Luminescence Dynamics in Tb³⁺-Doped CaWO₄ and CaMoO₄ Crystals

Abstract

Single crystals of CaWO(4) and CaMoO(4) doped with Tb(3+) have been grown by the flux growth method. Their luminescence properties have been investigated in the 10-600 K temperature range under different experimental conditions. In spite of very similar spectra at low temperature upon excitation at 365 nm, the crystals show a very different behavior as the temperature is raised or the excitation wavelength is changed. These differences have been accounted for on the basis of models that take into consideration the position of the energy levels of the rare earth relative to the bandgap of the host material.

Predicting metal-to-metal charge transfer in closed-shell transition metal oxides doped with Bi3+ or Pb2+

“…The observed signals are ascribed to Bi 3+ (6s 2 )?M n+ (d 0 ) MMCT (M n+ = Nb 5+ and Mo 6+ , respectively). Similar attributions of low-lying excitation signals to Bi-MMCT have been made in previous reports for the vanadates LnVO 4 :Bi 3+ (Ln = Y, Gd, La): [16][17][18][19] and the niobates LnNbO 4 :Bi 3+ (Ln = Y, Gd, La) [20][21][22].…”

“…It is ascribed to Bi 3+ (6s 2 )?Ti 4+ (d 0 ) MMCT. In the case of CaNb 2 O 6 :Bi 3+ and CaMoO 4 :Bi 3+ , the HFE is not observed (it is expected at about 36 000 cm À1 in the former [9] and 34 000 cm À1 in the latter [17]). The observed signals are ascribed to Bi 3+ (6s 2 )?M n+ (d 0 ) MMCT (M n+ = Nb 5+ and Mo 6+ , respectively).…”

Temperature and concentration quenching of Tb3+ emissions in Y4Al2O9 crystals

“…Such small E could be involved only in process between very closely lying levels. Cavalli et al [33] observed similar thermal behaviour of Tb 3+ 5 D 3 luminescence decay in CaWO 4 below 100 K and indicated that the variation of decay time can have origin in thermal population of the Stark components in the 5 D 3 multiplet. In [23] the measured energies of 5 D 3 manifold in YAG were: 26 157.5 cm −1 and 26 156.1 cm −1 giving very small energy gap.…”

The crystal structure and luminescence quenching of poly- and single-crystalline KYW2O8:Tb3+

“…This is in line with observations for other Tb 3 þ tungstates as f.i. CaWO 4 :Tb [20]. In undoped KYW only ligand-to-metal charge transfer absorption within the tungstate units is observed.…”