Nghiên cứu chế tạo và tính chất của vật liệu zn2sio4 và zn2sno4 không pha tạp và pha tạp các ion kim loại chuyển tiếp mn2 cr3

MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY LE THI THAO VIEN Synthesis and properties of undoped and transition metal (Mn2+, Cr3+) doped Zn2SiO4 and Zn2SnO4 phosphors DOCTORAL DISSERTATION ON MATERIAL SCIENCES HANOI – 2020 MINISTRY OF EDUCATION AND TRAINING HANOI UNIVERSITY OF SCIENCE AND TECHNOLOGY LE THI THAO VIEN Synthesis and properties of undoped and transition metal (Mn2+, Cr3+) doped Zn2SiO4 and Zn2SnO4 phosphors Majors: Material Sciences Code: 9440122 DOCTORAL DISSERTATION ON MATERIAL SCIENCES ADVISORS: Prof Dr PHAM THANH HUY Dr NGUYEN THI KHOI HANOI – 2020 COPYRIGHT DECLARATION This thesis compresses only my research results It does not contain any previous data submitted by any people or organizations except that have been marked in the references Hanoi, 15/11/2020 Advisor PhD Student Prof Dr Pham Thanh Huy Le Thi Thao Vien i ACKNOWLEDGEMENTS Although my name is on the cover of this dissertation, many people were of great importance to this research I want to take a moment to extend my gratitude to the involved The first, I would like to express my sincerest thanks to my supervisor, Prof Pham Thanh Huy, excellence and estimable teacher, for all of his supports His dedication to science has been encouraging me so much, protected me from the confusion since I started studying and researching at the Advanced Institute for Science Technology (AIST) This dissertation was carried out at AIST, together with several research groups researches I had garnered variable information from these seminars with free discussions coming from all of our group members Possibly just as important as the practical aid was the friendly, cooperative atmosphere at AIST; it made me enjoy virtually every second of working on my dissertation I wish to thank Associate prof Dao Xuan Viet; Dr Nguyen Tu; Dr Nguyen Duy Hung, and all of my teammates for their friendships with kind-hearts and unconditional assistance The last few months weren’t easy, and I want to thank all my dearest friends, who helped me get back on track when I lost my laptop and found many difficulties in life Without your care, understanding, and motivational speeches, this thesis would no doubt look different and not for the better Your friendship makes me realize what a lucky person I am For the last, more than I can say, I would like to express manifest thanks to my husband and two children for always being by my side, putting their truth in me during my duration at AIST Lastly, I want to mention my father, mother, my parents-in-law, and two sisters, and thank them for making me the person that I have become Le Thi Thao Vien ii CONTENTS LIST OF FIGURES viii LIST OF TABLES .xiv BRIEF INTRODUCTION Chapter INTRODUCTION 1.1 Background of Luminescence 1.1.1 Luminescence 1.1.2 Optical quenching 1.1.3 Electroluminescence 1.1.4 Thermoluminescence 10 1.2 Background of Transition Metal (TM) ions in the crystal field 10 1.2.1 Transition metals… .10 1.2.2 The