臺灣博碩士論文加值系統

在研究鈦酸鋇 (BaTiO3) 晶粒成長過程中，晶粒因液相 (liquid film) 、{111}成對雙晶 (double twin) 、晶界移動 (boundary mobility) 速率等的影響，會有部分晶粒相對其它晶粒而言快速的成長。但由於在研究晶粒成長的過程中，上述因素會同時發生而影響著晶粒成長。因此在決定二次異常晶粒成長的條件時，需要將其上述條件一個一個分離探討，以解決產生二次晶粒異常成長的主要條件。
在本實驗過程中，主要利用單層以及疊層BaTiO3粉末的燒結結果，來探討當試片發生二次晶粒異常成長現象時。並利用掃描式電子顯微鏡 (SEM) 去觀察試片不同區域是否含有第二相 (second phase) 、{111}成對雙晶以及不同區域上晶粒的鋇鈦原子比例差異，進而了解二次晶粒異常成長 (secondary abnormal grain growth) 的主要原因。
前人的研究說明了有關二次異常晶粒成長的現象是由於TPRE (twin-plane re-entrant edge) 的機制所引發的晶粒成長現象。因此本實驗去觀察在正常晶粒成長區域、主要晶粒異常成長區域、二次晶粒異常成長區域裡的晶粒。並確定這些不同成長型態區域中的晶粒都包含著{111}成對雙晶，這也說明了包含{111}成對雙晶的晶粒不一定能發生二次異常晶粒成長。因此我們認為TPRE並不是二次異常成長的主要原因。
然而上述的疊層試片當中，雖然有觀察到二次晶粒異常成長現象發生，卻不能確定二次異常晶粒成長現象的起源。因此吾人將TiO2-excess的單層試片包埋在BaO-excess的粉末中燒結，並觀察此試片發現二次異常晶粒成長現象發生在鋇鈦原子比例有差異的交界面上，然而在這些交界面上能觀察到許多且連續的第二相存在於晶界上。在二次異常成長晶粒的晶界以及三晶粒間隙處都能觀察到第二相的存在，而在主要異常成長過後的晶粒上，卻只能在晶粒間隙處能看到明顯的第二相。因此最後吾人推測二次異常晶粒成長是由於粉末組成有異的交界面上提供了大量的液相，使得在此交界面上的晶粒能完全潤濕而快速的成長。此部分推測還需要穿透式電子顯微鏡 (TEM) 進一步的去證實在二次異常成長晶粒的晶界處都能觀察到有液相存在，才能確定二次異常晶粒成長是決定於液相對晶粒的潤濕程度 (wetting angle) 。

Secondary abnormal grain growth (SAGG) during sintering of barium titanate has been explained in terms of twin plane re-entrant edge (TPRE) growth mechanism by {111} double twin lamellae. But during sintering of Ti-excess barium titanate, {111} double twins lamellae are observed with out SAGG. In our group, Lin founded that when combine two different Ba/Ti ratio of powder to sintering above the eutectic temperature, the SAGG is observed in the interface between two different powders. Therefore, this thesis consists of three major researches: (a) {111} double twin, (b) Ba/Ti ratio, (c) liquid phase.
In the experiment, we follow Lin’s experiment to sinter the specimen contain with SAGG. And in this specimen, it can observe the specimen divided into three type of growth grain: (a) top surface with normal grain growth (NGG), (b) intermediate layer with abnormal grain growth (AGG), (c) bottom layer with secondary abnormal grain growth. It can all observed {111} double twin in these three different type of layer. This result confirmed that SAGG are not induced by TPRE growth mechanism. Then we used SEM/EDS to analysis the Ba/Ti ratio in the different type of grain growth layer. The Ba/Ti ratio in this analysis is not differing in NGG, AGG and SAGG. Therefore, we used OM, SEM, TEM to observe the grain boundary and triple grain junction in NGG, AGG and SAGG. It can observe that only the grain boundary and triple grain junction in SAGG are complete wetting. The experimental results shows that the grain growth behavior controlled by the liquid phase wetting degree.

Abstract I
論文摘要 II
目錄 IV
表目錄 VIII
圖目錄 IX
第一章 前言 1
第二章 原理與文獻回顧 3
2-1 鈣鈦礦結構 3
2-2 鈦酸鋇結晶結構 3
2-3 正方晶 (tetragonal) 鈦酸鋇結構 5
2-4 燒結驅動力 9
2-5 主要異常晶粒成長 PAGG(primary abnormal grain growth) 和二次異常晶粒成長 SAGG(secondary abnormal grain growth)[12][13][14] 10
2-6 液相生成 (liquid phase formation) 12
2-7 面間夾角 (dihedral angle)[23] 13
2-8 雙晶面邊界 (twin plane re-entrant edge, TPRE)[4] 15
2-9 雙晶面邊界成長機制 (twin plane re-entrant mechanism)[7][8] 17
2-10 BaO-TiO2之平衡相圖[24] 20
第三章 實驗步驟 23
3.1 BaTiO3起始粉末 23
3-2 試片製程 26
3-3 觀察設備與試片前處理 35
3-3.1 X-ray繞射分析儀 35
3-3.2 光學顯微鏡 (OM) 35
3-3.3 掃瞄式電子顯微鏡 (SEM) 36
3-3.4 穿透式電子顯微鏡 (TEM) 37
第四章 實驗結果 39
4-1 添加晶種之BaTiO3試片 39
4-1.1 加入晶種之試片的微結構分析 39
4-2 單層試片-外圍環境與試片同組成 44
4-2.1 單層X-ray結晶相分析 44
4-2.2 單層表面微結構分析 47
4-2.2.1 單層BaO-excess 1.0007試片微結構分析 47
4-2.2.2 單層TiO2-excess 0.9889試片微結構分析 51
4-3 BaTiO3疊層研究 56
4-3.1 疊層表面微結構分析 57
4-3.1.1 疊層試片包埋在未過篩BaO-excess 1.0007粉末並燒結在1365oC/1 h微結構分析 57
4-3.1.2 疊層試片包埋在未過篩BaO-excess 1.0007粉末並燒結在1365oC/20 h微結構分析 62
4-3.1.3 疊層試片包埋在未過篩TiO2-excess 0.9889粉末並燒結在1365oC/20 h微結構分析 68
4-3.2 疊層試片x-ray繞射分析 72
4-3.2.1 疊層試片包埋在未過篩BaO-excess 1.0007粉末並燒結在1365oC/20 h X-ray繞射分析 72
4-3.2.2 疊層試片包埋在未過篩TiO2-excess 0.9889粉末並燒結在1365oC/20 h X-ray繞射分析 74
4-4 單層TiO2-excess 0.9889包埋在未過篩粉末中 76
4-4.1 單層TiO2-excess 0.9889包埋在未過篩BaO-excess 1.0007粉末並在常壓空氣下燒結1365oC/20 h微結構分析 77
4-4.2 單層TiO2-excess 0.9889包埋在未過篩BaO-excess 1.0007＋1 mol% BaO粉末並燒結在1365oC/20 h微結構分析 86
4-4.3 單層TiO2-excess 0.9889包埋在未過篩BaO-excess 1.0007＋1 mol% SiO2粉末並燒結在1365oC/20 h微結構分析 90
第五章討論 93
5-1 利用不同Ba/Ti 比例粉末燒結產生二次異常成長晶粒 93
5-2 利用微結構觀察二次異常晶粒成長與TPRE之關係 94
5-3 利用EDS分析化學計量影響晶界遷移率 95
5-4 晶粒潤濕程度與晶粒成長速率 96
第六章 結論 98
第七章 未來工作 99
參考文獻 100

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