JST Vol. 21 (1) Jan. 2013 - Pertanika Journal - Universiti Putra ...

Physico-Chemical and Electrical Properties of Bismuth Chromate Solid Solutions
Fig.10: The modulus spectroscopic plot of M”, -Z” versus log f of Bi 6Cr 2O 15 at 450 o C
CONCLUSION
Fig.11: The Arrhenius conductivity plots of Bi xCr 2O δ (4 ≤ x ≤ 7)
The solid solutions in the Bi 2O 3 – Cr 2O 3 system have been successfully synthesized via
conventional solid state method. Among the compounds synthesized in which Bi:Cr ratio range
from 1.5:1 to 4:1 and as determined from the X-ray diffraction (XRD) analyses, only four
were in the pure phase with the orthorhombic structure, i.e. Bi 4Cr 2O 12, Bi 5Cr 2O 13.5, Bi 6Cr 2O 15
and Bi 7Cr 2O 16.5. The SEM image showed a homogeneous dispersion of microstructure and
the presence of pores in the inter-granular area. The occurrence of the phase transitions at
high temperatures was confirmed by the thermal analyses. The thermal analyses showed an
irreversible endothermic peak at temperature ~ 800 o C on heating cycle. Besides, the TGA
results showed that there is a weight loss after 700 o C.
The activation energy for the solid solution in Bi 2O 3-Cr 2O 3 system is in the range 1.22
eV- 1.32 eV. The moderate ionic conductivity of the samples can be related to the moderate
Pertanika J. Sci. & Technol. 21 (1): 283 - 298 (2013)
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