The larger ZnAl2O4 grains tend to be located in the ZnO
grain boundaries and triple junction points, causing a decrease
in homogeneity of the targets, which may affect not only the
electrical resistivity of the ceramic targets but also the properties
of the deposited thin films. XPS analysis performed on the
sintered targets also shows a slightly tendency to an increase
in O content for targets sintered at temperatures higher than
1400 ◦C, which can be related with the volatilization of ZnO at
higher temperatures,20,32,33 and consequently a change in the
composition of the sintered composite.