Exploration On Manganese Doped Functional Luminescent Materials And Their Composite Fibers

As a one-dimensional form of material,optical fiber is an excellent optical research and device platform,which greatly promotes the development and progress of science and technology and society.With the development and upgrading of functional materials and the continuous improvement of fiber fabrication technology,the new type of composite fiber involving the integration of material,structure or function has become an important research direction of fiber waveguide and shows a broad application prospect in the fields of fiber laser,optical sensing,special lighting,biological medicine and so on.Transition metal manganese?Mn?ions have a variety of valence states.Their doped materials possess sorts of unique luminescence properties,which can also provide a probe for the regulation and optimization of matrix structure.Therefore,Mn-doped materials has unique research value and application advantages,which is expected to be used as precursor materials to explore the preparation of composite fiber.In view of the research and application status and development potential of composite fiber in afterglow and optical thermometry,in present work we aim to explore the composition of novel Mn-doped inorganic luminescent materials and make a study on the optical properties of manganese ions.In addition,systematic characterizations are conducted to dig out the structure-performance relationship and elucidate the inner mechanism.Subsequently,the preliminary work of composite fiber based on as-prepared materials is carried out in order to pave the way for the subsequent development of optical fibers.The specific research contents and results are as follows:?1?A series of novel Mn²⁺-doped germanate photonic glasses exhibiting red to near-infrared long-lasting luminescence?530-830 nm?are developed.Provoked by the understanding of amorphous structure continuity,facile network topology is utilized as tuning strategy,resulting in the enhancement of photoluminescence and afterglow from 30 mins to longer than 24 h.The density of correlative electronic defects increases with their depth gradually deepening from 0.69,0.78,and 0.83 e V to 0.80,0.85,and 0.90 e V.Multiple measurements reveal that the internal structure evolves towards regular crosslinking,promoting the incorporation and stabilization of Mn²⁺along with the change of band-gap and defects,all of which are conducive to afterglow.The possible attribution of defects stems not only from the structural intrinsic state,but also from defects caused by the photo-oxidation of Mn²⁺.Coupled with various factors,the mechanism of persistence and its regulation is expounded in detail.These results deepen the understanding of the structure-activity dependence and provide meaningful reference for the rational design of functional materials with lasting afterglow or high luminous efficiency.?2?A novel Mn⁴⁺-doped deep-red phosphor La Ti Sb O₆:Mn⁴⁺for optical thermometry is found,and its phase structure and luminescence properties are systematically investigated.The title phosphor exhibits specific single-band narrow emission?FWHM=?31 nm?in deep-red region centered at 683 nm with strong wide absorption.We determine the optimal doping concentration and concentration quenching mechanism of Mn⁴⁺,and reveal the lattice displacement and structure-performance relationship of Mn⁴⁺through crystal field theory and time-resolved spectral analysis.The luminescent thermal quenching characteristics of La Ti Sb O₆:Mn⁴⁺over the range of 0-478 K were characterized to systematically evaluated the dependence of optical properties on temperature,explaining the corresponding thermal quenching mechanism.The results exhibit that the Mn⁴⁺-lifetime can be exploit for optical thermometry due to its wide measurement range covering the most relevant interval?273-373K?and high sensitivity(S_R=2.75%K^-1).Meanwhile,the environment with high temperature and humidity is established to examine the superior robustness and inertness of the phosphor.This work not only suggests La Ti Sb O₆:Mn⁴⁺as a promising candidate,but also lays a foundation for the subsequent composite study of materials.?3?The preliminary research of afterglow-based composite glass fiber is carried out.Firstly,the practical prospect of as-synthesized Mn²⁺-doped germanate glass with persistent luminescence is discussed by setting up the pattern display and tissue-penetrating measurement.On this basis,the design and preparation of bulk glass is conducted to ascertain the relevant melting process and eliminated the influence of bubble,fringe and other factors.We also inspect the fiber-drawing performance of the optimized bulk glass in a simple way.The experimental results manifest that this kind of glass is expected to be used as precursor material of fiber core,and help to promote the design and final drawing of composite fiber.?4?The preliminary research of optical thermometric composite fiber is developed through low temperature sintering method to evaluate the phosphor-in-glass?Pi G?integration of La Ti Sb O₆:Mn⁴⁺and glass,which simulates the composition of composite fiber.In view of the excellent stability of the phosphor,it can coexist well with the carrier substrate without ascertainable interfacial reaction.The Pi G product yields intriguing improved performance(S_R=3.01%K^-1)inherited from La Ti Sb O₆:Mn⁴⁺.Moreover,YAG:Ce³⁺and La Ti Sb O₆:Mn⁴⁺co-embedded heterogeneous Pi G architecture is conceptually engineered to realize the dual-mode thermometry integrating the Mn⁴⁺-lifetime and fluorescence intensity ratio?FIR?from the Ce³⁺/Mn⁴⁺non-thermally-coupled system,which utilizes their diverse emission and thermoeffect.The FIR mode features excellent repeatability with S_Rreaching 1.61%K^-1.Dopant isolation provided by matrix blocks unfavorable energy-transfer depletion,ensuring the stable,crosstalk-free operation of thermometry.These results indicate that La Ti Sb O₆:Mn⁴⁺meets the performance conditions as the fiber core material.The study expands new horizons with the topological composite pathway toward rational designing and perfecting multi-mode thermometer or other versatile constructions,and suggests accessible references to the subsequent preparation of phosphor-glass composite fiber in low temperature.