14673
While the cation exchange procedure , performed in solution phase approach , was restricted so far to chalcogenide based semiconductor nanocrystals , here ferrite - based nanocrystals were subjected to a Fe ( 2 + ) to Co ( 2 + ) cation exchange procedure .
 Chemical: ferrite; Chemical: Fe ( 2 + ); Chemical: Co ( 2 + )
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: ferrite, Fe ( 2 + ), Co ( 2 + ) 
Answer:
 Chemical: ferrite; Chemical: Fe ( 2 + ); Chemical: Co ( 2 + )