Polymorphism and Dielectric Properties of Bi2Ti4O11
Polymorphism and Dielectric Properties of Bi2Ti4O11
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DOI：
10.1111/j.1151-2916.1962.tb11058.x
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发表时间：
1962-11
影响因子：
3.9
通讯作者：
E. Subbarao
中科院分区：
文献类型：
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作者：
E. Subbarao
1962年11月美国陶瓷学会杂志-讨论和注释565由于热处理的重量损失约为0.50 jo。该研究揭示了新相Bi 2 Ti4 O 11（Bi 2 O3. 4TiO2）。如果Bi 3+或Ti 4+离子改变了它们的价态，则该组合物可能不是单相的，而是可能在具有平均化学式Bi 2-Ti，O 11的系统Bi-Ti-0中由两相组成。在这种情况下，可以预期更高的电导率或更深的颜色，但是在BizTi 4 O 11中没有观察到这种效果。Bi~ Ti 4011的X射线粉末衍射数据在表11中给出。BizTi 4011的差热分析揭示了在约250 ° C和1200 ° C下的两种可逆相变。在将BizTi 4011加热超过约1225 ℃的过程中，它似乎解离成Ti O2和富Bi相（BizTi 2 O 7和Bi 4 Ti O 12）。BizTiaOll陶瓷的线性热膨胀，使用熔融石英膨胀计测量，如图1所示。在25”和95 ℃之间没有可检测到的长度变化后，它在高达约250 ℃时经历了显著的收缩，然后以通常的方式膨胀。在350 ° C至500 ° C的区间内，线性膨胀系数为3.9 × 10 - 4/”C。在镀银陶瓷盘上测量的介电常数和tan δ的温度依赖性如图2所示。介电常数从室温值约40迅速增加到250 ℃时的90。在250 ℃至400 ℃之间，只有轻微的增加（90 ℃至100 ℃）。在约250 ℃下还观察到tan 6中的少量镍.热膨胀和介电数据表明BiLTi_4 O_1_1在250 ℃时发生相变。使用Sawyer-Tower循环，当以60 cps施加20 μ m/cm的场时，在25”和290 C之间可以获得无（DE）磁滞回线。多晶圆盘在150英寸至200 C之间极化，外加场为20 kv/cm，在室温下没有表现出任何压电响应。因此，看来这两种修改的BiLTi，Oll是非铁电的，可能是非压电的。之间未观察到其他介电异常
November 1962 Journal of The American Ceramic Society-Discussions and Notes 565 weight loss due to the heat treatment was about 0.50 jo. This study revealed a new phase, Bi2Ti4OI1 (Bi203. 4TiOz). If either Bi3+ or Ti4+ ions changed their valency, this composition may not have been single phase but may have been composed of two phases in the system Bi-Ti-0 with an average formula of Biz-Ti, Oll. In such a case, a higher electrical conductivity or deeper color could have been expected No such effects were observed, however, in BizTi4O1l. The X-ray diffraction powder data for Bi~ Ti4011 are given in Table 11. A differential thermal analysis of BizTi4011 revealed two reversible phase changes, at about 250" and 1200 C. During heating BizTi4011 beyond about 1225" C, it appeared to dissociate into Ti02 and Bi-rich phases (BizTi207 and Bi4TiaOlz). The linear thermal expansion of BizTiaOll ceramics, measured using a fused silica dilatometer, is shown in Fig. 1. After exhibiting no detectable length change between 25" and 95OC, it underwent a remarkable contraction up to about 250 C and then expanded in the usual manner. In the interval 350'to 500'C the linear expansion coefficient was 3.9 X 10-'per" c. The temperature dependence of the dielectric constant and tan 6, measured on silvered ceramic disks, is shown in Fig. 2. From a room-temperature value of about 40, the dielectric constant increased rapidly to 90 at 250'C. Between 250'and 400" C, there wa5 only a slight increase (90 to 100). A small niitiinium in tan 6 was also observed at about 250 C. The therinal-expansion and dielectric data indicated a phase change in BiLTi4Ol1 at 250 C. Using a Sawyer-Tower circ~ it,~ no (DE) hysteresis loops could be obtained between 25" and 290 C when a field of 20 kv per cm was applied at 60 cps. Polycrystalline disks, poled between 150" and 200 C with an applied field of 20 kv per cm, did not exhibit any piezoelectric response at room temperature. It therefore appeared that both modifications of BiLTi, Oll were nonferroelectric and probably nonpiezoelectric. N o other dielectric anomalies were observed between