The Transport Properties of Quasi–One-Dimensional Ba3Co2O6(CO3)0.7

Minnan Chen,Guohua Wang,Jiangtao Wu,Zhiwei Chen,Zhiling Dun,Feng Ye,Jie Ma,Qing Huang,Haidong Zhou,Yanzhong Pei,Vasudevan Rathinam,Jinlong Jiao,Gaoting Lin,Cangjin Li

doi:10.3389/fphy.2021.785801

Abstract

We have performed combined elastic neutron diffuse, electrical transport, specific heat, and thermal conductivity measurements on the quasi–one-dimensional Ba3Co2O6(CO3)0.7 single crystal to characterize its transport properties. A modulated superstructure of polyatomic CO32− is formed, which not only interferes the electronic properties of this compound, but also reduces the thermal conductivity along the c-axis. Furthermore, a large magnetic entropy is observed to be contributed to the heat conduction. Our investigations reveal the influence of both structural and magnetic effects on its transport properties and suggest a theoretical improvement on the thermoelectric materials by building up superlattice with conducting ionic group.

Highlights

Thermoelectric (TE) materials can recycle waste heat into usable electricity based on the Seebeck effect and are believed to play a significant role in efficient use of energy [1]
According to the Debye model, the lattice term of the total specific heat CP/T is linear with T2 at low T, but the data demonstrate a deviation from the linear relationship at low temperature and a nonzero intercept at 0 K
Neutron diffuse reveals that a modulated superstructure of CO32− is formed in Ba3Co2O6(CO3)0.7

Summary

INTRODUCTION

Thermoelectric (TE) materials can recycle waste heat into usable electricity based on the Seebeck effect and are believed to play a significant role in efficient use of energy [1]. As the energy conversion performance of TE materials is evaluated by the dimensionless figure of merit zT, zT S2σT/(κele + κlatt), where T is operating temperature, σ is electrical conductivity, S is Seebeck coefficient, κele is electronic thermal conductivity, and κlatt is lattice thermal conductivity, the research on the TE material is usually focused on two main approaches: (1) increasing the power factor S2σ through electronic structure or energy band engineering [2,3,4] and (2) reducing the lattice thermal conductivity κlatt by introducing additional phonon scattering and manipulating phonon structure [5,6,7,8,9]. We report neutron diffuse scattering, electrical conductivity, Hall effect, specific heat, and thermal conductivity of Ba3Co2O6(CO3)0.7 single crystal. The diffuse scattering studies, carrier concentration, electrical conductivity, and thermal conductivity, were carried out on the same crystal, and the sample for the measurement of the specific heat was cut from this crystal too

RESULTS AND DISCUSSION

CONCLUSION

DATA AVAILABILITY STATEMENT