Non-Debye domain wall response in KH 2 PO 4

Data obtained by dielectric spectroscopy reveal a strongly polydispersive, non-Debye dispersion appearing in potassium dihydrogen phosphate on cooling below the paraelectric-ferroelectric phase transition temperature T c . Characterized by a nearly frequency-independent dielectric loss and a real part of the permittivity decreasing in an almost linear way with frequency on a logarithmic scale, the corresponding relaxation mechanism is discussed in terms of dielectric contributions of elastic domain walls weakly pinned on quenched disorder.