New flexible ceramic film can continuously emit light at 375 ℃

On the track of "high-temperature luminescence" in flexible photoluminescent materials, the team led by Zhang Kun from Xi'an Engineering University has published their latest work in Advanced Optical Materials, pushing the temperature resistance limit of flexible visible luminescence to 375 ℃, and for the first time, using X-ray full scattering measurement to capture high-definition close-up of the microstructure of amorphous ceramic nanofibers through the "flexibility+high-temperature luminescence" mechanism. Master's student Mu Dan is the first author (now employed at Xianyang Normal University).

Flexible photoluminescent materials, as a type of optical material that can adapt to complex curved surfaces, have irreplaceable application value in extreme environmental monitoring, special equipment visualization, and high-temperature equipment identification. However, traditional flexible photoluminescent materials have significant limitations in their service performance under extreme conditions, mainly reflected in three aspects: (1) high-temperature resistance bottleneck of substrates: conventional flexible polymer substrates have poor high-temperature resistance, and even specially made organic polymers are difficult to work for long periods of time above 300 ℃, which cannot meet the needs of extreme scenarios such as aerospace; (2) Difficulties in regulating luminescence uniformity: uneven dispersion of luminescent centers leads to poor luminescence uniformity at high temperatures; (3) High temperature luminescence quenching effect: When the temperature exceeds 200 ℃, traditional flexible luminescent materials are prone to a sharp decrease in luminescence intensity (quenching), severely limiting their luminescent applications in extreme environments. Therefore, there is an urgent need to make breakthrough progress in the field of flexible photoluminescent materials with extreme temperature stability to promote the development of flexible light-emitting devices.

In order to achieve stable luminescence in a wide temperature range and excellent mechanical properties of flexible luminescent materials, Zhang Kun's team successfully prepared flexible amorphous Sm2O3-La2O3-ZrO2 (SLZ) nanofiber thin films using electrospinning combined with subsequent calcination, providing a new paradigm for the development of flexible high-temperature photoluminescent devices. The core advantages of this flexible luminescent nanofiber film are as follows: (1) Ultra wide temperature range luminescence without fading: from a low temperature of -12 ℃ to a high temperature of 375 ℃, the red light brightness and color hardly change, covering the temperature range of the vast majority of extreme application scenarios. (2) The temperature resistance limit is extended to 375 ℃: After continuous heating at 375 ℃ for 24 hours, the material did not show structural cracking or wrinkles, and the luminous brightness did not significantly decrease, solving the pain point of traditional materials that are prone to aging at high temperatures. (3) Stable luminescence after repeated bending: After multiple repeated bending tests, the excellent mechanical properties of the material can still be maintained; Even when folded or stretched, the luminescent function is not affected at all, significantly better than most flexible luminescent materials.

The excellent performance of this thin film material comes from its unique amorphous nanofiber structure. Short range Order - Stable Luminescence Center: Strong short-range order indicates the formation of [SmO] polyhedra and the rigidity of local coordination structures, ensuring the environmental stability of the luminescent center (Sm3+), thereby ensuring the stability of photoluminescence and laying the foundation for luminescence uniformity. Medium range Order - Luminescence and Mechanical Enhancement: The [Sm3] - O - [Sm3] medium range ordered continuous structure suppresses the destruction of the coordination environment at high temperatures and effectively reduces luminescence quenching at high temperatures; Simultaneously improving the toughness of amorphous oxides enhances the mechanical strength and deformation resistance of the material. Long range disorder - amorphous structure softening: Long range disorder avoids the "weak surface" (easily fractured atomic plane) formed by the regular arrangement of atoms in crystalline materials, significantly reducing the brittleness of the material, improving flexibility and fracture resistance, and enabling it to adapt to mechanical stress in extreme environments.

Summary

This study developed an amorphous oxide ceramic nanofiber luminescent film that is resistant to extreme temperatures, overcoming the limitations of traditional photoluminescent materials and creating the highest visible luminescence temperature record for flexible photoluminescent materials. For the first time, the key role of the short/medium range ordered structure of amorphous ceramic nanofibers in performance was revealed. Amorphous ≠ chaotic, and its amorphous structure design provides a new idea for solving the collaborative regulation problem of "high temperature flexibility luminescence stability". The ultra wide temperature range luminescence stability, high temperature mechanical reliability, and excellent flexibility of SLZ nanofiber film are expected to promote breakthroughs in the application of flexible optical devices in extreme environment monitoring, high-temperature equipment visualization identification, special protective equipment, and other fields, providing important experimental basis and support for the functional expansion of flexible optoelectronic materials. Theoretical support.