段維新臺灣大學：材料科學與工程學研究所鄭彥威Cheng, Yen-WeiYen-WeiCheng2007-11-262018-06-282007-11-262018-06-282004http://ntur.lib.ntu.edu.tw//handle/246246/55237本實驗以起始粉末BaCO3及TiO2，利用固態反應法 (solid-state reaction)，在1100℃溫度持溫2小時煆燒，製備不同鋇鈦比(Ba/Ti ratio)的鈦酸鋇粉末．所得的粉末再以不同的持溫溫度，於空氣中燒結，探討不同鋇鈦比在燒結過程中的燒結行為與微結構的變化，與密度、介電常數的影響．本實驗進而在不同的鋇鈦比鈦酸鋇中添加不同的重量百分率的銀，在不同持溫溫度燒結，探討銀對不同鋇鈦比的鈦酸鋇，與密度、微結構、電性的影響． 　　對於不同的鋇鈦比的鈦酸鋇在空氣中燒結時，在鋇多的系統，發現中間相Ba2TiO4的存在．微結構的晶粒呈現正常的成長，但不易緻密．在鈦多的系統，燒結溫度超過共晶溫度(1320℃)之後，試樣發現有Ba6Ti17O40的高溫液相生成，晶粒呈現異常成長，但因液相產生有較佳的緻密化行為，但由於高溫液相會殘存在晶界，使介電常數降低． 　　在不同鋇鈦比的鈦酸鋇中添加銀系統中，微量的銀會使晶粒成長，使晶粒尺寸變大；但當含量超過固溶度之後，會阻止晶粒粗化，得到較小的晶粒尺寸．由於銀離子和鋇離子的半徑尺寸相似，在晶格中會發生置換的反應現象，當銀的添加量不同，微結構、燒結行為、密度及電性都會受到影響．而銀在鈦酸鋇的固溶度，因鋇鈦比的不同表現也不同．In the present study, a solid-state reaction technique is used to prepare the barium titanate powders with different Ba/Ti ratios. The calcination was carried out at 1100℃ for 2h. The non-stoichiometric BaTiO3 samples were sintered at various temperatures in air. The effects of Ba/Ti ratio on the sintering behavior, microstructures and dielectric properties are investigated. In the present study, Ag is doped into the non-stoichiometric BaTiO3. The Ag-containing BaTiO3 was sintered in air at different temperature. The influence of the Ag powders on the dielectric properties and microstructure of the non-stoichiometric BaTiO3 is investigated. In the Ba-rich system, a small amount of Ba2TiO4 is found in the Ba-rich system. The presence of Ba2TiO4 phase inhibits densification, the grains exhibit equiaxis shape. However, the density of the Ba-rich specimen is low. In the Ti-rich system, Ba6Ti17O4 phase is found, indicating the presence of a liquid phase during sintering while the temperature is higher than the eutectic temperature (1320℃). The presence of the liquid phase enhances the densification, and abnormal grains are also formed. The dielectric constant of the Ti-rich BaTiO3 is thus degraded. While doping silver into BaTiO3, a small amount of silver can increase the amount of abnormal grain and its size. When the silver content is higher than the solubility, the silver inclusions can inhibit the coarsening of BaTiO3. There are some replacements of Ba2+ with Ag+. The dielectric constant and relative density depend strongly on silver content and sintering temperature above or below eutectic point. The Ag solubility in Ti-rich BaTiO3 is higher than that in Ba-rich BaTiO3.Chapter 1 Introduction………………………………………………1 Chapter 2 Literature Survey………………………………………3 2-1 The Synthesis of Barium Titanate……………………………3 2-2 The Solid-State Reaction………………………………………4 2-2.1 The Purpose……………………………………………………4 2-2.2 The Reaction Mechanism During Calcination……………4 2-2.3 The Influence with A/B Ration on Barium Titanate……5 2-3 The Characteristics of Barium Titanate……………………9 2-4 The Microstructure of BaTiO3………………………………10 2-5 The Sintering Behavior of BaTiO3…………………………12 2-6 The Dielectrical Properties of BaTiO3……………………13 2-7 The Solubility of Additives in BaTiO3……………………14 2-8 Effect of Ag on BaTiO3………………………………………15 2-8.1 The Characteristics of Silver……………………………15 2-8.2 The Effect of the Ag on the perovskite structure…15 2-8.3 The Defect Chemistry of BaTiO3/Ag System……………16 Chapter 3 Experimental Procedures……………………………22 3-1 Preparation of BaTiO3 Powders………………………………22 3-1.1 The Phase Identification for Powders…………………22 3-1.2 Preparation of the Specimens……………………………22 3-1.2.1 Preparation of the Specimens for Electrical Properties Analysis…………………………………………………22 3-1.2.2 Preparation of the Specimens for Shrinking Properties Analysis…………………………………………………23 3-1.3 Phase Identification………………………………………23 3-1.4 Microstructure Observation………………………………23 3-1.5 The Density Measurement……………………………………24 3-1.5.1 Apparent Density……………………………………24 3-1.5.2 Relative Density………………………………………24 3-1.6 The Dielectric Constant……………………………………24 3-2 Preparation of BaTiO3/Ag Composite………………………27 3-2.1 Starting Materials…………………………………………27 3-2.2 Experimental Procedure……………………………………27 3-2.3 Preparation of the Sspecimens……………………………27 3-2.3.1 Preparation of the Specimens for Electrical Properties Analysis………………………………………………27 3-2.3.2 Preparation of the Specimens for Shrinking Properties Analysis…………………………………………………27 3-2.4 The Phase Identification for Powders…………………27 3-2.5 The Microstructure Observation…………………………27 3-2.6 The Measurement of the Density…………………………27 3-2.6.1 Apparent Density…………………………………………27 3-2.6.2 Theoretical Density……………………………………28 3-2.6.3 Relative Density………………………………………28 3-2.7 The Dielectric Constant Observation……………………28 3-2.8 Powder Observation.…………………………………………28 3-2.9 The Measurement of Solubility -The EPMA analysis…28 Chapter 4 Results and Discussion………………………………31 4-1 Thermal Analysis………………………………………………31 4-1.1 DSC Analysis…………………………………………………31 4-1.2 TGA Analysis…………………………………………………31 4-2 Phase Analysis…………………………………………………31 4-3 Particle Size Distribution…………………………………32 4-4 Phase Analysis of the Fired Specimens……………………32 4-5 Microstructure Observation…………………………………32 4-6 Density Measurement…………………………………………34 4-7 Densification Kinetics………………………………………34 4-8 Dielectric Properties…………………………………………35 4-9 Morphology of BaTiO3/Ag Powder……………………………53 4-10 Relatively Density of the Ag/ BaTiO3 Composite………53 4-11 The Ag/ BaTiO3 Composite Microstructure………………54 4-12 Dielectric Properties Ag/ BaTiO3…………………55 4-13 The Ag Solubility of Ag in BaTiO3 Analysis……………55 Chapter 5 Conclusions………………………………………………71 References……………………………………………………………727699561 bytesapplication/pdfen-US鋇鈦比微結構銀鈦酸鋇介電燒結sinteringBa/Ti ratiosilverdielectricbarium titanatenon-stoichiometrymicrostructurethesishttp://ntur.lib.ntu.edu.tw/bitstream/246246/55237/1/ntu-93-R91527060-1.pdf