Study on the structure and optical properties of phosphor Ca3La3(BO3)5:Dy3+ for potential application in temperature sensing

Structure and luminescence properties of single-component melilite Sr2MgSi2O7:Ce/Tb/Sm for n-UV wLEDs

“…27 According to Dexter's theory of eqn (7): I / x = k [1 + β ( x ) θ /3 ] −1 ,where I and x are Ce concentration and PL intensity; k and β are constants; θ (= 6, 8 and 10) is a function of multipole–multipole (dipole–dipole (d–d), dipole–quadrupole (d–q), or quadrupole–quadrupole (q–q)) interactions. 28 Accordingly, the dependence of lg ( I / x ) is calculated to be relatively linear, and the slope (− θ /3) equals ∼−1.5 (Fig. S3c†).…”

Crystal Structure, Photoluminescence, and “Abnormal” High Stability of Ca3Y(GaO)3(BO3)4: Dy3+/Sm3+/La3+ for n-UV wLEDs

“…The almost no change of the asymmetry ratio indicates that the occupied site environment has no direct relationship to the unusual phenomena. On the other hand, the thermal coupling energy levels (TCELs) of Dy between the 4 I 15/2 and 4 F 9/2 (200 cm –1 < Δ E ≈ 1000 cm –1 < 2000 cm –1 , obeys the Boltzmann-type distribution parametrized by temperature , ) could give some clues (Figure d), which is also the reason that the Dy-activated phosphor could be applied in the optical thermometric field. Specifically, under excitation ①, the electrons in ground states initially transfer to the highest excited states (i.e., 6 P 3/2 ) and then relax in a nonradiative and multiphonon relaxation (MPR) way ② to the lowest energy level 4 F 9/2 .…”

“…Of note, relatively speaking, the investigation on codoping of ion pairs of Dy 3+ /Sm 3+ with tunable full-color-PL phosphors was rarely investigated. Dy 3+ ions could be both played as the “cool” white-light luminescent center and sensitizer, due to the 4f-4f transitions from 4 F 9/2 to 6 H 15/2, 13/2, 11/2 located at red (very weak), yellow, and blue regions, respectively. − Naturally, to change the “cool” into “warm” white PL with high CRI and low CCT, the red-emitting activator Sm 3+ , originated from the transitions of 4 G 5/2 to 6 H 11/2, 9/2, 7/2, 5/2 , , could be codoped with Dy 3+ ions. Interestingly, due to both Dy/Sm ions including the hypersensitive electric dipole transitions (EDT) as compared with the relatively stable magnetic dipole transitions (MDT), the intensity ratios of PL peaks could be further easily tuned and helped to obtain the desired color-tunable PL via modification of the local site environments of the dopants.…”

Stable color-tunable Ca3Y(GaO)3(BO3)4:Bi3+/Tb3+/Eu3+ phosphors for application in n-UV-pumped wLEDs

“…Down-conversion phosphor-converted white light-emitting diodes ( pc-wLEDs) are regarded universally as the new generation of solid-state lighting sources and have the trend of replacing the traditional and high energy-guzzling bulbs and incandescent/fluorescent lamps owing to their advantages of high luminous efficiency, low energy consumption, cost-effectiveness, long lifespan as well as environmental sustainability. [18][19][20][21] Till date, commercially available pc-wLED on the market is composed of a Y 3 Al 5 O 12 :Ce 3+ yellow phosphor and a blue LED chip. 22,23 However, this approach typically generates 'cool' white light with high correlated color temperature (CCT) and low color rendering index (CRI) owing to the red light-emitting PL deficiency (Scheme S1a, ESI †).…”