Abstract

• Dihydrogen Phosphate (ADP) NH4H2PO4 have been grown by slow evaporation technique from the supersaturated solution at room temperature. The pure and doped (KDP-ADP) crystals show a phase transition like phenomena named as high temperature phase transition at a characteristic temperature Tp. Upon heating above the Tp, the pure and doped (KDP-ADP) crystals experience a thermal dehydration. In order to investigate the nature of phase transition in MH2PO4-type crystals (M=K or NH4), temperature-dependent resistivity measurements on mixed KDP-ADP crystals performed. The activation energies of pure and doped (KDP-ADP) crystals were 0.45eV for KDP, 1.3eV for A-KDP, 1.17eV for K-ADP and 2.87eV for ADP.