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1

Observation of the spin Seebeck effect  

Microsoft Academic Search

The generation of electric voltage by placing a conductor in a temperature gradient is called the Seebeck effect. Its efficiency is represented by the Seebeck coefficient, S, which is defined as the ratio of the generated electric voltage to the temperature difference, and is determined by the scattering rate and the density of the conduction electrons. The effect can be

K. Uchida; S. Takahashi; K. Harii; J. Ieda; W. Koshibae; K. Ando; S. Maekawa; E. Saitoh

2008-01-01

2

Spin Seebeck Effect Experiments Niklas Roschewsky  

E-print Network

Spin Seebeck Effect Experiments Niklas Roschewsky Master Thesis #12;#12;Technical University Munich Walther-MeiÃ?ner-Institute for Low Temperature Research Bavarian Academy of Sciences and Humanities Spin #12;#12;Contents 1 Introduction 1 2 Theory of the spin Seebeck effect 5 2.1 Electron charge and spin

Gross, Rudolf

3

Current heating induced spin Seebeck effect  

SciTech Connect

A measurement technique for the spin Seebeck effect is presented, wherein the normal metal layer used for its detection is exploited simultaneously as a resistive heater and thermometer. We show how the various contributions to the measured total signal can be disentangled, allowing to extract the voltage signal solely caused by the spin Seebeck effect. To this end, we performed measurements as a function of the external magnetic field strength and its orientation. We find that the effect scales linearly with the induced rise in temperature, as expected for the spin Seebeck effect.

Schreier, Michael, E-mail: michael.schreier@wmi.badw.de; Roschewsky, Niklas; Dobler, Erich; Meyer, Sibylle; Huebl, Hans; Goennenwein, Sebastian T. B. [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany)] [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Gross, Rudolf [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany) [Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Physik-Department, Technische Universität München, Garching (Germany)

2013-12-09

4

Theory of the spin Seebeck effect.  

PubMed

The spin Seebeck effect refers to the generation of a spin voltage caused by a temperature gradient in a ferromagnet, which enables the thermal injection of spin currents from the ferromagnet into an attached nonmagnetic metal over a macroscopic scale of several millimeters. The inverse spin Hall effect converts the injected spin current into a transverse charge voltage, thereby producing electromotive force as in the conventional charge Seebeck device. Recent theoretical and experimental efforts have shown that the magnon and phonon degrees of freedom play crucial roles in the spin Seebeck effect. In this paper, we present the theoretical basis for understanding the spin Seebeck effect and briefly discuss other thermal spin effects. PMID:23420561

Adachi, Hiroto; Uchida, Ken-ichi; Saitoh, Eiji; Maekawa, Sadamichi

2013-03-01

5

Observation of the spin Seebeck effect.  

PubMed

The generation of electric voltage by placing a conductor in a temperature gradient is called the Seebeck effect. Its efficiency is represented by the Seebeck coefficient, S, which is defined as the ratio of the generated electric voltage to the temperature difference, and is determined by the scattering rate and the density of the conduction electrons. The effect can be exploited, for example, in thermal electric-power generators and for temperature sensing, by connecting two conductors with different Seebeck coefficients, a device called a thermocouple. Here we report the observation of the thermal generation of driving power, or voltage, for electron spin: the spin Seebeck effect. Using a recently developed spin-detection technique that involves the spin Hall effect, we measure the spin voltage generated from a temperature gradient in a metallic magnet. This thermally induced spin voltage persists even at distances far from the sample ends, and spins can be extracted from every position on the magnet simply by attaching a metal. The spin Seebeck effect observed here is directly applicable to the production of spin-voltage generators, which are crucial for driving spintronic devices. The spin Seebeck effect allows us to pass a pure spin current, a flow of electron spins without electric currents, over a long distance. These innovative capabilities will invigorate spintronics research. PMID:18843364

Uchida, K; Takahashi, S; Harii, K; Ieda, J; Koshibae, W; Ando, K; Maekawa, S; Saitoh, E

2008-10-01

6

Spin pumping and spin Seebeck effect  

NASA Astrophysics Data System (ADS)

Utilization of a spin current, a flow of electrons' spins in a solid, is the key technology in spintronics that will allow the achievement of efficient magnetic memories and computing devices. In this technology, generation and detection of spin currents are necessary. Here, we review inverse spin-Hall effect and spin-current-generation phenomena recently discovered both in metals and insulators: inverse spin-Hall effect, spin pumping, and spin Seebeck effect. (1)Spin pumping and spin torque in a Mott insulator system We found that spin pumping and spin torque effects appear also at an interface between Pt and an insulator YIG.. This means that we can connect a spin current carried by conduction electrons and a spin-wave spin current flowing in insulators. We demonstrate electric signal transmission by using these effects and interconversion of the spin currents [1]. (2) Spin Seebeck effect We have observed, by using the inverse spin-Hall effect [2], spin voltage generation from a heat current in a NiFe, named the spin-Seebeck effect [3]. Surprisingly, spin-Seebeck effect was found to appear even in insulators [4], a situation completely different from conventional charge Seebeck effect. The result implies an important role of elementary excitation in solids beside charge in the spin Seebeck effect. In the talk, we review the recent progress of the research on this effect. This research is collaboration with K. Ando, K. Uchida, Y. Kajiwara, S. Maekawa, G. E. W. Bauer, S. Takahashi, and J. Ieda. [4pt] [1] Y. Kajiwara and E. Saitoh et al. Nature 464 (2010) 262. [0pt] [2] E. Saitoh et al., Appl. Phys. Lett. 88 (2006) 182509. [0pt] [3] K. Uchida and E. Saitoh et al., Nature 455 (2008)778. [0pt] [4] K. Uchida and E. Saitoh et al.,Nature materials 9 (2010) 894 - 897.

Saitoh, Eiji

2012-02-01

7

Exciton Seebeck effect in molecular systems.  

PubMed

We investigate the exciton dynamics under temperature difference with the hierarchical equations of motion. Through a nonperturbative simulation of the transient absorption of a heterogeneous trimer model, we show that the temperature difference causes exciton population redistribution and affects the exciton transfer time. It is found that one can reproduce not only the exciton population redistribution but also the change of the exciton transfer time induced by the temperature difference with a proper tuning of the site energies of the aggregate. In this sense, there exists a site energy shift equivalence for any temperature difference in a broad range. This phenomenon is similar to the Seebeck effect as well as spin Seebeck effect and can be named as exciton Seebeck effect. PMID:25106568

Yan, Yun-An; Cai, Shaohong

2014-08-01

8

Time resolved spin Seebeck effect experiments  

NASA Astrophysics Data System (ADS)

In this Letter, we present the results of transient thermopower experiments, performed at room temperature on yttrium iron garnet/platinum bilayers. Upon application of a time-varying thermal gradient, we observe a characteristic low-pass frequency response of the ensuing thermopower voltage with cutoff frequencies of up to 37 MHz. We interpret our results in terms of the spin Seebeck effect, and argue that small wavevector magnons are of minor importance for the spin Seebeck effect in our thin film hybrid structures.

Roschewsky, Niklas; Schreier, Michael; Kamra, Akashdeep; Schade, Felix; Ganzhorn, Kathrin; Meyer, Sibylle; Huebl, Hans; Geprägs, Stephan; Gross, Rudolf; Goennenwein, Sebastian T. B.

2014-05-01

9

Seebeck effect at the atomic scale.  

PubMed

The atomic variations of electronic wave functions at the surface and electron scattering near a defect have been detected unprecedentedly by tracing thermoelectric voltages given a temperature bias [Cho et al., Nat. Mater. 12, 913 (2013)]. Because thermoelectricity, or the Seebeck effect, is associated with heat-induced electron diffusion, how the thermoelectric signal is related to the atomic-scale wave functions and what the role of the temperature is at such a length scale remain very unclear. Here we show that coherent electron and heat transport through a pointlike contact produces an atomic Seebeck effect, which is described by the mesoscopic Seebeck coefficient multiplied by an effective temperature drop at the interface. The mesoscopic Seebeck coefficient is approximately proportional to the logarithmic energy derivative of local density of states at the Fermi energy. We deduced that the effective temperature drop at the tip-sample junction could vary at a subangstrom scale depending on atom-to-atom interaction at the interface. A computer-based simulation method of thermoelectric images is proposed, and a point defect in graphene was identified by comparing experiment and the simulation of thermoelectric imaging. PMID:24745445

Lee, Eui-Sup; Cho, Sanghee; Lyeo, Ho-Ki; Kim, Yong-Hyun

2014-04-01

10

Simple Demonstration of the Seebeck Effect  

ERIC Educational Resources Information Center

In this article we propose a simple and low-cost experimental set-up through which science educators can demonstrate the Seebeck effect using a thermocouple and an instrumentation amplifier. The experiment can be set up and conducted during a 1-hour laboratory session. (Contains 3 tables and 3 figures.)

Molki, Arman

2010-01-01

11

Communication Seebeck effect in steel fiber reinforced cement  

E-print Network

Communication Seebeck effect in steel fiber reinforced cement Sihai Wen, D.D.L. Chung* Composite cement, in addition to yielding more reversibility and linearity in the variation of the Seebeck voltage; Electrical properties; Silica fume; Thermoelectric 1. Introduction The Seebeck effect refers

Chung, Deborah D.L.

12

Surface sensitivity of the spin Seebeck effect  

NASA Astrophysics Data System (ADS)

We have investigated the influence of the interface quality on the spin Seebeck effect (SSE) of the bilayer system yttrium iron garnet (YIG)-platinum (Pt). The magnitude and shape of the SSE is strongly influenced by mechanical treatment of the YIG single crystal surface. We observe that the saturation magnetic field ( H sat SSE) for the SSE signal increases from 55.3 mT to 72.8 mT with mechanical treatment. The change in the magnitude of H sat SSE can be attributed to the presence of a perpendicular magnetic anisotropy due to the treatment induced surface strain or shape anisotropy in the Pt/YIG system. Our results show that the SSE is a powerful tool to investigate magnetic anisotropy at the interface.

Aqeel, A.; Vera-Marun, I. J.; van Wees, B. J.; Palstra, T. T. M.

2014-10-01

13

Seebeck effect in carbon fiber-reinforced cement  

SciTech Connect

The Seebeck effect in carbon fiber-reinforced cement paste was found to involve electrons from the cement matrix and holes from the biers. The two contributions were equal at the percolation threshold, with a fiber content between 0.5 and 1.0% by mass of cement. The hole contribution increased monotonically with increasing fiber content below and above the percolation threshold. The fiber addition increased the linearity and reversibility of the Seebeck effect. Silica fume and latex as admixtures had minor influence on the Seebeck effect. The Seebeck effect in concrete is of interest because it gives the concrete the ability to sense its own temperature. No attached or embedded sensor is needed since the concrete itself is the sensor. This means low cost, high durability, large sensing volume, and absence of mechanical property degradation due to embedded sensors. As the temperature affects the performance and reliability of concrete, its detection is valuable.

Wen, S.; Chung, D.D.L.

1999-12-01

14

Theory of phonon-driven spin Seebeck effect  

NASA Astrophysics Data System (ADS)

Spin Seebeck effect refers to a thermal spin injection occurring over millimeter scales from a ferromagnet into an attached nonmagnetic metal [Uchida et al., Nature 455, 778 (2008)]. We discuss the importance of the phonon-drag process in the spin Seebeck effect. Our theory of phonon-drag spin Seebeck effect [Adachi et al., Appl. Phys. Lett. 97, 252506 (2010)] explains simultaneously the local nature of the spin Seebeck effect [Jaworski et al., Nature Materials 9, 898 (2010); Uchida et al., Nature Materials 10, 737 (2011)] and the signal enhancement at low temperatures [Jaworski et al., Phys. Rev. Lett. 106, 186601 (2011)]. We also discuss the difference between our approach and that developed in Xiao et al., Phys. Rev. B 81, 214418 (2010).

Adachi, Hiroto; Ohe, Jun-Ichiro; Takahashi, Saburo; Maekawa, Sadamichi

2012-02-01

15

Giant spin Seebeck effect in a non-magnetic material.  

PubMed

The spin Seebeck effect is observed when a thermal gradient applied to a spin-polarized material leads to a spatially varying transverse spin current in an adjacent non-spin-polarized material, where it gets converted into a measurable voltage. It has been previously observed with a magnitude of microvolts per kelvin in magnetically ordered materials, ferromagnetic metals, semiconductors and insulators. Here we describe a signal in a non-magnetic semiconductor (InSb) that has the hallmarks of being produced by the spin Seebeck effect, but is three orders of magnitude larger (millivolts per kelvin). We refer to the phenomenon that produces it as the giant spin Seebeck effect. Quantizing magnetic fields spin-polarize conduction electrons in semiconductors by means of Zeeman splitting, which spin-orbit coupling amplifies by a factor of ?25 in InSb. We propose that the giant spin Seebeck effect is mediated by phonon-electron drag, which changes the electrons' momentum and directly modifies the spin-splitting energy through spin-orbit interactions. Owing to the simultaneously strong phonon-electron drag and spin-orbit coupling in InSb, the magnitude of the giant spin Seebeck voltage is comparable to the largest known classical thermopower values. PMID:22785317

Jaworski, C M; Myers, R C; Johnston-Halperin, E; Heremans, J P

2012-07-12

16

Anisotropic magnetothermal transport and spin Seebeck effect  

NASA Astrophysics Data System (ADS)

The anisotropic properties of thermal transport in insulating or conducting ferromagnets are derived on the basis of the Onsager reciprocity relations applied to a magnetic system. It is shown that the angular dependence of the temperature gradient takes the same form as that of the anisotropic magnetoresistance, including anomalous and planar Hall contributions. The measured thermocouple generated between the extremities of the nonmagnetic electrode in thermal contact to the ferromagnet follows this same angular dependence. The sign and amplitude of the magnetovoltaic signal is controlled by the difference of the Seebeck coefficients of the thermocouple.

Wegrowe, J.-E.; Drouhin, H.-J.; Lacour, D.

2014-03-01

17

Longitudinal spin Seebeck effect: from fundamentals to applications  

NASA Astrophysics Data System (ADS)

The spin Seebeck effect refers to the generation of spin voltage as a result of a temperature gradient in ferromagnetic or ferrimagnetic materials. When a conductor is attached to a magnet under a temperature gradient, the thermally generated spin voltage in the magnet injects a spin current into the conductor, which in turn produces electric voltage owing to the spin-orbit interaction. The spin Seebeck effect is of increasing importance in spintronics, since it enables direct generation of a spin current from heat and appears in a variety of magnets ranging from metals and semiconductors to insulators. Recent studies on the spin Seebeck effect have been conducted mainly in paramagnetic metal/ferrimagnetic insulator junction systems in the longitudinal configuration in which a spin current flowing parallel to the temperature gradient is measured. This ‘longitudinal spin Seebeck effect’ (LSSE) has been observed in various sample systems and exclusively established by separating the spin-current contribution from extrinsic artefacts, such as conventional thermoelectric and magnetic proximity effects. The LSSE in insulators also provides a novel and versatile pathway to thermoelectric generation in combination of the inverse spin-Hall effects. In this paper, we review basic experiments on the LSSE and discuss its potential thermoelectric applications with several demonstrations.

Uchida, K.; Ishida, M.; Kikkawa, T.; Kirihara, A.; Murakami, T.; Saitoh, E.

2014-08-01

18

Longitudinal spin Seebeck effect: from fundamentals to applications.  

PubMed

The spin Seebeck effect refers to the generation of spin voltage as a result of a temperature gradient in ferromagnetic or ferrimagnetic materials. When a conductor is attached to a magnet under a temperature gradient, the thermally generated spin voltage in the magnet injects a spin current into the conductor, which in turn produces electric voltage owing to the spin-orbit interaction. The spin Seebeck effect is of increasing importance in spintronics, since it enables direct generation of a spin current from heat and appears in a variety of magnets ranging from metals and semiconductors to insulators. Recent studies on the spin Seebeck effect have been conducted mainly in paramagnetic metal/ferrimagnetic insulator junction systems in the longitudinal configuration in which a spin current flowing parallel to the temperature gradient is measured. This 'longitudinal spin Seebeck effect' (LSSE) has been observed in various sample systems and exclusively established by separating the spin-current contribution from extrinsic artefacts, such as conventional thermoelectric and magnetic proximity effects. The LSSE in insulators also provides a novel and versatile pathway to thermoelectric generation in combination of the inverse spin-Hall effects. In this paper, we review basic experiments on the LSSE and discuss its potential thermoelectric applications with several demonstrations. PMID:25105889

Uchida, K; Ishida, M; Kikkawa, T; Kirihara, A; Murakami, T; Saitoh, E

2014-08-01

19

Charging of heated colloidal particles using the electrolyte Seebeck effect Arghya Majee and Alois Wrger  

E-print Network

Charging of heated colloidal particles using the electrolyte Seebeck effect Arghya Majee and Alois on the Seebeck effect of the electrolyte solution: Laser heating of a nonionic particle accumulates in its. In general one of the species moves more rapidly, thermoelectric field E FIG. 1: Left panel: Seebeck effect

Boyer, Edmond

20

Erratum to ``Seebeck effect in carbon fiber reinforced cement''$ Sihai Wen, D.D.L. Chung*  

E-print Network

Erratum Erratum to ``Seebeck effect in carbon fiber reinforced cement''$ Sihai Wen, D.D.L. Chung.D.L. Chung). Paper 1. S. Wen and D.D.L. Chung, Seebeck effect in carbon fiber reinforced cement, Cem. Concr. Res. 29 (12), (1999) 1989­1993. Paper 2. S. Wen and D.D.L. Chung, Seebeck effect in steel fiber

Chung, Deborah D.L.

21

Field-Effect Modulation of Seebeck Coefficient in Single PbSe Nanowires  

E-print Network

Field-Effect Modulation of Seebeck Coefficient in Single PbSe Nanowires Wenjie Liang,,| Allon I were able to tune the Seebeck coefficient of single PbSe nanowires from 64 to 193 µV·K-1 . This direct conductivity, S is the thermoelectric power (also called the Seebeck coefficient), is the thermal conductivity

Yang, Peidong

22

Seebeck effect in carbon fiber-reinforced cement  

Microsoft Academic Search

The Seebeck effect in carbon fiber-reinforced cement paste was found to involve electrons from the cement matrix and holes from the fibers. The two contributions were equal at the percolation threshold, with a fiber content between 0.5 and 1.0% by mass of cement. The hole contribution increased monotonically with increasing fiber content below and above the percolation threshold. The fiber

Sihai Wen; D. D. L. Chung

1999-01-01

23

Enhanced Thermoelectric Performance and Anomalous Seebeck Effects in Topological Insulators  

NASA Astrophysics Data System (ADS)

Improving the thermoelectric figure of merit zT is one of the greatest challenges in material science. The recent discovery of topological insulators (TIs) offers new promise in this prospect. In this work, we demonstrate theoretically that zT is strongly size dependent in TIs, and the size parameter can be tuned to enhance zT to be significantly greater than 1. Furthermore, we show that the lifetime of the edge states in TIs is strongly energy dependent, leading to large and anomalous Seebeck effects with an opposite sign to the Hall effect. These striking properties make TIs a promising material for thermoelectric science and technology.

