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These results are in good accord with that reported in JCPDS data cards.
In addition, all the NBE peaks show a blue shift compared with those of pure ZnO film, which confirms that alloying Mg in ZnO increases the fundamental band gap energy of ZnO.
Each defect has its corresponding defect level, and the defect type determines the position and number of emission peak, but concentration determines the peak intensity.
Look, Recent advances in ZnO materials and devices, Mater.
Shi, et al., Electronic structure of ZnO and its defects, Sci.

Furthermore, the intrinsic anisotropy and the higher surface energy in the polar surface of ZnO promote the preferential growth along the [0001] direction and one-dimensional (1D) ZnO can be obtained under different conditions.
In addition, ZnO nanostructures prepared by these methods conventionally have poor dispersion.
All the diffraction peaks can be exclusively indexed to wurtzite structure of ZnO with lattice constants of a=3.24 Å and c=5.19 Å, which is in good agreement with the literature values (JCPDS card number 36-1451).
Each spine of the fourlings is a ZnO crystal, elongating along the c-axis.
The ball-like ZnO nanostructure was formed through the aggregation of nano-sheets.

There are number of investigations on photoluminescence (PL) property of ZnO nanocrystals [5, 6].
The preparation conditions will have significant effect on the visible luminescence properties of ZnO which can alter the surface chemistry and luminescence properties of ZnO colloids [9].
ZnO nanostructures were synthesized using chemical precipitation method [11].
The crystal system was found to be hexagonal using standard JCPDS card. 79-0205.
Fig. 3 PL spectra of PVP capped ZnO nanostructures Conclusion PVP capped ZnO nanostructures were synthesized by chemical precipitation method.

ZnO normally crystallizes in hexagonal wurtzite structure.
Results and Discussion XRD patterns in Fig.1 shows all the diffraction peaks indexed for hexagonal wurtzite structure of ZnO and the diffraction data fitted very well to the JCPDS card number 36-1451 for ZnO.
ZnO growth in cloudy solution where Zn2+/OH- = 1:7.5 showed precipitation of ZnO with very small particles.
However, ZnO growth in clear solution in which Zn2+/OH- = 1:20 led to precipitation of ZnO in a more uniform hexagonal manner.
Acknowledgements The authors would like to thank Department of Materials Science and Engineering, Silpakorn University, Silpakorn University Research and Development Institute and Office of the Higher Education Commission under contract number SURDI_MUA 54/01/02 for financial support.

The XRD pattern of bacteria/ZnO core-shell spheres without calcination in Fig. 1a is similar with that of calcined at 700˚C in Fig. 1b except for lower intensity of the diffraction peaks, comfirming that the shells of the two samples are composed of wurtzite ZnO (JCPDS card NO. 36-1451, a=3.249Å, c=5.206Å) nanocrystals.
(b) ZnO hollow spheres after calcination at 700˚C.
Fig. 4 TEM images of (a) Bacteria/ZnO core-shell spheres.
(b) ZnO hollow spheres after calcination.
(c) An individual ZnO hollow sphere.

Morphological, Structural and UV Sensing Properties of Fe-Doped ZnO Nanorods Q.
Numbers of ZnO deposition techniques like radio frequency deposition [5], chemical vapor deposition [6], spray pyrolysis [7] and sol-gel [8] has been implemented by the researchers.
All the diffraction peaks are associated with the JCPDS card no. 036-1451 of the hexagonal ZnO structure.
XRD patterns of the ZnO:Fe (0.8 at%, 1 at% and 3 at%) nanorods.
At 3 at% Fe-doped ZnO nanorods the higher photoresponse was obtained while minimum obtained at 0.8 at % Fe doped ZnO nanorods.

Al-doped ZnO Nanoparticles Synthesized by Sonochemical-assisted Method *K.
Al is one of the most proper element widely used as a dopant for ZnO.
Meanwhile, peak position appeared at 31.41° and 36.97° initially appeared as calcination temperature reached to 900-1000 oC, are plane of AlZnO (JCPDS card number 96-900-7020).
Possible mechanism for the formation of ZnO by sonochemical process is suggested.
After calcinations, this product can transform to well-defined ZnO nanoparticles.

A number of synthetic routes have been employed to synthesize ZnO nanoparticles and nanorods.
Interestingly, we found that ZnO nanoparticles are readily produced by the reaction of zinc metal with ethanol.
Figure 2: FESEM images of nano-rods of ZnO prepared by zinc metal with ethanol at 100o C for (a) 24 hrs and (b) 48 hrs.
The corresponding EDX analysis confirming the existence of Zn and O The XRD patterns (fig. 4) of the ZnO nanoparticles could be indexed to the hexagonal wurtzite structure (space group: P63mc; a = 0.3249 nm, c = 0.5206 nm, JCPDS card No. 36-1451).
The growing temperature for the ZnO nanorods was just 100o C.

It could be seen that all these XRD peaks could be indexed as the hexagonal ZnO, consistent with the values in the standard card (JCPDS 36-1451).
Tt could be seen that the response of sensor made of pencil-like ZnO nanorods was much higher than that of needle-like ZnO nanorods.
Growth Mechanism of 1D ZnO Nanocrystals.
The growth units of the ZnO crystals are the complex of in the hydrothermal process, whose coordination numbers of Zn2+ is four.
Thus it reduced the growth rate of ZnO crystals leading to the formation of the elongated ZnO nanorods with bigger aspect ratios.

On the basis of the remarkable physical properties and the versatile applications of the ZnO material, a number of 1D ZnO nanomaterials with different morphologies such as wires [5], rods [6], needles [7], columns [8], towers [9], belts [10], nails [11], helices [12], combs [13], and Tetrapod [14] have been successfully synthesized.
The FTIR spectrum has been recorded using a SHIMADZU FTIR – 8400S spectrometer in the wave number range of 400 - 4000 cm-1.
EDAX spectrum of flower-like ZnO nanostructures.
They are in agreement with the standard JCPDS 036–1451 card with the lattice parameter values of a = 0.3249 nm and c = 0.5206 nm.
Zinc oxide, with a high surface reactivity owing to a large number of native defect sites arising has emerged to be an efficient photocatalyst material compared to other metal oxides [25-27].