Optical temperature sensing based on phonon-assisted population of Dy3+ sensitized by Gd3+ in Gd2Ge2O7 nanophosphors

Reddish-orange emitting Eu2−x Gd x Ge2O7 pyrogermanate ceramic phosphors: synthesis and role of Eu3+/Gd3+ substitution on the optical features

“…For clarity, figure 7 presents a partial energy levels diagram of Gd 3+ and Eu 3+ . In addition, Eu 3+ f -f bands (circles) are observed at 318, 327, 361, 381, 392, 394, 415, 463, 525, and 533 nm, which can be attributed to the transitions from ground-state 7 F 0 to the 5 H 4 , 5 H 3 , 5 D 4 , 5 L 7 , 5 L 6, 5 L 6 , 5 D 3 , 5 D 2 , and 5 D 1 excited states, and 5 D 1 ← 7 F 1 , respectively, in agreement with previous works [6,26,28,29,35,47,48]. A broadband centered at approximately 260 nm emerges all spectra in figure 6(a), which corresponds to O 2− → Eu 3+ CTB.…”

“…Nowadays, RE 2 X 2 O 7 (RE = Y, Sc, La-Lu, X = Ti, Zr, Hf, Si, Ge, Sn) ceramics have gained notoriety in the development of new smart materials due to their interesting and unique properties for the wide application potentialities in strategic scientific areas. Although they have been explored since the 60's [1,2] due to their chemical versatility, recently a growing number of publications have been registered, focusing on luminescent [3][4][5][6] and magnetic [7][8][9][10] properties, as well as catalytic applications [11], that ultimately depend on the crystalline and electronic structures.…”

High Quantum Yield Gd4.67Si3O13:Eu3+ Red-Emitting Phosphor for Tunable White Light-Emitting Devices Driven by UV or Blue LED

“…S a increases monotonically while S r reaches its maximum value 1.05 × 10 –2 K –1 at 456 K. The temperature sensitivity of Gd 3.67 EuSi 3 O 13 was calculated to be 3094.29056/ T 2 . In the application of optical temperature measurement, the performance of GSO:Eu 3+ is better than that of our previous work GGO:Dy 3+ phosphors whose S r maximum is about 6.4 × 10 –3 K –1 and the temperature sensitivity is found to be 2029.5/ T 2 …”

“…However, a weak peak centered at 537 nm (Eu 3+ : 5 D 1 → 7 F 1 ) is sharply increased as the temperature goes up to 510 K, as shown in Figure b,d, which can be attributed to the change in the population between thermally coupled energy levels (Eu 3+ : 5 D 1 and 5 D 0 ) with the assistance of phonons. The detailed process can be referred to in our previous related work . After that, the continuously rising temperature breaks through the temperature quenching potential barrier between the 5 D 1 energy level and the CT band and competes with the phonon-assisted thermal coupling effect, leading to a decrease in the intensity.…”

“…In the application of optical temperature measurement, the performance of GSO:Eu 3+ is better than that of our previous work GGO:Dy 3+ phosphors whose S r maximum is about 6.4 × 10 −3 K −1 and the temperature sensitivity is found to be 2029.5/T 2 . 32 Fabrication and Performance of Warm White LEDs. To demonstrate the device performance for the synthesized GSO:Eu 3+ phosphors, as shown in Figure 9, a series of LEDs with various CCTs were fabricated by combining the 395 nm UV chip or 460 nm blue chip, YAG:Ce 3+ yellow phosphor, and Gd 3.67 EuSi 3 O 13 .…”