Xu, Yong; Gan, Zhongxue; Zhang, Shou-Cheng

2014-06-01

24

Charging of Heated Colloidal Particles Using the Electrolyte Seebeck Effect  

E-print Network

We propose a novel actuation mechanism for colloids, which is based on the Seebeck effect of the electrolyte solution: Laser heating of a nonionic particle accumulates in its vicinity a net charge Q, which is proportional to the excess temperature at the particle surface. The corresponding long-range thermoelectric field provides a tool for controlled interactions with nearby beads or with additional molecular solutes. An external field Eext drags the thermocharged particle at a velocity that depends on its size and absorption properties; the latter point could be particularly relevant for separating carbon nanotubes according to their electronic band structure.

Arghya Majee; Alois Würger

2014-01-29

25

Spin-Seebeck effect in amorphous ferromagnetic alloys  

NASA Astrophysics Data System (ADS)

Since its first discovery in 2008 [1], continuous research on spin-Seebeck effect (SSE) has established a theory for the driving mechanisms of SSE: in the presence of a thermal gradient, the spin waves (magnons) present in ferromagnets are brought out of thermal equilibrium. It is suspected that their return to thermal equilibrium is what launches a spin flux, which then is converted into a voltage in a separate material by strong spin-orbit interactions. While it is proven that substrate phonons affect the spin-Seebeck signals [2], another possible mechanism that can drive magnons out of equilibrium can be magnon thermal conductivity. Here, to isolate the magnon and phonon contributions, we investigate the relation between SSE and magnon thermal conductivity in amorphous ferromagnetic alloys (Metglas). Because Metglas has high Curie temperature, yet mostly localized phonon modes, the magnon contribution to SSE is expected to be larger than in crystalline ferromagnets. Experimental SSE data as well as magneto-thermal conductivity data will be presented. [4pt] [1] K. Uchida et al., Nature 455, 778 (2008).[0pt] [2] C.M. Jaworski et al., PRL 106, 186601 (2011).

Jin, Hyungyu; Yang, Zihao; Myers, Roberto; Heremans, Joseph

2013-03-01

26

Tunable spin Seebeck effect in a double Rashba molecule embedded in an Aharonov-Bohm interferometer  

NASA Astrophysics Data System (ADS)

We study the spin-dependent thermoelectric properties of a Rashba quantum dot-molecule embedded in an Aharonov-Bohm interferometer. We show that by tuning conveniently both the Aharonov-Bohm and the Rashba spin orbit-induced phases, the different components of spin can have Seebeck coefficients of equal magnitude and different signs, so that the charge Seebeck coefficient vanishes while the spin Seebeck coefficient is finite. This means that a temperature gradient can produce in this system a spin voltage at the time that the charge voltage is zero, occurring an equivalent to the spin Seebeck effect observed in ferromagnets.

Gómez-Silva, G.; Ávalos-Ovando, O.; Ladrón de Guevara, M. L.; Orellana, P. A.

2014-09-01

27

Thermoelectric Seebeck effect in oxide-based resistive switching memory.  

PubMed

Reversible resistive switching induced by an electric field in oxide-based resistive switching memory shows a promising application in future information storage and processing. It is believed that there are some local conductive filaments formed and ruptured in the resistive switching process. However, as a fundamental question, how electron transports in the formed conductive filament is still under debate due to the difficulty to directly characterize its physical and electrical properties. Here we investigate the intrinsic electronic transport mechanism in such conductive filament by measuring thermoelectric Seebeck effects. We show that the small-polaron hopping model can well describe the electronic transport process for all resistance states, although the corresponding temperature-dependent resistance behaviours are contrary. Moreover, at low resistance states, we observe a clear semiconductor-metal transition around 150?K. These results provide insight in understanding resistive switching process and establish a basic framework for modelling resistive switching behaviour. PMID:25141267

Wang, Ming; Bi, Chong; Li, Ling; Long, Shibing; Liu, Qi; Lv, Hangbing; Lu, Nianduan; Sun, Pengxiao; Liu, Ming

2014-01-01

28

Nonlinear thermokinetic phenomena due to the Seebeck effect.  

PubMed

We propose a novel mechanism to produce nonlinear thermokinetic vortex flows around a circular cylinder with ideally high thermal conductivity in an electrolyte. That is, the nonlinear thermokinetic slip velocity, which is proportional to the square of the temperature gradient [?(T)0(2)], is derived based on the electrolyte Seebeck effect, heat conduction equation, and Helmholtz–Smoluchowski formula. Different from conventional linear thermokinetic theory, our theory predicts that the inversion of the temperature gradient does not change the direction of the thermokinetic flows and thus a Janus particle using this phenomenon can move to the both hotter and colder regions in a temperature gradient field by changing the direction of its dielectric end. Our findings bridge the gap between the electro- and thermo-kinetic phenomena and provide an integrated physical viewpoint for the interface science. PMID:25003210

Sugioka, Hideyuki

2014-07-22

29

Thermoelectric Seebeck effect in oxide-based resistive switching memory  

PubMed Central

Reversible resistive switching induced by an electric field in oxide-based resistive switching memory shows a promising application in future information storage and processing. It is believed that there are some local conductive filaments formed and ruptured in the resistive switching process. However, as a fundamental question, how electron transports in the formed conductive filament is still under debate due to the difficulty to directly characterize its physical and electrical properties. Here we investigate the intrinsic electronic transport mechanism in such conductive filament by measuring thermoelectric Seebeck effects. We show that the small-polaron hopping model can well describe the electronic transport process for all resistance states, although the corresponding temperature-dependent resistance behaviours are contrary. Moreover, at low resistance states, we observe a clear semiconductor–metal transition around 150?K. These results provide insight in understanding resistive switching process and establish a basic framework for modelling resistive switching behaviour. PMID:25141267

Wang, Ming; Bi, Chong; Li, Ling; Long, Shibing; Liu, Qi; Lv, Hangbing; Lu, Nianduan; Sun, Pengxiao; Liu, Ming

2014-01-01

30

Seebeck effect in PbTe films and EuTe/PbTe superlattices  

NASA Astrophysics Data System (ADS)

Theoretical calculations of the Seebeck coefficients of bulk PbTe and PbTe based superlattices were described in the framework of Boltzmann equation, taking into account temperature dependent band gaps, nonparabolicity, and anisotropy of effective masses. It is shown that the temperature gradient along the superlattice layer works more effectively on the enhancement of the thermoelectric figure of merit than the temperature gradient normal to the superlattice layer. Calculated Seebeck coefficients were compared to the experimental values for n-type PbTe, p-type PbTe, and EuTe/PbTe superlattices. The Seebeck coefficient of p-type PbTe was higher than that of n-type PbTe. The relatively high Seebeck coefficient is explained by the contribution from other extrema in the valence band. The EuTe/PbTe [001] superlattice shows higher Seebeck coefficients than PbTe bulk owing to the large density of states.

Ishida, Akihiro; Yamada, Tomohiro; Cao, Daoshe; Inoue, Yoku; Veis, Martin; Kita, Takuji

2009-07-01

31

Magneto-Seebeck effect in spin-valve with in-plane thermal gradient  

NASA Astrophysics Data System (ADS)

We present measurements of magneto-Seebeck effect on a spin valve with in-plane thermal gradient. We measured open circuit voltage and short circuit current by applying a temperature gradient across a spin valve stack, where one of the ferromagnetic layers is pinned. We found a clear hysteresis in these two quantities as a function of magnetic field. From these measurements, the magneto-Seebeck effect was found to be same as magneto-resistance effect.

Jain, S.; Lam, D. D.; Bose, A.; Sharma, H.; Palkar, V. R.; Tomy, C. V.; Suzuki, Y.; Tulapurkar, A. A.

2014-12-01

32

Large spin Seebeck effects in zigzag-edge silicene nanoribbons  

SciTech Connect

Using the first-principles methods, we investigate the thermospin properties of a two-probe model based on zigzag-edge silicene nanoribbons (ZSiNRs). Compared with the odd-width ZSiNRs, the spin Seebeck coefficient of the even-width ZSiNRs is obviously enhanced at room temperature. This fact is attributed to a nearly perfect symmetry of the linear conductance gap with the different spin index with respect to the Fermi level induced by the different parity of the wave functions. More interestingly, the corresponding charge Seebeck coefficient is near zero. Therefore, when a thermal bias is presented in the even-width ZSiNRs, a nearly pure spin current is achieved. Meanwhile, the spin polarization of the current approaches infinite.

Yang, Xi-Feng; Liu, Yu-Shen, E-mail: ysliu@cslg.edu.cn; Feng, Jin-Fu, E-mail: fengjinfu@cslg.edu.cn [College of Physics and Engineering, Changshu Institute of Technology and Jiangsu Laboratory of Advanced Functional materials, Changshu 215500 (China); Wang, Xue-Feng, E-mail: xf-wang1969@yahoo.com [College of Physics, Optoelectronics and Energy, Soochow University, Suzhou 215006 (China)

2014-08-15

33

Molecular Dependence of the Large Seebeck Effect in ?-Type Organic Conductors  

NASA Astrophysics Data System (ADS)

We study the Seebeck effect in the ?-type organic conductors, ?-(EDO-S,S-DMEDT-TTF)2(AuBr2)1+y and ?-(P-S,S-DMEDT-TTF)2(AuBr2)1+y, where EDO-S,S-DMEDT-TTF and P-S,S-DMEDT-TTF are abbreviated as OOSS and NNSS, respectively, both experimentally and theoretically. Theoretically in particular, we perform first-principles band calculation for the two materials and construct a two-orbital model, on the basis of which we calculate the Seebeck coefficient. We show that the calculated temperature dependence of the Seebeck coefficient S is semi-quantitatively consistent with the experimental observation. In both materials, the absolute value of the Seebeck coefficient is maximum at a certain temperature, and this temperature is lower for NNSS than for OOSS. From a band structure viewpoint, we find that this can be traced back to the narrowness of the band gap between the upper and the lower pudding-mold type bands. On the other hand, the Seebeck coefficient of NNSS in the low temperature regime steeply increases with increasing temperature, which is due to the narrowness of the upper band. These differences in thermoelectric properties demonstrate the effectiveness of controlling the band structure through molecular modification.

Aizawa, Hirohito; Kuroki, Kazuhiko; Yoshino, Harukazu; Mousdis, George A.; Papavassiliou, George C.; Murata, Keizo

2014-10-01

34

Observation of the spin Seebeck effect in epitaxial Fe3O4 thin films  

NASA Astrophysics Data System (ADS)

We report the experimental observation of the spin Seebeck effect in magnetite thin films. The signal observed at temperatures above the Verwey transition is a contribution from both the anomalous Nernst (ANE) and spin Seebeck (SSE) effects. The contribution from the ANE of the Fe3O4 layer to the SSE is found to be negligible due to the resistivity difference between Fe3O4 and Pt layers. Below the Verwey transition, the SSE is free from the ANE of the ferromagnetic layer and it is also found to dominate over the ANE due to magnetic proximity effect on the Pt layer.

Ramos, R.; Kikkawa, T.; Uchida, K.; Adachi, H.; Lucas, I.; Aguirre, M. H.; Algarabel, P.; Morellón, L.; Maekawa, S.; Saitoh, E.; Ibarra, M. R.

2013-02-01

35

Photo-Seebeck effect in tetragonal PbO single crystals  

SciTech Connect

We report the observation of photo-Seebeck effect in tetragonal PbO crystals. The photo-induced carriers contribute to the transport phenomena, and consequently the electrical conductivity increases and the Seebeck coefficient decreases with increasing photon flux density. A parallel-circuit model is used to evaluate the actual contributions of photo-excited carriers from the measured transport data. The photo-induced carrier concentration estimated from the Seebeck coefficient increases almost linearly with increasing photon flux density, indicating a successful photo-doping effect on the thermoelectric property. The mobility decreases by illumination but the reduction rate strongly depends on the illuminated photon energy. Possible mechanisms of such photon-energy-dependent mobility are discussed.

Mondal, P. S.; Okazaki, R.; Taniguchi, H.; Terasaki, I. [Department of Physics, Nagoya University, Nagoya 464-8602 (Japan)

2013-11-07

36

Predicted rectification and negative differential spin Seebeck effect at magnetic interfaces  

NASA Astrophysics Data System (ADS)

We study the nonequilibrium Seebeck spin transport across metal-magnetic insulator interfaces. The conjugate-converted thermal-spin transport is assisted by the exchange interaction at the interface, between conduction electrons in the metal lead and localized spins in the insulating magnet lead. We predict the rectification and negative differential spin Seebeck effect and resolve their microscopic mechanism, as a consequence of the strongly fluctuated electronic density of states in the metal lead. The rectification of spin Peltier effect is also discussed. The phenomena predicted here are relevant for designing efficient spin/magnon diode and transistor, which could play crucial roles in controlling energy and information in functional devices.

Ren, Jie

2013-12-01

37

Communication Role of moisture in the Seebeck effect in cement-based materials  

E-print Network

.D.L. Chung* Composite Materials Research Laboratory, University at Buffalo, State University of New York, Buffalo, NY 14260-4400, USA Received 12 June 2003; accepted 24 May 2004 Abstract Moisture in the form of liquid water contributes little, if any, to the Seebeck effect in cement-based materials. Moisture loss

Chung, Deborah D.L.

38

Extracting the effective mass of electrons in transparent conductive oxide thin films using Seebeck coefficient  

SciTech Connect

A method is proposed that combines Seebeck coefficient and carrier concentration to determine the electron effective mass of transparent conductive oxide (TCO) thin films. Experiments were conducted to test the validity of this approach on the transparent conductive Ga-doped ZnO thin films deposited by magnetron sputtering. An evident agreement of the calculated electron effective mass of the films is observed between the proposed approach and the previous studies. Besides, the optical carrier concentration and mobility derived from the calculated electron effective mass and spectroscopic ellipsometry using a complex dielectric function are consistent with those from direct Hall-effect measurement. The agreements suggest that Seebeck coefficient can serve as an alternative tool for extracting the effective mass of electrons in TCO films.

Wang, Yaqin; Zhu, Junhao; Tang, Wu, E-mail: tang@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2014-05-26

39

Magnon, phonon, and electron temperature profiles and the spin Seebeck effect in magnetic insulator/normal metal hybrid structures  

NASA Astrophysics Data System (ADS)

We calculate the phonon, electron, and magnon temperature profiles in yttrium iron garnet/platinum bilayers by diffusive theory with appropriate boundary conditions, in particular taking into account interfacial thermal resistances. Our calculations show that in thin film hybrids, the interface magnetic heat conductance qualitatively affects the magnon temperature. Based on published material parameters we assess the degree of nonequilibrium at the yttrium iron garnet/platinum interface. The magnitude of the spin Seebeck effect derived from this approach compares well with experimental results for the longitudinal spin Seebeck effect. Additionally, we address the temperature profiles in the transverse spin Seebeck effect.

Schreier, Michael; Kamra, Akashdeep; Weiler, Mathias; Xiao, Jiang; Bauer, Gerrit E. W.; Gross, Rudolf; Goennenwein, Sebastian T. B.

2013-09-01

40

Magneto-Seebeck effect in R FeAsO (R =rare earth) compounds: Probing the magnon drag scenario  

NASA Astrophysics Data System (ADS)

We investigate the Seebeck effect in R FeAsO (R =rare earth) compounds as a function of temperature and magnetic field up to 30 T. The Seebeck curves are characterized by a broad negative bump around 50 K, which is sample dependent and strongly enhanced by the application of a magnetic field. A model for the temperature and field dependence of the magnon drag contribution to the Seebeck effect by antiferromagnetic (AFM) spin fluctuation is developed. It accounts for the magnitude and scaling properties of such bump feature in our experimental data in LaFeAsO. This analysis accounts for the apparent inconsistency of literature Seebeck effect data on these compounds and has the potential to extract precious information on the coupling between electrons and AFM spin fluctuations in these parent compound systems, with implications on the pairing mechanism of the related superconducting compounds.

Caglieris, F.; Braggio, A.; Pallecchi, I.; Provino, A.; Pani, M.; Lamura, G.; Jost, A.; Zeitler, U.; Galleani D'Agliano, E.; Manfrinetti, P.; Putti, M.

2014-10-01

41

Seebeck coefficient of one electron  

SciTech Connect

The Seebeck coefficient of one electron, driven thermally into a semiconductor single-electron box, is investigated theoretically. With a finite temperature difference ?T between the source and charging island, a single electron can charge the island in equilibrium, directly generating a Seebeck effect. Seebeck coefficients for small and finite ?T are calculated and a thermally driven Coulomb staircase is predicted. Single-electron Seebeck oscillations occur with increasing ?T, as one electron at a time charges the box. A method is proposed for experimental verification of these effects.

Durrani, Zahid A. K., E-mail: z.durrani@imperial.ac.uk [Department of Electrical and Electronic Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom)

2014-03-07

42

Cation intersite distributions in iron-bearing minerals via electrical conductivity\\/seebeck effect  

Microsoft Academic Search

The equilibrium high temperature cation intersite distributions in iron-bearing minerals which exhibit small polaron “hopping”\\u000a conduction can be determined by a technique which combines electrical conductivity and Seebeck effect. The procedure is demonstrated\\u000a for ferrospinels (Fe3O4) - FeAl2O4 and Fe3O4 - CoFe2O4) and applied to the olivine Fe2SiO4 - Mg2SiO4 system.

T. O. Mason

1987-01-01

43

Surface polarization enhanced Seebeck effects in vertical multi-layer metal-polymer-metal thin-film devices.  

PubMed

We explore a new mechanism to develop Seebeck effects by using temperature-dependent surface polarization based on vertical multi-layer Al-P3HT:PCBM-Al thin-film devices. Here, the temperature-dependent surface polarization functions as an additional driving force, as compared with the traditional driving force from the entropy difference, to diffuse the charge carriers under a temperature gradient towards the development of Seebeck effects. The temperature-dependent surface polarization is essentially generated by both the thermally dependent polarization through the charge-phonon coupling mechanism and the thermally modulated interface dipoles by Fermi electrons. It is noted that the entropy difference often causes an inverse relationship between the Seebeck coefficient and electrical conductivity in thermoelectric developments. However, this temperature-dependent surface polarization provides a mechanism allowing a co-operative relationship between the Seebeck coefficient and electrical conductivity. We demonstrate simultaneously the enhanced Seebeck coefficient and electrical conductivity by using the dielectric interface through the temperature-dependent surface polarization to diffuse charge carriers in the Al-MoO3-P3HT:PCBM-Al thin-film device. PMID:25213557

Liu, Qing; Hu, Dehua; Wang, Hongfeng; Stanford, Michael; Wang, Hsin; Hu, Bin

2014-10-28

44

Bachelor Thesis Joule Heating Induced Spin Seebeck  

E-print Network

Bachelor Thesis Joule Heating Induced Spin Seebeck Effect Erich Dobler Date: 23 August 2013 #12;#12;Contents 1 Introduction 1 2 The Spin Seebeck Effect 2 2.1 Spin Currents.3 The Inverse Spin Hall Effect . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.4 The Spin Seebeck

Gross, Rudolf

45

Investigation of the magnetic properties of insulating thin films using the longitudinal spin Seebeck effect  

SciTech Connect

The longitudinal spin Seebeck effect is used as a detector for the magnetic properties and switching characteristics of magnetic thin insulating films. We use a 300 nm and a 20?nm thick Yttrium Iron Garnet (YIG, Y{sub 3}Fe{sub 5}O{sub 12}) film prepared by pulsed laser deposition and afterwards coated by platinum for the detection of the thermally excited magnons by the inverse spin Hall effect. The inverse spin Hall signals reveal a magnetic uniaxial anisotropy along the direction of the platinum stripe in the thicker film. For the thin film we find a more isotropic behavior, which is complementarily observed using the magnetoresistance occurring at the platinum/YIG interface. We explain our results on the basis of x-ray diffraction data, which reveal a miscut of the substrate and film surface and an expansion of the YIG lattice. Both findings favor a growth-induced magnetic anisotropy that we observe.

