= 0.0 – 0.5 system.*

The layered oxides originated from the perovskite structure create an enormous family of compounds that produces a very rich physics. For the case of 3d elements, this family was at the beginning of the discovery of high Tc superconductivity in the oxides or giant magnetoresistance in manganates. A layer structure always plays, an essential role. We have started a study of the different members of the Ruddlesden-Popper series based on chromium. We report the synthesis and their magnetic behaviour on Sr_1-xK_xCrO_z x= 0.0 – 0.5 system (SKCO). The technique of manufacture used was solid-state reaction. We focus here on the SKCO rhombohedra unit cell (PDF 00-029-1047), and its magnetic characterization. The TG analysis gives the idea of the reaction temperatures. By solid-state reaction we obtain SKCO Primitive rhombohedra structure that reaction stars from 723 K. SKCO rhombohedra is an insulator with an antiferromagnetic (AFM) transition at T_N= 280 K. Only when x= 0.10 we observe the introduction of K in the crystal structure at room temperature. The highest reaction temperature used was 933 K.