Effectively enhanced comprehensive electrical performance ...
The samples which individually ball milled in the tumbling ball mill for x h (x = 3, 6, 12, 24 and 48), and then sand milled in the horizontal sand mill for 15 min were defined as S1, S2, S3, S4 and S5, respectively. For comparison, the sample with ball milling for 48 h and without sand milling was defined as S5 N.