Kehlberger, A., E-mail: kehlberg@uni-mainz.de; Jakob, G.; Kläui, M. [Institute of Physics, University of Mainz, 55099 Mainz (Germany); Onbasli, M. C.; Kim, D. H.; Ross, C. A. [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2014-05-07

46

Investigation of the magnetic properties of insulating thin films using the longitudinal spin Seebeck effect  

NASA Astrophysics Data System (ADS)

The longitudinal spin Seebeck effect is used as a detector for the magnetic properties and switching characteristics of magnetic thin insulating films. We use a 300 nm and a 20 nm thick Yttrium Iron Garnet (YIG, Y3Fe5O12) film prepared by pulsed laser deposition and afterwards coated by platinum for the detection of the thermally excited magnons by the inverse spin Hall effect. The inverse spin Hall signals reveal a magnetic uniaxial anisotropy along the direction of the platinum stripe in the thicker film. For the thin film we find a more isotropic behavior, which is complementarily observed using the magnetoresistance occurring at the platinum/YIG interface. We explain our results on the basis of x-ray diffraction data, which reveal a miscut of the substrate and film surface and an expansion of the YIG lattice. Both findings favor a growth-induced magnetic anisotropy that we observe.

Kehlberger, A.; Jakob, G.; Onbasli, M. C.; Kim, D. H.; Ross, C. A.; Kläui, M.

2014-05-01

47

Quantitative Temperature Dependence of Longitudinal Spin Seebeck Effect at High Temperatures  

NASA Astrophysics Data System (ADS)

We report temperature-dependent measurements of longitudinal spin Seebeck effects (LSSEs) in Pt /Y3Fe5O12 (YIG )/Pt systems in a high temperature range from room temperature to above the Curie temperature of YIG. The experimental results show that the magnitude of the LSSE voltage in the Pt /YIG /Pt systems rapidly decreases with increasing the temperature and disappears above the Curie temperature. The critical exponent of the LSSE voltage in the Pt /YIG /Pt systems at the Curie temperature is estimated to be 3, which is much greater than that for the magnetization curve of YIG. This difference highlights the fact that the mechanism of the LSSE cannot be explained in terms of simple static magnetic properties in YIG.

Uchida, Ken-ichi; Kikkawa, Takashi; Miura, Asuka; Shiomi, Junichiro; Saitoh, Eiji

2014-10-01

48

Fokker-Planck approach to the theory of the magnon-driven spin Seebeck effect  

NASA Astrophysics Data System (ADS)

Following the theoretical approach by J. Xiao [Phys. Rev. BPRBMDO1098-012110.1103/PhysRevB.81.214418 81, 214418 (2010)] to the spin Seebeck effect, we calculate the mean value of the total spin current flowing through a normal metal/ferromagnet interface. The spin current emitted from the ferromagnet to the normal metal is evaluated in the framework of the Fokker-Planck approach for the stochastic Landau-Lifshitz-Gilbert equation. We show that the total spin current depends not only on the temperature difference between the electron and the magnon baths, but also on the external magnetic field and magnetic anisotropy. Apart from this, the spin current is shown to saturate with increasing magnon temperature, and the saturation temperature increases with increasing magnetic field and/or magnetic anisotropy.

Chotorlishvili, L.; Toklikishvili, Z.; Dugaev, V. K.; Barna?, J.; Trimper, S.; Berakdar, J.

2013-10-01

49

Large-tunneling anisotropic magneto-Seebeck effect in a CoPt/MgO/Pt tunnel junction  

NASA Astrophysics Data System (ADS)

We theoretically investigate the tunneling anisotropic magneto-Seebeck effect in a realistically modeled CoPt /MgO /Pt tunnel junction using coherent transport calculations. For comparison we study the tunneling magneto-Seebeck effect in CoPt /MgO /CoPt as well. We find that the magneto-Seebeck ratio of CoPt /MgO /Pt exceeds that of CoPt /MgO /CoPt for small barrier widths, reaching 175 % at room temperature. This provides a sharp contrast to the magnetoresistance, in which CoPt /MgO /CoPt performs better by one order of magnitude for all barrier widths. Thus, by switching from two ferromagnetic layers to one (so that spin-orbit coupling alone governs the magnetic transport anisotropy), the magnetoresistance ratio diminishes while the magneto-Seebeck ratio remains comparable or improves considerably. We therefore demonstrate that magnetic tunability can increase when caused solely by spin-orbit coupling. This result sheds light on the role that spin-orbit coupling plays in magnetically tuning the properties of tunnel junctions.

Amin, V. P.; Zemen, J.; Železný, J.; Jungwirth, T.; Sinova, Jairo

2014-10-01

50

Robust longitudinal spin-Seebeck effect in Bi-YIG thin films.  

PubMed

In recent years, the coupling of magnetic insulators (bismuth-doped yttrium iron garnet, Bi-YIG) with platinum has garnered significant interest in spintronics research due to applicability as spin-current-driven thermoelectric coatings. These coatings bridge the gap between spintronics technologies and thermoelectric materials, providing a novel means of transforming waste heat into electricity. However, there remain questions regarding the origins of the spin-Seebeck effect (SSE) as well as claims that observed effects are a manifestation of magnetic proximity effects, which would induce magnetic behavior in platinum. Herewith we provide support that the voltages observed in the Bi-YIG/Pt films are purely SSE voltages. We reaffirm claims that magnon transport theory provides an ample basis for explaining SSE behavior. Finally, we illustrate the advantages of pulsed-laser deposition, as these Bi-YIG films possess large SSE voltages (even in absence of an external magnetic field), as much as twice those of films fabricated via solution-based methods. PMID:24651124

Siegel, Gene; Prestgard, Megan Campbell; Teng, Shiang; Tiwari, Ashutosh

2014-01-01

51

Robust longitudinal spin-Seebeck effect in Bi-YIG thin films  

NASA Astrophysics Data System (ADS)

In recent years, the coupling of magnetic insulators (bismuth-doped yttrium iron garnet, Bi-YIG) with platinum has garnered significant interest in spintronics research due to applicability as spin-current-driven thermoelectric coatings. These coatings bridge the gap between spintronics technologies and thermoelectric materials, providing a novel means of transforming waste heat into electricity. However, there remain questions regarding the origins of the spin-Seebeck effect (SSE) as well as claims that observed effects are a manifestation of magnetic proximity effects, which would induce magnetic behavior in platinum. Herewith we provide support that the voltages observed in the Bi-YIG/Pt films are purely SSE voltages. We reaffirm claims that magnon transport theory provides an ample basis for explaining SSE behavior. Finally, we illustrate the advantages of pulsed-laser deposition, as these Bi-YIG films possess large SSE voltages (even in absence of an external magnetic field), as much as twice those of films fabricated via solution-based methods.

Siegel, Gene; Prestgard, Megan Campbell; Teng, Shiang; Tiwari, Ashutosh

2014-03-01

52

Observation of vortex-lattice melting in YBa2Cu3O7-delta by Seebeck-effect measurements  

Microsoft Academic Search

Observation of vortex-lattice melting by Seebeck-effect measurements is reported. This technique does not require a transport current and may be related to the analogous resistivity measurements in the limit of zero current. The YBa2Cu3O7-delta single crystals displayed a measurable effect in the b axis direction in the as-grown condition but virtually no signal in the a axis direction. The b

H. Ghamlouch; M. Aubin; R. Gagnon; L. Taillefer

1996-01-01

53

Magnetotransport properties and Seebeck effect in the superconductor FeSe0.5Te0.5  

NASA Astrophysics Data System (ADS)

We carried out measurements of the electrical resistivity, magnetoresistance, Hall resistivity and Seebeck effect in a highly oriented sample of the Fe-based FeSe0.5Te0.5 superconductor. Complementary structural and magnetic characterizations were also performed. Our sample do not show long-range magnetic order down to 4.2 K. Superconductivity occurs with critical temperature Tc ? 15 K. In the normal phase, the resistivity versus temperature behavior mimics that of a Kondo-lattice system. The magnetoresistance, Hall coefficient and Seebeck coefficient show sign reversals. These results are discussed with basis on the combined effects from two-band conduction and weak magnetic fluctuations. Effects from superconducting fluctuations are also observed near Tc.

Pimentel, J. L., Jr.; Pureur, P.; Avila, M. A.; Ribeiro, R. A.

2014-04-01

54

Size and temperature effects on the Seebeck coefficient of thin bismuth films  

Microsoft Academic Search

The electrical resistivity and the Seebeck coefficient of thermally evaporated thin bismuth films of thicknesses from 300 to 1900 Å have been measured in the temperature range 300-470 K. The latter is negative and its magnitude is found to increase initially with increasing temperature, reach a maximum, and then decrease with a further rise in temperature. The temperature at which

V. Damodara Das; N. Soundararajan

1987-01-01

55

High Seebeck effects from conducting polymer: Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) based thin-film device with hybrid metal/polymer/metal architecture  

SciTech Connect

Conductive polymers are of particular interest for thermoelectric applications due to their low thermal conductivity and relatively high electrical conductivity. In this study, commercially available conducting polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) was used in a hybrid metal/polymer/metal thin film design in order to achieve a high Seebeck coefficient with the value of 252lV/k on a relatively low temperature scale. Polymer film thickness was varied in order to investigate its influence on the Seebeck effect. The high Seebeck coefficient indicates that the metal/polymer/metal design can develop a large entropy difference in internal energy of charge carriers between high and low-temperature metal electrodes to develop electrical potential due to charge transport in conducting polymer film through metal/polymer interface. Therefore, the metal/polymer/metal structure presents a new design to combine inorganic metals and organic polymers in thin-film form to develop Seebeck devices

Stanford, Michael G [ORNL; Wang, Hsin [ORNL; Ivanov, Ilia N [ORNL; Hu, Bin [University of Tennessee, Knoxville (UTK)

2012-01-01

56

Observation of vortex-lattice melting in YBa2Cu3O7-? by Seebeck-effect measurements  

NASA Astrophysics Data System (ADS)

Observation of vortex-lattice melting by Seebeck-effect measurements is reported. This technique does not require a transport current and may be related to the analogous resistivity measurements in the limit of zero current. The YBa2Cu3O7-? single crystals displayed a measurable effect in the b axis direction in the as-grown condition but virtually no signal in the a axis direction. The b axis data are combined with the results of Blatter and Ivlev to produce a phase diagram taking into account both thermal and quantum fluctuations.

Ghamlouch, H.; Aubin, M.; Gagnon, R.; Taillefer, L.

1996-10-01

57

Generation of pure spin currents via spin Seebeck effect in self-biased hexagonal ferrite thin films  

NASA Astrophysics Data System (ADS)

Light-induced generation of pure spin currents in a Pt(2.5 nm)/BaFe12O19(1.2 ?m)/sapphire(0.5 mm) structure is reported. The BaFe12O19 film had strong in-plane uniaxial anisotropy and was therefore self-biased. Upon exposure to light, a temperature difference (?T) was established across the BaFe12O19 thickness that gave rise to a pure spin current in the Pt via the spin Seebeck effect. Via the inverse spin Hall effect, the spin current produced an electric voltage across one of the Pt lateral dimensions. The voltage varied with time in the same manner as ?T and flipped its sign when the magnetization in BaFe12O19 was reversed.

Li, Peng; Ellsworth, David; Chang, Houchen; Janantha, Praveen; Richardson, Daniel; Shah, Faisal; Phillips, Preston; Vijayasarathy, Tarah; Wu, Mingzhong

2014-12-01

58

Half-metallic properties, single-spin negative differential resistance, and large single-spin Seebeck effects induced by chemical doping in zigzag-edged graphene nanoribbons  

NASA Astrophysics Data System (ADS)

Ab initio calculations combining density-functional theory and nonequilibrium Green's function are performed to investigate the effects of either single B atom or single N atom dopant in zigzag-edged graphene nanoribbons (ZGNRs) with the ferromagnetic state on the spin-dependent transport properties and thermospin performances. A spin-up (spin-down) localized state near the Fermi level can be induced by these dopants, resulting in a half-metallic property with 100% negative (positive) spin polarization at the Fermi level due to the destructive quantum interference effects. In addition, the highly spin-polarized electric current in the low bias-voltage regime and single-spin negative differential resistance in the high bias-voltage regime are also observed in these doped ZGNRs. Moreover, the large spin-up (spin-down) Seebeck coefficient and the very weak spin-down (spin-up) Seebeck effect of the B(N)-doped ZGNRs near the Fermi level are simultaneously achieved, indicating that the spin Seebeck effect is comparable to the corresponding charge Seebeck effect.

Yang, Xi-Feng; Zhou, Wen-Qian; Hong, Xue-Kun; Liu, Yu-Shen; Wang, Xue-Feng; Feng, Jin-Fu

2015-01-01

59

Half-metallic properties, single-spin negative differential resistance, and large single-spin Seebeck effects induced by chemical doping in zigzag-edged graphene nanoribbons.  

PubMed

Ab initio calculations combining density-functional theory and nonequilibrium Green's function are performed to investigate the effects of either single B atom or single N atom dopant in zigzag-edged graphene nanoribbons (ZGNRs) with the ferromagnetic state on the spin-dependent transport properties and thermospin performances. A spin-up (spin-down) localized state near the Fermi level can be induced by these dopants, resulting in a half-metallic property with 100% negative (positive) spin polarization at the Fermi level due to the destructive quantum interference effects. In addition, the highly spin-polarized electric current in the low bias-voltage regime and single-spin negative differential resistance in the high bias-voltage regime are also observed in these doped ZGNRs. Moreover, the large spin-up (spin-down) Seebeck coefficient and the very weak spin-down (spin-up) Seebeck effect of the B(N)-doped ZGNRs near the Fermi level are simultaneously achieved, indicating that the spin Seebeck effect is comparable to the corresponding charge Seebeck effect. PMID:25591376

Yang, Xi-Feng; Zhou, Wen-Qian; Hong, Xue-Kun; Liu, Yu-Shen; Wang, Xue-Feng; Feng, Jin-Fu

2015-01-14

60

High temperature Seebeck coefficient metrology  

SciTech Connect

We present an overview of the challenges and practices of thermoelectric metrology on bulk materials at high temperature (300 to 1300 K). The Seebeck coefficient, when combined with thermal and electrical conductivity, is an essential property measurement for evaluating the potential performance of novel thermoelectric materials. However, there is some question as to which measurement technique(s) provides the most accurate determination of the Seebeck coefficient at high temperature. This has led to the implementation of nonideal practices that have further complicated the confirmation of reported high ZT materials. To ensure meaningful interlaboratory comparison of data, thermoelectric measurements must be reliable, accurate, and consistent. This article will summarize and compare the relevant measurement techniques and apparatus designs required to effectively manage uncertainty, while also providing a reference resource of previous advances in high temperature thermoelectric metrology.

Martin, J. [Materials Science and Engineering Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Tritt, T. [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States); Uher, C. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2010-12-15

61

High temperature Seebeck coefficient metrology  

SciTech Connect

We present an overview of the challenges and practices of thermoelectric metrology on bulk materials at high temperature (300 to 1300 K). The Seebeck coefficient, when combined with thermal and electrical conductivity, is an essential propertymeasurement for evaluating the potential performance of novel thermoelectricmaterials. However, there is some question as to which measurement technique(s) provides the most accurate determination of the Seebeck coefficient at high temperature. This has led to the implementation of nonideal practices that have further complicated the confirmation of reported high ZT materials. To ensure meaningful interlaboratory comparison of data, thermoelectricmeasurements must be reliable, accurate, and consistent. This article will summarize and compare the relevant measurement techniques and apparatus designs required to effectively manage uncertainty, while also providing a reference resource of previous advances in high temperature thermoelectric metrology.

Martin, J.; Tritt, T.; Uher, Ctirad

2010-01-01

62

The Low-Temperature Seebeck Coefficient in Insulators  

NASA Astrophysics Data System (ADS)

We show the existence of a space-charge effect in the measurement of the low-temperature Seebeck coefficient in insulators. The Seebeck coefficient is obtained by measurement of the voltage due to a temperature gradient . The space-charge effect makes the voltage go to zero in insulators, even if the Seebeck coefficient does not vanish. We propose that the Seebeck coefficient does not actually vanish in insulators, contrary to common belief. We also propose that variable-range hopping is not observed in conductivity measurements.

Mahan, G. D.

2015-01-01

63

Joule heating-induced coexisted spin Seebeck effect and spin Hall magnetoresistance in the platinum/Y3Fe5O12 structure  

NASA Astrophysics Data System (ADS)

Spin Seebeck effect (SSE) and spin Hall magnetoresistance (SMR) are observed simultaneously in the Pt/Y3Fe5O12 hybrid structure when thermal gradient is produced by Joule heating. According to their dependences on applied current, these two effects can be separated. Their dependence on heating power and magnetic field is systematically studied. With the increase of heating power, the SSE enhances linearly, whereas the SMR decreases slowly. The origin of the spin currents is further analyzed. The heating power dependences of the spin currents associated with the SSE and the SMR are found to be different.

Wang, W. X.; Wang, S. H.; Zou, L. K.; Cai, J. W.; Sun, Z. G.; Sun, J. R.

2014-11-01

64

Nanoscale Spin Seebeck Rectifier: Controlling Thermal Spin Transport across Insulating Magnetic Junctions with Localized Spin  

E-print Network

The spin Seebeck effect is studied across a charge insulating magnetic junction, in which thermal-spin conjugate transport is assisted by the exchange interactions between the localized spin in the center and electrons in metallic leads. We show that, in contrast with bulk spin Seebeck effect, the figure of merit of such nanoscale thermal-spin conversion can be infinite, leading to the ideal Carnot efficiency in the linear response regime. We also find that in the nonlinear spin Seebeck transport regime, the device possesses the asymmetric and negative differential spin Seebeck effects. In the last, the situations with leaking electron tunneling are also discussed. This nanoscale thermal spin rectifier, by tuning the junction parameters, can act as a spin Seebeck diode, spin Seebeck transistor and spin Seebeck switch, which could have substantial implications for flexible thermal and information control in molecular spin caloritronics.

