High-pressure phase diagram of O2 and N2 binary system: formation of the kagome-lattice of O2

Recently, in the mixture of oxygen and nitrogen molecules, the appearance of a new solid phase, which does not occur for either pure component, has been reported under high pressure. We consider that the magnetic interaction of oxygen molecules would play a main role of the formation of the phase. In this paper, the high-pressure phase diagram of the binary system has been investigated by examining the x-ray diffraction patterns of the polycrystalline or powder samples. The solid phase was stable in a rather wide pressure and concentration range than previous report. From the Reitveld refinement the structure of the phase was identified to be a hexagonal structure with seven molecules in the unit cell. The results of x-ray diffraction, Raman scattering and magnetization measurements have suggested a magnetic order of oxygen molecules on the Kagome-lattice.