The Role of Hydrogen Bonds in Antiferroelectricity of NH₄H₂PO₄

Abstract

From a microscopic viewpoint on the role of two kinds of hydrogen bonds, antiferroelectric phase transition in NH₄H₂PO₄ is re-examined. The role played by the protons of NH₄ ions is explicitely taken into account, and it is shown that the hydrogen bonding effect of NH₄ ions with neighbouring oxygens may be renormalized into the effective antiferroelectric interaction between protons which form the network of hydrogen bonds connecting PO₄ groups.