Jie Ren; Jonas Fransson; Jian-Xin Zhu

2014-06-20

65

CO{sub 2} laser induced temperature profiles in n-GaAs: An analytical model probed with the Seebeck effect  

SciTech Connect

An analytic model describing the distribution of the electron temperature created by absorption of an optical beam with a cylindrical symmetry in a layered structure was developed. Main attention was paid to the contribution of the lattice heating in the stationary and nonstationary regimes. It was shown that both the spatial distribution of the incident stationary beam and the temporal distribution of the incident pulses can be retrieved from the spatial and temporal electron temperature dependences near the illuminated surface. Electron temperature distributions can be measured using the thermoelectric effect. Experimental results of the spatial and temporal measurements of the thermoelectric voltage were compared with the theoretical calculations and a satisfactory agreement between experimental and theoretical results was found near the incident beam center for the quasistationary regime. The experimentally derived Seebeck detector's responsivity equals 17.5 {mu}V/W cm{sup -2}.

Stiens, J.; Vandermeiren, W.; De Tandt, C.; Vounckx, R.; Shkerdin, G.; Kotov, V. [Laboratory for Micro- and Photonelectronics, ETRO-FirW, VUB, Pleinlaan 2, B-1050 Brussels (Belgium); Institute of Radio Engineering and Electronics of the Russian Academy of Sciences, Vvedenskogo Square 1, 141120 Fryazino (Moscow Region) (Russian Federation)

2006-12-01

66

Simultaneous detection of the spin-Hall magnetoresistance and the spin-Seebeck effect in platinum and tantalum on yttrium iron garnet  

NASA Astrophysics Data System (ADS)

The spin-Seebeck effect (SSE) in platinum (Pt) and tantalum (Ta) on yttrium iron garnet has been investigated by both externally heating the sample (using an on-chip Pt heater on top of the device) and by current-induced heating. For SSE measurements, external heating is the most common method to obtain clear signals. Here we show that also by current-induced heating it is possible to directly observe the SSE, separate from the also present spin-Hall magnetoresistance (SMR) signal, by using a lock-in detection technique. Using this measurement technique, the presence of additional second-order signals at low applied magnetic fields and high heating currents is revealed. These signals are caused by current-induced magnetic fields (Oersted fields) generated by the used ac current, resulting in dynamic SMR signals.

Vlietstra, N.; Shan, J.; van Wees, B. J.; Isasa, M.; Casanova, F.; Ben Youssef, J.

2014-11-01

67

Uncertainty analysis for common Seebeck and electrical resistivity measurement systems.  

PubMed

This work establishes the level of uncertainty for electrical measurements commonly made on thermoelectric samples. The analysis targets measurement systems based on the four probe method. Sources of uncertainty for both electrical resistivity and Seebeck coefficient were identified and evaluated. Included are reasonable estimates on the magnitude of each source, and cumulative propagation of error. Uncertainty for the Seebeck coefficient includes the cold-finger effect which has been quantified with thermal finite element analysis. The cold-finger effect, which is a result of parasitic heat transfer down the thermocouple probes, leads to an asymmetric over-estimation of the Seebeck coefficient. A silicon germanium thermoelectric sample has been characterized to provide an understanding of the total measurement uncertainty. The electrical resistivity was determined to contain uncertainty of ±7.0% across any measurement temperature. The Seebeck coefficient of the system is +1.0%/-13.1% at high temperature and ±1.0% near room temperature. The power factor has a combined uncertainty of +7.3%/-27.0% at high temperature and ±7.5% near room temperature. These ranges are calculated to be typical values for a general four probe Seebeck and resistivity measurement configuration. PMID:25173324

Mackey, Jon; Dynys, Frederick; Sehirlioglu, Alp

2014-08-01

68

Uncertainty analysis for common Seebeck and electrical resistivity measurement systems  

NASA Astrophysics Data System (ADS)

This work establishes the level of uncertainty for electrical measurements commonly made on thermoelectric samples. The analysis targets measurement systems based on the four probe method. Sources of uncertainty for both electrical resistivity and Seebeck coefficient were identified and evaluated. Included are reasonable estimates on the magnitude of each source, and cumulative propagation of error. Uncertainty for the Seebeck coefficient includes the cold-finger effect which has been quantified with thermal finite element analysis. The cold-finger effect, which is a result of parasitic heat transfer down the thermocouple probes, leads to an asymmetric over-estimation of the Seebeck coefficient. A silicon germanium thermoelectric sample has been characterized to provide an understanding of the total measurement uncertainty. The electrical resistivity was determined to contain uncertainty of ±7.0% across any measurement temperature. The Seebeck coefficient of the system is +1.0%/-13.1% at high temperature and ±1.0% near room temperature. The power factor has a combined uncertainty of +7.3%/-27.0% at high temperature and ±7.5% near room temperature. These ranges are calculated to be typical values for a general four probe Seebeck and resistivity measurement configuration.

Mackey, Jon; Dynys, Frederick; Sehirlioglu, Alp

2014-08-01

69

Polarimetric pixel using Seebeck nanoantennas.  

PubMed

Optical nanoantennas made of two metals are proposed to produce a Seebeck voltage proportional to the Stokes parameters of a light beam. The analysis is made using simulations in the electromagnetic and thermal domains. Each Stokes parameter is independently obtained from a dedicated nanoantenna configuration. S1 and S2 rely on the combination of two orthogonal dipoles. S3 is given by arranging two Archimedian spirals with opposite orientations. The analysis also includes an evaluation of the error associated with the Seebeck voltage, and the crosstalk between Stokes parameters. The results could lead to the conception of polarization sensors having a receiving area smaller than 10?(2). We illustrate these findings with a design of a polarimetric pixel. PMID:24921575

Cuadrado, Alexander; Briones, Edgar; González, Francisco J; Alda, Javier

2014-06-01

70

Estimation of the thermal band gap of a semiconductor from Seebeck measurements  

SciTech Connect

It is shown that the magnitude of the Seebeck coefficient of a semiconductor has a maximum value that is close to one-half the energy gap divided by eT. An expression for the position of the Fermi level at which the Seebeck coefficient has a maximum or minimum value is derived, with account taken of the mobility and effective mass ratios. It is concluded that measurement of the Seebeck coefficient as a function of temperature on any novel semiconductor is one of the simplest ways of estimating its band gap.

Goldsmid, H.J.; Sharp, J.W. [Marlow Industries, Inc., Dallas, TX (United States)

1999-07-01

71

Apparatus Tests Thermocouples For Seebeck Inhomogeneity  

NASA Technical Reports Server (NTRS)

Automated apparatus reveals sources of error not revealed in calibration. Computer-controlled apparatus detects and measures Seebeck inhomogeneities in sheathed thermocouples. Measures thermocouple output voltage as function of position of probe along sharp gradient of temperature. Abnormal variations in voltage-versus-position data indicative of Seebeck inhomogeneities. Prototype for development of standard method and equipment for routine acceptance/rejection testing of sheathed thermocouples in industrial and research laboratories.

Burkett, Cecil G., Jr.; Bauserman, Willard A., Jr.; West, James W.

1995-01-01

72

Seebeck Nanoantennas for Infrared Detection and Energy Harvesting Applications  

E-print Network

In this letter we introduce a new type of infrared sensor, based on thermocouple nanoantennas, which enables the energy detection and gathering in the mid-infrared region. The proposed detector combines the Seebeck effect, as a transduction mechanism, with the functionalities of the optical antennas for optical sensing. By using finite-element numerical simulations we evaluate the performance and optical-to-electrical conversion efficiency of the proposed device, unveiling its potential for optical sensing and energy harvesting applications.

Briones, Edgar; Martinez-Anton, J C; Cuadrado, Alexander; McMurtry, Stefan; Hehn, Michel; Montaigne, François; Alda, Javier; González, Javier

2014-01-01

73

Estimation of the thermal band gap of a semiconductor from seebeck measurements  

Microsoft Academic Search

It is shown that the magnitude of the Seebeck coefficient of a semiconductor has a maximum value that is close to one-half\\u000a the energy gap divided by eT. An expression for the position of the Fermi level at which the Seebeck coefficient has a maximum\\u000a or minimum value is derived, with account taken of the mobility and effective mass ratios.

H. J. Goldsmid; J. W. Sharp

1999-01-01

74

Can Seebeck coefficient identify quantum interference in molecular conduction?  

E-print Network

We look for manifestations of quantum interference effects in the Seebeck coefficient of a molecular junction, when the electronic conductance exhibits pronounced destructive interference features due to the presence of quasi-degenerate electronic states which differ in their spatial symmetry. We perform our analysis by considering three separate limits for electron transport: coherent, fully dephased, and suffering inelastic scattering with molecular vibrations. We find that while the conductance displays strong signatures of the underling transport mechanisms: destructive quantum interference features in the coherent case and thermal activation characteristics in the inelastic limit, the Seebeck coefficient conceals details of electron dynamics while it robustly reveals information about the energy characteristics of the junction. We provide closed-form expressions for the electronic conductance and the thermopower of our system as a function of temperature, gate voltage and hybridization energy in differen...

Simine, Lena; Segal, Dvira

2014-01-01

75

Seebeck Coefficient Measured With Differential Heat Pulses  

NASA Technical Reports Server (NTRS)

Common experimental errors reduced because pulse technique suppresses drifts in thermoelectric measurements. Differential-heat-pulse apparatus measures Seebeck coefficient in semiconductors at temperatures up to 1,900 K. Sample heated to measuring temperature in furnace. Ends of sample then differentially heated a few degrees more by lamps. Differential temperature rise and consequent Seebeck voltage measured via thermocouple leads. Because pulse technique used, errors that often arise from long-term drifts in thermoelectric measurements suppressed. Apparatus works with temperature differences of only few degrees, further increasing accuracy of coefficients obtained.

Zoltan, L.; Wood, C.; Stapfer, G.

1986-01-01

76

Apparatus Measures Seebeck Coefficient And Resistivity  

NASA Technical Reports Server (NTRS)

Electrical measurements made by four point probes, two of which double as temperature probes. Laboratory apparatus measures both Seebeck coefficients and electrical resistivities of candidate thermoelectric materials at temperatures from ambient to 1,300 K. Apparatus makes possible to take both measurements alternately and in rapid succession during same heating cycle, thereby reducing distortion.

Zoltan, Leslie D.; Wood, Charles; Fleurial, Jean-Pierre; Liu, Yixin

1993-01-01

77

Huge Seebeck coefficients in non-aqueous electrolytes  

E-print Network

The Seeebeck coefficients of the non-aqueous electrolytes tetrabutylammonium nitrate, tetraoctylphosphonium bromide and tetradodecylammonium nitrate in 1-octanol, 1-dodecanol and ethylene-glycol are measured in a temperature range from T=30 to T=45 C. The Seebeck coefficient is generally of the order of a few hundreds of microvolts per Kelvin for aqueous solution of inorganic ions. Here we report huge values of 7 mV/K at 0.1M concentration for tetrabutylammonium nitrate in 1-dodecanol. These striking results open the question of unexpectedly large kosmotrope or "structure making" effects of tetraalkylammonium ions on the structure of alcohols.

M. Bonetti; S. Nakamae; M. Roger; P. Guenoun

2011-02-11

78

PHYSICAL REVIEW B 90, 174435 (2014) Model for the spin-dependent Seebeck coefficient of InSb in a magnetic field  

E-print Network

PHYSICAL REVIEW B 90, 174435 (2014) Model for the spin-dependent Seebeck coefficient of InSb; published 25 November 2014) We develop a simple theory for the spin-dependent Seebeck effect in n-doped InSb in an external magnetic field. We consider spin-1/2 electrons in the conduction band of InSb with a temperature

Stroud, David

79

Combination of PVA with Graphene to Improve the Seebeck Coefficient for Thermoelectric Generator Applications  

NASA Astrophysics Data System (ADS)

Ultrasensitive thermoelectric (TE) materials are essential for the next generation of self-powered electronic devices. In this work, a graphene-based TE generator was fabricated. For 50 to 1000 graphene layers the average Seebeck coefficient was 90 ?V/K. We also report improvement of the Seebeck coefficient by use of a hybrid material containing 10% poly(vinyl alcohol) (PVA) and 90% graphene oxide prepared and tested under the same conditions. The results show that the Seebeck coefficient is improved by an average of 30% compared with graphene alone. Because the fabrication process is facile, scalable, and cost effective, it could also be applicable to other fields of science and engineering.

Mahmoud, L.; Abdul Samad, Y.; Alhawari, M.; Mohammad, B.; Liao, K.; Ismail, M.

2015-01-01

80

Model for the spin-dependent Seebeck coefficient of InSb in a magnetic field  

NASA Astrophysics Data System (ADS)

We develop a simple theory for the spin-dependent Seebeck effect in n -doped InSb in an external magnetic field. We consider spin-1 /2 electrons in the conduction band of InSb with a temperature gradient parallel to the applied magnetic field. In the absence of spin-orbit interactions, a Boltzmann equation approach leads to a spin current parallel to the field and proportional to the temperature gradient. The calculated spin-dependent Seebeck coefficient oscillates as a function of magnetic field B ; the peak positions are approximately periodic in 1 /B . The oscillations arise when the Fermi energy crosses the bottom of a Landau band.

Pike, Nicholas A.; Stroud, David

2014-11-01

81

The Seebeck coefficient of iodine  

E-print Network

B-9 of Appendix B& also equation B-11 of Appendix B). Q ? ? [r+ 2+in ? + ? ln ? ] k 2 3 m*kT e n 2 2 (1. 4) where n is the concentration of carriers, m* is the effective mass of the carriers, h is Planck's constant, and r is a constant... of the order of unity which depends on the electron scattering mechanism (see Appendix D). Equation (1. 4) can be written as given in (6). Q = ? 0. 0862 [in ' + ? ln ? + r + 2] (1. 5) 4, 7 X 10 3 m*T n 2 m where m is the electronic mass, and Q...

Perez-Fernandez, Domingo Miguel

1968-01-01

82

Thermoelectric measurement equipments This instrument is designed for simultaneous measurement of Seebeck coefficient and  

E-print Network

measurement of Seebeck coefficient and electric conductivity for the evaluation of thermoelectric be used for simultaneous measurement of both Seebeck coefficient and electric resistance (resistivity method Seebeck coefficient : Static dc method Electric resistance : Four-terminal method Atmosphere Low

Taya, Minoru

83

Measurement of Seebeck coefficient perpendicular to SiGe superlattice  

Microsoft Academic Search

Seebeck coefficient is one of the key parameters to evaluate the performance of thermoelectric coolers. However, it is very difficult to directly measure Seebeck coefficient perpendicular to thin film devices because of the difficulty of creating a temperature gradient and measuring localized temperature and voltage change simultaneously. In this paper, a novel method is described and it is used to

Yan Zhang; Gehang Zeng; Rajeev Singh; James Christofferson; Edward Croke; John E. Bowers; Ali Shakouri

2002-01-01

84

Seebeck effect in steel fiber reinforced cement  

Microsoft Academic Search

Cement pastes containing short steel fibers, which contribute to electron conduction, exhibit positive values (up to 68 ?V\\/°C) of the absolute thermoelectric power. A steel fiber content of 1.0% by mass of cement gives a higher value of the absolute thermoelectric power than a content of 0.5% by mass cement, in addition to yielding more reversibility and linearity in the

Sihai Wen; D. D. L Chung

2000-01-01

85

ErAs/InGaAs superlattice Seebeck coefficient Gehong Zeng, John E. Bowers  

E-print Network

ErAs/InGaAs superlattice Seebeck coefficient Gehong Zeng, John E. Bowers Department of Electrical scattering centers for phonons. Electron filtering by heterostructure barriers can also enhance Seebeck-plane Seebeck coefficient of the superlattice layers.. Using these device patterns, the combined Seebeck

Bowers, John

86

Thermal and transport properties of the Heusler-type Fe2VAl1-xGex(0<=x<=0.20) alloys: Effect of doping on lattice thermal conductivity, electrical resistivity, and Seebeck coefficient  

Microsoft Academic Search

We report on the thermoelectric properties of the Heusler-type Fe2VAl1-xGex alloys with compositions 0<=x<=0.20 . While Fe2VAl(x=0) exhibits a semiconductorlike behavior in electrical resistivity, a slight substitution of Ge for Al causes a significant decrease in the low-temperature resistivity and a large enhancement in the Seebeck coefficient, reaching -130muV\\/K for x=0.05 at around room temperature. Comparison with the Fe2VAl1-xSix system

Y. Nishino; S. Deguchi; U. Mizutani

2006-01-01

87

System to Measure Thermal Conductivity and Seebeck Coefficient for Thermoelectrics  

NASA Technical Reports Server (NTRS)

The Seebeck coefficient, when combined with thermal and electrical conductivity, is an essential property measurement for evaluating the potential performance of novel thermoelectric materials. However, there is some question as to which measurement technique(s) provides the most accurate determination of the Seebeck coefficient at elevated temperatures. This has led to the implementation of nonstandardized practices that have further complicated the confirmation of reported high ZT materials. The major objective of the procedure described is for the simultaneous measurement of the Seebeck coefficient and thermal diffusivity within a given temperature range. These thermoelectric measurements must be precise, accurate, and reproducible to ensure meaningful interlaboratory comparison of data. The custom-built thermal characterization system described in this NASA-TM is specifically designed to measure the inplane thermal diffusivity, and the Seebeck coefficient for materials in the ranging from 73 K through 373 K.

Kim, Hyun-Jung; Skuza, Jonathan R.; Park, Yeonjoon; King, Glen C.; Choi, Sang H.; Nagavalli, Anita

2012-01-01

88

The impact of commonly used approximations on the computation of the Seebeck coefficient and mobility of polar semiconductors  

NASA Astrophysics Data System (ADS)

Seebeck coefficient modeling and measurement has important applications in direct thermal to electrical energy conversion and solid-state physics. The computations of the Seebeck coefficient and mobility of polar semiconductors in the literature often employ certain approximations, notably the relaxation time approximation (RTA) and the truncation of the Boltzmann transport equation. We study the accuracy of these approximations as a function of the effective mass, temperature, and carrier concentration using a recently developed technique for rigorous solution of the Boltzmann transport equation. We find that the approximations give rise to considerable error in the computed Seebeck coefficients of heavily doped semiconductors with a low effective mass, and that the RTA is entirely inapplicable for the accurate computation of the mobility of several important materials.

Ramu, Ashok T.; Bowers, John E.

2012-10-01

89

Resistivity, Hall Constant, and Seebeck Coefficient of CsAu  

Microsoft Academic Search

Measurements of resistivity, Hall constant, and Seebeck coefficient have established that CsAu is an n-type semiconductor with carrier concentrations 1018-1019 cm-3. The carrier concentration is essentially independent of temperature over the range 4.2-300°K and the mobility is 30-60 cm2V-1 sec-1. It is suggested that excess cesium introduces an impurity band which overlaps the conduction band. The Seebeck coefficient (-0.023 mV\\/°K

Frederick Wooten; George A. Condas

1963-01-01

90

Fast Seebeck coefficient measurement based on dynamic method.  

