated lattice [3][4][5][6][7]9]. However, from the TSD three spin-allowed and broad band transitions are expected to be observed in absorption spectrum of Cr 4þ ion.…”

“…The Cr 4þ -doped compounds correspond to weak-field situations for which Dq=B ¼ 1:221:6, whereas the Mn 5þ and Fe 6þ ones correspond to situations for which Dq=B ¼ 1:922:2. On the Tanabe-Sugano diagram (TSD) this situation corresponds to positions below and above the crossing point of 1 E and 3 T 2 states [3,[6][7][8][9], respectively. Chromium-doped forsterite samples show fluorescence emission from both Cr 4þ and Cr 3þ ions.…”

“…The study of materials based on inorganic crystals doped with d 2 transitions metal ions has recently received a great deal of interest due to near infrared (NIR) laser action around 1:2 mm in chromium-doped crystals [1][2][3][4][5]. The characteristic infrared emissions of Cr-doped inorganic crystals are presently associated with tetrahedrally coordinated Cr 4þ that has the electron structure Arð3d 2 Þ. Cr 4þ -doped materials present wide bands and the emission can be assign to spin allowed transition ð 3 T 2 !…”

Chromium-doped silica optical fibres: influence of the core composition on the Cr oxidation states and crystal field

“…The Cr(Al) spectrum was treated first, because all the bands could be assigned to Cr 4+ . They are tentatively assigned to electronic spin-allowed transitions of Cr 4+ in distorded tetrahedral symmetry Cs [16,17]. The distortion of the perfect tetrahedral symetry partially lifts the degeneracy of some energy levels such as 3 T 1 ( 3 F) and causes the presence of several peaks assigned to one transition.…”