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標題: | 以固相法製備介電Ba5Nb4O15及其燒結行為與微波電性 Sintering Behavior and Microwave Property of Ba5Nb4O15 Dielectric Material and its Preparation |
作者: | Chung-Ya Tsao 曹中亞 |
指導教授: | 段維新 |
關鍵字: | 微波,Ba5Nb4O15,層狀鈣鈦礦相,異方性晶粒成長,晶體結構,化學機械性,優選方向,液相燒結, microwave,Ba5Nb4O15,layered perovskite,anisotropic grain growth,structure,mechanochemical,preferred orientation,liquid phase sintering, |
出版年 : | 2017 |
學位: | 博士 |
摘要: | 固相反應製程技術是目前製造介電陶瓷材料的生產方法之一。在眾多微波介電質材料中, Ba5Nb4O15具有高電介質以及低損失特性,可用於低溫共燒陶瓷技術(Low Temperature Cofiring Ceramic Technology)的選擇材料之一。本研究將分三種方向探討Ba5Nb4O15材料與固相反應製程之關聯及影響。
第一階段是探討陽離子空缺型Ba5Nb4O15材料的高溫燒結行為,在無施加壓力的條件下,最高燒結密度僅能達到理論值的93%,當燒結溫度高於1250°C,密度將隨燒結溫度提升而逐漸下降,此去燒結現象來自於燒結溫度高於1250°C晶粒開始異常成長以及溫度高於1350°C後,鈮離子還原反應所造成。雖然微波特性的介質常數下降,但是品質因子卻可以提高到40,000以上,其原因與鈣鈦礦結構中陽離子晶格有序化程度有強烈的關聯性。 第二階段是探討Ba5Nb4O15粉末在研磨過程中的機械化學行為。在無球磨粉碎條件下,品質因子可以提高至40,000以上,但是研磨後鋇離子溶出晶格體,產生的BaCO3結晶物質析出於水系漿料中,燒結後密度以及品質因子明顯下降。由於微觀結構的燒結晶粒成長具有優選方向,利用X-ray繞射極圖分析以及EBSD方法確認(0 0 5)為優選結晶面,與前次實驗相同,米勒指數 (0 1 13)平面的有序化程度與品質因子有強烈的關聯性。 最後階段則是研究少量添加物質CuO以及B2O3的低溫助燒結行為,大幅度地降低燒結溫度達400°C以上,可以將此組成用於與銀共燒結的積層陶瓷結構中,並且無銀擴散反應的現象,由微觀結構分析確認經過研磨製程也會產生BaCO3析出物質。 Solid state reaction technique is one of the methods to prepare dielectric ceramic materials. A potential microwave ceramic, Ba5Nb4O15, is the potential candidate of LTCC material. Its microwave dielectric exhibits high permittivity and low loss characteristics. The present study investigates three aspects of this microwave ceramic. The sintering behavior of the cation-deficient perovskite, Ba5Nb4O15, is investigated in the first part. The highest density can be achieved through pressureless sintering is only 93%. The low sintered density is related to a density decrease, de-sintering, at a sintering temperature above 1250°C. Such de-sintering is contributed by the formation of abnormal grains (>1250°C) and the reduction of niobium ions (>1350°C). Though the permittivity of sintered Ba5Nb4O15 is lower after sintering at a temperature higher than 1400°C, its quality factor is higher than 40,000. The increase in quality factor shows a strong dependence on the cation ordering in the perovskite structure. The mechanochemical behavior during the milling of Ba5Nb4O15 powder is investigated in the second part. Maximum quality factor >40,000 can be achieved without ball milling. After milling, the precipitated BaCO3 from water base slurry reduces the sintered density, degrades the quality factor. Such precipitate is formed due to the leaching of barium ion from lattice structure. Through the pole figure analysis, the Ba5Nb4O15 (0 0 5) plane is the preferred oriented growth plane. The ordering of plane (0 1 13) shows a strong influence on the quality factor of Ba5Nb4O15 after mechanical treatment. The last part focus on the effect of a small amount of additives CuO and B2O3 on the sintering behavior. The sintering temperature is reduced by almost 400oC. The cofiring with silver metal to form multilayered structure is then possible. No silver migration is observed when cofire with silver metal. The microstructure analysis confirms the BaCO3 is also formed as resulted from the use of milling process. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/2370 |
DOI: | 10.6342/NTU201702760 |
全文授權: | 同意授權(全球公開) |
顯示於系所單位: | 材料科學與工程學系 |
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