Defect Enrichment in Near Inverse Spinel Configuration to Enhance the Persistent Luminescence of Fe³⁺

Abstract

Up to now, PersL materials emitting visible light have been extensively studied and applied in emergency signage, optical data storage and anti-counterfeiting, energy-saving catalysis, and many other aspects. [10][11][12][13][14][15][16][17][18][19] Recently, near-IR (NIR) PersL materials have received particular interest due to their great application prospects in various biomedical applications, such as autofluorescence-free bioimaging, longterm biomolecule tracking. [20][21][22][23][24][25][26][27] However, in stark contrast to the evolving progress in the research of the PersL materials in visible region, the study concerning the design and development of NIR PersL materials is still lacking. [28,29] Hence, it is significantly important to develop and make up the number of NIR PersL materials.The luminescent materials are composed of matrixes and activators, the activators exist as emission centers while the matrixes provide an appropriate crystal environment for activators. [30] At present, most reported NIR PersL materials are based on Cr 3+ emitters. [28] Nevertheless, the toxicity of chromium might lead to biosafety and biodistribution issues of these Cr 3+ -activated materials in organisms, which would severely hindered further practical bioapplications. [31][32][33] As an essential element of the human body, the promising and so far rarely investigated ferric ions can be a considerable candidate for activator ions to address the toxicity issue of Cr 3+ . [34] Unfortunately, the number of studies on the rational design of Fe 3+doped NIR PersL remains very quiet. [35,36] Hitherto, the majority of the research concerning Fe 3+ -activated luminescent materials is devoted to their photoluminescence (PL) properties and the related luminescence thermometer application. [37,38] This may be because Fe 3+ is usually regarded as a luminescent quencher, and it is hard to control the crystal environments of the matrixes for achieving PersL of Fe 3+ . Therefore, it is vital importance to explore a special crystal structure and regulate the defect properties for the development of Fe 3+ -activated NIR PersL materials.Spinel configuration can be one of the best host material candidates when designing PersL materials owing to the easy formation of vacancies and anti-site defects. [39,40] However, the PersL from Fe 3+ doped in spinel-type compounds has never been reported before. [41] Herein, we propose a new strategy of defect enrichment for the activation of PersL, and in contrast to the normal spinel configuration, we demonstrate that the crystal structure of near inverse spinel ensures more numerous Spinel configuration is a kind of broadly considered host candidate when designing persistent luminescence (PersL) materials due to the easy generation of vacancies and anti-site defects. Here, a new strategy of defect enrichment for the activation of PersL is proposed, and in contrast to the spinel configuration, it is demonstrated that the crystal structure of near inverse spinel ensures more numerous defects to activat...

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“…Another activator, Fe 3+ , is an essential element ion of the human body; moreover, it is non-toxic and can be regarded as a friendly dopant 20 , 21 . Thus, its optical properties are worth exploring.…”

A new class of battery-free, mechanically powered, piezoelectric Ca5Ga6O14:Tb3+ phosphors with self-recoverable luminescence

“…4(f)). On the other hand, the Hoogenstraaten method was also adopted to estimate the average trap depths of the two traps: 30 b…”

“…4(f)). On the other hand, the Hoogenstraaten method was also adopted to estimate the average trap depths of the two traps: 30 where β (K s −1 ) is the heating rate, E (eV) is the average trap depth, T m (K) is the peak temperature in the TL glow curves, and s is the frequency factor. The TL glow curves at different heating rates β from 1 to 5 K s −1 are shown in Fig.…”

Manipulating trap distribution and density by chemical unit cosubstitution for near-infrared persistent luminescent Zn1−2xLixGa2+xO4:Cr3+ solid solutions

“…11 Luminescent centers such as lanthanide activators (Er 3+ , Pr 3+ , Nd 3+ , Tm 3+ , Ho 3+ , and Yb 3+ ) and transition metal ions (Cr 3+ , Mn 4+ , and Fe 3+ ) are frequently chosen for NIR emission in persistent phosphors. [12][13][14][15][16] Common lanthanide activators usually emit narrow-band NIR lines accompanied by very weak and narrow absorption peaks. Trivalent chromium (Cr 3+ ) has been established as a favorable broadband NIR emitter ranging from 650 nm to 1000 nm in gallates, aluminates, stannates and silicates due to its spin-forbidden 2 E -4 A 2 transition or spin-allowed 4 T 2 -4 A 2 transition in an octahedral coordination crystal field, which largely depends on the crystal field environments of the host matrices.…”