Self-reduction of Mn⁴⁺ to Mn²⁺: NaY₉Si₆O₂₆:Mn²⁺ red phosphors with excellent thermal stability for NUV LEDs

Abstract

Luminous properties play an essential role in the phosphor-converted white light-emitting diodes for high-quality illumination, where the self-reducing behavior of doped activators and excellent thermal stability have received significant attention....

Modulating Mn self-reduction and multimodal luminescence in CaSb2O6 through La3+ doping for quadruple-mode dynamic anti-counterfeiting and optical temperature sensing applications

“…In addition to these three stronger excitation bands, two weaker peaks (centered at about 401 and 480 nm) caused by the characteristic absorption of Mn 2+ were also observed in the excitation spectrum, corresponding to the 6 A 1 – 4 A 1 , 4 E(G) and 6 A 1 – 4 T 2 transitions of Mn 2+ , respectively. 20 The excitation spectrum (monitored at 675 nm) spans from 250 to 600 nm and contains two distinct excitation bands centered at 335 and 485 nm. These two peaks stem from the absorption of the 4 A 2 – 4 T 1 and 4 A 2 – 4 T 2 transitions of Mn 4+ , respectively.…”

“…The self-reduction of Mn ions has attracted increasing attention, such as Zn 2 GeO 4 :Mn, NaY 9 Si 6 O 26 :Mn 2+ and LaM 1−x Al 11−y O 19 :xMn 2+ ,yMn 4+ (M = Mg, Zn) systems. [18][19][20] It is worth noting that among the previous reports on self-reducing Mn 2+ or Mn 2+ ,Mn 4+ -co-doped phosphors, the Mn 2+ /Mn 4+ ratio was not tunable. [21][22][23] Furthermore, most of the reports did not provide a detailed explanation of the self-reduction phenomenon of Mn or the specific reasons for controlling the self-reduction process.…”

Achieving excellent thermostable red emission in singly Mn2+-doped near-zero thermal expansion (NZTE) material Li2Zn3(P2O7)2

“…Another absorption band ranging from 400 to 450 nm was noted, originating from the d–d transition of Mn 2+ . 33,34 In addition, there was a weak valley in the wavelength of about 600 nm in the diffuse reflection spectra of the LZPO: x Mn 2+ ( x = 0.05, 0.1, 0.3) phosphors (Fig. S2, ESI†).…”