Growth And Properties Of Mn Ion-doped Single Crystals

The transition metal Mn²⁺ion has a 3d⁵ electronic structure outside the nucleus,and is a typical light-emitting ion.It can emit strong green light under ultravio let light.Mn⁴⁺has a 3d³ electronic structure outside the nucleus,which can emit strong red light under ultraviolet light,which is perfectly matched with blue light emission.It is an ideal emission center ion.It has been widely used in the fields of green flat display,laser and lighting.Exploring new manganese ion-doped crystalline materials has always been a research direction that people are keen on.In this paper,a Mn²⁺ion-doped Na₅Lu₉F₃₂ single crystal was synthesized by the Bridgman method to prepare a new efficient and stable photofunctional material.In addition,a Mn⁴⁺red light-emitting Be Al₂O₄ single crystal was grown by the Czochralski method.The XRD diffraction pattern was tested to determine its crystal structure,and its optical characteristics and luminescence mechanism were verified from various aspects such as absorption spectrum,transmission spectrum,emission spectrum,fluorescence decay life,and pump power,and the manganese ions in different crystal fields were calculated Lattice parameters.The introduction of this article introduces the research purpose,the application of transition ion doping in the field of laser crystals and LEDs.The preparation methods of Na₅Lu₉F₃₂ and Be Al₂O₄ single crystals are introduced.In the second chapter,Mn²⁺ion doped Na₅Lu₉F₃₂ single crystals were grown by Bridgman method.The crystal structure and luminescence mechanism of Mn²⁺ion doped Na₅Lu₉F₃₂ single crystal were analyzed by XRD diffraction spectrum,absorption spectrum and emission spectrum.The lattice parameters of Mn²⁺ion doped Na₅Lu₉F₃₂ single crystal were calculated.The calculated values for the crystal field（Dq）and Racah parameters indicate a stable cubic crystal structure of Mn²⁺ion surrounded by eight F^-ligands can be formed with the introduction of Mn²⁺ion into Na₅Lu₉F₃₂single crystals.The third chapter mainly introduces a novel red-emitting Mn⁴⁺doped Be Al₂O₄ single crystal is synthesized by a Czochralski technique.Narrow red emission is observed from the Mn⁴⁺ions occupying Al³⁺sites in distorted octahedrons.The XRD diffraction patterns,excitation and emission spectra,thermal quenching,temperature change spectra,and lifetime decay curves were used to analyze the luminescence mechanism.Both the luminescence intensity and lifetime are reduced along with the increase of temperature from 298 to 503 K.The thermal quenching behavior of Mn⁴⁺emission is ascribed to the crossover via the ⁴T₂ state.The results show Be Al₂O₄:Mn⁴⁺single crystal may be a suitable material to improve the performance of WLEDs.The fourth chapter mainly introduces the improved Bridgman method to grow Ce³⁺/Yb³⁺/Ho³⁺three-doped Na₅Lu₉F₃₂ single crystal.The optical properties of upconversion was analyzed by XRD diffraction pattern,absorption,emission spectrum and fluorescence lifetime curve.Na₅Lu₉F₃₂ single crystal is an excellent candidate host material for Ce³⁺/Yb³⁺/Ho³⁺tri-doped system to investigate the UC luminescence and other optical properties.As the increasing concentration of Ce³⁺ions,the intensity ratios of red to green light（R/G）increase from 0.05 to 55.9.The results indicate the introduction of Ce³⁺ion is an effective way to improve the color purity of Ho³⁺ions in Na₅Lu₉F₃₂ single crystals.The last chapter of the thesis summarizes and forecasts,summarizes the main research contents of the full text,and makes a prospect and expectation for the future research.