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首页> 外文期刊>Journal of Materials Research >Canonical-glass-like behavior of the polycrystalline relaxor ferroelectric (1―x)PbMg_(1/3)Nb_(2/3)O_(3-x)PbZrO_3: Heat-capacity study
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Canonical-glass-like behavior of the polycrystalline relaxor ferroelectric (1―x)PbMg_(1/3)Nb_(2/3)O_(3-x)PbZrO_3: Heat-capacity study

机译：多晶弛豫铁电体（1―x）PbMg_（1/3）Nb_（2/3）O_（3-x）PbZrO_3的规范玻璃样行为：热容量研究

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摘要

A solid solution of lead magnesium niobate (PMN), a relaxor ferroelectric, with lead zirconate (PZ), an antiferroelectric, gives rise to a system that behaves like a relaxor ferroelectric for lower concentrations of PZ, and like a normal ferroelectric above 50% substitution by PZ. This paper reports the heat-capacity behavior of (1 ― x)PMN―xPZ for the composition range x = 0.30 to 0.95 and temperature range 300―600 K. It was observed that, although the atomic structure of the material is basically crystalline throughout, with sharp x-ray diffraction peaks, the crossover from normal―ferroelectric behavior to relaxor―ferroelectric behavior (on decreasing x) is accompanied by a matching crossover from crystalline behavior to glassy behavior, as exhibited in the heat-capacity plots. In other words, the heat-capacity curves for the relaxor compositions bear resemblance to those observed for canonical or conventional glasses, with the glass-transition temperature and the continuous step in specific heat changing gradually as a function of the composition parameter x. However, not all properties match those for canonical glasses. For example, soaking for 24 h at a temperature or 10 to 20 K below the mean glass-transition temperature does not raise the specific heat to a value nearly equal to the value in the unfrozen state. Similarly, the glass-transition temperature (for 0.7PMN―0.3PZ) increases, though only marginally (from 337 K to 343 K), when the rate of heating across the transition is increased by a factor of 50 (from 0.1 K per minute to 5 K per min.). Further, the temperature interval ΔT over which most of the glass transition occurs in the relaxor ferroelectric is typically as large as 30―40 K, compared to only about 10 K for canonical glasses.
机译：弛豫铁电体铌酸铅镁（PMN）与反铁电体锆酸铅（PZ）的固溶体产生的系统在较低的PZ浓度下表现得像弛豫铁电体，而在50％以上时就像普通的铁电体被PZ取代。本文报道了（1 ― x）PMN ― xPZ在组成范围x = 0.30到0.95以及温度范围300到600 K时的热容行为。观察到，尽管材料的原子结构在整个过程中基本上是晶体在具有锐利的X射线衍射峰的情况下，从正态铁电行为到弛豫铁电行为（随着x的减小）的交叉伴随有从结晶行为到玻璃态行为的匹配交叉，如热容量图所示。换句话说，松弛剂组合物的热容量曲线与标准玻璃或常规玻璃观察到的相似，玻璃化转变温度和比热中的连续步骤根据成分参数x逐渐变化。但是，并非所有属性都与标准眼镜的属性匹配。例如，在低于平均玻璃化温度的温度或10至20 K的温度下浸泡24小时不会将比热提高到几乎等于未冻结状态下的值。同样，当玻璃化转变温度提高了50倍（从每分钟0.1 K开始）时，玻璃化转变温度（对于0.7PMN〜0.3PZ）仅略有增加（从337 K增至343 K），但仅略有增加。到每分钟5 K）。此外，弛豫铁电体中大部分玻璃化转变发生的温度间隔ΔT通常高达30-40 K，而标准玻璃仅为10 K.

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