Tham khảo tài liệu 'modern developments in x-ray and neutron optics episode 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 358 Th. Krist et al. can be seen that are nearly parallel to the surface. We characterized the crystal orientation by the ratio of the area under the respective peaks. From the change in the position of the peaks related to the bulk value we determined the lattice distortion. As far as we know no publication in the literature has dealt so far with XRD measurements on Ni Ti supermirrors. In all samples both Ni and Ti show polycrystalline structure. Generally four maxima occur in the spectra which can be identified as face-centered cubic fcc Ni lattice Nifcc 200 NijCc 111 and hexagonal close-packed hcp Ti lattice Tihcp 011 Tihcp 002 . For the best quality mirror - prepared on a smooth substrate - the XRD spectra only show one Ni and one Ti peak. This means that both materials crystallize with a preferred orientation with the Ni 200 planes and Ti 011 planes parallel to the substrate surface. The medium quality mirror was prepared on a similarly smooth substrate however the quality is not the same. Again a similar orientation is preferred but not to the same extent even though Ni 111 and Ti 002 reflections appear. The worst mirror was prepared on a quite rough substrate. We can see that all four peaks appear with no preferred orientation in this case. Summarizing we can say that there are two ways of orientation Ni 200 is connected to Ti 011 and Ni 111 to Ti 002 5 . On a rough substrate both orientations are present and the reflectivity is low R 50 . In this case Ơ nm where Ơ is the rms microroughness measured by X-ray reflectivity. On a smooth substrate ơ the Ni 200 Ti 011 orientation is preferred. The more this orientation is preferred the better is the quality of the mirror reflectivity R 80 as can be seen in Fig. . In Fig. one can see the extent of orientation depending on the reflectivity of supermirrors with m 3. Circles represent the ratio of the area under the maxima Ni 200 and Ni 111 . Triangles are for the ratio of the area under the maxima
