Fig.2: XRD patterns of LaCoO3 nanoparticles, using urea as fuel and calcined at 600°C in air a) sample LCU1 F/O=1, b) sample LCU2 F/O=2.
Finally, crystallite size and the average crystallite size was estimated according to the Debye and Scherrer formula from the (110), (024) and (214) reflection of the LaCoO3 phase at 2q≈ 32.9°, 47.5° and 58.9° respectively, and is represented in Table 2.
\(D=\frac{0.94\lambda}{\beta\cos\theta}\) (1)
Where:
D is the crystallite size
λ is the X-ray wavelength (1.5418 Å)
β is the full width of the half maximum (FWHM) of the diffraction peak
θ is the Bragg diffraction angle
It was evident from the calculation that LaCoO3synthesized using glycine exhibited the lowest crystallite size (~14.9 and 28.1 nm) compared to when urea was used (~41.6 and 25.7 nm). The larger crystallite size of the LaCoO3 phase observed in the LCU1 sample was indicative of the greater growth of its crystal domains. This result reveals that glycine and urea act in opposite manner, while increasing fuel ratio in glycine increase the crystallite size and purity, increasing urea decreases crystallite size and improves purity.
Table 2. Crystallite size, average crystallite size and Z-average size of four samples synthesized with different fuel and fuel to oxidizer ratio (F/O).