Preparation of three-dimensionally ordered macroporous perovskite materials

In this paper, we use La_{0. 8}Sr_{0. 2}MnO₃ and La_{0. 7}Ca_{0. 2}Sr_{0. 1}MnO₃ as examples to demonstrate a preparation method for three-dimensionally ordered macroporous (3DOM) perovskite thermochromic materials. Polystyrene spheres with an average diameter of 220 nm were self-assembled into a three-dimensionally ordered colloidal crystal template. A mixed metal nitrate solution prepared using La(NO₃)₃·6H₂O, Ca(NO₃)₂·4H₂O, Sr(NO₃)₂, Mn(CH₃COO)₂·4H₂O and an ethanol precursor was used to fill the interstitial voids of the polystyrene colloidal crystal templates. 3DOM La_{0. 8}Sr_{0. 2}MnO₃ and La_{0. 7}Ca_{0. 2}Sr_{0. 1}MnO₃ materials were then obtained after the sphere templates were removed via drying and calcination. The results show that the framework of the 3DOM materials can have different thicknesses and pore shrinkage rates by varying the filling times. In addition, the Curie temperatures of the 3DOM and bulk La_{0. 8}Sr_{0. 2}MnO₃ materials can be varied by altering the preparation method.