Photoluminescence of Mn²⁺ in the Borosulfate Zn[B₂(SO₄)₄] : Mn²⁺—A Tool to Detect Weak Coordination Behavior of Ligands

Abstract

The impact of the surrounding ligand field is successfully exploited in the case of Eu2+ to tune the emission characteristics of inorganic photoactive materials with potential application in e.g., phosphor‐converted white light‐emitting diodes (pc‐wLEDs). However, the photoluminescence of Mn2+ related to intraconfigurational 3d5‐3d5 transitions is also strongly dependent on local ligand field effects and has been underestimated in this regard so far. In this work, we want to revive the idea how to electronically tune the emission color of a transition metal ion in inorganic hosts by unusual electronic effects in the metal‐ligand bond. The concept is explicitly demonstrated for the weakly coordinating layer‐like borosulfate ligand in the Mn(II)‐containing solid solutions Zn1‐xMnx[B2(SO4)4] (x = 0, 0.03, 0.04, 0.05, 0.10). Zn[B2(SO4)4]:Mn2+ shows orange narrow‐band luminescence at 590 nm, which is an unusually short wavelength for octahedrally coordinated Mn2+ and indicates an uncommonly weak ligand field. On the other hand, the analysis of the interelectronic Racah repulsion parameters reveals ionic Mn‐O bonds with values close to the Racah parameters of the free Mn2+ ion. Overall, this strategy demonstrates that electronic control of the metal‐ligand bond can be a tool to make Mn2+ a potent alternative emitter to Eu2+ for inorganic phosphors.

Color-resolved mechanoluminescence of Eu and Mn co-doped SrMg2(PO4)2

“…The emission band is attributed to the 4 T 1 → 6 A 1 transition of Mn 2+ ions. 28 Interestingly, the ML intensity gradually increases and then achieves maximum intensity when the concentration of Mn 2+ reaches 0.02. Fig.…”

Mn–Mn Magnetic Coupling Interaction-Induced Red Emission in a Tetra-Coordinated Lattice

“…Due to the fact that all absorption and emission transitions are spin-forbidden, the intensities are always low. The DR spectra of LC 1– x M x GO ( x = 10%, 20%, 30%) samples are shown in Figure S9B, and the absorption covering from 240 to 300 nm is attributed to the charge transfer band (CTB) between the Mn 2+ and O 2– ions while the absorption covering from 410 to 480 nm originates from the transitions of the 6 A 1 ( 6 S) state to the 4 E 2 (D), 4 T 2 (G), and 4 T 1 (G) states . It is worth noting that the absorption corresponding to CTB shifts to low energy direction as the doping content increases, and the absorption of transitions from the 6 A 1 ( 6 S) state to the 4 E 2 (D), 4 T 2 (G), and 4 T 1 (G) states are slightly enhanced.…”

Highly efficient blue-green dual-narrow-emission in RbAl11O17:Eu2+,Mn2+ toward wide-color-gamut human-centric backlights

“…Currently, phosphors, quantum dots (QDs), and metal halide chalcogenides activated by the transition metal Mn occupy an important position in various types of luminescent materials due to the unique d–d ubiquitous forbidden leaps of Mn 2+ that are strongly influenced by the crystal field. 19–22 When Mn 2+ is surrounded by four ligands, the lower ligand field strength induces typical green emission. 23,24 The tremendous strength of Mn 2+ doped green phosphors lies in their ultra-narrow half-height widths of less than 54 nm, with the narrowest being up to 26 nm.…”