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    題名: (1- x)Na0.5K0.5NbO3-xSrTiO3弛緩鐵電體介電特性之研究
    The studies of dielectric properties for (1- x)Na0.5K0.5NbO3-xSrTiO3 relaxor ferroelectric ceramics
    Authors: 洪宇澤
    Yu-Tse Hung
    貢獻者: 洪群雄
    Cheng-Shong Hong
    Keywords: 弛緩體;介電
    relaxor;dielectric
    Date: 2011-07-20
    Issue Date: 2011-10-18 14:20:55 (UTC+8)
    Abstract: 隨著環保意識的抬頭,危害人體與環境造成影響之有毒物質,已經逐漸的被國際組織禁用。直到目前為止特性良好的介電陶瓷材料則皆為含鉛材料,故發展無鉛陶瓷材料為當前時代的潮流。鈮酸鈉鉀(Na1-xKx)NbO3為具有鈣鈦礦結構(Perovskite structure)之鐵電材料,其良好的介電特性成為無鉛介電陶瓷材料的熱門選擇之一。
    本研究,以固態反應法製作陶瓷材料,探討鈦酸?(SrTiO3)對鈮酸鈉鉀(Na1-xKx)NbO3弛緩鐵電體介電特性及相變化行為之影響。研究結果分為三個部分,第一部分藉摻雜不同濃度之鈦酸?(SrTiO3),得知晶體結構從orthorhombic(斜方晶)轉變為tetragonal(正方晶),摻雜濃度為0.15(mol%) SrTiO3時有最大介電常數2300,相變點隨著鈦酸?(SrTiO3)含量增加往低溫偏移;第二部分討論燒結溫度對(1- x)Na0.5K0.5NbO3-xSrTiO3弛緩鐵電的影響,得知燒結溫度並不會對晶體結構有重大改變,摻雜濃度0.03ST(mol%)以下燒結溫度約為1050℃,超過此摻雜濃度燒結溫度則需達到1200℃,相變點也不會隨著燒結溫度變化而有所偏移;第三部分利用0.89Na0.5K0.5NbO3-0.11SrTiO3與0.85Na0.5K0.5NbO3-0.11SrTiO3雙層電容器,藉以寬化居里溫度以及提高介電常數。
    With the raise of environmental sense, the toxic substances impacts of human and environmental have been inhibiting by the International environmental organizations. Until now the dielectric ceramic with the best properties, are almost lead materials, so focuses on development of lead-free dielectric ceramic are trend of the times. (Na1-xKx)NbO3 as having perovskite structure of the ferroelectric material, the dielectric become the popular choice one of lead-free dielectric ceramic materials because of it’s excellent properties.
    In this study, use the solid state reaction to fabricate samples, then study the dielectric properties and phase-change behavior of (Na0.5K0.5)NbO3-SrTiO3 relaxor ferroelectric.
    The study are divided into three parts. The first part investigate the effect of SrTiO3 dopants. The crystal structure changes from orthorhombic to tetragonal when increasing the amount of SrTiO3,the maximum dielectric constant 2300 isobtaned at 0.15(mol%) SrTiO3,and the phase transition temperatures shifted to low temperature when increasing the amount of SrTiO3.The second part investigate the effect of changing sintering temperature. The crystal structure is not obviously changed by the sintering temperature, the sintering temperature are increased when increasing the amounts of SrTiO3 dopants,it’s sintering temperature are about 1050℃ and 1200℃ changed under and over 0.03(mol%) SrTiO3 respectively, and the phase transition temperatures are not obviously changed by the sintering temperature.The third part made two-layer structure capacitance by using 0.89Na0.5K0.5NbO3-0.11SrTiO3 and 0.85Na0.5K0.5NbO3-0.11SrTiO3 ceramics. Then the dielectric constant is enhanced and the temperature-electric peak is broadened.
    Appears in Collections:[電子工程學系] 博碩士論文
    [電子系] 洪群雄

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