| 摘要: | 本研究目的為製備具高溫離子導電性的鈣鈦礦結構的氧化鐵鈷釔共摻雜鋯酸鋇(BCFZY)材料，並嘗試分別與氧化鋅(ZnO)形成雙相複合材，特別是針對雙相複合材的燒結行為進行深入的分析與研究。在本研究中，BCFZY粉體是利用固態反應法經過高溫煆燒後合成，與前述各氧化物原料粉體經過濕式混和後，乾燥過篩完的粉體以模壓成型的方式製成複合材生胚，經過高溫燒結後可以得到緻密的BCFZY雙相複合材樣品。複合材樣品分別以X光繞射法(XRD)進行結晶結構分析、掃描式電子顯微鏡(SEM)與能量散射光譜儀(EDS)進行微結構與成分的分析、熱機械分析儀(TMA)進行燒結收縮行為分析、阿基米德法進行樣品的體密度分析等，最後緻密的雙相複合材樣品，使用二點式電壓電流法進行導電性質的分析。當BCFZY原料粉體經過1100°C持溫15小時的煆燒後，可成功合成具有鈣鈦礦結構的BCFZY粉體；其與氧化鋅形成的複合材坯體，經過1100°C持溫24小時的燒結後，可以得到緻密度最高的雙相複合材，其平均密度約為5.55 g/cm3；在電子顯微鏡微結構分析中發現液相燒結的現象；由導電性分析得知，純BCFZY樣品溫度於400°C時導電度最高55.02 S/cm，而添加50%氧化鋅之樣品於400°C時導電度最高68.56 S/cm。BCFZY添加75%ZnO的樣品出現了二階段的導電現象，其活化能於300~400°C的範圍約為0.112 eV，而500~800 °C的範圍則為0.459 eV。這種現象是由於p-n異質結構(p-n heterojunction)導電機制，使得具有H+/O2-/e-三重導電的BCFZY與ZnO，形成的複合材而抑制電子的傳導的作用，進而實現了良好的二元離子導體(H+/O2-)功能。
The purpose of this research is to synthesize the perovskite-type cobalt, iron, and yttrium co-doped barium zirconate (BCFZY), which have high temperature ion conduction, as well as to fabricate their composites combined with either zinc oxide (ZnO), yttria stabilize zirconia (YSZ), or barium zirconiate (BZ), respectively. The key researches are especially focused on the sintering behavior of these duel-phasic composite. In this research, BCFZY powders are synthesized by a solid state reaction methods after calcined at high temperature. After wet-mixing of the raw materials of BCFZY, the dried and sieved powders are formed green compacts by a die pressing method. Then The BCFZY composites can be obtained after sintered at high temperature. These composites are analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrum (EDS), thermo-mechanical analysis, and Arachnid’s methods to understand their crystal structures, microstructures, chemical compositions, shrinkage behaviors after sintering, and the densities. The dense composite are further measured the electrical conductivity by a two-point I-V methods. After calcined at 1100°C for 15 h, the pure perovskite-type BCFZY powders can be synthesized successfully. And combined with ZnO, the dense duel-phasic composite can be fabricated after sintered at 1100°C for 24 h. The average bulk density of these samples are around 5.55 g/cm3 T.D. From the SEM microstructure analysis, the liquid phase sintering was during sintered composite at 1100°C. According to the electrical conductivity analysis, the pure BCFZY sample and that with 50% ZnO have the highest conductivity of 55.02 S/cm and 68.56 S/cm at 400°C, respectively. The composite sample with BCFZY and 75% ZnO has a two-stage electrical conduction phenomenon, and its activation energy is about 0.112 eV in the range of 300-400°C,
and 0.459 eV in the range of 500-800°C. This phenomenon is due to the p-n heterojunction conduction mechanism, which makes the BCFZY and ZnO composite blocked the electronic conduction from the BCFZY phase (H+/O2-/e- triple conduction) of BCFZY and ZnO, and only achieving ionic conduction (H+/O2-). |
