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Mechanoluminescence (ML) is used in many areas, in particular for ML-based optical thermometry. However, ML-based thermometry is limited owing to the lack of a strong theoretical foundation. Here, using CaZnOS:Er3+and the well-established Boltzmann distribution, a solid and novel ML thermometry framework is established. Upon external force stimulation, CaZnOS:Er3+generates bright green ML ascribed to the 2H11/2→ 4I15/2and 4S3/2→ 4I15/2transitions of Er3+. And the populations at the 2H11/2and 4S3/2excited states are confirmed to follow the Boltzmann distribution during the ML process. The utility of this novel ML thermometry framework is demonstrated here on a practical example. Further, potential applications of CaZnOS:Er3+to anti-counterfeiting and information encryption are discussed. These results demonstrate that CaZnOS:Er3+luminescent materials are promising for multifunctional applications (especially for temperature sensing), and provide the foundation for future ML applications.

Mechanoluminescent (ML) smart materials are expected to be used in stress sensors, new displays, and advanced flexible optoelectronic devices, because of their unique mechanical-to-light energy conversion properties. However, the narrow-range ML emission characteristics of single materials limit their application scope. In this work, we report on the broadband multimodal emission in Sb-doped CaZnOS layered semiconductors. A series of CaZnOS layer-structured powders with different Sb3+doping concentrations were synthesised using a high-temperature solid-phase method. The CaZnOS:Sb3+phosphor achieved a wide range of ML spectra (400–900 nm), adjustable photoluminescence with double luminescent peaks located at 465 and 620 nm, and the X-ray-induced luminescence characteristics were systematically studied. We have also achieved ultra-broad warm white light ML emission of Sb3+and Bi3+co-doped samples. Therefore, it can be expected that these ML phosphors will be used in smart lighting, displays, visible stress sensors, and X-ray imaging and detections.

ZnS/CaZnOS:Mn2+luminescent ceramic components exhibit both photoluminescence (PL) and mechanoluminescence (ML). A PL material luminesces upon optical irradiation, whereas ML material converts mechanical energy into optical energy. ML materials have important application prospects in new light sources, damage detection, healthcare and anti-counterfeit encryption. In this paper, we report the preparation of luminescent ZnS/CaZnOS:Mn2+ceramic parts via vat photopolymerization 3D printing and discuss possible applications. We use manganese-doped zinc sulphide/zinc calcium oxysulfide powder as the raw luminescent ceramic powder and investigate the slurry preparation, vat photopolymerization 3D printing and sintering to fabricate photoluminescent and ML ceramic prototypes. The powder particle size was 9–10 µm, the coupling agent was 4 wt% silane (KH-570), and the photoinitiator was 2 wt% diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide. The result is a manganese-doped photosensitive slurry with uniform stability and fluidity, a solid content of 50 vol%, and a viscosity of 3 Pa·s. This slurry has excellent characteristics for vat photopolymerization 3D printing, with a penetration depth Cd= 35.03 µm and a theoretical exposure energy Ec= 2.26 mJ/cm2. ZnS/CaZnOS:Mn2+parts manufactured in this study exhibit both PL when irradiated by a light source and ML when extruded and rubbed. The photon intensity as high as 200 × 105is released from ZnS/CaZnOS:Mn2+when irradiated at 339 nm, which is nearly 50% more than that released when irradiated at 290 nm. The intensity of ML photons emitted increases with the applied mechanical force, with up to 1700 intensity emitted. Conventional forming methods mainly involve coating parts with luminescent materials mixed with polydimethylsiloxane polymer, surrounding ZrO2cores by a shell layer of ML hybrid material and other traditional processes, which cannot produce complex structures or provide long-lasting luminescence. This study thus combines the luminescent material ZnS/CaZnOS:Mn2+and vat photopolymerization 3D printing to produce complex parts with low surface roughness (Sa = 5.92 µm and Sz = 53.11 µm before sintering, and Sa = 5.09 µm and Sz = 50.73 µm after sintering) and high chemical stability. These results expand the applications of ZnS/CaZnOS-based luminescent ceramic materials and vat photopolymerization 3D printing.