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Crystal chemistry, polymorphisms, and phase transformations of lithium-containing metal phosphates
| DC Field | Value | Language |
|---|---|---|
| dc.contributor.advisor | 김승주 | - |
| dc.contributor.author | 김성철 | - |
| dc.date.accessioned | 2018-11-08T08:17:00Z | - |
| dc.date.available | 2018-11-08T08:17:00Z | - |
| dc.date.issued | 2017-02 | - |
| dc.identifier.other | 24515 | - |
| dc.identifier.uri | https://dspace.ajou.ac.kr/handle/2018.oak/12301 | - |
| dc.description | 학위논문(박사)--아주대학교 일반대학원 :에너지시스템학과,2017. 2 | - |
| dc.description.tableofcontents | Chapter 1. General introduction 1 1.1. Orthophosphates 1 1.1.1. Structure of orthophosphates 2 1.1.1.1. Tridymite-related structures 2 1.1.1.2. Olivine-type structures 4 1.1.1.3. Glaserite-like structures 5 1.1.2. Current issues in orthophosphates 7 1.1.2.1. Applications to luminescent host 7 1.1.2.2. Applications to lithium ion batteries 7 1.1.2.3. Crystallographic studies 8 1.2. Phase transformations 10 1.2.1. Classification of phase transformation 10 1.2.2. Solid-solid phase transformations 12 1.2.2.1. Nucleation and growth mechanism 14 1.2.2.2. Spinodal decomposition 17 1.2.3. Time-temperature-transformation (TTT) diagram 19 1.3. Powder diffraction techniques for structural analysis 22 1.3.1. Powder vs. single-crystal diffraction 23 1.3.2. Ab initio structure determination 24 1.4. Objectives 30 Chapter 2. Phase transition, spinodal decomposition and reentrant phase formation in LiSrPO4 32 2.1. Introduction 32 2.2. Experimental 33 2.2.1. Synthesis 33 2.2.2. Structural analysis 33 2.2.3. Thermal analysis 34 2.2.4. Microstructural study 34 2.3. Results 34 2.3.1. Crystal structure of new polymorph 34 2.3.2. Thermo-diffractometric study 41 2.3.3. Thermal expansion measurements 42 2.3.4. Phase analysis 46 2.3.5. Thermal analysis 49 2.3.6. Morphology 52 2.4. Discussion 55 2.4.1. Phase transition 55 2.4.2. Reentrant phase formation and coherent behavior 57 2.5. Conclusions 60 Chapter 3. Crystal structure of LiBaPO4: Polymorphism and phase transition 61 3.1. Introduction 61 3.2. Experimental 61 3.2.1. Synthesis 61 3.2.2. Structural analysis 62 3.2.3. Thermal analysis 62 3.3. Results and Discussion 63 3.3.1. Structure description 63 3.3.1.1. Polymorph I: Monoclinic phase 63 3.3.1.2. Polymorph II: Trigonal phase 68 3.3.2. Phase transition 73 3.4. Conclusions 76 Chapter 4. Comparative study on the phase transformations and nonlinear-optical property in LiMPO4 (M = Ca, Sr, Ba) 77 4.1. Introduction 77 4.2. Experimental 79 4.2.1. Synthesis and structural analysis 79 4.2.2. Phase transformation analysis 79 4.2.3. Optical spectroscopy 80 4.3. Results and Discussion 80 4.3.1. Structure refinements 80 4.3.2. Comparison of phase transformation behaviors 84 4.3.3. Raman spectroscopy 90 4.3.4. Second-harmonic generation (SHG) 92 4.4. Conclusions 95 Chapter 5. Synthesis, crystal structure, and ionic conductivity of a new layered metal phosphate, Li2Sr2Al(PO4)3 96 5.1. Introduction 96 5.2. Experimental 97 5.2.1. Synthesis 97 5.2.2. Single-crystal X-ray diffraction 97 5.2.3. Ionic conductivity measurements 98 5.3. Results and discussion 99 5.3.1. Structure determination 99 5.3.2. Structure description 106 5.3.3. Powder synthesis and ionic conductivity 109 5.4. Conclusions 114 REFERENCES 115 | - |
| dc.language.iso | eng | - |
| dc.publisher | The Graduate School, Ajou University | - |
| dc.rights | 아주대학교 논문은 저작권에 의해 보호받습니다. | - |
| dc.title | Crystal chemistry, polymorphisms, and phase transformations of lithium-containing metal phosphates | - |
| dc.title.alternative | Sung-Chul Kim | - |
| dc.type | Thesis | - |
| dc.contributor.affiliation | 아주대학교 일반대학원 | - |
| dc.contributor.alternativeName | Sung-Chul Kim | - |
| dc.contributor.department | 일반대학원 에너지시스템학과 | - |
| dc.date.awarded | 2017. 2 | - |
| dc.description.degree | Doctoral | - |
| dc.identifier.localId | 770665 | - |
| dc.identifier.url | http://dcoll.ajou.ac.kr:9080/dcollection/jsp/common/DcLoOrgPer.jsp?sItemId=000000024515 | - |
| dc.subject.keyword | Crystal structure | - |
| dc.subject.keyword | Phase transformation | - |
| dc.subject.keyword | Phosphate | - |
