以類纖鐵礦層狀型態之鈦酸鹽經由水熱合成法製備片狀鈦酸鋇之研究

Using Alkali Metal Titanate with the Lepidocrocite-like Layered Structure to Prepare Platelike Particles of Barium Titanate by Hydrothermal Synthesis

鄭開駿(Kai-Chun Cheng)

指導教授 ： 王錫福

共同指導教授 ： 盧俊安(Jun-An Lu)

國立臺北科技大學/工程學院/工程科技研究所/碩士(2014年)

摘要

因片狀鈦酸鋇具有特殊的非等向性，在適度調控結晶方向下，可得到優異的性質，本研究藉由水熱合成法製備在特定方位上具有晶軸取向之片狀鈦酸鋇，前驅物以類纖鐵礦層狀型態之鈦酸鹽K0.8Ti1.73Li0.27O4作為主體。先以固相反應法合成出鹼金屬鈦酸鹽K0.8Ti1.73Li0.27O4，接著將層狀鈦酸鹽進行酸性處理，以K+、Li+取代成H+，形成質子鈦酸鹽H1.07Ti1.73O4，而合成出的鈦酸鹽為層狀形態，本研究改利用熔鹽合成法來獲得分散的粉體，製備出片狀的鹼金屬鈦酸鹽，並將質子鈦酸鹽加入丙胺溶液攪拌，達到分層的效果，最後階段再與氯化鋇及礦化劑-氫氧化鈉進行水熱合成，研究藉由調整氫氧化鈉的濃度及混合溶劑-乙醇與水的比例來控制溶解析出機制之反應速率，以原位轉換機制為主導保持前驅物形貌，降低表面溶解析出顆粒，成功的合成出片狀鈦酸鋇，具有高的晶軸取向性。

關鍵字

鈦酸鋇 ； 纖鐵礦 ； 片狀 ； 晶軸取向

並列摘要

Because plate-like barium titanate has special anistropic properties, we could adequately control crystalline orientation to get superior properties. In this research, BaTiO3 with platelike particle morphology was prepared by using a hydrothermal synthesis, showing a high degree of crystal-axis orientation. A titanate K0.8Ti1.73Li0.27O4 with a lepidocrocite-like layered structure was used as a precursor. In the first step, the Alkali Metal Titanate K0.8Ti1.73Li0.27O4 was synthesized by solid-state reaction method. In the second step, the layered H+ form titanate H1.07Ti1.73O4 was prepared by treatment of KTLO in HCl (1 M) solution to exchange K+ and Li+ in the layered structure with H+. In this study, we change the method from solid-state synthesis to molten salt synthesis for preparing dispersed powder. Layered titanate K0.8Ti1.73Li0.27O4, with plate-like morphology was prepared by this process. After treating Protonic titanate H1.07Ti1.73O4 in 0.5 M propylamine solution, the exfoliated sheets were obtained. There are two simultaneous mechanisms in the formation of BaTiO3 under the hydrothermal conditions. One is situ-topotactic mechanism, and another is dissolution-deposition mechanism. We control the reaction rate of dissolution-deposition mechanism by adjusting different concentration of NaOH and proportion of ethanol-water mixed solvents. To retain precursor’s morphology and reduce the number of particles formed by dissolution-deposition reaction in surface via soft chemical synthesis which is predominant in situ topotactic transformation reaction. In this research, we successfully synthesized BaTiO3 with plate-like particle morphology which shows a high degree of crystal-axis orientation.

並列關鍵字

BaTiO3 ； Lepidocrocite ； Platelike ； Orientation

參考文獻

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