  In this work, we use the liquid ammonia method to successfully intercalate
potassium atoms into ZrTe5 single crystal, and find a transition from semimetal
to semiconductor at low temperature in the intercalated ZrTe5. The resistance
anomalous peak is gradually suppressed and finally disappears with increasing
potassium concentration. Whilst, the according sign reversal is always observed
in the Hall resistance measurement. We tentatively attribute the
semimetal-semiconductor transition to the lattice expansion induced by atomic
intercalation and thereby a larger energy band gap.
