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Fig 2 shows the mass percent and the visual grain size of films as a function of the number of coating cycles.
All the XRD peaks were identified with the standard card JCPDS 36-1451in the recorded range of 2θ.
Fig 4 indicates that the transmittance of ZnO films gradually decreased as the number of coating cycles increased.
Higher values of magneto-resistance for different thicknesses have been found in ZnO thin films. a,b and c are for different number of layers as "a" is for 3 layers i.e. 860 nm thickness, "b" is for 5 layers i.e. 1160 nm thickness and "c" is for 10 number of layers i.e. 1510 nm thickness.
Resistivity and sheet resistance measurements with thickness: Resistivity measurements of ZnO thin films for different number of layers are done.

The total density of state of ZnO ZnO nanoparticle characterization.
It is clear that all of the peaks in Fig. 4 matched with the standard JCPDS cards of ZnO (JCPDS 79-2205) with a wurtzite hexagonal structure.
It was noticeable that ZnO NPs in the S2a and S2bstructures were a compact combination of ZnO nanoflakes.
However, the number of nanoflakes in S2b was higher than S2a.
Increasing the particles number will work on reducing the interfacial tension more due to Brownian motion [22, 23].

It has been reported by Baruah et al. that ZnO has emerged as a more efficient photocatalyst than TiO2 due to its high surface reactivity owing to its large number of active surface defect states [11].
The peak positions are found well matching with those of the standard pattern of ZnO hexagonal phase with a wurtzite structure phase according to (JCPDS card No. 36-1451).
According to (JCPDS card No. 07-0155) attributed to simonkolleite material, the incomplete reaction leads to the appearance of diffraction peaks relative to (Zn5(OH)8Cl2H2O) phase.
The lattice constants of the ZnO structures are calculated and are in agreement with the reported values which are a = b = 3.249 Å and c = 5.207 Å according to the JCPDS data reflecting the high crystallinity of namely Zn(CH3COO)2 and Zn(NO3)2 precursors produced ZnO NPs.
ISSN Number: 2149-2123

ZnO and δ-MnO2 with different bandgap energy was studied.
The structure of ZnO could be described as a number of alternating planes composed of tetrahedrally coordinated O2- and Zn2+ stacked along the c-axis.ZnO can be used for a number of applications such as NO2 gas sensor[11], UV laser[12], light emitting diode[13], solar cell [14] and nanogenerator[15]. d-MnO2 has a narrower bandgap energy (1.30eV)[16].
The XRD pattern of δ-MnO2 at molar ratio 6:1 could be indexed as δ-MnO2 (refers to JCPDS 80- 1098)as shown in Fig. 1(a).No diffraction peaks for other polymorphous of MnO2could be detected.The morphology of the δ-MnO2 nanoparticles obtained was examined by FESEM as depicted inFig. 1(b).
ZnO nanoparticles.XRD analysis of the as-received nanoparticles could be indexed to hexagonal ZnO (JSPDS Card No. 41-488) as shown in Fig. 2(a).
δ-MnO2 ZnO Slope (min-1) 0.0067 0.0273 St. error 4.14E-04 7.66E-04 R-square 0.9812 0.9981 Fig. 7: Degradation of RhB aqueous solution by δ-MnO2 and ZnO nanoparticles.

Results and Discussion Fig. 1 shows the XRD pattern of the CuAlO2 powders, all the diffraction peaks match well with JCPDS data card no. 35-1401, showing that the crystalline structure of the CuAlO2 powders is 3R polytypes which belongs to the R3m space group, and has a trend to grow in the (0 0 l) orientation [15].
The measured lattice parameters are a = 2.8553 Å and c = 16.943 Å , which are closely to the standard lattice parameters of JCPDS data card no. 35-1401: a = 2.8567 Å and c = 16.943 Å, the measured lattice parameters also agreed with those previously reported for this material [16] as well.
Even at the shortest holding time (5 h), all the diffraction peaks match well with JCPDS data card no. 35-1401.
Moreover, it should be noted that the number of elongated grains and the degree of elongation in elongated grains increase with sintering temperatures.
Kukreja, Transparent P-AgCoo2/N-Zno Diode Heterojunction Fabricated by Pulsed Laser Deposition,, Thin Solid Films. 515 (2007) 7352-7356

