Geoscience Reference
In-Depth Information
T
(
°
C)
650
K
5
La(MoO
4
)
4
K
5
Sm(MoO
4
)
4
K
5
Sm(MoO
4
)
4
KSm(MoO
4
)
2
Sm
2
MoO
6
Sm
2
MoO
4
600
KSm(MoO
4
)
2
Sm
2
MoO
6
KLa(MoO
4
)
2
550
La(OH)
3
SmMoO
4
OH
500
LaMoO
4
OH
K
5
Gd(MoO
4
)
4
Gd
2
MoO
6
K
5
Gd(MoO
4
)
4
K
5
Ho(MoO
4
)
4
600
KGd(MoO
4
)
2
Ho
2
MoO
6
Ho
2
MoO
6
KHo(MoO
4
)
2
Gd
2
MoO
6
550
K
5
Gd(MoO
4
)
4
KGd(MoO
4
)
2
Gd
2
MoO
4
KHo(MoO
4
)
2
500
HoMoO
4
OH
GdMoO
4
OH
1:1
1:2
1:3
1:4
1:1
1:2
1:3
1:4
N(Ln
2
O
3
/MoO
3
)
N(Ln
2
O
3
/MoO
3
)
Figure 8.17 TN-diagram of crystallization in the system R
2
O
3
a
K
2
MoO
4
a
H
2
O.
for “dry” conditions.
Figure 8.18
shows the photograph of an assembly of
γ
-Bi
2
MoO
6
single crystals obtained in NH
4
Fsolution.
Several oxymolybdates of 1:3 ratio have been obtained and the prominent ones
are Fe
2
(MoO
4
)
3
,In
2
(MoO
4
)
3
, and Fe
2
(MoO
4
)
3
obtained in 5
10 wt% LiCl solu-
500
C and P
tions at T
1000 atm.
Among the mixed rare earth molybdates, the prominent ones are M
1
R(MoO
4
)
2
(M
1
5
5
400
5
400
61]
. These double molybdates are
known for every series of rare earth elements (Ln
Li, Na, K); R
5
rare earth elements
[59
Lu, Y). They are prepared
by crystallization from solution, in the melt, solid-phase synthesis, and by the
hydrothermal method. The entire series of compounds are isostructural
5
La
to the
600
C,
tetragonal scheelite, CaWO
4
. The experimental conditions are T
5
525
P
5
50 wt% of K
2
MoO
4
were used as
solvents and KOH was added to obtain the desired pH of the growth media. The
other molybdates are
1000
1500 atm. Aqueous solutions of 5
-KBi(MoO
4
)
2
, KY(MoO
4
)
2
,K
5
R(MoO
4
)
4
,K
2
Pb(MoO
4
)
2
,
K
2
(K
0.5
R
0.5
)(MoO
4
)
2
, LiLa(MoO
4
)
2
, and so on
[62]
. The experimental conditions,
α
