**4. Conclusions**

As it is clear from the photocatalytic performance of the Nd0.6Sr0.4MnO<sup>3</sup> perovskite, the crystalline size (55 nm), which depends on the annealed temperature (500°C). The mixed phases (26.18% Orth and 73.82% Mono) in the Nd0.6Sr0.4MnO<sup>3</sup> perovskite as a result of annealing at 500°C is a superior photocatalyst than those of Nd0.6Sr0.4MnO<sup>3</sup> perovskite annealed at different temperatures. The maximum photodegradation of MB for the strontium doped neodymium manganites perovskite was achieved for those annealed at 500°C. As a result of the increase in the annealing temperature (annealing at 1150°C), the reduction to 60% in the photocatalytic efficiency was achieved. Comparing the overall photodegradation rates of the strontium doped neodymium manganites perovskite as a function of the annealing temperature we found 500°C annealing temperature is significantly 3-times higher than that of other temperatures. This superiority of the low annealing temperature in the case of Nd0.6Sr0.4MnO<sup>3</sup> perovskite is attributed to the forming these materials in mixed phases (double phases, Mono – Ortho phases) and its high crystallinity. Besides, the high Mn-O polyhedron distortion excited in these materials. So one can conclude that the annealing temperature plays very important role to improving the photocatalytic performance. The following factors; visiblelight absorption, narrow band gap and lattice distortion are the key factors that determine the high photocatalytic activity of the obtained in such materials and good example for that the Nd0.6Sr0.4MnO<sup>3</sup> perovskite annealed at 500°C.

## **Acknowledgements**

The author is thankful to the Deanship of Scientific Research in Najran University for their support NU/ESCI/15/011.

#### **Author details**

Ihab A. Abdel-Latif1,2\*

