An Approach to Control of Band Gap Energy and Photoluminescence upon Band Gap Excitation in Pr³⁺-Doped Perovskites La_1/3MO₃(M = Nb, Ta):Pr³⁺

Abstract

We synthesized polycrystalline pristine and Pr(3+)-doped perovskites La(1/3)MO(3) (M = Nb, Ta):Pr(3+) and investigated their crystal structure, optical absorption, and luminescence properties. The optical band gap of La(1/3)NbO(3) (3.2 eV) is smaller than that of La(1/3)TaO(3) (3.9 eV), which is primarily due to the difference in electronegativity between Nb and Ta. In La(1/3)NbO(3):Pr(3+), the red emission assigned to the f-f transition of Pr(3+) from the excited (1)D(2) level to the ground (3)H(4) state upon band gap photoexcitation (near-UV) was observed, whereas the f-f transition of Pr(3+) with blue-green emission from the excited (3)P(0) level to the ground (3)H(4) state was quenched. On the other hand, in La(1/3)TaO(3):Pr(3+), the blue-green emission upon band gap photoexcitation was observed. Their differences in emission behavior are attributed to the energy level of the ground and excited states of 4f(2) for Pr(3+), relative to the energy levels of the conduction and valence bands, and the trapped electron state, which mediates the relaxation of electron from the conduction band to the excited state of Pr(3+). La(1/3)NbO(3):Pr(3+) is a candidate red phosphor utilizing near-UV LED chips (e.g., λ = 375 nm) as an excitation source.

Polarization‐Induced Photoluminescence Quenching in (Ba0.7Ca0.3TiO3)–(BaZr0.2Ti0.8O3):Pr Ceramics

“…According to the energy level structure of Pr 3+ , the excited state 3 P 2 level could relax radiationlessly to 3 P 0 , 3 P 1, or 1D 2 state of the Pr 3+ ions, and then recombine to lower levels of 3 H 4 , 3 H 5 , 3 H 6 , and 3 F 2 . Therefore, the green emissions at 530 and 548 nm are coming from 3 P 1 → 3 H 5 and 3 P 0 → 3 H 5 transitions, the red spectral region at 602, 619, and 650 nm from 1 D 2 → 3 H 4 , 3 P 0 → 3 H 6 and 3 P 0 → 3 F 2 transitions, respectively . Although the 1 D 2 → 3 H 4 transition is spin forbidden, and partially allowed, the transition is still a major contribution to the emission cluster centered at 602 nm.…”

Long persistent and photo‐stimulated luminescence in Pr3+‐doped layered perovskite phosphor for optical data storage

“…The PersL of Pr 3+ ‐doped perovskite‐type titanates oxides with a chemical formula ATiO 3 have been studied intensively . Perovskite‐type oxides are appropriate host materials to realize the PersL, because they tolerate various constituent elements and consequently offer their suitable electronic structure which allows for electrons’ delocalization to conduction band (CB) of host and further transfer to traps . As a perovskite‐related compound, Ca 4 Ti 3 O 10 belongs to Ruddlesden‐Popper phase with composition Ca n+1 Ti n O 3n+1 (n = 3) .…”

Strong Red Emissions in Pr3+‐Doped (K0.5Na0.5)NbO3–CaTiO3 Diphase Ceramics

“…The PLE spectrum monitored at 447 nm (left) exhibits three sharp absorptions (B band) centered at 447, 473, and 486 nm, respectively. According to the energy levels of Pr 3+ , these narrow peaks are due to the intra‐4 f transitions of Pr 3+ from the 3 H 4 absorption to the excited states 3 P J ( J = 0,1,2), corresponding to 3 H 4 → 3 P 2 at 447 nm, 3 H 4 → 3 P 1 at 473 nm, and 3 H 4 → 3 P 0 at 486 nm transitions, respectively . The strongest peak centered at 447 nm can match well with the commercially available blue light‐emitting diode chips .…”

“…3 P 0 at 486 nm transitions, respectively. 22,23 The strongest peak centered at 447 nm can match well with the commercially available blue light-emitting diode chips. 24 In the range 250-430 nm, a weak broad band is obviously observed (A band).…”