| dc.subject.keyword | Spinodal decomposition | - |
| dc.description.alternativeAbstract | This thesis focuses on the crystal structures and phase transformations of lithium metal phosphates LiMPO4 (M = Ca, Sr, Ba). It shows that a correlation exists between the nonlinear optical property and the crystal structure. The synthesis of a new complex metal phosphate was also proposed based on the lattice design concept. Each compound was synthesized by solid state reaction or the molten salt method. X-ray diffraction (XRD), thermophysical analysis, field emission scanning electron microscopy (FE-SEM), Raman spectroscopy, measurement of optical second harmonic generation, and impedance analysis were employed for structural analysis and characterization. Chapter 1 describes the crystal structure and the physical properties of inorganic phosphates, gives an introduction to phase transformation, describes the procedure for crystal structure determination using powder diffraction, and states the purpose of this paper. Spinodal decomposition, which is one of the unique phase transformation phenomena, is described along with the classification according to the phase transition mechanism. ABPO4 (A, B = alkali, alkaline earth metal)-type inorganic phosphates have different coordination bonds between metal ions and PO4 units depending on the sizes of the A and B ions. The structures are closely related to tridymite, olivine, and glaserite minerals. ABPO4 compounds have attracted much attention as phosphors, optical materials, and electrode materials for secondary batteries due to their structural stability. However, the detailed structures remain unclear. The crystal structure, phase transformation and physicochemical properties of lithium metal phosphates, LiMPO4 (M = Ca, Sr, Ba), are discussed. The synthesis, crystal structure, and electrochemical properties of a new lithium metal phosphate Li2Sr2Al(PO4)3, with an intergrowth-type 2-D layered structure, are also discussed. In Chapter 2, the crystal structure of LiSrPO4 and the phase transformation with temperature are analyzed. LiSrPO4 exists in two polymorphs: a monoclinic phase at room temperature, and a hexagonal phase at high temperatures. In Particular, spinodal decomposition and reentrant phase formation, which are rare in ceramics, have been reported for the first time. Phase decomposition into Sr3(PO4)2 and Li3PO4 occurred at about 650 °C; the separated phases disappeared and returned to the hexagonal LiSrPO4 phase at 830 °C. The phase transformations were influenced by the morphology of the sample. The bulk sample did not show phase decomposition on cooling because it allows larger strain than the powder sample, which is an energy barrier that prevents phase decomposition. Chapter 3 shows the structural change of LiBaPO4 with temperature. Two kinds of polymorphs were confirmed, which were different from the crystal structures previously assumed to be orthorhombic or hexagonal. LiBaPO4 exhibited a monoclinic to hexagonal phase transition above 600 °C. In Chapter 4, a comparative study on the crystal structures and the phase trans-formation behavior of LiMPO4 (M = Ca, Sr, Ba) was undertaken. The correlations between the crystal structure and the second harmonic generation (SHG) and Raman scattering were investigated. The phase transformations in LiMPO4 were related to the lattice energy of each phase and can simply be compared by the lattice volumes. Phase separation occurs when the lattice volume difference between M3(PO4)2 and LiMPO4 is sufficiently large. The trend of SHG observed in LiMPO4 was consistent with the structural distortion of the polyhedron calculated using the bond-valence method. In Chapter 5, the synthesis, crystal structure, and ionic conductivity of the new lithium metal phosphate, Li2Sr2Al(PO4)3, with a layered structure are discussed. Li2Sr2Al(PO4)3 is a new intergrowth-type compound in which two different phosphate units, LiO4 and PO4 groups are alternately stacked. The ionic conductivity of this compound was measured using an impedance analyzer. | - |
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