Lithium hopping motion

The polaron radius, if greater than (2), will be very sensitive to m —or, more exactly, to the bandwidth of the undistorted lattice. A particularly striking effect is that in materials like NiO doped with lithium, where the carriers are Ni3 + ions and in which the hole moves from one Ni2+ ion to another. The mass enhancement for a free carrier is rather small (about 5), while a bound carrier hopping round the Li+ ion on the sites available to it behaves like a small polaron with an activation energy for motion (see Bosman and van Daal (1970) and Chapter 6 below). 

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