Structure and magnetic interactions in the solid solution Ba3−xSrxCr2O8

Solid solutions of the magnetic insulators Ba3Cr2O8 and Sr3Cr2O8 (Ba3−xSrxCr2O8) have been prepared in polycrystalline form for the first time. Single crystalline material was obtained using a mirror image floating zone technique. X-ray diffraction data taken at room temperature indicate that the space group of Ba3−xSrxCr2O8 remains unchanged for all values of x, while the cell parameters depend on the chemical composition, as expected. Magnetization data, measured from 300K down to 2K, suggest that the interaction constant Jd within the Cr5+ dimers varies in a peculiar way as a function of x, starting at Jd=25K for x=0, then first slightly dropping to Jd=18K for x≈0.75, before reaching Jd=62K for x=3.