Biomedical Engineering Reference
In-Depth Information
0
2
0
0
250
300
350
400
450
5
0
0
0
2
00
250
300
350
400
450
5
0
0
3
6
34
404.62°C
40% La doped B
F
O
3
4
-2
50% La doped BFO
3
2
32
394.53°C
-2
-4
3
0
2
8
30
-6
-4
2
6
-8
2
4
28
-6
297.09°C
2
2
-10
426.64°C
376.96°C
2
0
26
-12
3
98.72
°C
1
8
-8
-14
1
6
24
200
250
300
350
400
450
500
200
250
300
350
400
450
500
Temperature (°C)
Temperature (°C)
(
a
)
(
b
)
Figure 13.33
Heat capacity and Heat l ow vs Temp. curve of Bi
1-x
La
x
FeO
3
(x=0.4 &x=0.5.).
With a further increase of concentration from x=0.2 to x=0.3 and 0.4
(Figure 13.32b and 13.33a), the thermal anomaly shit ed towards the
higher temperature. For compound x=0.3, in specii c heat curve the anti-
ferromagnetic phase transition temperature shit ed up to 395 C, while in
heat l ow curve it shit ed up to 389 C. h e broadness of these peaks are
less than the compound with x=0.2 concentration. For the compound with
x=0.4 concentration, the specii c heat curve shows an exothermic peak
around the same temperature at about 395 C, whereas the heat l ow curve
shows a shit in endothermic peak from 389 C to 376 C.
When the Bi site is 50% substituted with La, the heat l ow curve
(Figure 13.33b) indicates an exothermic peak around 297 C with a shal-
low indication of endothermic peak around 399 C, and no other thermal
events occurred up to the measured temperature region. h e specii c heat
curve in the same i gure indicates a kink around 300 C, just above the exo-
thermic peak in the heat l ow curve. Furthermore, the specii c heat curve
indicates an exothermic very dif use peak just above the endothermic peak
of heat l ow curve around 400 C. h e dif used endo- and exothermic peak
of heat l ow and specii c heat curves may be due to ferromagnetic to para-
magnetic transition, which is yet to be coni rmed by magnetic measure-
ment, while the exothermic peak around 297 C in the heat l ow curve
needs further explanation.
4.7
Summary and Conclusion
Multiferroic materials exhibit two or more properties, i.e., the ferroelectric,
ferroelastic ferromagnetic and ferrotoroidic, simultaneously. Multiferroism
is currently a subject of intensive investigation because it potentially
