Dielectric properties of ferroelectric betaine phosphite crystals with a high degree of deuteration

Crystal Structure, Raman Spectroscopy and Dielectric Properties of New Semiorganic Crystals Based on 2-Methylbenzimidazole

“…The magnitude of DC conductivity decreased with cooling in accordance to Arrhenius law with isotropic activation energy E a = 0.6 eV. This value of E a is smaller than for protonic conductivity in ferroelectrics with hydrogen bonds, where E a ≈ 0.8-1 eV [23,58,59], but is close to the value of activation energy of conductivity in proton superionics [63]. Note that both the sharp increase in conductivity above a certain temperature and the value of activation energy of conductivity is characteristic of proton superionics [63].…”

“…With heating above 250 K, a strong increase and a low frequency dispersion of εa and tg was observed. Such temperature behavior is characteristic for ionic (protonic) conductivity in crystals with hydrogen bonds [23,58,59]. Specific electric conductivity is calculated as  = 0tg = 0, where  = 2f the angular frequency.…”

“…Figure 11a shows the MBI-phosphite-specific conductivity  as a function of inverse temperature for a-, b-, and c*-axes in a semilogarithmic scale. In just-prepared crystal at heating above 250 K up to 330 K, the conductivity a along the a-axis did not reveal Such temperature behavior is characteristic for ionic (protonic) conductivity in crystals with hydrogen bonds [23,58,59]. Specific electric conductivity is calculated as σ = ωε 0 ε tgδ = ωε 0 ε", where ω = 2πf the angular frequency.…”

“…The only candidates for the role of charge carriers are the protons. Note that the proton conductivity has been observed in a large number of crystals with hydrogen bonds such as DBPI-DBP [23,58], MBI [59,62], etc.…”