The control of impurity is crucial to the ingot qualify and yield in the directional solidification of multi crystalline silicon for solar cells. The major impurities, such as metals, are mainly from the quartz crucible and the silicon nitride coating. The use of high-purity materials mitigates the problem, but it also increases the cost. Another way is to use diffusion barriers between silicon and these materials to reduce the incorporation of impurities. In this study, polysilazane and barium oxide coatings with different layer configurations were considered. With the diffusion barrier layer, the lifetime of the ingot was improved and the red zone was reduced. The wetting behaviors of these diffusion barriers in contact with silicon were also discussed. (C) 2014 Elsevier B.V. All rights reserved