It is indicated that the ZnO and BaCO3 nanocrystals have been grown independently. No other diffraction peak related to the other compounds or impurities was detected. The

crystallite sizes of the ZnO/BaCO3 nanoparticles were calculated using the Scherrer equation and obtained to be 17 ± 2, 18 ± 2, and 21 ± 2 nm, respectively. The calculations were applied on the ZB-NPs XRD pattern using parameters related to the (101) (for ZnO) diffraction peaks. A typical TEM image of ZB20-NPs is presented in Figure  2. The average particle size of the ZB20-NPs was obtained to be about 30 nm. It can be seen that the average value of the measured particle sizes is in selleckchem good agreement with the calculated crystallite sizes as expected. Figure 1 XRD patterns of the synthesized ZnO and ZB nanoparticles. Figure 2 Typical TEM image of the ZB20 nanoparticles and the corresponding size distribution histogram. UV–Vis diffuse reflectance spectra and bandgap UV–Vis reflectance spectra of the pure ZnO-NPs and ZB-NPs prepared at a calcination temperature of 650°C are shown in Figure  3. The relevant increase in the reflectance at wavelengths bigger than 375 nm can be related to the direct bandgap of ZnO due to the transition of an electron from the valence band Selleckchem PRIMA-1MET to the EX 527 in vivo conduction band (O2p → Zn3d) [28]. An obvious redshift in the reflectance edge was observed

for ZB-NPs compared to the pure ZnO. As obtained in the ‘XRD analysis’ section, the crystallite size of the ZnO nanoparticles is increased out by adding BaCO3; therefore, this redshift can be related to the quantum confinement effect or quantum size effects. This might be due to changes in their morphologies, crystallite size, and surface microstructures of the ZnO nanocrystals besides the BaCO3 nanocrystals. The result

of the UV–Vis spectroscopy can be used for calculating the optical bandgap of the materials. Using the Kubelka-Munk model is a way to calculate the optical bandgap, while the direct bandgap energies can be estimated from a plot of (αhν)2 versus the photon energy (hν) [22]. This method has been obtained from the Tauc relation, which is given by [29] (1) where A is a constant and m = 2 when the bandgap of the material is direct. Also, the absorption coefficient can be obtained from [30] (2) where R is the reflectance. Figure 3 The reflectance spectra of the synthesized (a) ZnO, (b) ZB10, and (c) ZB20 nanoparticles. The inset shows the obtained optical bandgap using the Kubelka-Munk method. The derivative method has been found as an easy and accurate method to calculate the optical bandgap compared to the Kubelka-Munk method. In this method, the direct bandgap can be estimated from the maximum of the first derivative of the absorbance data plotted versus energy or from the intersection of the second derivative with energy axis. The energy bandgap of the synthesized samples at 650°C was estimated from the methods mentioned above.