PubMed

A setup based on dynamic method was developed for fast Seebeck coefficient measurement from room temperature to 473 K. Two T-type thermocouples with a response time of less than 0.1 s were used to measure the dynamic temperatures of the sample. The Cu wires of the two thermocouples served as leads for Seebeck voltage measurement. The dynamic temperature feature of the setup was characterized. Test measurements were conducted with LaCo(0.9)Cu(0.1)O3 and LaCo(0.8)5Cu(0.15)O3 samples with the customized setup, and the results had a difference of ±8.4% compared with the data provided by ZEM-2 (Ulvac-Riko, Japan), which showed that the Seebeck measurement with the customized setup was reliable. In addition, the error on the Seebeck coefficient caused by the dynamic variation of temperature was discussed. The setup described in this paper has the advantage of fast Seebeck coefficient measurement with a measurement speed of about 14-23 K?min(-1). PMID:24880400

Zhou, Yang; Yang, Donghua; Li, Liangliang; Li, Fu; Li, Jing-Feng

2014-05-01

91

Development of a Seebeck coefficient Standard Reference Material  

NASA Astrophysics Data System (ADS)

We have successfully developed a Seebeck coefficient Standard Reference Material (SRM™), Bi2Te3, that is crucial for inter-laboratory data comparison and for instrument calibration. Certification measurements were performed using two different techniques on 10 samples randomly selected from a batch of 390 bars. The certified Seebeck coefficient values are provided from 10 to 390 K. The availability of this SRM will validate the measurement accuracy, leading to a better understanding of the structure/property relationships, and the underlying physics of new and improved thermoelectric materials. An overview of the measurement techniques and data analysis is given.

Lowhorn, Nathan D.; Wong-Ng, W.; Lu, Z. Q.; Thomas, E.; Otani, M.; Green, M.; Dilley, N.; Sharp, J.; Tran, T. N.

2009-08-01

92

Measurement of Seebeck coefficient using a large thermal gradient  

NASA Technical Reports Server (NTRS)

The integral method of measuring the Seebeck voltage, V(T), has been applied to short rod-shaped samples. In the present method, one end of the sample is held at a fixed temperature and the other end is automatically varied through a temperature T range of interest, up to a maximum temperature of 1000 C. The Seebeck coefficient is then obtained from the slope of the V(T) vs T curve. The method offers simplicity of sample handling and minimal operator involvement.

Wood, C.; Chmielewski, A.; Zoltan, D.

1988-01-01

93

A high temperature apparatus for measurement of the Seebeck coefficient  

SciTech Connect

A high temperature Seebeck coefficient measurement apparatus with various features to minimize typical sources of error is designed and built. Common sources of temperature and voltage measurement error are described and principles to overcome these are proposed. With these guiding principles, a high temperature Seebeck measurement apparatus with a uniaxial 4-point contact geometry is designed to operate from room temperature to over 1200 K. This instrument design is simple to operate, and suitable for bulk samples with a broad range of physical types and shapes.

Iwanaga, Shiho; Toberer, Eric S.; LaLonde, Aaron; Snyder, G. Jeffrey [Materials Science, California Institute of Technology, Pasadena, California 91125 (United States)

2011-06-15

94

Cross-Plane Seebeck Coefficient Anomaly in a High Barrier Superlattice with Miniband Formation  

E-print Network

Cross-Plane Seebeck Coefficient Anomaly in a High Barrier Superlattice with Miniband Formation., Univ. of California, Santa Barbara, CA 93106 ABSTRACT We have measured the cross-plane Seebeck concentrations. Contrary to the behavior of conventional bulk III-V materials, the Seebeck coefficient did

95

Measurementof Seebeck coefficient perpendicular to SiGe superlattice , Gehang Zeng2  

E-print Network

Page 1 Measurementof Seebeck coefficient perpendicular to SiGe superlattice Yan Zhang1 , Gehang, California 90265 Abstract Seebeck coefficient is one of the key parameters to evaluate the performance of thermoelectric coolers. However, it is very difficult to directly measure Seebeck coefficient perpendicular

96

Three-dimensional modeling of nanoscale Seebeck measurements by scanning thermoelectric microscopy  

E-print Network

Three-dimensional modeling of nanoscale Seebeck measurements by scanning thermoelectric microscopy of the Seebeck profiling is limited by the finite value of the phonon mean free path of the sample and the tip by the dimensionless figure of merit ZT. ZT is defined as ZT= S2 /k T, where S is the Seebeck coefficient, and and k

97

MAMMALIAN SPECIES No. 654, pp. 18, 3 figs. Perameles gunnii. By John H. Seebeck  

E-print Network

MAMMALIAN SPECIES No. 654, pp. 1­8, 3 figs. Perameles gunnii. By John H. Seebeck Published 23 with darker yellow-brown dorsal fur (Seebeck 1995a). P. bougainville, formerly widespread but allopatric stripe (Seebeck et al. 1990b). Skull of P. gunnii (Fig. 2) is similar to that of P. nasuta but is smaller

Hayssen, Virginia

98

Seebeck and Peltier coefficients of hydrogen electrodes related to the  

E-print Network

Seebeck and Peltier coefficients of hydrogen electrodes related to the PEMFC Papy Zefaniya Chemical and Technology #12;#12;Thermopower of concentration cell with hydrogen electrodes related to PEMFC Papy Mutuwa was encouraged by my Supervisor and my co-Supervisor Odne to read many interesting books and papers which

Kjelstrup, Signe

99

First principles explanation of the positive Seebeck coefficient of lithium.  

PubMed

Lithium is one of the simplest metals, with negative charge carriers and a close reproduction of free-electron dispersion. Experimentally, however, Li is one of a handful of elemental solids (along with Cu, Ag, and Au) where the sign of the Seebeck coefficient (S) is opposite to that of the carrier. This counterintuitive behavior still lacks a satisfactory interpretation. We calculate S fully from first principles, within the framework of Allen's formulation of Boltzmann transport theory. Here it is crucial to avoid the constant relaxation time approximation, which gives a sign for S which is necessarily that of the carriers. Our calculated S are in excellent agreement with experimental data, up to the melting point. In comparison with another alkali metal, Na, we demonstrate that within the simplest nontrivial model for the energy dependency of the electron lifetimes, the rapidly increasing density of states (DOS) across the Fermi energy is related to the sign of S in Li. The exceptional energy dependence of the DOS is beyond the free-electron model, as the dispersion is distorted by the Brillouin zone edge; this has a stronger effect in Li than other alkali metals. The electron lifetime dependency on energy is central, but the details of the electron-phonon interaction are found to be less important, contrary to what has been believed for several decades. Band engineering combined with the mechanism exposed here may open the door to new "ambipolar" thermoelectric materials, with a tunable sign for the thermopower even if either n- or p-type doping is impossible. PMID:24877957

Xu, Bin; Verstraete, Matthieu J

2014-05-16

100

Multifold Seebeck increase in RuO2 films by quantum-guided lanthanide dilute alloying  

NASA Astrophysics Data System (ADS)

Ab initio predictions indicating that alloying RuO2 with La, Eu, or Lu can increase the Seebeck coefficient ? manifold due to quantum confinement effects are validated in sputter-deposited La-alloyed RuO2 films showing fourfold ? increase. Combinatorial screening reveals that ? enhancement correlates with La-induced lattice distortion, which also decreases the thermal conductivity twentyfold, conducive for high thermoelectric figures of merit. These insights should facilitate the rational design of high efficiency oxide-based thermoelectrics through quantum-guided alloying.

Music, Denis; Basse, Felix H.-U.; Han, Liang; Devender; Borca-Tasciuc, Theo; Gengler, Jamie J.; Voevodin, Andrey A.; Ramanath, Ganpati; Schneider, Jochen M.

2014-02-01

101

Giant magnetoresistance and spin Seebeck coefficient in zigzag ?-graphyne nanoribbons  

NASA Astrophysics Data System (ADS)

We investigate the spin-dependent electric and thermoelectric properties of ferromagnetic zigzag ?-graphyne nanoribbons (Z?GNRs) using density-functional theory combined with non-equilibrium Green's function method. A giant magnetoresistance is obtained in the pristine even-width Z?GNRs and can be as high as 106%. However, for the doped systems, a large magnetoresistance behavior may appear in the odd-width Z?GNRs rather than the even-width ones. This suggests that the magnetoresistance can be manipulated in a wide range by the dopants on the edges of Z?GNRs. Another interesting phenomenon is that in the B- and N-doped even-width Z?GNRs the spin Seebeck coefficient is always larger than the charge Seebeck coefficient, and a pure-spin-current thermospin device can be achieved at specific temperatures.

Zhai, Ming-Xing; Wang, Xue-Feng; Vasilopoulos, P.; Liu, Yu-Shen; Dong, Yao-Jun; Zhou, Liping; Jiang, Yong-Jing; You, Wen-Long

2014-09-01

102

Giant magnetoresistance and spin Seebeck coefficient in zigzag ?-graphyne nanoribbons.  

PubMed

We investigate the spin-dependent electric and thermoelectric properties of ferromagnetic zigzag ?-graphyne nanoribbons (Z?GNRs) using density-functional theory combined with non-equilibrium Green's function method. A giant magnetoresistance is obtained in the pristine even-width Z?GNRs and can be as high as 10(6)%. However, for the doped systems, a large magnetoresistance behavior may appear in the odd-width Z?GNRs rather than the even-width ones. This suggests that the magnetoresistance can be manipulated in a wide range by the dopants on the edges of Z?GNRs. Another interesting phenomenon is that in the B- and N-doped even-width Z?GNRs the spin Seebeck coefficient is always larger than the charge Seebeck coefficient, and a pure-spin-current thermospin device can be achieved at specific temperatures. PMID:25214422

Zhai, Ming-Xing; Wang, Xue-Feng; Vasilopoulos, P; Liu, Yu-Shen; Dong, Yao-Jun; Zhou, Liping; Jiang, Yong-Jing; You, Wen-Long

2014-10-01

103

Electrical conductivity and Seebeck coefficient of (La, Ca) (Cr, Co)O 3  

Microsoft Academic Search

Electrical conductivity and Seebeck coefficients of (La, Ca) (Cr, Co)O3 were measured as a function of temperature. The electrical conductivity as measured in air from 100 to 1100 °C increased with increasing Co and Ca content. The Seebeck coefficients were positive, indicating p-type conductivity. The substitution of Co for Cr significantly decreased the Seebeck coefficients, indicating that the substitution resulted

R. Koc; H. U. Anderson

1992-01-01

104

An instrument for the high temperature measurement of the Seebeck coefficient and electrical resistivity  

NASA Astrophysics Data System (ADS)

A system for the simultaneous measurement of thermoelectric power and resistivity of one and/or two samples over a temperature range of 300-1000 K in a vacuum chamber is designed and implemented. A sample probe is developed to provide its easy mounting and usage. In addition, two samples can be measured at the same time. Measurement accuracy has been enhanced by beadless thermocouples and micro-heaters that are specifically designed in order to minimize the ‘cold-finger effect’ and to eliminate some possible source of contact, design and measurement errors. A broad range of physical types and shapes of samples, such as bulk, bar or disc, can be measured by a software controlled system. A differential steady-state method has been applied for Seebeck coefficient measurement. Resistivity measurement is conducted with the axial technique of the four-point probe method. Platinum wire and a niobium rod are chosen as the standard samples. The total data error for the Seebeck coefficient and resistivity measurements is estimated to be less than 2.6% and 1%, respectively.

Gunes, Murat; Parlak, Mehmet; Ozenbas, Macit

2014-05-01

105

Simultaneous Enhancement of the Electrical Conductivity and Seebeck Coefficient of PEDOT-block-PEG/SWCNTs Nanocomposites  

NASA Astrophysics Data System (ADS)

In this study, the thermoelectric (TE) performance of poly(3,4-ethylenedioxythiophene)-block-poly(ethylene glycol) (PEDOT-block-PEG), one of the most important poly(3,4-ethylenedioxythiophene) (PEDOT) derivatives, was studied. To improve its TE performance, different mass fractions of single-walled carbon nanotubes (SWCNTs) were incorporated by physical mixing. Blending with SWCNTs resulted in simultaneous enhancement of the electrical conductivity and Seebeck coefficient of the PEDOT-block-PEG/SWCNTs nanocomposites. At 300 K, the maximum electrical conductivity was increased from 0.51 to 78.6 S/cm, and the Seebeck coefficient was increased from 5.1 to 46.3 ?V/K. The thermal conductivity of the composite films was low (0.24-0.34 W/m/K). The maximum ZT of PEDOT-block-PEG/SWCNTs nanocomposites was 1.24 × 10-2 when the SWCNTs content was 66.7 wt.%. This study suggests that constructing PEDOT-block-PEG/SWCNTs nanocomposites might be an effective way of improving the TE properties of PEDOT-block-PEG.

Jiang, Qinglin; Liu, Congcong; Zhu, Danhua; Song, Haijun; Xu, Jingkun; Shi, Hui; Mo, Daize; Wang, Zhipeng; Zhu, Zhengyou

2014-11-01

106

High-temperature characteristics of Seebeck coefficients for AlInN alloys grown by metalorganic vapor phase epitaxy  

E-print Network

High-temperature characteristics of Seebeck coefficients for AlInN alloys grown by metalorganic://jap.aip.org/about/rights_and_permissions #12;High-temperature characteristics of Seebeck coefficients for AlInN alloys grown by metalorganic 18015, USA (Received 31 May 2011; accepted 15 July 2011; published online 23 August 2011) The Seebeck

Gilchrist, James F.

107

Cross-plane Seebeck coefficient of ErAs:InGaAs/InGaAlAs superlattices Gehong Zenga  

E-print Network

Cross-plane Seebeck coefficient of ErAs:InGaAs/InGaAlAs superlattices Gehong Zenga Department; published online 6 February 2007 We characterize cross-plane and in-plane Seebeck coefficients for Er. The microheater creates a local temperature difference, and the cross-plane Seebeck coefficients

Bowers, John

108

Conductivities and Seebeck Coefficients of Boron Carbides: ''Softening-Bipolaron'' Hopping  

SciTech Connect

The most conspicuous feature of boron carbides' electronic transport properties is their having both high carrier densities and large Seebeck coefficients. The magnitudes and temperature dependencies of the Seebeck coefficients are consistent with large contributions from softening bipolarons: singlet bipolarons whose stabilization is significantly affected by their softening of local vibrations. Boron carbides' high carrier densities, small activation energies for hopping ({approx} 0.16 eV), and anomalously large Seebeck coefficients combine with their low, glass-like thermal conductivities to make them unexpectedly efficient high-temperature thermoelectrics.

ASELAGE,TERRENCE L.; EMIN,DAVID JACOB; MCCREADY,STEVEN S.

2000-07-20

109

PHYSICAL REVIEW B 89, 054401 (2014) Extrinsic spin Hall effects measured with lateral spin valve structures  

E-print Network

of utilizing the ISHE is a detection of a spin dependent chemical potential arising from the spin Seebeck effect [2­7]. The spin Seebeck effect converts heat into spin current, and the generated spin current can in the ferromag- netic layer. To realize the detection of the spin Seebeck effect as well as the magnetization

Otani, Yoshichika

110

Multifold Seebeck increase in RuO{sub 2} films by quantum-guided lanthanide dilute alloying  

SciTech Connect

Ab initio predictions indicating that alloying RuO{sub 2} with La, Eu, or Lu can increase the Seebeck coefficient ? manifold due to quantum confinement effects are validated in sputter-deposited La-alloyed RuO{sub 2} films showing fourfold ? increase. Combinatorial screening reveals that ? enhancement correlates with La-induced lattice distortion, which also decreases the thermal conductivity twentyfold, conducive for high thermoelectric figures of merit. These insights should facilitate the rational design of high efficiency oxide-based thermoelectrics through quantum-guided alloying.

Music, Denis, E-mail: music@mch.rwth-aachen.de; Basse, Felix H.-U.; Schneider, Jochen M. [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, D-52074 Aachen (Germany); Han, Liang; Borca-Tasciuc, Theo [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180 (United States); Devender [Materials Science and Engineering Department, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180 (United States); Gengler, Jamie J. [Air Force Research Laboratory, Materials and Manufacturing Directorate, WPAFB, Ohio 45433 (United States); Spectral Energies, LLC, Dayton, Ohio 45431 (United States); Voevodin, Andrey A. [Air Force Research Laboratory, Materials and Manufacturing Directorate, WPAFB, Ohio 45433 (United States); Ramanath, Ganpati [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, D-52074 Aachen (Germany); Materials Science and Engineering Department, Rensselaer Polytechnic Institute, 110 8th St., Troy, New York 12180 (United States)

2014-02-03

111

Influence of Doping Concentration and Ambient Temperature on the Cross-Plane Seebeck Coefficient of InGaAs/InAlAs superlattices  

E-print Network

Influence of Doping Concentration and Ambient Temperature on the Cross-Plane Seebeck Coefficient the Seebeck coefficient perpendicular to the layer. In this paper, we discuss the Seebeck coefficients of In in bulk material -- the Seebeck coefficient did not decrease monotonically with doping concentration

112

Multifunctional probes for high-throughput measurement of Seebeck coefficient and electrical conductivity at room temperature  

NASA Astrophysics Data System (ADS)

An apparatus capable of rapid measurement of the Seebeck coefficient and electrical resistivity at room temperature is reported. The novel aspect of this apparatus is the use of 4 multifunctional probes that comprise a junction of two conductors at the tip and serve as both thermocouples and electrical contacts. In addition, one of the probes has a built-in heater that can establish a temperature gradient in the sample for the Seebeck measurement. The technique does not require special sample geometries or preparation of contacts and is suitable for bulk and thin film materials. Together with automated sample stage and data acquisition, the equipment is able to measure both the Seebeck coefficient and electrical resistivity in less than 20 s with good accuracy. Less than 5% and 4% relative errors were found for the measurement of the Seebeck coefficient and electrical resistivity, respectively. This makes the apparatus especially useful for high throughput evaluation of thermoelectric materials.

García-Cañadas, Jorge; Min, Gao

2014-04-01

113

A hot probe setup for the measurement of Seebeck coefficient of thin wires and thin films using integral method.  

PubMed

An experimental setup is developed for the measurement of the Seebeck coefficient of thin wires and thin films in the temperature range of 300-650 K. The setup makes use of the integral method for measuring the Seebeck voltage across the sample. Two pointed copper rods with in-built thermocouples serve as hot and cold probes as well as leads for measuring the Seebeck voltage. The setup employs localized heating and enables easy sample loading using a spring loaded mounting system and is fully automated. Test measurements are made on a constantan wire and indium tin oxide (ITO) thin film for illustration. The Seebeck voltage obtained for constantan wire is in agreement with the NIST data for copper constantan couple with an error of 1%. The calculated carrier concentration of ITO film from the Seebeck coefficient measurement is comparable with that obtained by electrical transport measurements. The error in the Seebeck coefficient is estimated to be within 3%. PMID:18315317

Kumar, S R Sarath; Kasiviswanathan, S

2008-02-01

114

A hot probe setup for the measurement of Seebeck coefficient of thin wires and thin films using integral method  

NASA Astrophysics Data System (ADS)

An experimental setup is developed for the measurement of the Seebeck coefficient of thin wires and thin films in the temperature range of 300-650K. The setup makes use of the integral method for measuring the Seebeck voltage across the sample. Two pointed copper rods with in-built thermocouples serve as hot and cold probes as well as leads for measuring the Seebeck voltage. The setup employs localized heating and enables easy sample loading using a spring loaded mounting system and is fully automated. Test measurements are made on a constantan wire and indium tin oxide (ITO) thin film for illustration. The Seebeck voltage obtained for constantan wire is in agreement with the NIST data for copper constantan couple with an error of 1%. The calculated carrier concentration of ITO film from the Seebeck coefficient measurement is comparable with that obtained by electrical transport measurements. The error in the Seebeck coefficient is estimated to be within 3%.

