Effective Repeatable Mechanoluminescence in Heterostructured Li_1−xNa_xNbO₃: Pr³⁺

Abstract

has been attracted to ML research by many groups around the world. According to the recovery performance of ML, it is generally believed that ML materials can be divided into trap-controllable and self-recoverable two modes. [9,10] The trap-controllable ML is associated with the captured carriers in shallow and deep traps at around below the conduction band or above the valence band. It relies on the induced energy releasing for the captured carriers from the traps, and it occurs for a certain level of mechanical stress (or strain) energy which is sufficient to activate the captured carriers releasing from the traps to recombine with emission centers, resulting in the ML phenomenon after removal the excitation source. [11,12] Self-recoverable ML materials are a special kind of luminescent materials, whose ML intensity can be output stable optical signals under the consecutive compressing-releasing cycles, and do not require light excitation to charge carriers. [13,14] Previous studies have shown that the self-recoverable ML materials depend on the generation of local piezoelectric fields, which promotes the process of electron-hole recombination and realizes the self-recoverable ML process. [15][16][17][18] However, either trap-controllable or self-recoverable ML still leads to some shortcomings. Trap-controllable mode is the current mainstream way to achieve ML, but its preirradiation process and relatively poor repeatability seriously affect the performance and accuracy of stress sensing. Self-recoverable mode can be considered as Mechanoluminescence (ML) is a striking optical phenomenon that is achieved through mechanical to optical energy conversion. Here, a series of Li 1−x Na x NbO 3 : Pr 3+ (x = 0, 0.2, 0.5, 0.8, 1.0) ML materials have been developed. In particular, due to the formation of heterostructure, the synthesized Li 0.5 Na 0.5 NbO 3 : Pr 3+ effectively couples the trap structures and piezoelectric property to realize the highly repeatable ML performance without traditional preirradiation process. Furthermore, the ML performances measured under sunlight irradiation and preheating confirm that the ML properties of Li 0.5 Na 0.5 NbO 3 : Pr 3+ can be ascribed to the dual modes of luminescence mechanism, including both trap-controllable and self-recoverable modes. In addition, DFT calculations further confirm that the doping of Na + ions in LiNbO 3 leads to electronic modulations by the formation of the heterostructures, which optimizes the trap distributions and concentrations. These modulations improve the electron transfer efficiency to promote ML performances. This work has supplied significant references for future design and synthesis of efficient ML materials for broad applications.

Enhancing the luminescence performance of Ca2−xSrxBO3Cl:Eu2+,Dy3+ by substitution of Sr2+ for Ca2+

“…As can be seen from the figure, the relationship appears to be linear, which in turn indicates that the traps acting on the afterglow are continuously distributed and that the release of the traps is a continuous and linear process. 41,42 We will analyse this in the subsequent TL spectra.…”

Near‐Infrared Mechanoluminescence of Cr3+ Doped Gallate Spinel and Magnetoplumbite Smart Materials

“…[7,8] Since the ML phenomenon was observed in the early 17th century, increasing efforts have been devoted to the discovery of novel ML materials via a universal trial-and-error process, with state-of-the-art representatives such as SrAl 2 O 4 :Eu 2+ ,Dy 3+ (green), [9,10] ZnS:Mn 2+ (yellow), [11,12] CaZnOS:Mn 2+ (red), [13,14] (Sr,Ba)Si 2 O 2 N 2 :Eu 2+ (cyan), [15] and LiNbO 3 :Pr 3+ (red). [7,16,17] These ML materials are all nondestructive and repeatable, playing an indispensable role in converting the local mechanical contact into a perceivable light-emitting signal. Sulfur-based compounds generally exhibit poor environmental resistance, and their practical applications in bio-medicine are constrained by the discovery of nearinfrared (NIR) ML materials.…”

Molten Salt Shielded Synthesis of Monodisperse Layered CaZnOS‐Based Semiconductors for Piezophotonic and X‐Ray Detection Applications

“…It cannot be ruled out that a small amount of manganese may enter the calcium cation site, making the coordination field around the manganese ions different. The other excitation peaks at ≈398 and 496 nm can be attributed to the electronic transitions of 6 A 1 ( 6 S) → 4 T 2 ( 4 D) and 6 A 1 ( 6 S) → 4 T 2 ( 4 G). As shown in Figure 4a, the intensity of the excitation band of the main lattice is much stronger than that and c,f) the excitation spectra of 290 and 342 nm, respectively.…”

“…As smart materials, ML semiconductors have attracted extensive attention and have made significant progress in recent years, owing to their important potential applications in the fields of piezophotonics, light‐generators, stress sensing, flexible, and stretchable displays, mechanical energy harvesting and conversion, and integrated tribotronic devices. [ 1–10 ] They can emit light and are regarded as smart creatures (like Noctiluca scintillans shining by the impact of waves) when exposed to external momentary stimuli. [ 11–14 ]…”

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light-generators, stress sensing, flexible, and stretchable displays, mechanical energy harvesting and conversion, and integrated tribotronic devices. [1][2][3][4][5][6][7][8][9][10] They can emit light and are regarded as smart creatures (like Noctiluca scintillans shining by the impact of waves) when exposed to external momentary stimuli. [11][12][13][14] Many materials discovered in nature provide the capability to emit light in response to dynamic forces/pressures, whether natural or man-made, such as quartz and sugar.

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