Lee Yongjae, Lee Jong-Won, Lee Hyun-Hwi, Lee Dong Ryeol, Kao Chi-Chang, Kawamura Taro, Yamamoto Yoshitaka, Yoon Ji-Ho
Department of Earth System Sciences, Yonsei University, Seoul 120-749, Republic of Korea.
J Chem Phys. 2009 Mar 28;130(12):124511. doi: 10.1063/1.3097763.
The high pressure compression behaviors of two hydroquinone compounds have been investigated using a combination of in situ synchrotron x-ray powder diffraction and Raman spectroscopy up to ca. 7 GPa. The structural integrity of the alpha-form hydroquinone clathrate is maintained throughout the pressure range, whereas the CH(4)-loaded beta-form hydroquinone clathrate decomposes and transforms to a new high pressure phase near 5 GPa. The bulk modulus (K) and its pressure derivative (K(')) of the alpha-form and the CH(4)-loaded beta-form hydroquinones are measured to be 8.2(3) GPa and 8.4(4), and 10(1) GPa and 9(2), respectively, representing one of the most compressible classes of crystalline solids reported in the literature. The corresponding axial compression behaviors, however, show greater contrast between the two hydroquinone compounds; the elastic anisotropy of the alpha-form is only marginal, being K(a):K(c) = 1.08:1, whereas that of the CH(4)-loaded beta-form is rather drastic, being K(a):K(c) = 11.8:1. This is attributed to the different dimensionality of the hydrogen bonding networks between the two structures and might in turn explain the observed structural instability of the beta-form, compared to the alpha-form.
利用原位同步辐射X射线粉末衍射和拉曼光谱相结合的方法，研究了两种对苯二酚化合物在高达约7吉帕压力下的高压压缩行为。在整个压力范围内，α型对苯二酚包合物的结构完整性得以保持，而负载CH(4)的β型对苯二酚包合物在接近5吉帕时分解并转变为一种新的高压相。测得α型和负载CH(4)的β型对苯二酚的体积模量（K）及其压力导数（K(')）分别为8.2(3)吉帕和8.4(4)，以及10(1)吉帕和9(2)，这代表了文献中报道的最可压缩的晶体固体类别之一。然而，两种对苯二酚化合物的相应轴向压缩行为表现出更大的差异；α型的弹性各向异性很小，K(a):K(c) = 1.08:1，而负载CH(4)的β型的弹性各向异性相当显著，K(a):K(c) = 11.8:1。这归因于两种结构之间氢键网络的维度不同，这反过来可能解释了与α型相比β型所观察到的结构不稳定性。
