水熱法合成PLZT單晶粉末礦物相及成份之關係

The Relationship between Mineral Phases and Compositions for PLZT Powders via Hydrothermal Method

顏富士(Fu-Su Yen) ； 陳燕銘(Yan-Min Chen) ； 向性一(Hsing-I Hsiang)

《鑛冶：中國鑛冶工程學會會刊》 37卷4期 (1993/12) Pp. 49-62

摘要

本研究於水熱系統生長PLZT單晶粉末，所使用的原料是利用化學共沉法作成的膠體，混合礦化劑KOH。藉此探討合成過程中，生成相及化學組成與溫度、時間、起始膠濃度及礦化劑濃度的關係，以建立生成相（結晶系）、與成分之間的關係。研究發現KOH濃度對生成的諸PLZT之溶解度有很大的影響。隨KOH濃度的升高，PLZT之溶解度變大，同時結構由c-PLZT漸漸變成t-PLZT。但KOH濃度過高時（4 M、8 M），因K進入PLZT結構，結晶結構仍屬立方晶相。因水熱合成法可能造成OH出現在O位置的現象，所以同一條件合成的PLZT結構較鬆、組成分布較廣，但均應屬具完整鈣鈦礦結構之礦物。由於營養用畢後，原先生成接近預定組成的PLZT會有鋯溶出結構，再生成富鈦之PLZT，所以生成接近預定組成的PLZT必需要在營養用畢之前停止長晶。以本研究而言，所使用起始膠濃度／KOH濃度比要大於1/5，較易控制生成立方晶相之PLZT。

並列摘要

In this study , synthesis of 9/65/35 c-PLZT powders via hydrothermal methods was performed using co-precipitated gels of Pb-La-Zr-Ti hydroxides as raw materials and KOH as the mineralizer. Attempts have been made to examine the relationships between the mineral powders and the chemical compositions of the PLZT phases formed. The solubility of PLZT is affected by the KOH con-centeration. Higher KOH concentrations leads to the transformation of c- to t-PLZT. However, as the KOH concentration used excesses 4 M, c-PLZT may be stabilized instead of t-PLZT. The PLZT formed by hydrothermal methods may have a relatively loose crystal structure. It allows the same PLZT phase to exhibit a wider variation ranges in chemical composition. PLZT powders with anticipated chemical compositions can be obtained if the synthesis processes is stopped before the nutrients is run out. The concentration ratios of gel/KOH used should be more than 1/5 for easy controlling of the c- PLZT formation.