Enthalpy and entropy of twin boundaries in superconducting YBa2Cu3O7−x
Enthalpy and entropy of twin boundaries in superconducting YBa2Cu3O7−x
复制标题
超导 YBa2Cu3O7−x 中孪晶边界的焓和熵
DOI：
10.1063/1.1999034
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发表时间：
2005
影响因子：
3.2
通讯作者：
S. Chan
中科院分区：
文献类型：
--
作者：
Lin;S. Chan
孪晶边界能(γtw)及其与温度的关系是评价YBa2Cu3O7−x超导中强磁通钉扎和高临界电流密度孪晶形态的重要因素。本文用孪晶间隔法和孪晶尖端法测量了晶界能随氧化温度的变化关系(45 0~6 80 ℃)。通过比较两种方法得到的孪晶能量，确定了孪晶间距法中所用的几何因子α。这一几何因素与双头尖端的锋利程度直接相关。根据单位面积孪晶界能随温度的变化关系，得到孪晶界面熵(ΔS)和热焓(Δh)分别为0.24mJ/km2和246mJ/m2。
Twin boundary energy (γtw) and its temperature dependence are important factors to be evaluated for engineering twin morphology for strong flux pinning and high critical current density in superconducting YBa2Cu3O7−x. Here, it has been measured as a function of oxygenation temperature from 450 to 680 °C using both the twin spacing method and a twin tip method. By comparing the twin energies obtained by the two methods, the geometrical factor α used in twin spacing method is determined. This geometrical factor is directly related to the sharpness of the twin tips. From the temperature dependence of twin boundary energy per unit area, twin boundary entropy (Δs) and enthalpy (Δh) for twin boundaries are projected to be 0.24mJ∕Km2 and 246mJ∕m2, respectively.