SPONTANEOUS MAGNETOSTRICTION EFFECTS IN A LPHA-PHASES AND BETA-PHASESOF OXYGEN

Strong spontaneous magnetostriction effects were discovered in the rho mbohedral phase of oxygen in x-ray powder diffraction studies. The eff ects have lead to considerable inhomogeneous deformation of lattice di stortios and to partially amorphous transformation of the crystals whe n the temperature approaches the antiferromagnetic transition point. T he results obtained permit us to assume that quasi-2D regions of short range magnetic order are formed in the basal planes of beta-oxygen. W e obtained experimental evidence that this low-temperature transformat ion is a first-order phase transition and that intermediate modulated magnetic structure could possibly be realized in its vicinity.