higher annealing rate is related to improvement in the crystallinity as also verified in our XRD analysis (see Fig. 3). The relevance of the degree of crystallinity and the magnitude of the band gap energy was also observed by the other research groups [27,28].
To investigate the effect of CdO concentration on property of ZnO, we have found different band gap energy by varying the amount of x. Based on our data analysis, band gap narrowing was observed by increasing the amount of x as shown in Table 2. It is well known that CdO is a low band gap energy semiconduc- tor unlike ZnO; hence, it is expected that the band gap energy of the (ZnO)1−x(CdO)x alloy nanofibers should be between these two materials (pure ZnO and CdO). Other researchers also reported band gap energy reduction in the mixed ZnO and CdO composition as compared to pure ZnO [29,30].