ESR and Electric Conductance Studies of the Fine-Powdered SnO2

A fine-powdered sample of high purity SnO2 gave a strong ESR signal (gav≈1.90) after reduction in vacuum. This BSR center, like the g≈1.96 center of ZnO, is associated with the n-type conduction. When the sample was exposed to O2 or H2, the spin concentration, the full half width and also the electric conductance were changed. These variations are well explained by assuming that the fine-powdered SnO2 has double donor centers originated from both bulk and surface oxygen vacancies, The gav≈1.90 center may be due to the un-ionized deep donor electrons trapped in the surface oxygen vacancy.