Dielectric and thermal studies of phase transition in (CH₃)₂NH₂H₂AsO₄

Abstract

Dielectric and AC calorimetric investigations were carried out for the single crystal of dimethylammonium dihydrogen arsenate, (CH₃)₂NH₂H₂AsO₄. The complex dielectric constant ε* was measured in a frequency range between 10 MHz and 13 GHz. The critical slowing-down phenomenon of polarization was observed above T_c . In the paraelectric phase, the relaxation time τ can be well explained by the quasi-one-dimensional Ising model. The activation energy was estimated to be E_a = 64.3 meV. The transition heat and the transition entropy were obtained as ΔQ = 240 J/mol and ΔS = 0.95 J/mol·K, respectively.

Key Words:

• (CH₃)₂NH₂H₂AsO₄
• phase transition
• dielectric dispersion
• quasi-one-dimensional
• transition heat
• transition entropy