کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5363803 | 1388306 | 2007 | 7 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Spin-deposited nanocrystalline lithium ferrite thin films: Fabrication and characterization Spin-deposited nanocrystalline lithium ferrite thin films: Fabrication and characterization](/preview/png/5363803.png)
Thin films of lithium ferrite (with general composition Li0.5Fe2.5O4) were fabricated at low temperatures (up to 650 °C) by citrate-route using spin-deposition technique. Deposited films consisted of nanometer-sized grains as evidenced by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. XRD patterns for annealed films showed broad peaks exhibiting a spinel phase. Size of nanocrystallites is estimated to be 3-7 nm using Scherrer's equation. Average grain size â¼8.5 nm is observed from TEM images of films annealed at 650 °C. Scanning electron micrographs show the formation of spherical aggregates of around 130 nm in diameter. The AFM analysis clearly evidenced the development of nanograins even at low (â¼500 °C) annealing temperatures. Significant decrease in complex dielectric permittivity (ââ²Â â jââ³) with frequency is observed in the low frequency (100 Hz-1 MHz) as well as in X-band microwave frequency (8-12 GHz) region. ââ² is found to be in the range of 15.7-33.9 in low frequency region, whereas in X-band microwave frequency region, it is found to lie between 3.9 and 4.9. Similarly, ââ³ is found to be 0.16-5.9 in the low frequency region, and 0.002-0.024 in the X-band microwave frequency region. Room temperature dc resistivity of these films is estimated to lie in the range of 106-108 Ω cm. These results strongly suggest that citrate-route processed nanocrystalline lithium ferrite thin films are promising candidates for monolithic microwave integrated circuits (MMICs).
Journal: Applied Surface Science - Volume 253, Issue 22, 15 September 2007, Pages 9039-9045