Facile in situ synthesis of zeolite-encapsulating Cs₂SiF₆:Mn⁴⁺ for application in WLEDs

Abstract

Stability test shows that the luminous efficiency of WLED with CSFM-Y reduces only 4% after duration of 120 h in the testing condition of high humidity (85%) and high temperature (85 °C), while the one with pure CSFM declines 28%.

Crystal structure and luminescence properties of thermally stable Sm3+-doped Sr9In(PO4)7 orange-red phosphor

“…According to the linear regression, the activation energy of thermal quenching (∆E) is determined to be 0.505 eV (figure 6(c)). The ∆E value is much higher than previous reports, which indicates that excited electrons of Sm 3+ ions have to pass over higher energy barrier to reach the crossing point 'A' of the ground and excited state parabolas and result in obvious thermal quenching of Sm 3+ -doped Sr 9 In(PO 4 ) 7 phosphor emerging above 150 • C. That is, at lower temperature (below 150 • C), almost no thermal quenching happens, which is in agreement with equation (5). Therefore, the obtained results indicate the excellent thermal stability of Sm 3+ -doped Sr 9 In(PO 4 ) 7 phosphor.…”

“…where ∆E refers to the activation energy of thermal quenching, k represents the Boltzmann constant, A denotes a constant, and T is the temperature. Obviously according to equation (5), with ∆E as a hypothetical invariable, R NR increased with temperature rising, and the emission intensity decreased. It is worth noting that at the same temperature the larger ∆E value (on behalf of the energy barrier) is, the less non-radiative transitions would appear.…”

“…White light emitting diodes (w-LEDs), the fourth generation light source, are widely utilized in displays, home lighting and indicator lamps [1][2][3][4][5] and have been rapidly developing worldwide due to their unique advantages, such as long lifetime, fine brightness, low energy consumption, eco-friendly nature and high energy conversion rate. Generally, they are either prepared by combining blue GaN-based LED chips with a yellow phosphor [Y 3 Al 5 O 12 :Ce 3+ (YAG: Ce)] or tricolor (red, green and blue) phosphors with a near ultra-violet LED chip (350-420 nm).…”

High Water Resistance and Luminescent Thermal Stability of LiyNa(2–y)SiF6: Mn4+ Red-Emitting Phosphor Induced by Codoping of Li+

“…In this study, we used KMnO 4 , NSF­(Na 2 SiF 6 ), and LNSF (Li y Na (2– y ) SiF 6 ) as raw materials to prepare NSF: Mn 4+ and LNSF:Mn 4+ through the H 2 O 2 -free method, and the corresponding equations are represented by the following reactions and . , In the methods, activator K 2 MnF 6 is obtained by self redox of KMnO 4 in KF-HF solution and finally enters the crystal lattice through ion exchange. …”

Improvement in luminescent properties and thermo-optical conversion mechanism of Na2SiF6:Mn4+,K+@GQDs

“…In addition, most Mn 4+ -doped uoride phosphors are prepared using KMnO 4 and H 2 O 2 as the starting materials, 24,25 where the activator K 2 MnF 6 is formed by the reaction of KMnO 4 and H 2 O 2 . However, the reaction is too violent to be applied in industry.…”