Author(s) |
Mandal, B. P.; Dutta, A.; Deshpande, S. K.; Basu, R. N.; Tyagi, A. K.
|
Three solid solutions of pyrochlores in the series
Nd2-yearsGdyZr2O7 (y = 0.8, 1.0, 1.2) were
synthesized by the gel combustion method using citric acid as fuel. This results in a soft
agglomerate powder as verified by dynamic light scattering. The single-phase nature of the
products has been confirmed by x-ray diffraction. The increase in full width at half-maxima
in the Raman spectra with an increase in Gd3+ content indicates that disorder increases with
Gd3+ content. The morphology and particle size of the products were investigated by
transmission electron microscopy. Scanning electron microscopy study reveals that the
sintered pellets have a density higher than 92% of theoretical densities. The total ionic
conductivity measurements in the temperature range 375–800 °C
show that with the increase of disorder (Gd3+ content) in the system the activation energy of conduction
increases from 0.98 to 1.06 eV and the preexponential factor, which is proportional to the
number of mobile species, also follow the same trend of increase. The total conductivity
measured in reducing atmosphere shows no change in electrical conductivity, which verifies
a negligible contribution of electronic contribution in this system.
|