As seen in Figure 3 that the prominent peaks of (100), (002), (101), (102) and (110) and other smaller diffraction peaks well correspond to the standard spectrum of wurtzite hexagonal ZnO structure (JCPDS card NO. 36-1451).
Figure 4 demonstrates the typical SEM image of the synthesized ZnO nanowires.
Figure 4: SEM image of the prepared ZnO nanowires.
And tiny ZnO nanoparticles formed from the dehydration of Zn(OH)42− ions.
When surfactant PEG was added to the precursor solution, a large number of tiny Zn(OH)42− and ZnO nanoparticles embedded into PEG long-chain substrate and easily grew along the long chain of PEG.

The existence of multiple diffraction peaks of (100), (002), (102), (110), (103),(200),(112) and (201) in the diffraction patterns suggests that the ZnO samples have a typical Hexagonal structure referring to JCPDS card no. 36-1451 data[7].
It is believed that as the particle size increases, the number of atoms that form a particle also get increasing which consequently render the valence and conduction electrons more attractive to the ions core of the particles, and hence decreasing the band gap of the particles.
Fig. 3, The method of extracting the band gaps of ZnO nanoparticles calcined at different calcination temperatures.
Tab. 1, Particle size and band gap of synthesized ZnO nanoparticles at different calcination temperatures.
Man Choi, Electrical and reducing gas sensing properties of ZnO and ZnO–CuO thin films fabricated by spin coating method, Sensors and Actuators B: Chemical, 55 (1999) 47-54

A number of techniques for synthesizing doped ZnO nanostructures have been developed.
For examples, Sn-doped ZnO nanorods (NRs) were produced by a mixture of ZnO, SnO2 and graphite powder at 1000oC for 60 min. [12]; Cu-doped ZnO NRs were synthesized by heating a mixture of Zn1-xCuxO powder with graphite powder at 960 oC for 15 min. [13]; Eu-doped ZnO NRs were grown from a mixture of Zn, ZnO and Eu2O3 powder [14] and In-doped ZnO NRs were synthesized using ZnO, In2O3 and graphite powder at 935 oC for 40 min. [15].
The diffraction peaks matched well with the hexagonal wurtzite structure of ZnO (lattice constant a = 0.3249 nm and c = 0.5205 nm, JCPDS Card No.36-1451).
The ZnO NRs have hexagonal tips.
SEM images of the (a) undoped ZnO NRs, (b) Fe-doped ZnO NRs with 30 min. doping duration, and (c) EDX spectrum of Fe-doped ZnO NRs with 30 min. doping duration.

Figure 6 shows the HRTEM image of silver nanoparticles deposited on the ZnO 1D rod, and was indexed assuming Fm-3m symmetry obtaining a unit cell value of 4.09 Å in agreement with the data reported for the JCPDS card number 065-2871.
XRD pattern of the ZnO, 1.5Ag/ZnO 1D (fresh and spent) and 5Ag/ZnO 1D catalysts.
space group P63mc corresponding to the JCPDS 36-1451).
After silver impregnation and thermal treatments, the XRD patterns of the 1.5Ag/ZnO and 5Ag/ZnO showed peaks corresponding to Ag 0 (JCPDS 065-2871) and peaks of the ZnO structure.
Between them, the 1.5Ag/ZnO one dimensional sample had the best H2 yield than ZnO and 5Ag/ZnO 1D samples.

The (1 0 0), (0 0 2), (1 0 1), (1 0 2), (1 1 0), (1 0 3) and (1 1 2) peaks appeared for sample A are the characteristic peaks of ZnO hexagonal wurtzite structure (JCPDS File Card No. 36145).
As respects, there was the same amount of precursors in two solution synthesis methods, growing up sample B until 30 min denotes the formation of low number of nucleuses in initiation of process and aggregation of crystallites carried out during the growth time.
While for sample B, synthesis under ultrasonic waves cause the production of more number of nucleuses and growth stage is followed by Ostwald ripening process.
XRD pattern of ultrasonic prepared ZnO demonstrated the existence of single phase ZnO, but additional peaks were appeared for conventional prepared ZnO indicated the incomplete conversion of precursors into ZnO.
Meulenkamp, Synthesis and growth of ZnO nanoparticles, J.