Abstract
We have measured resistivity, magnetization and magnetoresistance in polycrystalline La
0.7−
x
Pr
x
Sr
0.3MnO
3 with fixed carrier concentration. With decreasing the average ionic radius of the La site 〈
r
A
〉, we found a decrease in
T
c
, an increase in resistivity at
T
c
, and an increase in the magnitude of the magnetoresistance. The samples show a metal-insulator transition in the high-temperature paramagnetic phase with the variation of 〈
r
A
〉. These results demonstrate the close relationship between 〈
r
A
〉 and the band structure.