A degenerate gas of small polarons

Wemple (1965) and Wemple et al (1966) have made similar observations for KTa03 in a range of donor concentrations from 3 x 1017 to 1019 cm 3. The static dielectric constant is about 4500 at low temperatures and the mobilities are still higher (23000cm2 V 1 s 1 at 4K for the lowest concentration). 

We conclude from these results that a degenerate gas of small polarons is a valid concept. 

14 Anderson versus band-crossing or Mott transitions 

Which sort of transition is occurring in the new superconductors, such as the antiferromagnetic insulator La2 xSrxCu04 for small x, will be discussed in Chapter 9. 

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