Sarath Kumar, S. R.; Kasiviswanathan, S.

2008-02-01

115

Macro and Micro-Scale Features of Thermoelectric PbTe (Br, Na) Systems: Micro-FTIR Spectroscopy, Micro-Seebeck Measurements, and SEM/EDX Observations  

NASA Astrophysics Data System (ADS)

In this work, n-type and p-type PbTe doped with Br and Na, respectively, were thoroughly examined to determine the effect of the dopant on microstructure. Macro and micro homogeneity of the samples were studied by means of micro-Fourier-transform infrared (micro-FTIR) spectroscopy, micro-Seebeck measurements, and scanning electron microscopy with energy-dispersive x-ray analysis (SEM/EDX). SEM/EDX observations showed the samples were not single-phase materials—second phases were created by inclusions that disturbed the coherence of the matrix and, subsequently, drastically affected the Seebeck coefficient. In a micro-scale study, local variations of sodium content were detected in Na-doped samples; in Br-doped samples a second, PbBr2, phase was observed in the PbTe matrix. A direct effect of matrix dopant on Seebeck coefficient and plasmon frequency for the Br-doped and Na-doped samples was observed by use of the three complementary techniques.

Stefanaki, E. C.; Polymeris, G. S.; Nikolic, P. M.; Papageorgiou, Ch.; Pavlidou, E.; Hatzikraniotis, E.; Kyratsi, Th.; Paraskevopoulos, K. M.

2014-10-01

116

Dependence of Seebeck coefficient on a load resistance and energy conversion efficiency in a thermoelectric composite  

SciTech Connect

The thermo-emf {delta}V and current {delta}I generated by imposing the alternating temperature gradients (ATG) at a period of T and the steady temperature gradient (STG) on a thermoelectric (TE) composite were measured as a function of t, where t is the lapsed time and T was varied from 60 to or {infinity} s. The STG and ATG were produced by imposing steadily and alternatively a source voltage V in the range from 1.0 to 4.0 V on two Peltier modules sandwiching a composite. {delta}T, {delta}V, {delta}I and V{sub P} oscillate at a period T and their waveforms vary significantly with a change of T, where {delta}V and V{sub P} are the voltage drops in a load resistance R{sub L} and in resistance R{sub P} of two modules. The resultant Seebeck coefficient |{alpha}| = |{delta}V|/{delta}T of a composite under the STG was found to be expressed as |{alpha}| = |{alpha}{sub 0}|(1 - R{sub comp}/R{sub T}), where R{sub T} is the total resistance of a circuit for measuring the output signals and R{sub comp} is the resistance of a composite. The effective generating power {delta}W{sub eff} has a local maximum at T = 960 s for the p-type composite and at T = 480 s for the n-type one. The maximum energy conversion efficiency {eta} of the p- and n-type composites under the ATG produced by imposing a voltage of 4.0 V at an optimum period were 0.22 and 0.23% at {delta}T{sub eff} = 50 K, respectively, which are 42 and 43% higher than those at {delta}T = 42 K under the STG. These maximum {eta} for a TE composite sandwiched between two Peltier modules, were found to be expressed theoretically in terms of R{sub P}, R{sub T}, R{sub L}, {alpha}{sub P} and {alpha}, where {alpha}{sub P} and {alpha} are the resultant Seebeck coefficients of Peltier modules and a TE composite.

Yamashita, Osamu [Materials Science Co. Ltd., 5-5-44 Minamikasugaoka, Ibaraki, Osaka 567-0046 (Japan)], E-mail: yamashio567@yahoo.co.jp; Odahara, Hirotaka [Advanced Materials Co. Ltd., 4-6-10 Kizuri, Higashiosaka, Osaka 577-0827 (Japan); Ochi, Takahiro; Satou, Kouji [Faculty of Engineering, Ehime University, Bunkyocho, Matsuyama 790-8577 (Japan)

2007-10-02

117

A Study of the Measurement of Seebeck Coefficient of SiGe  

NASA Technical Reports Server (NTRS)

In 1821 German Physicist Thomas J. Seebeck discovered that heat could be converted into electricity when a temperature difference was applied across two points on a material. Theoretically, the generated voltage has a directly proportional relationship with the temperature difference. This relationship is the Seebeck coefficient that scientists always referred to when determining the efficiency of a thermoelectricity convention. In our experiments, however, hysteresis loops appeared when we plotted voltage against temperature difference, and the measured Seebeck appeared differently when the measurements were run under vacuum, air, and helium gas. Measurements were done by using a low-frequency AC measuring method. By simulating the experimental setup into a; thermal circuit, we found that the loop and inconsistency in measuring Seebeck coefficient could be explained by studying the behaviors of a RC circuit in a thermal sense. Under vacuum, the gap of the hysteresis loop can be largely eliminated if the time period of the temperature difference increased up to 4800s. The trend of the variations in measuring Seebeck coefficients in different environments can also be predicted by using different thermal circuit models.

Heung, King Yi

2005-01-01

118

Thermal Modeling and Analysis of a Sub-Compact Seebeck Furnace  

NASA Technical Reports Server (NTRS)

The Sub-Compact Seebeck Furnace (SCSF) is a third generation furnace designed as an experimental facility to study the phenomena of undercooling associated with directional solidification. It is intended to provide a double peak temperature profile along the axial direction with gradient zones at each end. By keeping the temperature in the central portion above the melting point of the sample, and cooling the ends of the furnace, a solid/liquid (S/L) interface can be maintained in each one of the gradient zones. A motorized motion control provides a motion to one-half of the furnace. The undercooling associated with the interface being directionally solidified can thus be studied. Modeling of the temperature profile is important to help assure that the furnace design provides the correct thermal characteristics. The furnace is designed with two halves that telescope. Results of thermal analysis based on an analytical solution using simple assumptions will be presented. The resulting temperature profile will show the salient features of the desired thermal profile and provide the general directions for thermal design. Experimental results will be used to compare with the analytical profile. Approach for numerical modeling to provide more detailed information such as two-dimensional effects will be discussed.

Wang, Francis C.; Peters, Palmer; Rose, M. Franklin (Technical Monitor)

2001-01-01

119

A hot probe setup for the measurement of Seebeck coefficient of thin wires and thin films using integral method  

Microsoft Academic Search

An experimental setup is developed for the measurement of the Seebeck coefficient of thin wires and thin films in the temperature range of 300-650 K. The setup makes use of the integral method for measuring the Seebeck voltage across the sample. Two pointed copper rods with in-built thermocouples serve as hot and cold probes as well as leads for measuring

S. R. Sarath Kumar; S. Kasiviswanathan

2008-01-01

120

Cross-plane Seebeck coefficient and Lorenz number in superlattices Z. Bian, M. Zebarjadi, R. Singh, Y. Ezzahri, and A. Shakouri  

E-print Network

Cross-plane Seebeck coefficient and Lorenz number in superlattices Z. Bian, M. Zebarjadi, R. Singh of cross-plane Seebeck coefficient for a superlattice structure with different doping concentrations to the bulk value. Most significantly, the Seebeck coefficient and the Lorenz number of superlattices do

121

Hall, Seebeck, and Nernst Coefficients of Underdoped HgBa2CuO4: Fermi-Surface Reconstruction in an Archetypal Cuprate Superconductor  

E-print Network

Hall, Seebeck, and Nernst Coefficients of Underdoped HgBa2CuO4þ: Fermi-Surface ReconstructionCuO4þ (Hg1201). We have measured the Hall (RH), Seebeck (S), and Nernst () coefficients of underdoped undergoes a reconstruction [11,12]. Comparative measurements of the Seebeck coefficient in YBCO and Eu

Taillefer, Louis

122

Seebeck and thermal conductivity analysis in amorphous/crystalline {beta}-K{<_2}Bi{<_8}Se{<_13} nanocomposite materials.  

SciTech Connect

In this work, ball milling is applied on {beta}-K{sub 2}Bi{sub 8}Se{sub 13} compounds in order to explore the potential of the process for the fabrication of nano-based material. Polycrystalline {beta}-K{sub 2}Bi{sub 8}Se{sub 13}, synthesized from melt, was ball milled under inert atmosphere. Powder x-ray diffraction showed a significantly increased disorder with ball milling time. TEM studies confirmed the presence of nanocrystalline material in an amorphous matrix, suggesting the development of crystalline/amorphous {beta}-K{sub 2}Bi{sub 8}Se{sub 13} nanocomposite material via ball milling process. Seebeck coefficient and thermal conductivity were analyzed based on the effective medium theory and show a significant contribution of a nanocrystalline phase.

Kyratsi, Th.; Hatzikraniotis, E.; Ioannou, M.; Chung, D. Y.; Tsiaoussis, I. (Materials Science Division); (Univ. Cyprus); (Aristotle Univ. Thessaloniki)

2011-01-01

123

Test structures to measure the Seebeck coefficient of CMOS IC polysilicon  

Microsoft Academic Search

We report on two thermal characterization structures to measure the Seebeck coefficient ? of CMOS IC polysilicon thin films relevant for integrated thermal microtransducers. The test structures were fabricated using a commercial 1.2 ?m CMOS process of Austria Mikro Systeme (AMS). The fabrication of the first structure relies on silicon micromachining. In contrast the second, planar, structure is ready for

M. Von Arx; O. Paul; Henry Baltes

1997-01-01

124

Measurement system of the Seebeck coefficient or of the electrical resistivity at high temperature.  

PubMed

A high temperature Seebeck coefficient or electrical resistivity apparatus has been designed and fabricated to measure sample with typical size ~10 × 1 × 1 mm(3). It can measure both transport properties from 300 K to 1000 K in argon atmosphere. The sample lies transversely on top of two metallic half-cylinders, which contain heating cartridges and allow temperature and thermal gradient control and reversal. The temperature gradient is measured by two type N thermocouples pressed against the upper surface of the sample. The key feature of this apparatus is the disk-shaped junction of each type N thermocouple which strongly improves the thermal contact with the sample. The Seebeck coefficient is obtained by averaging over two measured values with opposite thermal gradient directions (~±2 K). For the resistivity measurements, the temperature is stabilized and the temperature gradient is actively reduced below 0.2 K to make negligible any spurious thermal voltage. Uncertainties of ~3% for the Seebeck coefficient and 1% for the resistivity were obtained on Ni samples. The Seebeck coefficient and resistivity have also been measured on a skutterudite sample as small as ~7 × 1.5 × 0.5 mm(3) with very good agreement with literature. PMID:24182159

Rouleau, O; Alleno, E

2013-10-01

125

Simultaneous measurement of the Seebeck coefficient and thermal diffusivity for bulk thermoelectric materials  

NASA Astrophysics Data System (ADS)

We simultaneously measured the Seebeck coefficient and thermal diffusivity of a rectangular parallelepiped bulk thermoelectric material. We used one-dimensional heat conduction equation to show that a periodic heat cycle produces not only the thermoelectromotive force but also a certain phase shift angle between the edge and intermediate points of a sample along the length of the material. Based on the equation of the modified Angström method, an experiment at 300 K was performed using NIST standard material (SRM 3451, Bi2Te3 material) to measure the Seebeck coefficient and thermal diffusivity. The measured Seebeck coefficient was ?231 ± 3 µV/K, which corresponds to the published value. Using the same experimental setup as that for the thermal diffusivity measurement, the dependence of the phase shift angle on frequency was measured from 5 mHz to 10 Hz for the phase shift angle from ?8.2 to ?450°. The estimated thermal diffusivity was (1.53 ± 0.05) × 10?6 m2/s. We conclude that the modified Angström method can be used to measure the Seebeck coefficient and thermal diffusivity simultaneously.

Homma, Ryoei; Hasegawa, Yasuhiro; Terakado, Hiroki; Morita, Hiroyuki; Komine, Takashi

2015-02-01

126

Development and application of an instrument for spatially resolved Seebeck coefficient measurements  

NASA Astrophysics Data System (ADS)

The Seebeck coefficient is a key indicator of the majority carrier type (electrons or holes) in a material. The recent trend toward the development of combinatorial materials research methods has necessitated the development of a new high-throughput approach to measuring the Seebeck coefficient at spatially distinct points across any sample. The overall strategy of the high-throughput experiments is to quickly identify the region of interest on the sample at some expense of accuracy, and then study this region by more conventional techniques. The instrument for spatially resolved Seebeck coefficient measurements reported here relies on establishing a temperature difference across the entire compositionally graded thin-film and consecutive mapping of the resulting voltage as a function of position, which facilitates the temperature-dependent measurements up to 400 °C. The results of the designed instrument are verified at ambient temperature to be repeatable over 10 identical samples and accurate to within 10% versus conventional Seebeck coefficient measurements over the -100 to +150 ?V/K range using both n-type and p-type conductive oxides as test cases. The developed instrument was used to determine the sign of electrical carriers of compositionally graded Zn-Co-O and Ni-Co-O libraries prepared by combinatorial sputtering. As a result of this study, both cobalt-based materials were determined to have p-type conduction over a broad single-phase region of chemical compositions and small variation of the Seebeck coefficient over the entire investigated range of compositions and temperature.

Zakutayev, Andriy; Luciano, Frank J.; Bollinger, Vincent P.; Sigdel, Ajaya K.; Ndione, Paul F.; Perkins, John D.; Berry, Joseph J.; Parilla, Philip A.; Ginley, David S.

2013-05-01

127

Seebeck Enhancement Through Miniband Conduction in III-V Semiconductor Superlattices at Low Temperatures  

NASA Astrophysics Data System (ADS)

We present theoretically that the cross-plane Seebeck coefficient of InGaAs/InGaAlAs III-V semiconductor superlattices can be significantly enhanced through miniband transport at low temperatures. The miniband dispersion curves are calculated by self-consistently solving the Schrödinger equation with the periodic potential, and the Poisson equation taking into account the charge transfer between the two layers. Boltzmann transport in the relaxation-time approximation is used to calculate the thermoelectric transport properties in the cross-plane direction based on the modified density of states and group velocity. It is found that the cross-plane Seebeck coefficient can be enhanced more than 60% over the bulk values at an equivalent doping level at 80 K when the Fermi level is aligned at an edge of the minibands. Other thermoelectric transport properties are also calculated and discussed to further enhance the thermoelectric power factor.

Bahk, Je-Hyeong; Sadeghian, Ramin Banan; Bian, Zhixi; Shakouri, Ali

2012-06-01

128

Combined Seebeck and resistive SnO 2 gas sensors, a new selective device  

Microsoft Academic Search

Simultaneous measurements of electrical resistance R and Seebeck e.m.f. Vs of thick film SnO2 gas sensors were performed in air containing different concentrations pi of reducing gas (ethanol vapours, CO, CH4, C2H6 were successively used). The graphical representations of the Vs versus lnh values both for the identification of the reducing gas (selectivity) and for the determination of gas concentration.

Radu Ionescu

1998-01-01

129

Construction of Seebeck-coefficient measurement by Kelvin-probe force microscopy  

NASA Astrophysics Data System (ADS)

We previously developed techniques for measuring the Seebeck coefficient by Kelvin-probe force microscopy (KFM). However, the accuracy of the measurement was insufficient. In addition, the analysis of the obtained results was complicated by the existence of the Schottky contact at the bottom of the sample. In the present study, we introduce a new KFM control unit and a nanovoltmeter and modify the sample structure. These improvements (i) enhance the measurement accuracy, (ii) reduce the measurement time, and (iii) simplify the analysis.

Ikeda, Hiroya; Miwa, Kazutoshi; Salleh, Faiz

2012-06-01

130

Uncertainty Analysis of Seebeck Coefficient and Electrical Resistivity Characterization  

NASA Technical Reports Server (NTRS)

In order to provide a complete description of a materials thermoelectric power factor, in addition to the measured nominal value, an uncertainty interval is required. The uncertainty may contain sources of measurement error including systematic bias error and precision error of a statistical nature. The work focuses specifically on the popular ZEM-3 (Ulvac Technologies) measurement system, but the methods apply to any measurement system. The analysis accounts for sources of systematic error including sample preparation tolerance, measurement probe placement, thermocouple cold-finger effect, and measurement parameters; in addition to including uncertainty of a statistical nature. Complete uncertainty analysis of a measurement system allows for more reliable comparison of measurement data between laboratories.

Mackey, Jon; Sehirlioglu, Alp; Dynys, Fred

2014-01-01

131

Economical Route to Produce High Seebeck Coefficient Calcium Cobaltate for Bulk Thermoelectric Applications  

SciTech Connect

Phase pure calcium cobaltate (Ca1.24Co1.62O3.86) was prepared by Self-propagating High-temperature Synthesis (SHS) followed by a short post heat treatment. Prepared powders were characterized by XRD for phase purity, and SEM for particle size and distribution. Temperature histories at the center and on the surface of reaction pellet during the SHS process were monitored and recorded. Particles size of synthesized powders was reduced using a planetary mill to increase its specific surface area. Electrical conductivity, thermal conductivity and Seebeck coefficient of the prepared power were measured and figure of merit was reported.

Selig, Jiri [Lamar University; Lin, Sidney [Lamar University; Lin, Hua-Tay [ORNL; Johnson, D Ray [ORNL; Wang, Hsin [ORNL

2011-01-01

132

Seebeck coefficient study on Mn-doped YBa2Cu3O7- ?  

NASA Astrophysics Data System (ADS)

Superconducting samples of YBa2(Cu1-xMnx)3O7- ? with x=0, 0.01, 0.015, 0.02, 0.025, 0.035, and 0.05 have been prepared and the temperature variation of the Seebeck coefficient, S(T), has been measured over a temperature region of 77 to 250 K. The observed features of the results are analyzed in terms of the metallic diffusion model, the Nagaosa-Lee model, and a narrow band model. The physical parameters obtained are discussed.

Samuel, E. Isaac; Bai, V. Seshu; Sivakumar, K. M.; Ganesan, V.

1999-03-01

133

Round-robin measurements of two candidate materials for a Seebeck coefficient Standard Reference Material™  

NASA Astrophysics Data System (ADS)

A Standard Reference Material (SRM™) for the Seebeck coefficient is critical for inter-laboratory data comparison and for instrument calibration. To develop this SRM™, we have conducted an international round-robin measurement survey of two candidate materials—undoped Bi2Te3 and constantan (55% Cu and 45% Ni alloy). Measurements were performed in two rounds by twelve laboratories involved in active thermoelectric research using a number of commercial and custom-built measurement systems and techniques. We report the results of these measurements and the statistical analysis performed. Based on this extensive study, we have selected Bi2Te3 as the prototype standard material.

