CaCu_3Ti_4O_(12)和La_(2/3)Cu_3Ti_4O_(12)陶瓷的电导特性

Conductance of Like Perovskite Structure ACu_3Ti_4O_(12) Materials

采用固相反应法制备CaCu3Ti4O12和La2/3Cu3Ti4O12陶瓷材料并研究了其电导特性.结果表明,CaCu3Ti4O12和La2/3Cu3Ti4O12的电导率随温度的变化规律相似.在低温（〈150 K）区域,CaCu3Ti4O12的电导率随温度升高而增大,即呈负阻温特性;在150～170 K温度区域,电导率出现极大值,且其电导率极大值为La2/3Cu3Ti4O12的近4倍;在较高的温度（170～250 K）区域,电导率随温度的升高而减小.这是由于Ca^2＋被La^3＋替代后在该位置留下1/3空位而使La2/3Cu3Ti4O12的激活能高达1.01 eV的缘故.

CaCu3Ti4O12 and La2/3Cu3Ti4O12 materials were prepared by solid reaction process,and the conductance properties were measured and studied.The experimental data show that the conductance-temperature curves of CaCu3Ti4O12 and La2/3Cu3Ti4O12 are similar.In the lower temperature range（〈150 K）,the conductance increases with the temperature and the samples exhibit negative resistance-temperature properties.In the temperature range of 150-170 K,the conductance reaches its maximum.Then,in the higher temperature range（170-250 K）,the conductance decreases with the temperature.But the maximum value of conductance of CaCu3Ti4O12 is about 3 times larger than that of La2/3Cu3Ti4O12.Further（analysis） shows that after Ca^2＋ is replaced by La^3＋,one-third of vacancies remain in A sites,which results in the activation energy of La2/3Cu3Ti4O12） reaching 1.01 eV.The higher activation energy is the main cause of lower conductance of La2/3Cu3Ti4O12.