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100
90
8
7
Intensity (arb.unit)
0h
80h
140
160
5 10 15 20 25 30 35 40 45 50 55 60
2Θ( o )
Crystallite size (nm)
80
70
60
50
40
30
20
10
5mm balls
0.6mm balls
0
20 40 60 80 100 120 140 160 180
Milling time (h)
Figure 1: X-ray powder diffraction patterns of un-milled Figure 2: The variation of the apparent crystallite size
and ball milled samples (80h,140h and 160h) and strain size of [015] reflection with milling time
Typical SEM images presented in figure 3(a) and 3(b) show the morphology and the particle size of the ball
milled powders for 80 and 140h respectively. The particles do not present the typical plate-like Bi 2 Te 3
morphology. The average particle size was reduced when smaller grinding balls were used. Based on X-ray
analysis results, these particles consist of finer crystallites with average size of 25 and 15nm respectively. TEM
images are in progress to further study the crystallites.
6
5
4
3
2
1
0
e x10 3
(a)
(b)
Figure 3: SEM images of ball milled powders at (a)80h and (b)140h
Conclusions Nano-crystalline particles were fabricated by high energy ball milling of Bi 2 Te 3 bulk. The crystallite
size and lattice strain were investigated via powder X-ray diffraction analysis. The size decreases while the strain
increases with milling time. Further reduction of the crystallite size and enlargement of strain values occurs when
smaller grinding balls were used. SEM images point out the morphology of Bi 2 Te 3 particles.
Acknowledgments Financial support from INTERREG IIIA Greece-Cyprus is gratefully acknowledged.
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