摻雜錳離子對鈦酸鋇微結構之影響

摻雜過渡金屬之鈦酸鋇在一大氣壓下1400℃～1450℃燒結後會產生氧的損失，造成氧空缺。氧空位的增加能有效提升品質因子（Q．f）。在1450℃下燒結，其Q．f值由5548升高到7815 GHz，此系列材料其τ_f大於550 ppm/k，超過一般微波元件容許範圍。本文利用傳統固態反應法，以BaCO_3＋TiO_2摻雜不同比例之氧化錳（Mn_3O_4）形成Ba（Ti_(1-x)Mn_x）O_3，配方比分別為x＝0.15、0.3、0.4、0.5，在1450℃持溫兩小時燒結，冷卻至室溫中得到介穩定六方晶鈦酸鋇相，並利用介電性質檢測、XRD、SEM、TEM等分析方法，分析摻雜不同比例之氧化錳對於六方晶鈦酸鋇相變化及微結構之影響。本研究中發現摻雜量x≦0.5會使六方晶鈦酸鋇晶格常數縮小，當摻雜量達x＝0.5時，會使其結構產生改變並產生Ba（Ti_(1-x)Mn_x）O_3二次相，其結構如同BaFeO_3（JCPDS 74-0646）。品質因子隨著氧化錳含量的增加在x＝0.3時達到最高值（Q．f＝8804 GHz）。介電常數方面，隨著氧化錳含量增加而有下降的趨勢，並在x＝0.4時達到最低值。

關鍵字

六方晶鈦酸鋇；微結構；相變化；電子顯微鏡

並列摘要

Transition metal elements-doped BaTiO_3 ceramics sintered under 1 atm and 1,400℃-1,450℃ lose their oxygen content and form microstructure oxygen vacancies. The Q．f value increases as the oxygen vacancies increase. The Q．f values change from 5,548 to 7,815 GHz at 1,450℃. However, τ_f of these materials is over 550 ppm/k that exceeds the normal microwave dielectric limit. This research used traditional solid-state reaction to synthesize Ba(Ti_(1-x)Mn_x)O_3 ceramics from BaCO_3+TiO_2 and Mn_3O_4. The synthesis of the Ba(Ti_(1-x)Mn_x)O_3 was made with the reactants of different ratio x=0.15, 0.3, 0.4 and 0.5. They were sintered at 1,450℃ for 2 hours, and then cooled to room temperature to obtain metastable hexagonal barium titanates. The microstructures and properties of the Ba(Ti_(1-x)Mn_x)O_3 samples were analyzed by measuring their dielectric parameters, XRD, SEM and TEM. Results show that lattice parameters decrease as reactant concentration ratio (x) increases from 0.15 to 0.5. At x=0.5 a second phase similar to BaFeO_3 structure was detected. The quality factor (Q．f) reaches the maximum value (8,804 GHz) at x=0.3. The dielectric constant decreases as x increases and reaches the minimum value when x is at 0.4.

並列關鍵字

h-BaTiO_3 ； microstructure ； phase transformation ； TEM

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