High temperature phase transitions in N,N-diisopropylpropan-1-ammonium perchlorate

Abstract

Powder X-ray diffraction and second harmonic generation measurement show that N,N-diisopropylpropan-1-ammonium perchlorate (DAP) transforms from a noncentrosymmetric orthorhombic structure (space group Pna2₁) to a centrosymmetric tetragonal structure at 334 K, then to a higher symmetry centrosymmetric tetragonal structure at 374 K. Dielectric constant measurement reveals it is an improper ferroelectric to paraelectric phase transition at 334 K. The second nonlinear coefficient χ⁽²⁾ is as large as that of KH₂PO₄, a typical nonlinear optical material. Therefore, DAP may have many important applications in electric material fields.