Thompson, Russell B.Singh, M.2022-01-242022-01-241999-01https://doi.org/10.1080/13642819908206782http://hdl.handle.net/10012/17955This is an Accepted Manuscript of an article published by Taylor & Francis in Philosophical Magazine B on 1999-01-01, available online: http://www.tandfonline.com/10.1080/13642819908206782.We have developed a theory for variable-rangehopping (VRH) due to small polarons in quasi-two-dimensionalsystems at high temperatures.We included the effects of temperature, electric fields, magnetic fields and scattering in the derivation of the conductivity. We found that the conductivity for quasi-two- dimensional systems depends on these factors differently from three- dimensional systems. We applied the theory to explain the resistivity data of PrBa2Cu3p,Ga,07-l, at high temperatures ( T > 150K). To explain the low- temperature data ( T < 150K), we used the pure electron VRH mechanisms. Good agreement between theory and experiment was found.envariable range hoppingpolaronsArticle