Geoscience Reference
In-Depth Information
Figure 7.70 DTA curves for
the representative superionic
pyrophosphates: (a)
Na
2
CaMn
2
(P
2
O
7
)
2
, (b)
Na
2
CoZr(P
2
O
7
)
2
, (c)
Na
2
NiZr(P
2
O
7
)
2
, and (d)
Na
2
CaMn
2
(P
2
O
7
)
2
[302]
.
d
487
c
548
780
b
470
a
447
400
500
600
T
(°C)
700
800
Figure 7.71 Arrhenius plot for
the representative superionic
pyrophosphates: (a)
HNaCoP
2
O
7
; (b) HNaNiP
2
O
7
;
and (c) HNaZnP
2
O
7
[307]
.
3
1
0
-1
(b)
-3
(c)
-5
(a)
1
2
3
10
3
/
T
(K)
temperature and internal frequency.
Figures 7.71
shows the Arrhenius plots for the
representative superionic pyrophosphates.
The AVOPO
4
(A
Li, Na, K) group of compounds are very interesting and iso-
structural with the well-known nonlinear optical material KTiOPO
4
. These com-
pounds have high thermal stability and magnetic susceptibility. The experimental
results
5
show that
the Curie
Weiss
behavior:
λ
M
5
C/CT
2
θ
), where
