非鉛系鈦酸鉍鈉基陶瓷A、B位取代對鐵電壓電性能之影響

Study of ferroelectric and piezoelectric properties of（Bi0.5Na0.5）TiO3-based lead-free ceramics by different substitution in A-site or B-site

姚奕全(Yi-Quan Yao)

指導教授 ： 曾俊元

國立臺北科技大學/工程學院/材料科學與工程研究所/碩士(2007年)

摘要

本文針對（Bi0.5Na0.5）TiO3、（Bi0.5Na0.5）0.94Ba0.06ZrxTi1-xO3(x=0、0.01、0.02、0.04）、(1-x)(Bi0.5Na0.5)0.94Ba0.06TiO3-x[Bi(Na0.84k0.16)]0.5TiO3 [(1-x)BNB6T-(x)BNK16T; x=0~1] 與(1-x) (Bi0.5Na0.5)0.93Ba0.07TiO3-x [Bi( Na0.80 k 0.20)] 0.5TiO3 [(1-x)BNB7T-(x)BNK20T; x=0~1]材料系統，針對其結構相、微結構、介電性、壓電性的量測，了解對於影響BNT基特性的主要因素。
（Bi0.5Na0.5）0.94Ba0.06ZrxTi1-xO3（x=0、0.01、0.02、0.04）系統，皆可得到達理論密度97~99%之間的陶瓷體，且從SEM表面形貌觀察中可以得到印證。由介電常數對溫度的曲線結果中得知BNT在A-site添加Ba及在B-site添加Zr後，會由正常鐵電行為轉變為遲緩性的鐵電體，且在溫度升高的過程中會有一去極化的溫度產生，再去極化溫度會發生鐵電相-反鐵電相的相變化，而在居里溫度時會發生反鐵電相-順電相的相變化。當（Bi0.5Na0.5）0.94Ba0.06ZrxTi1-xO3材料成份為x=0.02、0.04時，經由TEM繞射分析結果中發現內部產生立方晶相，導致電滯曲線中殘留極化值與矯頑電場急遽下降，機電耦合因子（kp & kt）與壓電係數(d33)等壓電性質消失。
就(1-x)BNB6T-(x)BNK16T;與(1-x)BNB7T-(x)BNK20T(x=0~1)材料系統而言，組成經由XRD分析結果皆落於菱方晶與正方晶共存的兩相區間，但隨著x含量的增加，內部正方晶相的含量逐漸增加，使得去極化溫度的量測結果中顯示隨著x含量增加，正方晶相的含量逐漸增大，電域轉向較不易，相對使電域轉向所需得熱能增加，導致去極化的溫度升高。在鐵電、壓電性質的量測中，隨著x含量增加，由於正方晶內90o與180o電域轉向較菱方晶系71o與109o電域不易，導致其鐵電、壓電性能隨x含量的增加而逐漸降低。
對於在B位利用較大離子半徑的Zr4+取代較小離子半徑的Ti4+達2~4mole%的（Bi0.5Na0.5）0.94Ba0.06ZrxTi1-xO3材料成份中，由於B位離子位移回中心位置，使得Dipole消失，結構相會產生立方晶的順電相而使其鐵電、壓電性質消失，相對於在A位利用利用較大離子半徑的K+取代較小離子半徑的Na+的(1-x) (Bi0.5Na0.5)1-aBaaTiO3-x [Bi( Na1-b k b)] 0.5TiO3材料成份中，雖然有助於Dipole的增大，但相對造成其轉移不易，而使得整體鐵電壓電特性無明顯的提昇。因此，適當的選擇添加的元素，除了使Dipole的增大，其Dipole轉移的容易與否也是一未來研究的重要考量。

關鍵字

非鉛 ； 鈣鈦礦 ； 鈦酸鉍鈉 ； 壓電

並列摘要

In this experiment, the substitution of A-site or B-site in (Bi0.5Na0.5)TiO3 (BNT)-based materials were investigated, and the effected ferroelectric and piezoelectric properties by using different ionic radius were discussed in this research.
Ceramics with compositions belonging to the（Bi0.5Na0.5）0.94Ba0.06ZryTi1-yO3 [BNBZ100yT; y=0~0.04], (1-x)(Bi0.5Na0.5)0.94Ba0.06TiO3-x[Bi(Na0.84k0.16)]0.5TiO3 [(1-x)BNB6T-(x)BNK16T; x=0~1] and (1-x) (Bi0.5Na0.5)0.93Ba0.07TiO3-x [Bi( Na0.80 k 0.20)] 0.5TiO3 [(1-x)BNB7T-(x)BNK20T; x=0~1] were prepared successfully by the solid state reaction method. X-ray diffraction studies reveal the perovskite structure in BNBZ100yT, (1-x)BNB6T-(x)BNK16T and (1-x)BNB7T-(x)BNK20T ceramics sintered at 1160℃ for 2 h in air. The relative densities of the sintered ceramics were around 97~99%. The temperature dependent dielectric properties of BNB6T, BNB6Z4T, (1-x)BNB6T-(x)BNK16T and (1-x)BNB7T-(x)BNK20T ceramics show relaxor-like behavior.
The decrease in Pr, Ec and disappearance of piezoelectric property were found by the substitution of 2 mol% and 4 mol% Zr4+ for Ti4+ in these ceramics. Transmission electron microscope diffraction patterns reveal cubic crystalline phase existed in the BNB6Z4T ceramics leading to the disappearance of piezoelectric property. Decrease in grain size was also observed by the substitution of Zr4+ for Ti4+ in BNB6T ceramics.
For the (1-x)BNB6T-(x)BNK16T and (1-x)BNB7T-(x)BNK20T material systems.
As increased the amount of K+ substituted Na+ in A-site, the content of tetragonal phase in morphotropic phase boundary (MPB) will increase, which lead to higher depolarization temperature and deteriorated piezoelectricity of this material systems.

並列關鍵字

lead free ； persovkite ； （Bi0.5Na0.5）TiO3 ； piezoelectric

參考文獻

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