Quantification of inhomogeneity in mechanical properties of rocks in nanometer scale

用拉曼光谱和EBSD-SEM研究了石英单晶在压痕周围的变形情况，激光拉曼光谱显示远离压痕的石英在728波数处有明显的拉曼光谱和较强的谱带。206和464厘米-7，这是完整的a-石英的典型特征。当接近压痕时，清晰的条带逐渐移动和变宽。他们在印象的边缘有肩膀，最后在印象的中央分成两个子带。拉曼谱带的这种形状变化被认为与压痕实验在石英晶体内部产生的残余应力场有关。从拉曼谱带的位移波数可以估计出残余应力的大小，在压痕中心，最大压应力和拉应力分别超过2 GPA和0.1 GPA。扫描电子显微镜-EBSD研究表明，在压痕附近的六角形区域，Dauphine孪晶具有特征的Kikuchi带，并在背散射图像中形成对比。由于Dauphine双胞胎相对于凹痕有系统的发生，我们得出结论，Dauphine双胞胎是在凹痕测试过程中发展起来的。

We investigated how quartz single crystal deformes around the indentation impression by using the Raman microspectroscopy and the EBSD-SEM.The laser Raman microspectroscopy revealed that quartz far from the indentation impression exhibit clear Raman spectra with strong bands at wavenumbers of 728. 206 and 464 cm-7 which are typical for intact a-quartz. The clear bands gradually shift and broaden with approaching to the indentation impression. They have shoulders at the edge of the impression, and finally split into two subbands at the central part of the impression. Such shape change of the Raman bands is considered to be related to the generated residual stress field within the quartz crystal by the indentation test. The magnitude of the residual stress can be estimated from the shifted wavenumbers of the Raman bands, and the maximum compressive and tensile stresses are revealed to exceed 2 and 0.1 GPa, respectively, at the center of the indentation impression.The SEM-EBSD study revealed that Dauphine twins can be perceived with the characteristic Kikuchi bands and contrasts in the back scattered images in hexagonal areas close to the indentation impression. As Dauphine twins occur systematically with respect to the indented impression, we concluded that Dauphine twins have developed during the indentation test.