以水熱法合成PLZT單晶粉末之研究

On the Synthesis of Monosized PLZT Powders via Hydrothermal Methods

顏富士(Fu-Su Yen) ； 戴文光(Wen Kung Dai) ； 向性一(Hsing-I Hsiang)

《鑛冶：中國鑛冶工程學會會刊》 36卷3期 (1992/09) Pp. 79-91

摘要

以化學共沉法獲得之沉膠（起始原科）與礦化劑（KOH）混合後，可藉水熱系統於200～260°C低溫直接合成PLZT單晶粉末。而KOH濃度為決定其生成相、粒形之最主要因素。KOH濃度由0.1M增大至8M，PLZT之結晶相會由等軸晶相（KOH/0.1-0.5M）→正方晶相（KOH/1.0-2.0M）→等軸晶相（KOH/4.0-8.0M）。低KOH濃度（0.1、0.2M）時粉末之外形為單離良好之立方體，成份亦最接近原料膠體。單位晶胞a值變化不大。PLZT相在KOH濃度大於1M以後，及溶液原料濃度較小時，有生成富鈦相之可能。而在高KOH濃度（4～8M）時，則因部份K'進入其構造中，使等軸晶相能在富鈦比時存在。低溫（200°C）、低KOH濃度（0.1、0.2M），可生成大小均一、單離良好而組成與預計相等之立方體PLZT，但必須於營養用畢前停止晶體長成工作。本研究並初步提出在水熱系統中，KOH濃度對生成PLZT晶體粉末，所造成相平衡問題。

並列摘要

Synthesis of monosized PLZT powders via hydrothermal methods is preformed by using Pb-La-Zr-Ti precipitate in proportion of 91/9/65/35, mixed with mineralizer, KOH. As KOH concentrations were increased from 0.1 M to 8M, the PLZT phases were trasformed from cubic (KOH/0.1～0.5M) to tetragonal (KOH/1～2M) and back to cubic (KOH/4～8M). Particles of monodispered cube with chemical compositions near that of the starting materials were formed at low KOH concentrations (0.1 & 0.2M). PLZT crystals with narrowest particle size distribution and chemical compostion close to the anticipation can be obtained under 200°C and lower KOH concentration (0.1～0.2M) environments. Synthesis processes must be stopped before the nutrient is run out. Phase equilibria for the formation of PLZT under varying KOH concentrations in hydrothermal systems is also disccussed.