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Further analyses also proved that, with the increased precursor concentrations, the number density of the ZnO nanorods was progressively increased along with the more complete hexagonal wurtzite structures.
Fig. 3(b) demonstrates a calculated number density of the ZnO nanorods per 100 mm2 with respect to the utilized precursor concentration.
This limitation thus resulted in a nearly constant diameter size (Zone II) on the ZnO nanorods prepared at high concentrations, although the number density was significantly increased.
mm2 Fig. 3 Plots of (a) average diameter and the length, and (b) number density of the ZnO nanorods with respect to the utilized precursor concentration. 5 mM 20 mM Fig.4 compares and contrasts the selected XRD patterns of the ZnO nanorods synthesized in the aqueous solution with the precursor concentration 5 and 20 mM.
From the figure, both samples were identified as polycrystalline, according to the JCPDS 76-0704 standard card.

All the diffraction peaks of pure Co3O4 sample matched well with the standard XRD pattern of spinel Co3O4 (JCPDS card No. 42-1467).
The peaks at 35°, 64°, 82° and 45° correspond to (004), (103), (110) and (203) reflections of Ag (JCPDS card No. 41-1402).
Fig. 6 Dependences of the discharge specific capacitance and the columbic efficiency on the charge/discharge cycle numbers.

The three diffraction peaks at the values 28.5o, 47.7o and 56.3o, are corresponding to the lattice planes of (111), (220), and (311), respectively; which evidences the cubic ZnS structure (JCPDS No. 05-0566) [13].
It is worth mentioning that the calculated lattice constant of pure ZnS nanoparticles, a=0.5413 nm, is almost as the same as the value from the standard card (a=0.5425 nm).
Thus, the existence of Mn2+ pairs is important for the occurrence of the concentration quenching process; the excitation energy is transferred from one Mn2+ ion to its nearest Mn2+ ion by nonradiative transition and via a number of transfer steps, finally to a quenching site (such as defect state).
[13] JCPDS Card No. 5-566

In addition, all characteristic peaks of samples are well indexed to the literature values of Gd2O2S (JCPDS card number: 65-3449), which indicates that the molar ration of thiourea/Gd3+ has no significant effect on samples phase composition.
The pattern of (d) is the data of Gd2O2S with JCPDS card No. 65-3449 for comparison To study the effect of reaction time on sample morphologies, FE-SEM images of samples at different reaction times (t=6 h, 12 h, 24 h) are displayed in Fig. 2.

As can be seen, the planes (111), (002), (022), (113) and (222) of SiC are observed at 2 35.3, 41.0, 59.5, 71.3 and 75.0° corresponded to JCPDS card number 96-101-1032, respectively.
Moreover, the planes (111) of Si (JCPDS # 96-450-7227), (002), and (012) of C (JCPDS # 96-101-1061), and (010), (002), (011), (012) and (013) of SiO2 (JCPDS # 96-591-0148) are observed at 2θ 27.9, 25.7, 50.0, 20.0, 21.1, 22.6, 29.4 and 38.3°, respectively.

. �� �� �� �� �� Journal Title and Volume Number (to be inserted by the publisher) 3 Figure 2.
Journal Title and Volume Number (to be inserted by the publisher) 5 Figure 4.
The trend resembles that of the area/volume ratio for a sphere of decreasing diameter (shown in (b) as well). 2 4 6 8 10 12 14 16 18 20 0.5410 0.5411 0.5412 0.5413 0.5414 0.5415 0.5416 0.5417 0.0 0.5 1.0 1.5 ICDD JCPDS PDF #34-0394 (CeO2) Lattice parameter (nm) Average grain diameter, D (nm) Area/volume ratio 300 400 500 600 0.5410 0.5411 0.5412 0.5413 0.5414 0.5415 0.5416 0.5417 ICDD JCPDS PDF #34-0394 (CeO2) a0 (nm) Calcination Temperature (°C) 20 40 60 80 100 120 140 0 1000 2000 3000 Intensity (counts) 2� (degrees) Raw data MS-Rietveld GSR-Rietveld Figure 7.
Journal Title and Volume Number (to be inserted by the publisher) 7 quantity and quality of information extracted from a single diffraction pattern.
[18] JCPDS card #34-0394 [19] Audebrand N., Auffrédic J.P., Louër D., Chem.

The stretching-vibration mode (A2u) of Sn-O and deformation-vibration mode (Eu) of O-Sn-O were found to be broadened and shifted towards the higher wave numbers in case of cobalt doped samples.
The diffraction peaks in the figure are indexed to represent the rutile phase of SnO2 (JCPDS, card no. 77 - 0450) with a preferred orientation in (110) plane.
The A2u and Eu modes were found to be shifted toward the higher wave numbers with increase in cobalt contents, which may due to the change in O-Sn-O environment with the presence of cobalt.
Since, lighter molecules give their vibrational modes at higher wave numbers therefore, the appearance of the Eu and A2u modes at higher wave numbers could be due to the incorporation of cobalt into the tin oxide lattice via formation of cobalt substituted SnO2.

Wide band gap semiconductor nanocrystals containing a great number of defects, surface states or doped with optically active luminescence centers have created new opportunities for optical studies and development of applications.
The planar spacing of about 0.29 nm showed in Fig. 2c corresponds to the spacing for (101) planes of ZnS hexagonal structure reported in the database of Joint Committee on Powder Diffraction Standards (JCPDS) (Card 75-1547).
It corresponds to the spacing for (002) planes of ZnS hexagonal structure reported in JCPDS files (Card 75-1547).

The effect of annealing on the structural and electrical properties of copper films has been investigated by a number of workers [5-10].
These films have face cubic structure as confirmed by comparing the peak positions of the XRD patterns with the standard JCPDS card # 040836[11].
[11] JCPDS Card N0.040836 [12] B.D.

But in Fig. 2(d), the number of the fibers decreased and the diameter of the composite fibers increased.
All the peaks agreed well with the JCPDS card (No.89-1397), that conforming the formation of pure ZnO phase after the calcination.