Lowhorn, N. D.; Wong-Ng, W.; Zhang, W.; Lu, Z. Q.; Otani, M.; Thomas, E.; Green, M.; Tran, T. N.; Dilley, N.; Ghamaty, S.; Elsner, N.; Hogan, T.; Downey, A. D.; Jie, Q.; Li, Q.; Obara, H.; Sharp, J.; Caylor, C.; Venkatasubramanian, R.; Willigan, R.; Yang, J.; Martin, J.; Nolas, G.; Edwards, B.; Tritt, T.

2009-02-01

134

Laser Synthesis of Nanometric Iron Oxide Films with High Seebeck Coefficient and High Thermoelectric Figure of Merit  

NASA Astrophysics Data System (ADS)

Radiation of a KrF-laser ( ? = 248 nm) was used for the synthesis by reactive pulsed laser deposition (RPLD) of nanometric iron oxide [Fe2O3-X (0?×?1)] films with variable thickness, stoichiometry and electrical properties. Film deposition was carried out on <100>Si at its temperature to have being increased from 293 to 800 K. XRD analysis showed that films deposited on Si substrate had polycrystalline structure. Films demonstrated semiconductor temperature trend with variable band gap Eg about 1.0 eV or less depending on oxygen pressure, the number of laser pulses and substrate temperature. Film thickness (13-60 nm) depended on oxygen pressure, substrate temperature and number of laser pulses. The higher substrate temperature, the more crystallinity of the deposited iron oxides' films was resulting in increasing of thermo electromotive force coefficient (Seebeck coefficient, S). It was found out the optimum oxygen pressure in the reactor, substrate temperature and film thickness when the S coefficient was high as 12-4 mV/K in the range 240-330 K. The thermoelectric figure of merit (ZT) was high as 1-6 in the range 280-330 K. This makes nanometric Fe2O3-X films, synthesized by UV photons using RPLD method, an exceptionally strong candidate for effective thermo sensors and thermo converters operating at moderate temperature.

Mulenko, S. A.; Gorbachuk, N. T.; Stefan, N.

2014-12-01

135

Large Closed-Circuit Seebeck Current in Quaternary (Ti,Zr)NiSn Heusler Alloys  

NASA Astrophysics Data System (ADS)

In the (Ti x ,Zr y )Ni w Sn z quaternary system with a composition near ( x + y): w: z = 1:1:1 the existence of the half-Heusler (HH) phase has been confirmed, where Ti and Zr occupy one of the three lattice positions substitutionally. The goal of this study is to characterize the thermoelectric (TE) properties of such materials. TE properties were measured at large temperature differences up to ? T = 800 K, exhibiting Seebeck voltages of about ±50 mV corresponding to Seebeck coefficients above 0.07 mV/K, with the highest value measured for the (Ti0.4Zr0.6)Ni0.9Sn1.1 composition. Fe and Mn doping could not improve these values further. Measurements under closed-circuit conditions showed very high currents of 0.4 mA for specimens at this particular composition. According to the composition, interfaces between full-Heusler and HH phases are responsible for an electron pull-out phenomenon due to the electric field at their interfaces. First-principle calculations of the electronic band structure confirm this explanation for why (TiZr)NiSn and CrNiSn are p-type TEs whereas NbNiSn is an n-type TE. These considerations will be useful in the search for other such systems.

Wunderlich, Wilfried; Motoyama, Yuichiro; Sugisawa, Yuta; Matsumura, Yoshihiro

2011-05-01

136

An experimental apparatus for simultaneously measuring Seebeck coefficient and electrical resistivity from 100 K to 600 K.  

PubMed

In this paper, we report a fully automated experimental apparatus for measuring Seebeck coefficient and electrical resistivity of a sample simultaneously in a temperature range of 100-600 K. The Seebeck coefficient is measured using a quasi-steady temperature differential method in which two ceramic heaters are employed to alternately heat the sample. The sample holder is designed to reduce temperature disturbance on its base during a measurement cycle. To demonstrate the accuracy and reliability of the experimental setup, we have performed tests on reference materials including constantan and platinum. PMID:23635205

Guan, Aiqiang; Wang, Hanfu; Jin, Hao; Chu, Weiguo; Guo, Yanjun; Lu, Guiwu

2013-04-01

137

An experimental apparatus for simultaneously measuring Seebeck coefficient and electrical resistivity from 100 K to 600 K  

NASA Astrophysics Data System (ADS)

In this paper, we report a fully automated experimental apparatus for measuring Seebeck coefficient and electrical resistivity of a sample simultaneously in a temperature range of 100-600 K. The Seebeck coefficient is measured using a quasi-steady temperature differential method in which two ceramic heaters are employed to alternately heat the sample. The sample holder is designed to reduce temperature disturbance on its base during a measurement cycle. To demonstrate the accuracy and reliability of the experimental setup, we have performed tests on reference materials including constantan and platinum.

Guan, Aiqiang; Wang, Hanfu; Jin, Hao; Chu, Weiguo; Guo, Yanjun; Lu, Guiwu

2013-04-01

138

Measurement of the high-temperature Seebeck coefficient of thin films by means of an epitaxially regrown thermometric reference material  

NASA Astrophysics Data System (ADS)

The Seebeck coefficient of a typical thermoelectric material, silicon-doped InGaAs lattice-matched to InP, is measured over a temperature range from 300 K to 550 K. By depositing and patterning a thermometric reference bar of silicon-doped InP adjacent to a bar of the material under test, temperature differences are measured directly. This is in contrast to conventional two-thermocouple techniques that subtract two large temperatures to yield a small temperature difference, a procedure prone to errors. The proposed technique retains the simple instrumentation of two-thermocouple techniques while eliminating the critical dependence of the latter on good thermal contact. The repeatability of the proposed technique is demonstrated to be ±2.6% over three temperature sweeps, while the repeatability of two-thermocouple measurements is about ±5%. The improved repeatability is significant for reliable reporting of the ZT figure of merit, which is proportional to the square of the Seebeck coefficient. The accuracy of the proposed technique depends on the accuracy with which the high-temperature Seebeck coefficient of the reference material may be computed or measured. In this work, the Seebeck coefficient of the reference material, n+ InP, is computed by rigorous solution of the Boltzmann transport equation. The accuracy and repeatability of the proposed technique can be systematically improved by scaling, and the method is easily extensible to other material systems currently being investigated for high thermoelectric energy conversion efficiency.

Ramu, Ashok T.; Mages, Phillip; Zhang, Chong; Imamura, Jeffrey T.; Bowers, John E.

2012-09-01

139

Apparatus for measuring Seebeck coefficient and electrical resistivity of small dimension samples using infrared microscope as temperature sensor.  

PubMed

An apparatus for measuring the Seebeck coefficient (?) and electrical resistivity (?) was designed to operate under an infrared microscope. A unique feature of this apparatus is its capability of measuring ? and ? of small-dimension (sub-millimeter) samples without the need for microfabrication. An essential part of this apparatus is a four-probe assembly that has one heated probe, which combines the hot probe technique with the Van der Pauw method for "simultaneous" measurements of the Seebeck coefficient and electrical resistivity. The repeatability of the apparatus was investigated over a temperature range of 40 °C-100 °C using a nickel plate as a standard reference. The results show that the apparatus has an uncertainty of ±4.9% for Seebeck coefficient and ±5.0% for electrical resistivity. The standard deviation of the apparatus against a nickel reference sample is -2.43 ?VK(-1) (-12.5%) for the Seebeck coefficient and -0.4 ?? cm (-4.6%) for the electrical resistivity, respectively. PMID:23742579

Jaafar, W M N Wan; Snyder, J E; Min, Gao

2013-05-01

140

Size effects on thermoelectric behavior of ultrathin NaxCoO2 films  

NASA Astrophysics Data System (ADS)

Size effects in thermoelectric NaxCoO2 thin films are studied, focusing on the electrical resisitivity and Seebeck coefficient. For very thin films below 10 nm, we have observed an increase in resistivity, which is in agreement with theoretical models. In contrast to a predicted simultaneous suppression of the Seebeck coefficient for ultrathin films, we observe a constant Seebeck coefficient as a function of layer thickness due to changes in the structural properties as well as the presence of strong electron correlations. This preserved high Seebeck coefficient opens up new directions for NaxCoO2 ultrathin films as basic building blocks in thermoelectric superlattices with enhanced phonon scattering.

Brinks, Peter; Rijnders, Guus; Huijben, Mark

2014-11-01

141

Thermal Conductivity and Seebeck Coefficients of Icosahedral Boron Arsenide Films on Silicon Carbide  

SciTech Connect

The thermal conductivity of icosahedral boron arsenide (B{sub 12}As{sub 2}) films grown on (0001) 6H-SiC substrates by chemical vapor deposition was studied by the 3{omega} technique. The room temperature thermal conductivity decreased from 27.0 to 15.3 W/m K as the growth temperature was decreased from 1450 to 1275 C. This is mainly attributed to the differences in the impurity concentration and microstructure, determined from secondary ion mass spectrometry and high resolution transmission electron microscopy, respectively. Callaway's theory was applied to calculate the temperature-dependent thermal conductivity, and the results are in good agreement with the experimental data. Seebeck coefficients were determined as 107 {micro}V/K and 136 {micro}V/K for samples grown at 1350 C with AsH{sub 3}/B{sub 2}H{sub 6} flow ratio equals to 1:1 and 3:5, respectively.

Y Gong; Y Zhang; M Dudley; Y Zhang; J Edgar; P Heard; M Kuball

2011-12-31

142

Use of Photothermally Generated Seebeck Voltage for Thermal Characterization of Thermoelectric Materials  

NASA Astrophysics Data System (ADS)

A simple and accurate experimental procedure to measure simultaneously the thermal properties (conductivity, diffusivity, and effusivity) of thermoelectric (TE) materials using their Seebeck voltage is proposed. The technique is based on analysis of a periodically oscillating thermoelectric signal generated from a TE material when it is thermally excited using an intensity-modulated laser source. A self-normalization procedure is implemented in the presented method using TE signals generated by changing the laser heating from one side to another of the TE material. Experiments are done on a polyaniline carbon nanohybrid (6.6 wt.% carbon nanotubes), yielding a thermal conductivity of 1.106 ± 0.001 W/m-K. The results are compared with the results from photothermal infrared radiometry experiments.

Kuriakose, Maju; Depriester, Michael; King, Roch Chan Yu; Roussel, Frédérick; Sahraoui, Abdelhak Hadj

2014-06-01

143

Thermal conductivity and Seebeck coefficients of icosahedral boron arsenide films on silicon carbide  

NASA Astrophysics Data System (ADS)

The thermal conductivity of icosahedral boron arsenide (B12As2) films grown on (0001) 6H-SiC substrates by chemical vapor deposition was studied by the 3? technique. The room temperature thermal conductivity decreased from 27.0 to 15.3 W/m K as the growth temperature was decreased from 1450 to 1275 °C. This is mainly attributed to the differences in the impurity concentration and microstructure, determined from secondary ion mass spectrometry and high resolution transmission electron microscopy, respectively. Callaway's theory was applied to calculate the temperature-dependent thermal conductivity, and the results are in good agreement with the experimental data. Seebeck coefficients were determined as 107 ?V/K and 136 ?V/K for samples grown at 1350 °C with AsH3/B2H6 flow ratio equals to 1:1 and 3:5, respectively.

Gong, Y.; Zhang, Y.; Dudley, M.; Zhang, Y.; Edgar, J. H.; Heard, P. J.; Kuball, M.

2010-10-01

144

Copper(I) oxide based thermoelectric powders and pastes with high Seebeck coefficients  

NASA Astrophysics Data System (ADS)

Copper(I) oxide based compounds are investigated as earth abundant, environmentally friendly thermoelectric materials. Copper(I) oxide powders from different vendors are first examined, resulting in Seebeck coefficients of approximately 650 ?V/K. Pastes of the powders with two different polymer matrices, polychlorotrifluoroethene and polydimethylsiloxane, in various mass ratios produce values reaching 567 ± 5 ?V/K. Small quantities of transition metal oxides added to the already mentioned compounds produce further enhancements of 729 ± 4 ?V/K in case of the powders and 606 ± 5 ?V/K for the polymers. The results offer motivation for further research in the field of thermoelectric pastes, which is still in its foundation stage.

Andrei, Virgil; Bethke, Kevin; Rademann, Klaus

2014-12-01

145

Giant thermoelectric Seebeck coefficient of a two-dimensional electron gas in SrTiO3  

Microsoft Academic Search

Enhancement of the Seebeck coefficient (S) without reducing the electrical conductivity (sigma) is essential to realize practical thermoelectric materials exhibiting a dimensionless figure of merit (ZT=S2.sigma.T.kappa-1) exceeding 2, where T is the absolute temperature and kappa is the thermal conductivity. Here, we demonstrate that a high-density two-dimensional electron gas (2DEG) confined within a unit cell layer thickness in SrTiO3 yields

Hiromichi Ohta; Sungwng Kim; Yoriko Mune; Teruyasu Mizoguchi; Kenji Nomura; Shingo Ohta; Takashi Nomura; Yuki Nakanishi; Yuichi Ikuhara; Masahiro Hirano; Hideo Hosono; Kunihito Koumoto

2007-01-01

146

Electronic conductivity, Seebeck coefficient, defect and electronic structure of nonstoichiometric La 1? x Sr x MnO 3  

Microsoft Academic Search

In order to elucidate the relationship between the electrical properties and composition (d and x) of La1?xSrxMnO3+d, precise measurements were made on the conductivity, ?, and Seebeck coefficient, Q, for the oxide with 0?x?0.7 as a function of T and P(O2) up to 1273 K. Analysis was made for the high-temperature paramagnetic state using the nonstoichiometry data and defect and

Junichiro Mizusaki; Yuki Yonemura; Hiroyuki Kamata; Kouji Ohyama; Naoya Mori; Hiroshi Takai; Hiroaki Tagawa; Masayuki Dokiya; Kazunori Naraya; Tadashi Sasamoto; Hideaki Inaba; Takuya Hashimoto

2000-01-01

147

Enhancing the Seebeck effect in carbon fiber-reinforced cement by using intercalated carbon fibers  

Microsoft Academic Search

The absolute thermoelectric power of carbon fiber-reinforced cement paste was rendered as negative as ?17 ?V\\/°C by using bromine-intercalated carbon fibers, which had a high concentration of holes. The corresponding paste with pristine carbon fibers exhibited absolute thermoelectric power as negative as ?0.8 ?V\\/°C only.

Sihai Wen; D. D. L Chung

2000-01-01

148

Nernst and Seebeck coefficients of the cuprate superconductor YBa2Cu3O6.67: a study of Fermi surface reconstruction.  

PubMed

The Seebeck and Nernst coefficients S and nu of the cuprate superconductor YBa{2}Cu{3}O{y} (YBCO) were measured in a single crystal with doping p=0.12 in magnetic fields up to H=28 T. Down to T=9 K, nu becomes independent of field by H approximately 30 T, showing that superconducting fluctuations have become negligible. In this field-induced normal state, S/T and nu/T are both large and negative in the T-->0 limit, with the magnitude and sign of S/T consistent with the small electronlike Fermi surface pocket detected previously by quantum oscillations and the Hall effect. The change of sign in S(T) at T approximately 50 K is remarkably similar to that observed in La2-xBaxCuO4, La{2-x-y}Nd{y}Sr_{x}CuO{4}, and La{2-x-y}Eu{y}Sr{x}CuO{4}, where it is clearly associated with the onset of stripe order. We propose that a similar density-wave mechanism causes the Fermi surface reconstruction in YBCO. PMID:20366789

Chang, J; Daou, R; Proust, Cyril; Leboeuf, David; Doiron-Leyraud, Nicolas; Laliberté, Francis; Pingault, B; Ramshaw, B J; Liang, Ruixing; Bonn, D A; Hardy, W N; Takagi, H; Antunes, A B; Sheikin, I; Behnia, K; Taillefer, Louis

2010-02-01

149

Nernst and Seebeck Coefficients of the Cuprate Superconductor YBa2Cu3O6.67: A Study of Fermi Surface Reconstruction  

NASA Astrophysics Data System (ADS)

The Seebeck and Nernst coefficients S and ? of the cuprate superconductor YBa2Cu3Oy (YBCO) were measured in a single crystal with doping p=0.12 in magnetic fields up to H=28T. Down to T=9K, ? becomes independent of field by H?30T, showing that superconducting fluctuations have become negligible. In this field-induced normal state, S/T and ?/T are both large and negative in the T?0 limit, with the magnitude and sign of S/T consistent with the small electronlike Fermi surface pocket detected previously by quantum oscillations and the Hall effect. The change of sign in S(T) at T?50K is remarkably similar to that observed in La2-xBaxCuO4, La2-x-yNdySrxCuO4, and La2-x-yEuySrxCuO4, where it is clearly associated with the onset of stripe order. We propose that a similar density-wave mechanism causes the Fermi surface reconstruction in YBCO.

Chang, J.; Daou, R.; Proust, Cyril; Leboeuf, David; Doiron-Leyraud, Nicolas; Laliberté, Francis; Pingault, B.; Ramshaw, B. J.; Liang, Ruixing; Bonn, D. A.; Hardy, W. N.; Takagi, H.; Antunes, A. B.; Sheikin, I.; Behnia, K.; Taillefer, Louis

2010-02-01

150

The electronic-structure origin of the anisotropic thermopower of nanolaminated Ti3SiC2 determined by polarized x-ray spectroscopy and Seebeck measurements  

E-print Network

Nanolaminated materials exhibit characteristic magnetic, mechanical, and thermoelectric properties, with large contemporary scientific and technological interest. Here, we report on the anisotropic Seebeck coefficient in nanolaminated Ti3SiC2 single-crystal thin films and trace the origin to anisotropies in element-specific electronic states. In bulk polycrystalline form, Ti3SiC2 has a virtually zero Seebeck coefficient over a wide temperature range. In contrast, we find that the in-plane (basal ab) Seebeck coefficient of Ti3SiC2, measured on single-crystal films has a substantial and positive value of 4-6 muV/K. Employing a combination of polarized angle-dependent x-ray spectroscopy and density functional theory we directly show electronic structure anisotropy in inherently nanolaminated Ti3SiC2 single-crystal thin films as a model system. The density of Ti 3d and C 2p states at the Fermi level in the basal ab-plane is about 40 % higher than along the c-axis. The Seebeck coefficient is related to electron an...

