以固態反應法製備Ba(Fe1-xScxNb)0.5O3 (x = 0~1)陶瓷之結構及介電的影響

Effect of Sc3+ ion-doped on structure and dielectric properties of Ba(FeNb)0.5O3 ceramics prepared using solid state reaction method

紀承佑(Cheng-Yo Chi)

指導教授 ： 張益新

國立虎尾科技大學/電機資訊學院/電子工程系碩士班/碩士(2017年)

摘要

本研究是以兩次混合固態反應法來製備複合型鈣鈦礦結構Ba(Fe1-xScxNb)0.5O3 (BSFN)的陶瓷材料，以及以同價數的Sc3+離子取代Fe3+之離子。第一階段煆燒段形成(Fe1-xScxNb)O4，在添加碳酸鋇(BaCO3)後，接續進行第二階段煆燒形成Ba(Fe1-xScxNb)0.5O3之複合型鈣鈦礦陶瓷。
由XRD分析結果可以得知，全部之陶瓷樣品為單一相的Cubic鈣鈦礦結構。隨著Sc2O3摻雜量提高，可以觀察到繞射峰(110)往低角度偏移，且密度會下降。大量Sc3+的離子摻雜可以有效減少介電損失，但會犧牲介電常數。最佳介電性質為7mol%的Sc2O3摻雜，在1kHz頻率下量測，其介電常數及介電損失約分別為50000與0.9。樣品介電常數會隨著頻率增加而降低，為典型鐵電材料的弛緩特性。由Cole-Cole plot分析結果可以觀察到有兩個半圓存在，證實BSFN是屬於多重消散性弛緩過程。晶粒與晶界受到半導化影響，阻抗隨著溫度上升而降低，且晶粒與晶界之阻抗差異所形成之晶界層電容有較高的介電常數。

關鍵字

固態反應法 ； BFN ； 高介電材料

並列摘要

In this investigation, complex perovskite structure Ba(FeNb)0.5O3:Sc ceramic was prepared using two step solid state reaction. The Fe3+ ion is substituted with the same valence of Sc3+ ion to form Ba(Fe1-xScxNb)0.5O3 (x = 0~1) ceramic. (Fe1-xScxNb)O4 is formed by calcination in the first step. Afterwards, BaCO3 is added into the (Fe1-xScxNb)O4 in the second step, and then the complex perovskite structure Ba(Fe1-xScxNb)0.5O3 (x = 0~1) is formed when they were calcined at a high temperature.
The results of XRD analysis show that all ceramic samples are single phase of cubic complex perovskite structure. With Sc2O3 doping increasingly, the position of diffraction plane (110) shifts to a lower angle region, and its relative density decreases. When a large amount of Sc3+ ion is doped, the dielectric loss is effectively reduced, but sacrifices dielectric constant. The optimum dielectric property is doped with 7% Sc2O3 that the dielectric constant is about 50000 and the dielectric loss is about 0.9 at 1 kHz. The dielectric constant of sample decreases with increasing frequency, which is the relaxation characteristic of a typical ferroelectric material. By the results of Cole-Cole plot analysis, there are two semicircles exist which confirms that BSFN possesses a multiple dissipation relaxation process.
By the characteristics of semiconductivity, the impedance of the grain and grain boundary decreases with the rise of temperature, and the grain boundary layer’s capacitance which formed by the difference impedance between the grain and grain boundary leading to a high dielectric constant for Ba(Fe1-xScxNb)0.5O3 ceramics.

並列關鍵字

Solid state reaction method ； BFN ； High dielectric material

參考文獻

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