The effects of oxygen-catalysed and heat treatment on the precipitation synthesised ZnO nanoparticles

Figures & data

Figure 1. XRD pattern of the samples synthesised with catalysed O₂ and heat treated at 550, 700 and 850 °C. The inset figure represents XRD pattern for sample prepared without excess of O₂ under heat treatment at 550 °C.

Table 1. Average crystallite size calculated via Scherrer equation from (101) plane.

	ZnO prepared in excess of O2			ZnO prepared without excess of O2
Temp (°C)	2θ (degree)	FWHM (×10^−3 radian)	D, crystallite size (nm)	2θ (degree)	FWHM (×10^−3 radian)	D, crystallite size (nm)
550	36.3	6.839	21	36.35	6.839	21
700	36.40	6.735	22	36.30	6.473	23
850	36.25	4.482	33	36.35	4.937	30

Figure 2. SEM images of prepared ZnO nanoparticles (a)–(c) with excess of O₂ (d)–(f) without excess of O₂, under heat treatments at 550, 700 and 850 °C, respectively.

Figure 3. TEM images of the ZnO synthesised with excess of O₂ calcined at (a) 550 °C, (b) 700 °C and (c) 850 °C.

Table 2. Peak position and photon energy of the synthesised ZnO sample.

	ZnO prepared in excess of O2		ZnO prepared without excess of O2
Temp (°C)	Eg (eV)	λ (nm)	Eg (eV)	λ (nm)	Eg (eV)	λ (nm)
550	2.90	427	3.08	402	2.14	579
700	2.94	421	3.00	413	2.27	546
850	2.95	420	2.93	423	2.35	527

Figure 4. PL spectra of ZnO nanoparticles synthesised with excess of O₂ under different heat treatment. The inset shows PL spectra without excess of O₂ for comparison.

Figure 5. Calculated defects level in ZnO.

Figure 6. Impedance spectra of ZnO nanoparticles synthesised under O₂ diffusion and calcined at 850 °C.