Alternating‐Current Electrical Properties of CaMnO₃ below the Néel Temperature

Abstract

The alternating-current electrical properties of polycrystalline CaMnO 3 were investigated by alternating current compleximpedance analysis, and the dielectric properties were analyzed over the temperature and frequency ranges of 10 to 130 K and 20 Hz to 1 MHz, respectively. Direct-current conductivity and the Seebeck coefficient as a function of temperature also were analyzed. Below 120 K, a Debye-type dielectric relaxation peak was observed. Experimental results implied that the number of charge carriers, which were generated by Mn 3؉ , were not sufficient to stabilize small polarons, although it induced lattice distortion by the Jahn-Teller effect. Therefore, the thermal motion of Mn 3؉ between potential minimums produced by lattice distortion in the orthorhombic structure were believed to be the source of dielectric relaxation. The temperature dependence of conductivity of the grain interior ( gi ) below 120 K was believed to be due to variable rangehopping conduction, where gi Ϸ exp(؊T ؊1/4 ).

Dielectric Relaxation and Hopping Conduction in La2NiO4+δ

“…However, the details of the transport kinetics are still unknown. Although there are many ways of addressing polaron dynamics, dielectric relaxation measurements are useful metrics because the hopping process of polaron has a high probability of involving a dielectric relaxation process [12][13][14][15][16]. Furthermore, many perovskite materials have shown high dielectric or ferroelectric properties and the dipole unit in these systems plays an important role in the electronic transport phenomena [17,18].…”