Geoscience Reference
In-Depth Information
(a)
T
(ºC)
LiPr(WO
4
)
2
+
600
+
Pr
2
W
2
O
9
550
LiPr(WO
4
)
2
500
450
LiPr(WO
4
)
2
+
+
Pr
WO
4
OH
400
1:5
1:4
1:3
1:2
1:1
2:1
3:1
Pr
2
O
3
/WO
3
(b)
T
(ºC)
Pr
4
W
3
O
15
+
Pr
2
W
2
O
9
Pr
3
WO
6
Cl
3
+
600
Pr
2
W
2
O
9
+
Pr(OH)
2
Cl
Pr
2
W
2
O
9
+
+
PrWO
4
Cl
550
Pr
2
W
2
O
9
+
PrWO
4
OH
500
1:5
1:4
1:3
1:2
1:1
2:1
3:1
Pr
2
O
3
/WO
3
(c)
T
(ºC)
PrWO
4
Cl
+
+
PrWO
4
OH
Pr
2
W
2
O
9
600
Pr
3
WO
6
Cl
3
+
+
Pr(OH)
2
Cl
550
Pr
2
W
2
O
9
+
PrWO
4
Cl
500
PrWO
4
OH
PrWO
4
OH
+
PrWO
4
Cl
1:5
1:4
1:3
1:2
1:1
2:1
3:1
Pr
2
O
3
/WO
3
Figure 8.12 TN-diagram of crystallization (N
5
Pr
2
O
3
/WO
3
)
[46]
.
On the whole, the growth of alkali rare earth tungstates by the hydrothermal method
is quite complicated due to the high temperature of synthesis involved and the lack of
solubility data. Moreover, the crystals obtained by earlier workers were fine grained or
small rounded or subrounded.
