Crossover of large to small radius polaron in ionic crystals  

作　　者：M I Umo 

机构地区：[1]Department of Physics, University of Calabar, PMB 1115, Nigeria

出　　处：《Chinese Physics B》2016年第11期434-440,共7页中国物理B（英文版）

摘　　要：The crossover of large to small radius polaron is studied in terms of the inverse-relaxation time and temperature.It is found that the small radius polaron exists at higher temperature than the large radius polaron.A formula which relates the inverse-relaxation time to the ratio of arbitrary temperature and Debye temperature of the crystal is derived.The polaron crossover temperatures in NaCl and KBr are found from plotted graphs.The straight line emerging at the Debye temperature T_d of a graph reflects the increase of the inverse relaxation time for increasing temperature up to the collapse of the small radius polaron.The relationship between the small and large radius polarons is found and known ratios of the effective and the bare masses of the electrons for the two substances are used to validate our results.The small radius polaron＇s mass is later compared with the mass obtained from the hopping formula and is found to be approximately equal.Finally,we point out that the crossover temperature is material-specific since it depends on the Debye and the effective dielectric function.The crossover of large to small radius polaron is studied in terms of the inverse-relaxation time and temperature.It is found that the small radius polaron exists at higher temperature than the large radius polaron.A formula which relates the inverse-relaxation time to the ratio of arbitrary temperature and Debye temperature of the crystal is derived.The polaron crossover temperatures in NaCl and KBr are found from plotted graphs.The straight line emerging at the Debye temperature T_d of a graph reflects the increase of the inverse relaxation time for increasing temperature up to the collapse of the small radius polaron.The relationship between the small and large radius polarons is found and known ratios of the effective and the bare masses of the electrons for the two substances are used to validate our results.The small radius polaron＇s mass is later compared with the mass obtained from the hopping formula and is found to be approximately equal.Finally,we point out that the crossover temperature is material-specific since it depends on the Debye and the effective dielectric function.

关 键 词：relaxation radius crossover inverse straight ionic validate arbitrary phonon dielectric 

分 类 号：O73[理学—晶体学]