⁵⁷Fe and ¹¹⁹Sn Mössbauer studies of electron exchange processes in spinels of composition Zn²⁺[Zn _{(1-x) 2}²⁺Sn _{(1+x) 2}⁴⁺Fe_(1-x²⁺]O₄

Phases in the spinel series Zn²⁺[Zn _{(1-x) 2}²⁺Sn _{1+x 2}Fe_1-x³⁺Fe_x²⁺]O₄ have been prepared and studied by ⁵⁷Fe and ¹¹⁹Sn Mössbauer spectroscopy. For 0 = x = 0.75 the spinels remain paramagnetic down to 80 K. Evidence is found for fast localized electron hopping between adjacent Fe²⁺ and Fe³⁺ ions and also for the complete delocalization of electrons into a conduction band. A model which quantitatively accounts for this latter phenomenon is presented. © 1981.