کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1296621 | 1498338 | 2010 | 6 صفحه PDF | دانلود رایگان |

Dense, crack-free and uniform nanocrystalline La2−xAxMo2O9−δ (A = Ca, Sr, Ba, and K; x = 0, 0.05) (LAMOX) films were successfully synthesized on polycrystalline Al2O3 substrates by a modified sol–gel method. Pure LAMOX phases with an average grain size of 200–300 nm were obtained when the annealing temperature was about 650 °C. The cell parameter of nanocrystalline LAMOX films is larger than that of the corresponding microcrystalline samples. The conductivity of the nanocrystalline pure La2Mo2O9 film reaches 0.07 S/cm at 600 °C, much higher than that of the corresponding bulk materials. The 2.5%Ca, Sr, Ba, and K-doping can suppress the phase transition occurred at 580 °C in pure La2Mo2O9 and enhance the low-temperature ionic conductivity. Furthermore, the activation energy of conductivity in the nanocrystalline La2Mo2O9 films decreases to about 0.6 eV in comparison with 1.0 eV in the bulk ones. The increase of unit cell free volume resulted from the intrinsically larger cell parameter of nanocrystalline grains may be mainly responsible for the enhancement of conductivity and decrease of activation energy.
Journal: Solid State Ionics - Volume 181, Issues 33–34, 25 October 2010, Pages 1510–1515