Nd2Ti3O8.7微波介電陶瓷之製備及其微波特性之研究

Preparation and Investigation of Nd2Ti3O8.7 Dielectric Ceramics and its Microwave Properties

陳鼎文(Ting-Wen Chen)

指導教授 ： 王宏文

中原大學/理學院/化學研究所/碩士(2001年)

https://doi.org/10.6840/cycu200100281

摘要

中文摘要

本研究採用四種方法製備Nd2O3-TiO2系統中的介穩態化合物(Metastable Compound):Nd2Ti3O8.7(此化合物無法經由Nd2O3與TiO2的混和以固態物反應直接得到)。這四種方法分別是: 1.EDTA膠化法直接合成Nd2Ti3O8.7；2.利用化學的共沉法(coprecipitation)合成Nd2Ti3O8.7；3.氧化物混合法（未添加異質）；4.添加PbO、SrCO3、CaO於Nd4Ti9O24及Al2O3於Nd2Ti2O7，以固態反應法分別取代A位置與B位置，如： (AxNd2-x)Ti3O8.7，(A=Pb、Sr、Ca)及Nd2(Ti2/3R1/3)O8.7, (R=Al)。以XRD、TGA/DTA及SEM分析由這四種方法製備而得的Nd2Ti3O8.7原始粉末其相變化過程、熱分解行為、燒結顯微結構。其中添加Pb，Ca，Sr及Al可幫助形成Nd2Ti3O8.7，而添加Bi，Zr，Ba，Mg則不能形成Nd2Ti3O8.7，歸納結論得：原子大小類似的取代原子，其價電子數比所取代的原子（Nd，Ti）少，形成氧空缺者才容易幫助Nd2Ti3O8.7之形成。本實驗所得之最佳組成為：Nd2(Ti2/3Al1/3)3O8.5，及特性為：εr≒39 ，Q*f≒12,000(at 6.6GHz)，τf≒-3.3 ppm/℃。

關鍵字

微波介電陶瓷

並列摘要

Abstract

Reactive powders of stoichiometry Nd2Ti3O8.7 are prepared by four methods ：1. EDTA-gel method；2. Co-precipitation method；3. conventional mixed-oxide method；4. Mixed-Oxide with substitutions Pb，Sr，Ca on Nd4Ti9O24 and Al on Nd2Ti2O7. The corresponded phases，thermal decomposition behaviors and microstructures after calcination and sintering are investigated by XRD diffraction，DTA/TGA and SEM. Single phase of Nd2Ti3O8.7 could not be easily obtained by even very homogenous chemical solution methods. However, the substitution of Ti by Al or substitution of Nd by Ca, Sr, and Pb can readily promote the formation of single phase Nd2Ti3O8.7. The present study demenstrated that the factor facilitating the formation of Nd2Ti3O8.7 ceramic is not the homogeneity of composition but the oxygen vacancies in the system. The formation of oxygen vacancies is accomplished by substitution of ions with a less number of valence electrons and similar ionic size. The best properties obtained is derived from the substitutional dopant Al，i.e.：Nd2（Ti2/3Al1/3）3O8.5. The permittivity＝39 , Q*f＝12,000 (at 6.6GHz) and τf＝-3.3 ppm/℃ for Nd2（Ti2/3Al1/3）3O8.7 ceramic .

並列關鍵字

layered perovskite ； Temperature Coefficient of Resonant Frequency ； Quality Factor

參考文獻

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