CRYSTAL STRUCTURE AND CONDUCTIVITY FOR THE SYSTEMS Na3Sc2(PO4)3 and Ag3Sc2(PO4)3
Gennadii V. Shilov, Lev O. Atovmyan, Alex E. Ukshe, Viktor I. Kovalenko
Institute for Chemical Physics Research, Russian Academy of Sciences. 142432 Chernogolovka, Moscow Region, Russa.E-mail gshilov@icp.ru
The aim of the investigation was to define channeks of conductive crystal structures of single crystals Na3Sc2(PO4)3 and Ag3Sc2(PO4)3 using x- ray method.
The monocrystal of the composition Ag3Sc2(PO4)3 had been created by the method ofionic exchange in the Na3Sc2(PO4)3 monocrystal.
We found that after ionic exchange the symmetry of the monocrystal was rised from monoclinic to rhombohedral. We made a comparison of the crystals structures of Na3Sc2(PO4)3 defined at the four temperetures (25, 60, 170, 300oC) and Ag3Sc2(PO4)3 at the 28oC. We defined channels of conductivity in this crystal structures. We found that in the monocrystal Ag3Sc2(PO4)3 system the phase transitions were absent at the 20 - 500oC tempereture interval. Whereas two phase transitions are present in the Na3Sc2(PO4)3 system at 48 and 140oC.
The electrochemical measurings also indicated to the phase transitions absence in this temperature interval. The defined energy of activation was 0.3 eV. The data of both x-ray and electrochemical investigations indicated that Ag3Sc2(PO4)3 crystal system was superionic conductor at the room tempereture already.