Sanchez-Valle Carmen, Lethbridge Zoe A D, Sinogeikin Stanislav V, Williams Jennifer J, Walton Richard I, Evans Kenneth E, Bass Jay D
Institute for Mineralogy and Petrology, ETH Zurich, Zurich, Switzerland.
J Chem Phys. 2008 May 14;128(18):184503. doi: 10.1063/1.2912061.
Brillouin scattering measurements of the single-crystal elastic properties of the as-made zeolite silicalite mid R:(C(3)H(7))(4)NFmid R:(4)[Si(96)O(192)]-MFI provides the first experimental evidence for on-axis negative Poisson's ratios (auxeticity) in a synthetic zeolite structure. MFI laterally contracts when compressed and laterally expands when stretched along x(1) and x(2) directions in the (001) plane (nu(12)=-0.061, nu(21)=-0.051). The aggregate Poisson's ratio of MFI, although positive, has an anomalously low value nu=0.175(3) compared to other silicate materials. These results suggest that the template-free MFI-silicalite [Si(96)O(192)] might have potential applications as tunable sieve where molecular discriminating characteristics are adjusted by application of stress along specific axes.
对合成的R:(C(3)H(7))(4)NFmid R:(4)[Si(96)O(192)]-MFI型沸石硅铝酸盐单晶弹性性质进行的布里渊散射测量，为合成沸石结构中轴向负泊松比（负泊松效应）提供了首个实验证据。在(001)平面内，当沿x(1)和x(2)方向压缩时，MFI会横向收缩；拉伸时，MFI会横向膨胀（ν(12)= -0.061，ν(21)= -0.051）。与其他硅酸盐材料相比，MFI的总体泊松比虽为正值，但异常低，ν = 0.175(3)。这些结果表明，无模板的MFI型硅铝酸盐[Si(96)O(192)]可能具有作为可调筛的潜在应用，其中分子识别特性可通过沿特定轴施加应力来调节。
