Geoscience Reference
In-Depth Information
T
= 160 ºC
Yield = 0.99
0
1
2
3
4
5
6
7
0
0
-0.5
-0.5
-1
-1
PZTVPPT
-1.5
-1.5
-2
-2
-2.5
-2.5
0
1
2
3
m (C4H13NO)
4
5
6
7
Figure 10.39 Calculated yield of PbTiO
3
in the Pb
Ti
H
2
O complexing agent system for
various Pb/Ti ratios
[170]
.
greatly in the hydrothermal synthesis of phase-pure ceramics.
Figure 10.39
shows
the calculated yield of PbTiO
3
in the Pb
H
2
O complexing agent system for
various Pb/Ti ratios. A majority of the PZT systems incorporate intolerable
amounts of alkaline metals, which are introduced in the form of mineralizers. In
recent years, organic mineralizers are being used by a large number of workers.
For example, Riman et al.
[170]
have found that tetramethylammonium hydroxide
[N(CH
3
)
4
OH] is a favorable substitute for alkaline metal hydroxide mineralizers in
producing phase-pure PZT. Phase-pure MeTiO
3
(Me
Ti
Ca, Sr, and Ba) can be
obtained at input molalities of Ba, Sr, and Ca greater than 7
5
10
2
5
,10
2
6
, and
3
10
2
5
, respectively. Otherwise, the relative location of the 99.995% yield
regions for the three titanates will be similar to the pattern noted for stability dia-
grams
[163]
. In concentrated solutions, the consumption of OH
2
ions is caused by
the following predominant reactions:
5
3
Me
2
1
1
2OH
2
5
ð
:
Þ
TiO
2
1
MeTiO
3
1
H
2
O
10
1
Thus, 2 M of OH
2
is consumed for the synthesis of 1 M of MeTiO
3
, and only a
relatively small amount of OH
2
is necessary to ensure correct pH for respective
alkaline earth. Unlike the synthesis with nitrates,
the use of metal hydroxide
