Lanthanide doped strontium barium niobate: Optical spectroscopy and local structure at the impurity sites

Luminescence properties of Ba2NaNb5O15 crystals activated with Sm3+, Eu3+, Tb3+ or Dy3+ ions

“…This conclusion is in agreement with a previous work [8] concerning the site occupancy of Nd 3 + , but cannot be extended to other rare earth ions in absence of experimental evidences, as demonstrated in the case of SBN [16]. Finally, the observed analogies in the emission behaviour of Ln 3 + -doped BNN and SBN suggest interesting application perspectives for the investigated compounds.…”

“…Other weaker features are observed in the 360-380 nm range ( 7 F 0 -5 D 4 , 5 G 3 ) and at 415 nm ( 7 F 0 -5 D 3 ). The temporal profile of the 5 D 0 emission is a single exponential with decay time 0.95 ms, consistent with that reported for Eu 3 + in SBN (0.86 ms [16]). …”

“…Analogously to Sm:BNN, the luminescence spectrum of Eu:BNN (Fig. 3), measured upon 395 nm excitation, is very similar to that reported for Eu 3 + in flux grown SBN [15,16]. We can then reliably suppose that the active ions have the same local structure in BNN and SBN.…”

“…In this connection however, a recent paper has evidenced that the site occupancy of Eu 3 + in SBN depends on the growth conditions [17]. It is then worth to point out that the mentioned similarity concerns Eu:SBN grown by spontaneous nucleation in a strontium barium tetraborate flux by Bettinelli et al [16] who, on the basis of EXAFS measurements, located the Eu 3 + ions in the 12-fold A 2 sites of the SBN lattice. In agreement with previous literature [15], we ascribe the weak sharp line observed at 578 nm to the 5 D 0 -7 F 0 transition, the two intense unresolved emission bands peaking at 590 and 612 nm to the 5 D 0 -7 F 1 and 5 D 0 -7 F 2 transitions, respectively, the weak feature located at 649 nm to the 5 D 0 -7 F 3 and the manifold with main components peaking at 679, 690 and 702 nm to the 5 D 0 -7 F 4 transition.…”

Site location and crystal field ofNd3+ions in congruent strontium barium niobate

“…19,20 The lattice location of Eu 3+ ions has been also investigated in congruent SBN crystals grown by different methods. 13,21 It seems that the growth method affects the site location of these ions: while in SBN crystals slowly grown at high temperatures by using the Czochralski technique the B octahedral sites seems to be favored, 13 crystals grown at lower temperatures by spontaneous nucleation in a flux the Eu 3+ ions seem to occupy mainly the A1 site.…”