The Investigate Of The Upconversion Luminescence Regulation And Optical Function Of Rare Earth Doped Fluoride NaREF₄ Materials

Rare earth luminescent materials have become the focus and frontier of luminescent material research due to the stable physical and chemical properties,good monochromaticity,strong absorption characteristics,and high luminescence conversion efficiency.This work focuses on the study of upconversion luminescent materials in rare earth luminescent materials,that is,the materials that radiate short waves after absorbing long waves.The purpose is to clarify the effect of different substrates and different doping systems on the structure and properties of materials.This can reveal the effect mechanism of doped rare earth ions on the optical properties of materials,enrich the basic theoretical system of rare earth doped optics,and promote the development and application of rare earth resources in photonics.Based on the excellent characteristics of fluoride materials,the structural,electronic,and optical properties of three different matrix materials?-Na YF₄,?-Na Gd F₄,and?-Na Lu F₄ were studied,and the differences in various properties between different matrix systems were systematically analyzed.The Er³⁺and Yb³⁺doped materials were prepared by the hydrothermal method.Combining the analysis of the upconversion luminescence spectrum and the fluorescence decay curve,the upconversion luminescence mechanism of Er³⁺/Yb³⁺was determined under different excitation conditions.Under the excitation of these four wavelengths lasers(808 nm,980 nm,1064 nm,and 1550 nm),the emission peaks were observed at 521 nm,540 nm,and 655 nm in these samples,and fluorescence intensity of upconversion materials under different matrix systems changes.Controlling the spectral of upconversion materials by external stimuli is a convenient method,which is essential for a variety of studies.Through research,it was found that the Pr³⁺ion single doped material can perform spectral regulation by manipulating excitation power density,the green-red ratio increases from 0.02 to 1.07,and the color changes from red to green as the excitation power increases from 2.0 m W mm^-2 to 70.8 m W mm^-2.Combining the relationship between the upconversion fluorescence intensity and the pump energy and the fluorescence time decay performance,the upconversion luminescence mechanism of Pr³⁺ions to achieve luminescence regulation under different excitation powers is determined.Other upconversion spectral control materials can be further designed by combining other rare earth ions based on the unique multiphoton processes of Pr³⁺ion.Inspired by this,these upconversion materials could be utilized to design corresponding logic operations by manipulating external excitation conditions without changing input and output conditions.Dual-wavelength excitation has many unique advantages in upconverting photoluminescence.A novel concept of the logic gate using the external excitation source as the excitation input and the upconversion relative emission intensity as the output is proposed based on the unique dual-wavelength excitation effect of Er³⁺ions.The Er³⁺doped?-Na YF₄ material that can achieve the emission enhancement via simultaneous dual-wavelength pumping at 1550 nm and 1064 nm due to the matching energy level.Upon simultaneous dual-wavelength excitation,the green emission increased by 53%and the red emission increased by 336%compared to the single-wavelength excitation at 1550nm,while the green emission increased by 72%and the red emission increased by 2820%compared to the single-wavelength excitation at 1064 nm.Elementary logic operations and integrative logic operations are implemented by observing the change in two fluorescence emission bands(green and red)under the near-infrared excitation input conditions,which use these two excitation wavelengths as the input signal,and the relative conversion intensity of the above conversion as the output signal.The results not only provide a deep understanding of the upconversion luminescence mechanism under dual-wavelength excitation,but also offer a useful enlightenment for the development of novel micro/nanostructured materials for complex logic operations.Rational design of multicolor upconversion luminescence to achieve multi-functional optical applications holds exotic potential applications in high-tech field.The Er³⁺ions doped material prepared by the hydrothermal method can achieve multicolor upconversion luminescence by thermally manipulating the electron transition process under 1550 nm excitation conditions,which the green-red ratio of the sample decreases from 3.3 to 0.26,and the color output changes from green to yellow as the temperature increases from 100K to 350 K.The maximum absolute and relative sensitivities of the temperature sensor based on non-thermally coupled levels and thermally coupled levels of Er³⁺ions reached up to 0.054 K^-1 and 4.225%K^-1,respectively,which possesses highly sensitive temperature sensing characteristics.The Er³⁺-doped material exhibited thermochromic luminescence properties due to the unique thermal response mechanism,which enables the creation of novel anti-counterfeiting applications of visual reading and digital recognition in a secure manner.These results may provide useful enlightenment for the design and modulation of high-sensitivity temperature sensing materials for multifunctional applications.