Synthesis, crystal structure, electrical properties, and sodium transport pathways of the new arsenate Na4Co7(AsO4)6

Electrical properties and alkali-pathways simulation of new mixed conductor Na4Li0.62Co5.67Al0.71(AsO4)6

“…The BVS analyzes are in agreement with the suggestions deduced from the structural studies [20,26]: the most likely conduction pathways of the monoarsenates are in the [100] direction which is the direction of the tunnels. The dimensions of the hexagonal sections of tunnels along [100] direction of the three compounds are shown in figure 8(a).…”

“…The BVSE simulation model was used to define the alkali-ion transport pathways in the anionic frameworks of the isostructural materials Na 4 Co 7 (AsO 4 ) 6 [20]; Na 4 Co 5.63 Al 0.91 (AsO 4 ) 6 [26] and Na 4 Li 0.62 Co 5.67 Al 0.71 (AsO 4 ) 6 using the 3DBVSMAPPER computer program.…”

“…On the other hand, the crystallographic studies [20,25] show that the substitution of cobalt by aluminum allows to increase the unit cell parameters and the dimensions of the tunnel sections. In fact, the volume of the unit cell of Na 4 Co 7 (AsO 4 ) 6 is V=1019.65(16) Å 3 which is lower than those of Na 4…”

“…Other arsenate materials belonging to the same structural type have been synthesized [18][19][20][21][22][23][24]. Especially, LiCoAsO 4 arsenate with olivine structure [25] shows interesting electrochemical properties.…”

“…The electrical measurements of cobalt arsenate compounds show interesting electrical performance such as Ag 4 Co 7 (AsO 4 ) 6 ; Na 4 Co 5.63 Al0 .91 (AsO 4 ) 6 and Na 4 Co 7 (AsO 4 ) 6 which are classified as fast electrical conductors [18][19][20].…”