Phase transitions and thermal-stress-induced structural changes in a ferroelectric Pb(Zr0.80Ti0.20)O3 single crystal.
Phase transitions and thermal-stress-induced structural changes in a ferroelectric Pb(Zr0.80Ti0.20)O3 single crystal.
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铁电 Pb(Zr0.80Ti0.20)O3 单晶的相变和热应力引起的结构变化。
DOI：
10.1088/0953-8984/27/2/025901
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Frantti J
中科院分区：
文献类型：
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作者：
Frantti J
通过偏振拉曼散射研究了组成为 Pb (Zr 0.80 Ti 0.20) O 3 的锆钛酸铅单晶随温度的变化。拉曼光谱表明，铁电相和顺电相的局部结构都偏离平均结构。我们表明，该晶体具有多个不等价的复杂域边界，即使在铁电到顺电相变温度 T C 以上 200 K 的温度下，这些边界也没有表现出不稳定的迹象。解决了两种类型的边界。第一个边界在低于 T C 的铁电域之间形成。该边界在最高测量温度下保持稳定，并稳定域，以便在重复加热和冷却循环后它们具有相同的方向。这些域通常转变为立方顺电相。另一种类型的边界在 673 K 时形成，直到 923 K 都没有表现出不稳定的迹象。边界的形成是可逆的：它分别在加热和冷却过程中在 573 和 673 K 之间形成和消失。提出了一种将晶体分成具有不同 Zr/Ti 比率的薄片的模型。热应力引起的结构变化背后的物理机制与切片的不同热膨胀有关，这迫使域在每次加热和冷却循环后类似地生长。该结果对于非易失性存储器的开发很有趣，因为它意味着在材料转变为顺电相后可以恢复原始的铁电状态。它还表明，可以通过控制沉积具有所需成分的层来制备在高温下稳定的低对称性结构。
A single crystal of lead-zirconate-titanate, composition Pb (Zr 0.80 Ti 0.20) O 3, was studied by polarized-Raman scattering as a function of temperature. Raman spectra reveal that the local structure deviates from the average structure in both ferroelectric and paraelectric phases. We show that the crystal possesses several, inequivalent complex domain boundaries which show no sign of instability even 200 K above the ferroelectric-to-paraelectric phase transition temperature T C. Two types of boundaries are addressed. The first boundary was formed between ferroelectric domains below T C. This boundary remained stable up to the highest measurement temperatures, and stabilized the domains so that they had the same orientation after repeated heating and cooling cycles. These domains transformed normally to the cubic paraelectric phase. Another type of boundary was formed at 673 K and exhibited no signs of instability up to 923 K. The boundary formation was reversible: it formed and vanished between 573 and 673 K during heating and cooling, respectively. A model in which the crystal is divided into thin slices with different Zr/Ti ratios is proposed. The physical mechanism behind the thermal-stress-induced structural changes is related to the different thermal expansion of the slices, which forces the domain to grow similarly after each heating and cooling cycle. The results are interesting for non-volatile memory development, as it implies that the original ferroelectric state can be restored after the material has been transformed to the paraelectric phase. It also suggests that a low-symmetry structure, stable up to high temperatures, can be prepared through controlled deposition of layers with desired compositions.