Title Stydy on UV Excitable Lanthanide Doped M-SiAlON (M = La, Sr) Phosphors for White LEDs Author(s) 王, 春云 Citation 北海道大学. 博士(総合化学) 甲第12913号 Issue Date 2017-09-25 DOI 10.14943/doctoral.k012913 Doc URL http://hdl.handle.net/2115/71513 Type theses (doctoral) File Information Chunyun_Wang.pdf Instructions for use Hokkaido University Collection of Scholarly and Academic Papers : HUSCAP Study on UV Excitable Lanthanide Doped M-SiAlON (M = La, Sr) Phosphors for White LEDs Chunyun Wang Graduate School of Chemical Sciences and Engineering Hokkaido University July 2017 Table of contents Abstract ............................................................................................................................... 7 Chapter 1 Introduction .................................................................................................... 11 1.1 White LED ...................................................................................................................................... 11 1.2 Selections of phosphors for white LED .......................................................................................... 13 1.2.1 Selection of lanthanide ions ..................................................................................................................................... 13 1.2.2 Selection of host materials ....................................................................................................................................... 14 1.3 Theory of luminescence .................................................................................................................. 15 1.3.1 Effects of centroid shift, crystal field splitting and Stokes shift ............................................................................... 15 1.3.2 Effects of lanthanide energy level locations ............................................................................................................. 17 1.3.3 Theoretical models to predict lanthanide level locations ......................................................................................... 17 1.3.4 Methods to construct lanthanide energy level scheme ............................................................................................. 20 1.4 State-of-the-art of nitride and oxynitride phosphors ....................................................................... 21 1.5 Scope and overview of this thesis ................................................................................................... 22 1.6 References ....................................................................................................................................... 24 Chapter 2 Experimental .................................................................................................. 29 2.1 Synthesis of powder samples with solid-state reaction method ...................................................... 29 2.2. Structural characterization .............................................................................................................. 29 2.2.1 X-ray diffraction (XRD) .......................................................................................................................................... 29 2.2.2 Solid-state nuclear magnetic resonance (NMR) ....................................................................................................... 30 2.2.3 Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) ....................................... 31 2.3 Photoluminescence properties characterization .............................................................................. 32 2.3.1 Diffuse reflectance spectroscopy ............................................................................................................................. 32 2.3.2 X-ray absorption near edge structure (XANES) spectroscopy ................................................................................. 33 2.3.3 Photoluminescence (PL) spectroscopy ..................................................................................................................... 33 2.3.4 Quantum efficiency (QE) ......................................................................................................................................... 34 2.3.5 Temperature dependent photoluminescence ............................................................................................................ 35 2.3.6 Time-resolved photoluminescence (TRPL) and time-resolved emission spectroscopy (TRES) .............................. 35 2.4 References ....................................................................................................................................... 36 Chapter 3 Synthesis and photoluminescence properties of a phase pure green- emitting Eu doped JEM sialon (LaSi6-zAl1+zN10-zOz, z ~ 1) phosphor with a large red- shift of emission and unusual thermal quenching behavior ........................................ 39 3 3.1 Introduction ..................................................................................................................................... 39 3.2 Experimental section ....................................................................................................................... 40 3.2.1 Sample preparation................................................................................................................................................... 40 3.2.2 Characterization ....................................................................................................................................................... 40 3.3 Results and discussion ..................................................................................................................... 40 3.3.1 Phase identification and microstructure ................................................................................................................... 40 3.3.2 Photoluminescence properties .................................................................................................................................. 46 3.4 Conclusions ..................................................................................................................................... 55 3.5 References ....................................................................................................................................... 55 Chapter 4 Photoluminescence properties of JEM:Ln (Ln = Ce, Eu, Sm, Yb) and the 4f and 5d energy level locations of the lanthanides in JEM ......................................... 57 4.1 Introduction ..................................................................................................................................... 57 4.2 Experimental section ....................................................................................................................... 58 4.2.1 Synthesis .................................................................................................................................................................. 58 4.2.2 Characterization .................................................................................................................................................... 58 4.3 Results and discussion ..................................................................................................................... 58 4.3.1 Synthesis and XRD analysis of JEM:Ce .................................................................................................................. 58 4.3.2 Photoluminescence properties of JEM:Ce phosphors .............................................................................................. 59 4.3.3 Luminescence decay and redshift of JEM:0.01Ce phosphor.................................................................................... 61 4.3.4 Thermal quenching of JEM:Ce ................................................................................................................................ 64 4.3.5 Optical properties of JEM:Yb and JEM:Sm phosphors ........................................................................................... 65 4.3.6 Energy level locations of Ce, Eu, Sm and Yb in JEM.............................................................................................. 71 4.4 Conclusions ..................................................................................................................................... 75 4.5 References ....................................................................................................................................... 76 Chapter 5 Ce doped La3Si6.5Al1.5N9.5O5.5, a rare highly efficient blue-emitting phosphor at short wavelength toward high color rendering white LED application 79 5.1 Introduction ..................................................................................................................................... 79 5.2 Experimental section ....................................................................................................................... 80 5.2.1 Sample preparation................................................................................................................................................... 80 5.2.2 Characterization ....................................................................................................................................................... 80 5.3 Results and discussion ....................................................................................................................