A Dember Effect Study of Shifts in the Stoichiometry Of ZnS

An attempt was made to follow, by pulse Dember effect measurements, the changes in vacancy concentration in ZnS resulting from variations of temperature and sulfur pressure. The p-type Dember pulse increases at constant temperatures roughly as the square root of the sulfur pressure; it decreases with temperature for a constant sulfur pressure so as to indicate a reaction energy of 0.6 ev per zinc vacancy formed. The “n-type” pulse measured in material with no added sulfur increases with temperature, yielding an activation energy of 1.1 ev for each pair of vacancies formed. Firing the “pure” ZnS in a running vacuum at 900°C, on the other hand, yields p-type material, indicating that the formation of an isolated Zn vacancy is energetically considerably more favorable than the formation of an isolated S vacancy. This conclusion agrees with the reaction energies mentioned above. © 1963, The Electrochemical Society, Inc. All rights reserved.