Journal Home > Volume 3 , issue 3

We develop a theoretical model for quantitative analysis of temperature-dependent thermoelectric power of monovalent (Na) doped La0.97Na0.03MnO3 manganites. In the ferromagnetic regime, we have evaluated the phonon thermoelectric power by incorporating the scattering of phonons with impurities, grain boundaries, charge carriers and phonons. In doing so, we use the Mott expression to compute the carrier (hole) diffusion thermoelectric power ( Scdiff) using Fermi energy as carrier (hole)-free parameter, and Scdiff shows linear temperature dependence and phonon drag Sphdrag increases exponentially with temperature which is an artifact of various operating scattering mechanisms. It is also shown that for phonons the scattering and transport cross-sections are proportional to ω4 in the Rayleigh regime where ω is the frequency of the phonons. Numerical analysis of thermoelectric power from the present model shows similar results as those revealed from experiments.


menu
Abstract
Full text
Outline
About this article

Role of phonon drag and carrier diffusion in thermoelectric power of polycrystalline La0.97Na0.03MnO3 manganites

Show Author's information Dinesh VARSHNEY( )Dinesh CHOUDHARY
Materials Science Laboratory, School of Physics, Vigyan Bhawan, Devi Ahilya University, Khandwa Road Campus, Indore 452001, India

Abstract

We develop a theoretical model for quantitative analysis of temperature-dependent thermoelectric power of monovalent (Na) doped La0.97Na0.03MnO3 manganites. In the ferromagnetic regime, we have evaluated the phonon thermoelectric power by incorporating the scattering of phonons with impurities, grain boundaries, charge carriers and phonons. In doing so, we use the Mott expression to compute the carrier (hole) diffusion thermoelectric power ( Scdiff) using Fermi energy as carrier (hole)-free parameter, and Scdiff shows linear temperature dependence and phonon drag Sphdrag increases exponentially with temperature which is an artifact of various operating scattering mechanisms. It is also shown that for phonons the scattering and transport cross-sections are proportional to ω4 in the Rayleigh regime where ω is the frequency of the phonons. Numerical analysis of thermoelectric power from the present model shows similar results as those revealed from experiments.

Keywords:

phonon drag, carrier diffusion, thermoelectric power
Received: 04 April 2014 Revised: 09 June 2014 Accepted: 14 June 2014 Published: 02 September 2014 Issue date: September 2014
References(25)
[1]
Salamon MB, Jaime M. The physics of manganites: Structure and transport. Rev Mod Phys 2001, 73:583-626.
[2]
De Gennes P-G. Effects of double exchange in magnetic crystals. Phys Rev 1960, 118:141-154.
[3]
Millis AJ, Littlewood PB, Shraiman BI. Double exchange alone does not explain the resistivity of La1-xSrxMnO3. Phys Rev Lett 1995, 74:5144-5147.
[4]
Jaime M, Lin P, Salamon MB, et al. Low-temperature electrical transport and double exchange in La0.67(Pb,Ca)0.33MnO3. Phys Rev B 1998, 58:R5901-R5904.
[5]
Shannon RD. Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides. Acta Cryst 1976, A32:751-767.
[6]
Malavasi L, Mozzati MC, Ghigna P, et al. Lattice disorder, electric properties, and magnetic behavior of La1-xNaxMnO3+δ manganites. J Phys Chem B 2003, 107:2500-2505.
[7]
Mandal P. Temperature and doping dependence of the thermopower in LaMnO3. Phys Rev B 2000, 61:14675-14680.
[8]
Jaime M, Salamon MB, Rubinstein M, et al. High-temperature thermopower in La2/3Ca1/3MnO3 films: Evidence for polaronic transport. Phys Rev B 1996, 54:11914-11917.
[9]
Varshney D, Choudhary KK, Singh RK. Analysis of in-plane thermal conductivity anomalies in YBa2Cu3O7−δ cuprate superconductors. New J Phys 2003, 5:72.1-72.17.
[10]
Varshney D, Kaurav N. Numerical analysis of heat transport behavior in the ferromagnetic metallic state of La0.80Ca0.20MnO3 manganites. J Low Temp Phys 2007, 147:7-30.
[11]
Varshney D, Kaurav N. Analysis of low temperature specific heat in the ferromagnetic state of the Ca-doped manganites. Eur Phys J B 2004, 37:301-309.
[12]
Varshney D, Kaurav N. Low temperature specific heat analysis of LaMnO3+δ manganites. Int J Mod Phys B 2006, 20:4785-4797.
[13]
Varshney D, Singh RK, Khaskalam AK. Analysis of specific heat in YBa2Cu3O7-δ ceramic superconductors. Phys Status Solidi b 1998, 206:749-757.10.1002/(SICI)1521-3951(199804)206:2<749::AID-PSSB749>3.0.CO;2-W
[14]
Varshney D, Shah S, Singh RK. Specific heat studies in Ho–Ba–CuO superconductors: Fermionic and bosonic contributions. Bull Mater Sci 2000, 23:267-272.
[15]
Callaway J. Quantum Theory of the Solid State. London:Academic Press, 1991.
[16]
Barnard RD. Thermoelectricity in Metals and Alloys. London:Taylor and Francis Ltd., 1972.
[17]
Mott NF, Davis EA. Electronic Processes in Non-Crystalline Materials. Oxford:Clarendon, 1979.
[18]
Varshney D, Choudhary D, Shaikh MW. Interpretation of metallic and semiconducting temperature-dependent resistivity of La1-xNaxMnO3 (x = 0.07, 0.13) manganites. Comput Mater Sci 2010, 47:839-847.
[19]
Varshney D, Choudhary D, Shaikh MW, et al. Electrical resistivity behaviour of sodium substituted manganites: Electron–phonon, electron–electron and electron–magnon interactions. Eur Phys J B 2010, 76:327-338.
[20]
Shaikh MW, Varshney D. Structural properties and electrical resistivity behaviour of La1-xKxMnO3 (x = 0.1, 0.125 and 0.15) manganites. Mater Chem Phys 2012, 134:886-898.
[21]
Varshney D, Dodiya N. Electrical resistivity of the hole doped La0.8Sr0.2MnO3 manganites: Role of electron–electron/phonon/magnon interactions. Mater Chem Phys 2011, 129:896-904.
[22]
Varshney D, Dodiya N. Interpretation of metallic and semiconducting temperature dependent resistivity of La0.91Rb0.06Mn0.94O3 manganites. Solid State Sci 2011, 13:1623-1632.
[23]
Das S, Dey TK. Structural and magnetocaloric properties of La1−yNayMnO3 compounds prepared by microwave processing. J Phys D: Appl Phys 2007, 40: 1855-1863.
[24]
Vergara J, Ortega-Hertogs RJ, Madurga V, et al. Effect of disorder produced by cationic vacancies at the B sites on the electronic properties of mixed valence manganites. Phys Rev B 1999, 60:1127-1135.
[25]
Dubi Y, Di Ventra M. Colloquium: Heat flow and thermoelectricity in atomic and molecular junctions. Rev Mod Phys 2011, 83:131.
Publication history
Copyright
Rights and permissions

Publication history

Received: 04 April 2014
Revised: 09 June 2014
Accepted: 14 June 2014
Published: 02 September 2014
Issue date: September 2014

Copyright

© The author(s) 2014

Rights and permissions

Open Access: This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.

Reprints and Permission requests may be sought directly from editorial office.

Return