9048
To separate interface and bulk transport from the total oxygen diffusivity of the multilayer system , the ( average ) thickness of the YSZ - layers in the multilayers was varied from 45 nm to 12 nm .
 Chemical: oxygen; Chemical: YSZ
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
 Chemical: oxygen; Chemical: YSZ