Anisotropic conductivity of the vanadium bronze Na0.33V2O5

Electronic Conduction in Oxides

“…5.42), which is larger by 100 times along the b axis than perpendicular to it [629]. 5.42), which is larger by 100 times along the b axis than perpendicular to it [629].…”

“…,B-Na0 .3 3 V 2 0 5 is, however, not metallic and the conductivity at 300K is about 10 4 sm-1 [628,629]. Thus even if the electrons accumulate on one kind of the three v sites, v1, v2, and v3, they are half occupied and good conductivity would be expected if the electrons were itinerant.…”

“…Holstein, Yamashita and Kurosawa, and Bottger and Bryksin have calculated the mobility of the small polaron as (5.37) [547][548][549][550][551]. However, since the temperature range is 80 K to [629], which is characteristic of variable-range hopping conduction (VRH). However, since the temperature range is 80 K to [629], which is characteristic of variable-range hopping conduction (VRH).…”

“…Conductivity of single crystalline Na, V 205[629].II and .L stand for parallel and perpendicular to the b axis. Conductivity of single crystalline Na, V 205[629].II and .L stand for parallel and perpendicular to the b axis.…”

Infrared properties of the quasi-one-dimensional superconductorβ−Na0.33V2O5under pressure

“…5 A similar phase diagram was recently found for the lowdimensional vanadate ␤-Na 0.33 V 2 O 5 . 6 The anisotropy of its metallic character 7,8 can be explained by its crystal structure consisting of three kinds of chains built by three crystallographically inequivalent V sites: zigzag double chains composed of edge-sharing ͑V1͒O 6 octahedra, two-leg ladders composed of corner-sharing ͑V2͒O 6 octahedra, and zig-zag double chains of edge-sharing ͑V3͒O 5 polyhedra, oriented along the b axis. 9 At ambient pressure ␤-Na 0.33 V 2 O 5 undergoes three phase transitions: 8,10 ordering of the sodium ions at 240 K, a metal-insulator transition around 135 K caused by charge ordering on the V sites 11 due to electronic correlations, and an antiferromagnetic transition at 22 K. Recently, the pressure-temperature phase diagram was investigated by dc resistivity and ac susceptibility measurements for pressures P up to 9 GPa.…”