Electron transport in CaMnO3 − δ at elevated temperatures: a mobility analysis

Abstract

The drift mobility of electron charge carriers in oxygen non-stoichiometric manganite CaMnO 3− δ was calculated by combining the total electrical conductivity and oxygen non-stoichiometry data at 700-950°С and oxygen partial pressure varying between 10 −6 and 1 atm. The carrier concentration changes with pressure and temperature were obtained with the help of the earlier-developed defect model involving reactions of oxygen exchange and thermal excitation of manganese sites. The activation energy for mobility is found to increase with oxygen non-stoichiometry. High-temperature electron transport properties of the manganite CaMnO 3−δ can be explained in terms of activated jumps of n-type small polarons in adiabatic regime. The relatively small mobility of charge carriers is explained by strong localization of polarons on manganese sites.

Enhancement of redox- and phase-stability of thermoelectric CaMnO3− by substitution

“…First principle studies [28] as well as experiments [18] show that oxygen deficiency largely effects the Seebeck coefficient. The additional charge due to the oxygen loss is compensated by the reduction of Mn 4 þ to Mn 3 þ [14,29].…”

“…The changes in |S| can be semi-quantitatively described using Heikes'-formula [4]. Likewise, the reduction due to oxygen loss causes a higher Mn 3 þ /Mn 4 þ ratio with identical consequences on the transport properties [18]. The reduction can be seen as a "self-doping" process where the additional Mn 3 þ significantly affects the transport properties.…”

Thermoelectric properties of A-site substituted Lanthanide Ca0.75R0.25MnO3

“…In recent years, more and more attentions are focus on oxide thermoelectric materials, such as layered perovskite Ca 3 Co 4 O 9 [1][2][3][4], electronic doped CaMnO 3 [5][6][7][8][9][10], and electronic doped Ti oxide [11][12][13][14], because they are more suitable for high temperature application in respect that their structural and chemical stability, low cost and so on. The efficiency of a TE generator depends on the material's TE dimensionless figure of merit (ZT).…”

Determining CLOU Reaction Kinetics for Combined Oxygen Carriers—Discussing the Experimental Methods

“…As for the perovskite the deviations are not surprising. It is well‐known that the oxygen content of a perovskite is dependent on both the temperature and the surrounding partial pressure of oxygen . It is therefore no surprise that the rate at which the oxygen is released from the perovskite is also affected.…”