Abstract
The electric-field induced ball formation has been observed with MgB
2 powder in a strong static or quasi-static electric field. The effect of temperature and magnetic field on the ball formation shows surprising features. For quite a wide range of temperature from
T
c=39 K and below, the ball size is proportional to (1−
T/
T
c). As the temperature further goes below 20 K, the ball size becomes almost a constant. If MgB
2 particles are in a strong electric field and a moderate magnetic field, the electric-field induced balls align in the magnetic-field direction to form ball chains.