Geoscience Reference
In-Depth Information
Table 10.10 XRD Analysis of Titanates Produced by Microwave-Hydrothermal and
Conventional-Hydrothermal Techniques
[391]
Compound Concentration
(M)
T
(
C)
Duration
(h)
Reaction Products in
Order of Abundance as
Determined by XRD
PbTiO
3
Pb(NO
3
)
2
TiCl
4
KOH
Microwave-hydrothermal
0.4079
0.4
6
138 0.5
PbO, PbTiO
3
0.4079
0.4
6
138 1.0
PbO, PbTiO
3
0.4079
0.4
6
164 0.5
PbO, PbTiO
3
0.4079
0.4
6
164 1.0
PbO, PbTiO
3
0.3
0.25
2
194 0.5
PbTiO
3
, PbO
0.3
0.25
3
194 0.5
PbTiO
3
, trace PbO
0.3
0.25
4
194 0.5
PbTiO
3
, trace PbO
Conventional-hydrothermal
0.4079
0.4
4
195 24
PbTiO
3
BaZrO
3
Ba(NO
3
)
2
Zr(NO
3
)
2
KOH
Microwave-hydrothermal
0.3113
0.3144
10
194 2
BaZrO
3
0.3113
0.3144
10
130 2
BaZrO
3
Conventional-hydrothermal
0.3113
0.3144
10
194 2
BaZrO
3
SrZrO
3
SrZrO
3
Zr(NO
3
)
2
KOH
Microwave-hydrothermal
0.3113
0.3113
10
138 0.5
SrZrO
3
0.3113
0.3113
10
138 1
SrZrO
3
0.3113
0.3113
10
164 0.5
SrZrO
3
0.3113
0.3113
10
164 1
SrZrO
3
0.3113
0.3113
10
194 2
SrZrO
3
Conventional-hydrothermal
0.3113
0.3113
10
138 24
SrZrO
3
0.3113
0.3113
10
138 24
SrZrO
3
700
C) and high pressures due to friction effects and adia-
batic heating of gas bubbles (if present in the slurry), while the bulk system is close to
room temperature
[400]
. Consequently, the thermodynamics of the local reaction
environment favor reactions which may otherwise be kinetically inhibited at the
bulk system temperature and pressure. Low-cost raw materials can be used for most
hydrothermal and mechanochemical
temperatures (up to 450
hydrothermal processes which, when coupled
with the use of conventional autoclaves and mills, can lead toward the development of
low-cost powder synthesis processes. Mechanochemical
hydrothermal synthesis was
performed at room temperature utilizing system compositions so that the model calcu-
lations indicated would yield phase-pure HAp powders. These conditions were effec-
tive for synthesis of phase-pure undoped HAp, carbonate-substituted HAp (CO
3
HAp),
