CRYSTALLOCHEMISTRY AND PHYSICAL-PROPERTIES OF NEW PHASES IN RH2O3-SROBINARY-SYSTEM

Preliminary results are presented concerning X-ray powder diffraction, electrical resistivity, thermal stability and magnetic susceptibility data of the four phases found in the Rh2O3-SrO system within the comp ositional interval of 0-70 mol% SrO. Only Sr2RhO4 was already describe d in the literature; Sr3Rh2O6.5, SrRh2O4 and SrRh3O55 are completely n ew. The first two crystallize in a hexagonal system with the unit cell parameters corresponding to: a = 9.602 Angstrom, c = 8.222 Angstrom a nd a = 3.054 Angstrom, c = 11.39 Angstrom; respectively, while SrRh3O5 5 is monoclinic with a = 14.554 Angstrom, b = 12.193 Angstrom, c = 7.9 03 Angstrom and beta = 98.53 degrees. It has been found that in these phases resistivity strongly depends on oxygen content and Ph-ions exhi bit variable oxidation state. Al the Rh2O3-SrO binaries represent inte resting objects for more detailed studies of the nature of several mag netic anomalies exhibited by them. (C) 1997 Elsevier Science S.A.