Characterization of structural transitions and lattice dynamics of hybrid organic–inorganic perovskite CH3NH3PbI3
Jin Feng1, Ji Jian-Ting2, Xie Chao3, Wang Yi-Meng1, He Shu-Na1, Zhang Lei4, Yang Zhao-Rong4, Yan Feng3, Zhang Qing-Ming2, 5, †
       

(a) Temperature dependence of the lattice constants across the tetragonal–orthorhombic transition. Temperature evolution of the (b) (002) and (c) (020) diffraction peaks.