Phase coexistence in PZT ceramics
Phase coexistence in PZT ceramics
复制标题
PZT 陶瓷中的相共存
DOI：
10.1016/s0955-2219(99)00003-5
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
P. Mantas
中科院分区：
文献类型：
--
作者：
M. Soares;A. Senos;P. Mantas
在锆钛酸铅陶瓷中，在致形相边界（MPB）附近的成分中，低温四方和菱形铁电相共存，这一事实的解释仍然是一个有争议的问题。假设这是由准电相向铁电相冷却过程中的热涨落猝灭造成的，可以用相的统计分布模型来描述相的共存。在该模型中，相共存区宽度（Δx）与晶粒尺寸G有关，可以看出Δx∝G−3。在这项工作中，我们检验了这种关系在PZT功率和陶瓷上的适用性。即使经过长时间的热处理，在900、1000和1100°C下的煅烧粉末也不能达到化学平衡，因此我们考虑了烧结样品的结果。在这些样本中，我们发现Δx∝G−3/2而不是Δx∝G−3的预测关系。为了解释这种关系，我们假设模型中的基本体积是铁电畴而不是材料的晶粒，基于畴尺寸和晶粒尺寸之间的抛物线关系。用热力学数据计算的基本体积与畴的体积很好地吻合。©
In lead zirconate titanate ceramics, the low temperature tetragonal and rhombohedral ferroelectric phases coexist for compositions near the morphotropic phase boundary (MPB), and the explanation of this fact remains a controversial issue. A model of a statistical distribution of the phases can describe the coexistence of the phases, assuming that it results from the thermal fluctuation quenching during the cooling from the paraelectric to the ferroelectric phases. In this model the width of the phase coexistence region (Δx) is related to the grain size, G, and it should be observed that Δx∝G−3. In this work we checked the applicability of this relation on PZT powers and ceramics. Chemical equilibrium is not attained in calcined powders at 900, 1000 and 1100°C, even after long time heat treatments, and therefore we considered the results from sintered samples. In these samples, instead of the Δx∝G−3predicted relation, we found that Δx∝G−3/2. To explain this relation, we assumed that the elementary volume in the model is the ferroelectric domain instead of the grain of the material, based in a parabolic relation between the domain size and the grain size. Calculation of the elementary volumes using thermodynamic data is in good agreement with the volumes of the domains. ©