effect of crystal fields on the separation of TM ions… 11 1.2.3 Tanabe-Sugano diagrams 15 1.2.4 Energy levels of Mn2+ ion in a crystal field 18 1.2.5 Energy levels of Cr3+ ion in a crystal field 20 1.3 Literature review of transition metal (Mn2+, Cr3+) doped Zn2SiO4 and Zn2SnO4 phosphors 22 1.3.1 Structure and optical properties of Zn2SiO4: Mn2+ 22 1.3.2 Structure and optical properties of Zn2SnO4, Zn2SnO4:Mn2+ ………………………………………………………………………………………………………………………… 24 1.4 Phosphor-based LEDs 26 1.4.1 LED .26 1.4.2 Phosphor-based LEDs 27 1.4.3 LED application in agricultural lighting 30 Chapter EXPERIMENTAL TECHNICS .32 2.1 Introduction 32 2.2 Synthesis of Zn2SiO4, Zn2SiO4:Mn2+, Zn2SnO4, Zn2SnO4:Mn2+, Zn2SnO4:Cr3+, Zn2SnO4:Cr3+, Al3+ 33 2.2.1 Materials .33 2.2.2 Synthesis of Zn2SiO4 33 2.2.3 Synthesis of Zn2SiO4: Mn2+ 34 2.2.4 Synthesis of Zn2SnO4 34 2.2.5 Synthesis of Zn2SnO4:Mn2+ 34 2.2.6 Synthesis of Zn2SnO4:Cr3+ and Zn2SnO4:Cr3+, Al3+ 34 iii 2.2.7 Mechanical milling .35 2.3 Techincal methods 35 2.3.1 Structural characterisation 35 2.3.2 Photoluminescent characterization 30 2.4 LED package process .43 2.4.1 Die bonding 44 2.4.2 Wire Bonding 45 2.4.3 Phosphor Dosing 45 2.4.4 Dispensing 46 2.4.5 Curing 47 2.4.6 Testing 47 Chapter STRUCTURE AND OPTICAL PROPERTIES OF Zn2SiO4 AND Zn2SiO4:Mn2+ PHOSPHORS 48 3.1 Introduction 48 3.2 Structure and optical properties of Zn2SiO4 phosphors 49 3.2.1 X-ray diffraction of Zn2SiO4 49 3.2.2 Phosphor morphology of Zn2SiO4 50 3.2.3 Vibrational analysis: Raman spectra of Zn2SiO4 51 3.3 Structure and optical properties of Zn2SiO4:Mn2+ phosphors 55 3.3.1 X-ray diffraction of Zn2SiO4:Mn2+ 55 3.3.2 3.3.3 Phosphor morphology of Zn2SiO4:Mn2+ 57 Vibrational analysis of Zn2SiO4:Mn2+ 58 3.3.4 Optical properties of Zn2SiO4:Mn2+ 61 3.3.5 Thermoluminescence (TL) properties and Decay time of Mn2+ doped Zn2SiO4 64 3.3.6 Application of Mn2+ doped Zn2SiO4 on UV LED .66 3.4 Conclusion 67 Chapter STRUCTURE AND OPTICAL PROPERTIES OF Zn2SnO4 AND Zn2SnO4:Mn2+ PHOSPHORS 68 4.1 Introduction 68 4.2 Structural and optical properties of Zn2SnO4 phosphors .69 4.2.1 X-ray diffraction of Zn2SnO4 69 Optical properties of Zn2SnO4 74 4.3 Structural and optical properties of Zn2SnO4:Mn2+ 80 4.3.1 X-ray diffraction of Zn2SnO4:Mn2+ 80 4.2.2 iv 4.3.2 4.3.3 Phosphor morphology of Zn2SnO4:Mn2+ 84 Optical properties of Zn2SnO4:Mn2+ 84 4.3.4 Decay time of 5%Mn2+ doped Zn2SnO4 89 4.3.5 Temperature-dependent PL and internal quantum efficiency of Zn2SnO4:5%Mn2+ phosphors 91 4.3.6 Application of un-doped and Mn2+ doped Zn2SnO4 on LED 92 4.4 Conclusion 93 Chapter OPTICAL PROPERTIES OF Zn2SnO4:Cr3+ AND Zn2SnO4:Cr3+, Al3+ FOR PLANT CULTIVATION LED 95 5.1 Introduction 95 5.2 Structural and optical properties of Zn2SnO4:Cr3+ phosphors .97 5.2.1 X-ray diffraction of Zn2SnO4:Cr3+ 97 5.2.2 5.2.3 Phosphor morphology of Zn2SnO4:Cr3+ 100 Optical properties of Zn2SnO4:Cr3+ 101 Application of the prepared phosphor for fabricating infrared LEDs 105 5.3 Structural and optical properties of Zn2SnO4:Cr3+, Al3+ phosphors 106 5.3.1 X-ray diffraction and FESEM of Zn2SnO4:Cr3+,Al3+ .106 5.2.4 Crystal field analysis 109 5.3.3 The effect of Al3+ on optical properties of ZTO: Cr3+ .111 5.3.4 Application of the prepared phosphor .116 5.4 Conclusion .117 CONCLUSIONS AND FUTURE WORKS .120 PUBLICATIONS 123 RELATED PUBLICATIONS 124 REFERENCES 125 5.3.2 v LIST OF ACRONYMS Acronyms Full name EDX/EDS: Energy-Dispersive X-ray spectroscopy LED: Light Emitting Diode NIR: Near-infrared PL: Photoluminescence SEM: Scanning Electron Microscope XRD: X-Ray Diffraction FESEM: Field emission scanning electron Microscope PLE: Photoluminescence excitation UV: Ultraviolet HWHM: Half-Width at half-maximum IR: Infra-red TM: Transition Metal EL: Electroluminescence NBOH: Non – bridging oxygen hole centers RGB: Red, Green and Blue FTIR: Fourier – transform infrared spectroscopy HEBM: High – energy planetary ball mill AIST: Advanced Institute for Science and Technology JCPDS: Joint committee on powder diffraction standards FWHM: Full width at half maximum vi Zni: Zinc interstitials Sni: Tin interstitials Oi: Oxygen interstitials Vo: Oxygen vacancy WBG: Wide band gap ZTO: Zinc stannate VZn: Zinc vacancy VSn: Tin vacancy TG-DTA: Thermogravimetry/Different thermal analyzer CRI: Color rendering index CCT: Correlated color temperature BM: Brurstein – Moss WLED White light-emitting diode QE Quantum efficiency AO Atomic orbitals vi LIST OF FIGURES No Name Page Figure 1.1 Shapes of d orbitals and ligand positions ○: Ligands for octahedral symmetry: Ligands for tetrahedral symmetry Figure 1.2 The separation of AO d of the transition metal ions in octagonal symmetry Figure 1.3 Figure 1.4 Figure 1.5 The separation of AO d of the central ion by the crystal field in different symmetry The separation of energy levels of some transition metal ions due to electrostatic interaction (a) and the energy level separation of Cr3+ ions when take into account the spin-orbit interaction L-S (with B = 918 cm-1) (b) 3d level splitting caused by the crystal field 14 15 Energy level diagram for the d2 configuration (From Figure 1.6 Figure 1.7 Figure 1.8 Figure 1.9 Figure 1.10 Kamimura, H., Sugano, S., and Tanabe, Y., Ligand Field Theory and its Applications, Syokabo, Tokyo, 1969) Energy level diagram for the d3 configuration (From Kamimura, H., Sugano, S., and Tanabe, Y., Ligand Field Theory and its Applications, Syokabo, Tokyo, 1969) Energy level diagram for the d5 configuration (From Kamimura, H., Sugano, S., and Tanabe, Y., Ligand Field Theory and its Applications, Syokabo, Tokyo, 1969) Tanabe–Sugano diagram for the Mn2+ in Zn2SiO4 crystal field Tanabe–Sugano diagram for the Cr3+ electron configuration in the octahedral crystal field C/B = 4.7 16 17 17 19 21 (a) The number of SiO4− units that are connected together Figure 1.11 by sharing the oxygen atoms and (b) Structure of the Willemite -Zn2SiO4 23 Figure 1.12 Structural models for the cubic spinel -Zn2SnO4 25 Figure 1.13 General approaches for achieving white LEDs (A) Singleemitting-layer structure (B) Multi emitting layer structure (C) Tandem structure (D) Pixelated structure (E) Downconversion white LEDs vi 27