The high pressure behaviors of hydrate Cu-BTC metal-organic framework (MOF) in terms of phase stability, compressibility and reversibility were investigated in situ by synchrotron X-ray powder diffraction as well as vibrational spectroscopy. Two phase transitions, caused by the interaction of water and the sample framework, were revealed by the vibrational spectroscopies. Compressibility of the hydrate Cu-BTC also displays soft and hard regimes, which is the same scenario as non-hydrate Cu-BTC with a pressure transmitting medium. It is further confirmed that the residual water molecules in hydrate Cu-BTC can serve as a pressure transmitting medium with small molecule size under high pressure. Our results not only prove the high stability of Cu-BTC but also provide spectroscopic evidence for the interactions taking place between the guest molecules and the sample framework. Such findings could provide further guidelines for improving Cu-BTC's absorption and storage abilities.

Ru/BC multilayer mirrors are used for hard X-ray monochromators with moderate spectral resolution and high integral flux. To overcome the problem of large compressive stress inherent in Ru/BC multilayers, a reactive sputtering technique using a mixture working gas of argon and nitrogen with different partial pressures was tested, and the fabricated multilayers had a period of 3 nm. The intrinsic stress was essentially reduced after nitridation and relaxed to zero value at approximately 15% partial pressure of nitrogen in the working gas. Interface roughness was slightly increased which can be caused by the polycrystalline structure inside the nitridated samples. More importantly, the nitridated multilayers showed an enhanced reflectance (67% at 8.04 keV photon energy) as compared with the one fabricated with pure Ar (54%). The structure analysis with transmission electron microscopy and X-ray photoelectron spectroscopy demonstrated that nitrogen incorporated into a multilayer structure was mostly located in the BC layers forming BN compounds, which suppressed the diffusion of boron, stabilized the interfaces and enhanced the reflectance.

A comparative study of Mo/B 4 C and Mo x C 1-x /B 4 C multilayers deposited by DC magnetron sputtering technology was presented in this paper. Using a homemade real-time stress measure instrument, the stress of two kinds of multilayers was investigated. Characterizations of the multilayers before and after annealing were performed by grazing incident and at-wavelength near-normal incident x-ray reflectivity. Experimental results show that after replacing Mo by Mo x C 1-x , Mo x C 1-x /B 4 C multilayers obtain relatively smaller compressive stress compared with Mo/B 4 C multilayers. The corresponding stress value changes from −0.99 GPa to −0.36 Gpa. Mo x C 1-x /B 4 C multilayers have also proven to have better thermal stability up to 600°C. After repeatedly annealing from 100°C to 600°C, Mo/B 4 C multilayers had a ∼2% decrease in near-normal incident reflectivity, while Mo x C 1-x /B 4 C multilayers had a smaller 1.4% loss of reflectivity and a higher stability temperature.

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