On the Composition Function of Graded Thermoelectric Materials

Schilz, J.; Müller, Eckhard; Helmers, L.; Kang, Yixin; Noda, Yasutoshi; Niino, Masayuki

doi:10.4028/www.scientific.net/msf.308-311.647

Cited by 13 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Development of TE sensors and generators is likewise supported by probing methods in a wide range. Functionally graded materials (FGM) are considered for enhancement of conversion efficiency by expansion of application temperatures in TEGs or linearisation of sensor characteristics and enhancement of sensitivities 66–70. FGM approaches are ultimately relying on local property information since a proof of effective property gradation and feedback to numerical system simulation has to be given in order to improve device performance in the course of development 71, 72.…”

Section: Thermopower Probing In Practisementioning

confidence: 99%

Probing thermopower on the microscale

Ziółkowski

Karpinski

Dasgupta

et al. 2012

Physica Status Solidi (a)

Self Cite

View full text Add to dashboard Cite

Thermoelectric (TE) generators provide electrical energy from direct conversion of heat by means of the Seebeck effect; without moving parts, completely silent, and with negligible maintenance. As any other heat engine this conversion exploits only a fraction of the Carnot efficiency (Rowe (ed.), CRC Handbook of Thermoelectrics (CRC Press Inc., 1995), p. 19 [1]). The TE efficiency is linked to the thermoelectric figure of merit Z, which itself is given by basic material properties: Z ¼ S 2 s/k. These are the electrical conductivity s, the thermal conductivity k and the Seebeck coefficient or thermopower S, which is known as the factor of proportionality between voltage output and applied temperature difference in a given TE sample. A distinct sensitivity to the carrier concentration and structural variations make the control and stabilisation of thermopower very challenging in complex material structures since degradation by diffusion, decomposition or evaporation can be observed in many cases during synthesis, operation and even in the process of characterisation of TE semiconductors; particularly at elevated temperatures. Investigating structural and compositional properties, stability, and performance of TE materials, and consequently aiming to understand their interaction, mainly methods like X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) or integral temperature dependent measurements of particular transport properties are used. Although TE materials research satisfies highest requirements on accuracy, the above mentioned techniques are not perfectly qualified to investigate promising material classes thoroughly. Against the background of usually complex material structures this article aims to show, that an efficient characterisation of TE materials becomes accessible for several questions by use of a spatially resolved determination of the thermopower.

show abstract

Section: Thermopower Probing In Practisementioning

confidence: 99%

Probing thermopower on the microscale

Ziółkowski

Karpinski

Dasgupta

et al. 2012

Physica Status Solidi (a)

Self Cite

View full text Add to dashboard Cite

show abstract

“…On the one hand, a physically inhomogeneity is possible, i.e., the material's properties are temperature dependent; on the other hand, there is a chemical inhomogeneity in which you find the material's properties position dependent in a sample. 27,28,31 If mainly this T dependence is considered, one can express the material properties as spatial profiles over the length of a TE leg equivalently, as there is a steady temperature profile T(x) available for any performance parameter in the one-dimensional (1D) steady state. Exemplarily, for the Seebeck coefficient, the spatial profile is then given by S(x) 5 S[T(x)].…”

Section: Introductionmentioning

confidence: 99%

Performance optimization of a thermoelectric generator element with linear, spatial material profiles in a one-dimensional setup

et al. 2011

Self Cite

View full text Add to dashboard Cite

Graded and segmented thermoelectric elements are studied in order to improve the performance of thermogenerators that are exposed to a large temperature difference. The linear thermodynamics of irreversible processes is extended by assuming spatially dependent material parameters like the Seebeck coefficient, the electrical and thermal conductivities. For the particular case in which these transport coefficients exhibit a constant gradient, we present an analytical solution of the onedimensional thermal energy balance in terms of Bessel functions. Given linear spatial material profiles, we discuss the optimization of performance parameters like the electrical power P el and the efficiency g of a graded thermogenerator element of fixed length and fixed boundary temperatures. The results are compared with the constant properties model, i.e., physically and chemically homogeneous material, as a suitable reference for performance evaluation.

show abstract

“…The conversion efficiency of TE is dependent on figure of merit, Z =S 2 σ/κ.The general characteristics of TE material are summarized as follows [2]: (1) Z consists of three parameters: Seebeck coefficient (S), electrical conductivity (σ) and thermal conductivity (κ); (2) The value of Z is sensitively dependent upon material species, composition, dopant level, structure and temperature; (3) The peak value of Z exists at the peculiar temperature.…”

Section: Introductionmentioning

confidence: 99%

Functionally Graded Thermoelectric Materials

Ge¹,

2007

KEM

View full text Add to dashboard Cite

Functionally graded thermoelectric material (TE FGM) is one of main research direction in research field of thermoelectric (TE) materials all over world. A lot of research work on TE FGM has been done to improve the conversion efficiency of TE. Here the development of TE FGM in recent years is discussed in the aspects of the model design, the materials selection, the barrier or joining choice and the device fabrication.

show abstract

On the Composition Function of Graded Thermoelectric Materials

Cited by 13 publications

References 0 publications

Probing thermopower on the microscale

Probing thermopower on the microscale

Performance optimization of a thermoelectric generator element with linear, spatial material profiles in a one-dimensional setup

Functionally Graded Thermoelectric Materials

Contact Info

Product

Resources

About