ACu3Ti4O12氧化物介電性質之研究 (A = Ca, La, Nd, Gd)

Abstract

近年來，立方鈣鈦酸型相關結構的晶體CaCu3Ti4O12，由於其具有不尋常的高介電常數的性質，引起相當的重視。目前已知CaCu3Ti4O12在室溫低頻交流電源作用之下具有高達104~105的介電常數。這樣的高介電常數在很廣的溫度範圍內幾乎不隨溫度而變，這樣的性質對於將來在電子元件上的應用是很有展望性的。 在我的論文當中，除了CaCu3Ti4O12之外，我以部份的稀土元素取代鈣原子，製備並研究LaCu3Ti4O12、La2/3Cu3Ti4O12、NdCu3Ti4O12、GdCu3Ti4O12這些氧化物，測量其中的介電性質、用幾種不同方式了解其物理性質，觀察這些物質微觀結構與介電性質的關係，也了解這些性質主要可以歸因於微粒與微粒邊界效應。此外，也發現以1050 ℃ 燒結的LaCu3Ti4O12具有穩定的高介電係數和低耗損因子的特性。

In recent years, there has been considerable interest in CaCu3Ti4O12 (CCTO), a material with a cubic perovskite-related crystal structure because of its peculiar dielectric property. CCTO is known to exhibit an enormously large low-frequency dielectric permittivity ( is of the order of 104~105). The high dielectric constant persists over a broad temperature range. This dielectric feature makes some of them promising for the applications in various microelectronic devices. In this essay, besides CaCu3Ti4O12, Ca atoms are replaced by some of the rare earth elements. LaCu3Ti4O12, La2/3Cu3Ti4O12, NdCu3Ti4O12, and GdCu3Ti4O12 are first prepared and their properties are also investigated. Several models have been taken to explain their behavior on physics. We investigated the mechanisms that govern these dielectric properties, and analyzed the data of dielectric constants (both real and imaginary part) and loss tangent. The relation between microscopic structure and dielectric properties were discussed, it is realized that high dielectric constant phenomenon can be mainly attributed to the grain and grain boundary effects. Besides, it is found that LaCu3Ti4O12 sintered at 1050 ℃ is provided with very steadily high dielectric constant and low loss factor.