PhD Thesis Arne Lüker final version V4 - Cranfield University

B Site Doping of PST 40/60
section 5.1 it can be said that the films are well crystallised. SEM (Fig. 6.2) and AFM
pictures (Fig. 6.3) can confirm this.
(a) PST pure (b)
PST 1mol% Mn
(c) PST 3 mol% Mn (d)
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It is quite obvious that the increasing Mn content has a remarkable influence on the
microstructure of (Pb,Sr)TiO3. The clearly visible grains in 6.2(a) have an average grain
size of 150 nm. With increasing Mn content the grains become smaller, ~ 80 nm in
6.2(b), and indistinct in 6.2(c), finally in 6.2(b), the microstructure has a sponge-like
appearance.
PST 5 mol% Mn
Fig. 6.2: SEM images of (Pb0.4,Sr0.6)(Ti1-x,Mnx)O3. (a) x=0, (b) x=0.01, (c) x=0,03 and (d) x=0.05
The AFM images indicate a decrease of the roughness with increasing Mn content
from 3.37 nm for pure PST down to 1.69 nm for PST with 5 mol% Mn. Sun at al. [17]
have doped the A site of BST with K + and showed a clear relationship between grain
size/surface roughness and dielectric properties of BST thin films. Both, the
roughness/grain size and dielectric constant increased with the doping level up to 7.5