Relaxor behavior in multiferroic BiMn2O5 ceramics

Abstract

In polycrystalline BiMn 2 O 5 , a broad thermal stimulated depolarization current curve has been observed in the range from 10 K to 300 K and the pyroelectric coefficient determined. In magnetic susceptibility measurements reported in the literature, features appearing in the pyroelectric coefficient could also be identified for the same temperatures, suggesting a connection between electric and magnetic data above the Néel temperature. A detailed study of the dielectric constant from 240 K to 700 K for an extended range of frequencies revealed a broad maximum at low frequencies, characteristic of relaxor ferroelectrics, following Vogel-Fulcher relation. A freezing temperature of the polar nanoregions T f ¼ 512 K has been determined. This high temperature ferroelectric behavior is attributed to the Bi 3þ in the distorted BiO 8 cage.

Hydrostatic pressure influence on electric relaxation response of bismuth manganite ceramics

“…We note that VF was fitted from 330 to 390 K. The crossover from Arrhenius to VF dependence is consistent with DSC measurements, which exhibited a change in the slope of the temperature dependence of the heat flow in the vicinity of 325 K. Hence, we deduce that the BM ceramics exhibits the glassy features corresponding to structural disorder. It is worth mentioning that the occurrence of disorder behavior also related to VF dependence, fulfilled in the 520−570 K range, was previously reported for multiferroic BiMn 2 O 5 ceramics …”

“…It is worth mentioning that the occurrence of disorder behavior also related to VF dependence, fulfilled in the 520−570 K range, was previously reported for multiferroic BiMn 2 O 5 ceramics. 24 The hydrostatic pressure test conducted in isobaric conditions, P = 800 and 1600 MPa, was conducted in the 253-363 K range. The relaxation process visible in isobaric ε"(f)…”

Electrochemical supercapacitor based on multiferroic BiMn 2 O 5

“…In the previous investigation [32] we discovered a pyroelectric effect in the range of 77e500 K in the a-axis direction of BiMn 2 O 5 monocrystals. The pyroelectric properties were also reported [33,34] for polycrystalline BiMn 2 O 5 in a wide temperature range. The pyroelectric current changed its sign with switching the direction of the poling field of the polycrystalline material [34].…”

“…The studies of frequency dependence of the dielectric constant revealed [35] a low temperature dielectric relaxation, attributed to the hopping of charge between Mn 3þ and Mn 4þ , and high temperature dielectric relaxation, related to oxygen defects. The analysis of the dielectric constant at different conditions [33] suggested a relaxor type ferroelectric behavior at high temperatures. However, no direct evidence of ferroelectric hysteresis behavior was observed at room temperature [30].…”

EDTA-assisted hydrothermal synthesis and magnetic properties of urchin-like YbMn2O5 microspheres

“…However, it is of very difficulty in garnering single crystalline phase YbMn 2 O 5 with controlled microstructure owing to process characters [12]. In fact, several wet chemical methods, including sol-gel method [13] and hydrothermal synthesis [14,15], were developed to synthesize RMn 2 O 5 powders. Among them, hydrothermal synthesis has been receiving much interest due to its great advantages, such as low process temperature, one-step synthesis procedure, and easy handing [16,17], for example, YbMn 2 O 5 nanorods with diameter ~ 40 nm and ~ 500 nm in length were synthesized by a simple hydrothermal method [18].…”