Magnuson, Martin; Van Nong, Ngo; Eklund, Per; Hultman, Lars; 10.1103/PhysRevB.85.195134

2012-01-01

151

Electronic-structure origin of the anisotropic thermopower of nanolaminated Ti3SiC2 determined by polarized x-ray spectroscopy and Seebeck measurements  

NASA Astrophysics Data System (ADS)

Nanolaminated materials exhibit characteristic magnetic, mechanical, and thermoelectric properties, with large contemporary scientific and technological interest. Here we report on the anisotropic Seebeck coefficient in nanolaminated Ti3SiC2 single-crystal thin films and trace the origin to anisotropies in element-specific electronic states. In bulk polycrystalline form, Ti3SiC2 has a virtually zero Seebeck coefficient over a wide temperature range. In contrast, we find that the in-plane (basal ab) Seebeck coefficient of Ti3SiC2, measured on single-crystal films, has a substantial and positive value of 4-6 ?V/K. Employing a combination of polarized angle-dependent x-ray spectroscopy and density functional theory we directly show electronic structure anisotropy in inherently nanolaminated Ti3SiC2 single-crystal thin films as a model system. The density of Ti 3d and C 2p states at the Fermi level in the basal ab plane is about 40% higher than along the c axis. The Seebeck coefficient is related to electron and hole-like bands close to the Fermi level, but in contrast to ground state density functional theory modeling, the electronic structure is also influenced by phonons that need to be taken into account. Positive contribution to the Seebeck coefficient of the element-specific electronic occupations in the basal plane is compensated by 73% enhanced Si 3d electronic states across the laminate plane that give rise to a negative Seebeck coefficient in that direction. Strong phonon vibration modes with three to four times higher frequency along the c axis than along the basal ab plane also influence the electronic population and the measured spectra by the asymmetric average displacements of the Si atoms. These results constitute experimental evidence explaining why the average Seebeck coefficient of Ti3SiC2 in polycrystals is negligible over a wide temperature range. This allows the origin of anisotropy in physical properties of nanolaminated materials to be traced to anisotropies in element-specific electronic states.

Magnuson, Martin; Mattesini, Maurizio; Nong, Ngo Van; Eklund, Per; Hultman, Lars

2012-05-01

152

Effets Seebeck et Nernst dans les cuprates: Etude de la reconstruction de la surface de Fermi sous champ magnetique intense  

NASA Astrophysics Data System (ADS)

Ce memoire presente des mesures de transport thermoelectrique, les effets Seebeck et Nernst, dans une serie d'echantillons de supraconducteurs a haute temperature critique. Des resultats obtenus recemment au Laboratoire National des Champs Magnetiques Intenses a Grenoble sur La1.7Eu0.2Sr0.1 CuO4, La1.675Eu0.2Sr0.125CuO 4, La1.64Eu0.2Sr0.16CuO4, La1.74Eu0.1Sr0.16CuO4 et La 1.4Nd0.4Sr0.2CuO4 sont analyses. Une attention particuliere est accordee aux equations de la theorie semi-classique du transport et leur validite est verifiee. La procedure experimentale et les materiaux utilises pour concevoir les montages de mesures sont expliques en detail. Enfin, un chapitre est dedie a l'explication et l'interpretation des resultats de transport thermoelectrique sur YBa2Cu3O6+delta publies au cours de l'hiver 2010 dans les revues Nature et Physical Review Letters. Les donnees d'effet Seebeck dans les echantillons de La 1.8-x,Eu0.2SrxCuO 4, ou un changement de signe est observe, permettent de conclure a la presence d'une poche d'electrons dans la surface de Fermi qui domine le transport a basse temperature dans la region sous-dopee du diagramme de phase. Cette conclusion est similaire a celle obtenue par des mesures d'effet Hall dans YBa 2Cu3O6+delta et elle cadre bien dans un scenario de reconstruction de la surface de Fermi. Les donnees d'effet Nernst recueillies indiquent que la contribution des fluctuations supraconductrices est limitee a un modeste intervalle de temperature au-dessus de la temperature critique.

Laliberte, Francis

2010-06-01

153

Observations of Co4+ in a Higher Spin State and the Increase in the Seebeck Coefficient of Thermoelectric Ca3Co4O9  

SciTech Connect

Ca{sub 3}Co{sub 4}O{sub 9} has a unique structure that leads to exceptionally high thermoelectric transport. Here we report the achievement of a 27% increase in the room-temperature in-plane Seebeck coefficient of Ca{sub 3}Co{sub 4}O{sub 9} thin films. We combine aberration-corrected Z-contrast imaging, atomic-column resolved electron energy-loss spectroscopy, and density-functional calculations to show that the increase is caused by stacking faults with Co4+-ions in a higher spin state compared to that of bulk Ca{sub 3}Co{sub 4}O{sub 9}. The higher Seebeck coefficient makes the Ca{sub 3}Co{sub 4}O{sub 9} system suitable for many high temperature waste-heat-recovery applications.

Klie, Robert F [University of Illinois, Chicago; Qiao, Q. [University of Illinois, Chicago; Paulauskas, T. [University of Illinois, Chicago; Gulec, A. [University of Illinois, Chicago; Rebola, A. [University of Illinois, Chicago; Ogut, Serdar [University of Illinois, Chicago; Prange, Micah P [Vanderbilt University; Idrobo Tapia, Juan C [ORNL; Pantelides, Sokrates T. [Vanderbilt University; Kolesnik, S. [Northern Illinois University; Dabrowski, B. [Argonne National Laboratory (ANL); Ozdemir, M. [University of Alabama, Tuscaloosa; Boyraz, C. [University of Alabama, Tuscaloosa; Mazumdar, Dipanjan [University of Alabama, Tuscaloosa; Gupta, Dr. Arunava [University of Alabama, Tuscaloosa

2012-01-01

154

Electronic structures of AlB2-type superconducting YbGa1+xSi1-x alloys probed by NMR and Seebeck coefficient  

NASA Astrophysics Data System (ADS)

We report the electronic properties of the AlB2-type compounds YbGa1+xSi1-x (x =0, 0.15, and 0.3) studied by means of the nuclear magnetic resonance (NMR) and the Seebeck coefficient measurements. These materials are of current interest due to the presence of superconductivity with Yb element. From the analysis of G69a NMR spin-lattice relaxation rates, we deduce the Ga 4s partial Fermi level density of states Ns(EF) for these compounds. The result indicates a gradual increase in Ns(EF) with increasing x in YbGa1+xSi1-x. In addition, the evolution of the Seebeck coefficient feature can be understood well within the band-filling scenario. From the Seebeck coefficient analysis, we find that the variation in the total Fermi level density of states N(EF) is not consistent with the trend of superconducting temperature Tc which shows a gradual decrease with Ga content. These observations support the hypothesis that the electronic Fermi level density of states is not the key factor in determining the superconducting transition temperature of YbGa1+xSi1-x.

Fang, C. P.; Lue, C. S.; Hsu, Y. D.; Kuo, Y. K.

2010-10-01

155

Transport Properties of Bulk Thermoelectrics An International Round-Robin Study, Part I: Seebeck Coefficient and Electrical Resistivity  

SciTech Connect

Recent research and development of high temperature thermoelectric materials has demonstrated great potential of converting automobile exhaust heat directly into electricity. Thermoelectrics based on classic bismuth telluride have also started to impact the automotive industry by enhancing air conditioning efficiency and integrated cabin climate control. In addition to engineering challenges of making reliable and efficient devices to withstand thermal and mechanical cycling, the remaining issues in thermoelectric power generation and refrigeration are mostly materials related. The figure-of-merit, ZT, still needs to improve from the current value of 1.0 - 1.5 to above 2 to be competitive to other alternative technologies. In the meantime, the thermoelectric community could greatly benefit from the development of international test standards, improved test methods and better characterization tools. Internationally, thermoelectrics have been recognized by many countries as an important area for improving energy efficiency. The International Energy Agency (IEA) group under the implementing agreement for Advanced Materials for Transportation (AMT) identified thermoelectric materials as an important area in 2009. This paper is Part I of the international round-robin testing of transport properties of bulk thermoelectrics. The main focuses in Part I are on two electronic transport properties: Seebeck coefficient and electrical resistivity.

Wang, Hsin [ORNL; Porter, Wallace D [ORNL; Bottner, Harold [Fraunhofer-Institute, Freiburg, Germany; Konig, Jan [Fraunhofer-Institute, Freiburg, Germany; Chen, Lidong [Chinese Academy of Sciences; Bai, Shengqiang [Chinese Academy of Sciences; Tritt, Terry M. [Clemson University; Mayolett, Alex [Corning, Inc; Senawiratne, Jayantha [Corning, Inc; Smith, Charlene [Corning, Inc; Harris, Fred [ZT-Plus; Gilbert, Partricia [Marlow Industries, Inc; Sharp, Jeff [Marlow Industries, Inc; Lo, Jason [CANMET - Materials Technology Laboratory, Natural Resources of Canada; Keinke, Holger [University of Waterloo, Canada; Kiss, Laszlo I. [University of Quebec at Chicoutimi

2013-01-01

156

Transport Properties of Bulk Thermoelectrics—An International Round-Robin Study, Part I: Seebeck Coefficient and Electrical Resistivity  

NASA Astrophysics Data System (ADS)

Recent research and development of high-temperature thermoelectric materials has demonstrated great potential for converting automobile exhaust heat directly into electricity. Thermoelectrics based on classic bismuth telluride have also started to impact the automotive industry by enhancing air-conditioning efficiency and integrated cabin climate control. In addition to engineering challenges of making reliable and efficient devices to withstand thermal and mechanical cycling, the remaining issues in thermoelectric power generation and refrigeration are mostly materials related. The dimensionless figure of merit, ZT, still needs to be improved from the current value of 1.0 to 1.5 to above 2.0 to be competitive with other alternative technologies. In the meantime, the thermoelectric community could greatly benefit from the development of international test standards, improved test methods, and better characterization tools. Internationally, thermoelectrics have been recognized by many countries as a key component for improving energy efficiency. The International Energy Agency (IEA) group under the Implementing Agreement for Advanced Materials for Transportation (AMT) identified thermoelectric materials as an important area in 2009. This paper is part I of the international round-robin testing of transport properties of bulk thermoelectrics. The main foci in part I are the measurement of two electronic transport properties: Seebeck coefficient and electrical resistivity.

Wang, Hsin; Porter, Wallace D.; Böttner, Harald; König, Jan; Chen, Lidong; Bai, Shengqiang; Tritt, Terry M.; Mayolet, Alex; Senawiratne, Jayantha; Smith, Charlene; Harris, Fred; Gilbert, Patricia; Sharp, Jeff W.; Lo, Jason; Kleinke, Holger; Kiss, Laszlo

2013-04-01

157

Effect of off-stoichiometry on the transport properties of the Heusler-type Fe2VAl compound  

Microsoft Academic Search

We report on the effect of off-stoichiometry on the temperature dependence of electrical resistivity, the Seebeck coefficient, and the Hall coefficient in the Heusler-type Fe2VAl compound. While the stoichiometric Fe2VAl exhibits a semiconductorlike resistivity behavior, a small deviation of the Al content from stoichiometry causes a significant decrease in the low-temperature resistivity and a large enhancement in the Seebeck coefficient.

Y. Nishino; H. Kato; M. Kato; U. Mizutani

2001-01-01

158

Valley photothermoelectric effects in transition-metal dichalcogenides  

NASA Astrophysics Data System (ADS)

We theoretically investigate photothermoelectric effects, i.e., the photoenabled versions of the Seebeck and Nernst effects in monolayer transition metal dichalcogenides (TMDCs) using semiclassical transport theory. We find that monolayer TMDCs subjected to circular polarized light show anomalous thermoelectric properties as a result of strong spin-orbit interaction and broken inversion symmetry. The Seebeck coefficient for photogenerated carriers is relatively large and changes its sign at a critical carrier density. In addition, a nontrivial photo-Nernst effect emerges in the absence of an external magnetic field or magnetic moments.

Konabe, Satoru; Yamamoto, Takahiro

2014-08-01

159

Thermomagnetic effects in semiconductors and semimetals  

Microsoft Academic Search

The principal thermomagnetic effects in semiconductors and semimetals are discussed, with emphasis on the physical processes which affect the transport coefficients. The Seebeck, Nernst, Righi-Leduc, Peltier, Ettingshausen and magnetothermal resistance coefficients are defined and the Kelvin-Onsager relations between the coefficients are discussed. The Boltzmann equation for electrons is discussed rather briefly, with some comments on its limitations, and references to

R T Delves

1965-01-01

160

Ratchet effects in graphene and quantum wells with lateral superlattice  

SciTech Connect

Theoretical and experimental studies on the ratchet effects in graphene and in quantum wells with a lateral superlattice excited by alternating electric fields of terahertz frequency range are presented. We discuss the Seebeck ratchet effect and helicity driven photocurrents and show that the photocurrent generation is based on the combined action of a spatially periodic in-plane potential and a spatially modulated light.

Golub, L. E.; Nalitov, A. V.; Ivchenko, E. L. [Ioffe Physical-Technical Institute of the Russian Academy of Sciences, St. Petersburg (Russian Federation); Olbrich, P.; Kamann, J.; Eroms, J.; Weiss, D.; Ganichev, S. D. [Terahertz Center, University of Regensburg, Regensburg (Germany)

2013-12-04

161

Thermoelastic-strain-induced thermoelectric effect in n-Ge  

NASA Astrophysics Data System (ADS)

A new physical mechanism responsible for the appearance of anomalous thermo-emf in n-Ge, the sign of which is opposite to that of the Seebeck thermo-emf, is considered. It is shown that the anomalous thermoelectric effect is related to the redistribution of charge carriers in the energy extrema of bands during thermoelastic deformation of the crystal.

Musaev, A. M.

2014-10-01

162

Hall, Seebeck, and Nernst Coefficients of Underdoped HgBa2CuO4+?: Fermi-Surface Reconstruction in an Archetypal Cuprate Superconductor  

NASA Astrophysics Data System (ADS)

Charge-density-wave order has been observed in cuprate superconductors whose crystal structure breaks the square symmetry of the CuO2 planes, such as orthorhombic YBa2Cu3Oy (YBCO), but not so far in cuprates that preserve that symmetry, such as tetragonal HgBa2CuO4+? (Hg1201). We have measured the Hall (RH), Seebeck (S), and Nernst (?) coefficients of underdoped Hg1201 in magnetic fields large enough to suppress superconductivity. The high-field RH(T) and S(T) are found to drop with decreasing temperature and become negative, as also observed in YBCO at comparable doping. In YBCO, the negative RH and S are signatures of a small electron pocket caused by Fermi-surface reconstruction, attributed to charge-density-wave modulations observed in the same range of doping and temperature. We deduce that a similar Fermi-surface reconstruction takes place in Hg1201, evidence that density-wave order exists in this material. A striking similarity is also found in the normal-state Nernst coefficient ?(T), further supporting this interpretation. Given the model nature of Hg1201, Fermi-surface reconstruction appears to be common to all hole-doped cuprates, suggesting that density-wave order is a fundamental property of these materials.

Doiron-Leyraud, Nicolas; Lepault, S.; Cyr-Choinière, O.; Vignolle, B.; Grissonnanche, G.; Laliberté, F.; Chang, J.; Bariši?, N.; Chan, M. K.; Ji, L.; Zhao, X.; Li, Y.; Greven, M.; Proust, C.; Taillefer, Louis

2013-04-01

163

Effect of off-stoichiometry on the transport properties of the Heusler-type Fe{sub 2}VAl compound  

SciTech Connect

We report on the effect of off-stoichiometry on the temperature dependence of electrical resistivity, the Seebeck coefficient, and the Hall coefficient in the Heusler-type Fe{sub 2}VAl compound. While the stoichiometric Fe{sub 2}VAl exhibits a semiconductorlike resistivity behavior, a small deviation of the Al content from stoichiometry causes a significant decrease in the low-temperature resistivity and a large enhancement in the Seebeck coefficient. Substantial enhancements for the Seebeck coefficient are in reasonable accord with changes in the Hall coefficient and can be explained on the basis of the electronic structure, where the Fermi level shifts slightly from the center of a pseudogap due to off stoichiometry.

Nishino, Y.; Kato, H.; Kato, M.; Mizutani, U.

2001-06-15

164

Seebeck coefficient in organic semiconductors  

E-print Network

in tandem with conventional heat engines have the potency to increase the overall efficiency of an energy generation process above what the heat engine would have had having worked alone. An example of this is the thermoelectric generator developed by BMW... to harvest waste heat from a vehicle’s exhaust. Back in 2003, BMW developed a thermoelectric generator capable of generating a power of 80 W from a vehicle’s exhaust. In 2011, with improved design and superior thermoelectric materials, BMW demonstrated a 600...

Venkateshvaran, Deepak

2014-07-01

165

Perfect spin filtering and large spin thermoelectric effects in organic transition-metal molecular junctions.  

PubMed

We present ab initio studies of spin-polarized transport properties and thermospin effects in cyclopentadienyl-iron molecular junctions. It is found that the spin-up transmission coefficient at the Fermi level shows an odd-even oscillating behaviour, while the spin-down transmission coefficient has an exponential decay with the molecule length. The spin polarization at the Fermi level rapidly tends toward a saturation value close to 100% with the molecule length. This is ascribed to the existence of different orbital states for different spin components at the Fermi level. In addition, we find that the spin-up Seebeck coefficient oscillates between positive and negative values, while the spin-down Seebeck coefficient always has a positive value and monotonically increases with the molecule length. Therefore in some cases, the spin Seebeck coefficient is even larger than the corresponding charge Seebeck effect. Finally, we also provide a possibility of utilizing cyclopentadienyl-iron molecular junctions to achieve the pure spin current without an accompanying charge current at about room temperature. PMID:24788691

Yang, X F; Liu, Y S; Zhang, X; Zhou, L P; Wang, X F; Chi, F; Feng, J F

2014-06-21

166

Origin of large thermopower in LiRh2O4 : Calculation of the Seebeck coefficient by the combination of local density approximation and dynamical mean-field theory  

NASA Astrophysics Data System (ADS)

Motivated by the newly synthesized mixed-valent spinel LiRh2O4 for which a large thermopower is observed in the metallic cubic phase above 230 K [Y. Okamoto , Phys. Rev. Lett. 101, 086404 (2008)], we calculate the Seebeck coefficient by the combination of local density approximation and dynamical mean-field theory (LDA+DMFT) . The experimental values are well reproduced not only by LDA+DMFT but also by the less involved Boltzmann equation approach. A careful analysis of the latter shows unexpectedly that the origin of the large thermopower shares a common root with a very different oxide: NaxCoO2 . We also discuss how it is possible to further increase the power factor of LiRh2O4 through doping, which makes the material even more promising for technological applications.

Arita, R.; Kuroki, K.; Held, K.; Lukoyanov, A. V.; Skornyakov, S.; Anisimov, V. I.

2008-09-01

167

Effect of aluminum on the thermoelectric properties of nanostructured PbTe.  

PubMed

In the present work, the effect of aluminum (Al) on the thermoelectric properties of PbTe is studied. Aluminum doped PbTe samples, fabricated by a ball milling and hot pressing, have Seebeck coefficients between -100 and -200 ?V K-1 and electrical conductivities of (3.6-18) × 104 S m-1 at room temperature, which means that Al is an effective donor in PbTe. The first principle calculations clearly show an increase of the density of states close to the Fermi level in the conduction band due to Al doping, which averages up the energy and effective mass of electrons, resulting in enhancement of the Seebeck coefficient. The maximum figure-of-merit ZT of 1.2 is reached at 770 K in the Al0.03PbTe sample. PMID:23912680

Zhang, Qinyong; Yang, Siqi; Zhang, Qian; Chen, Shuo; Liu, Weishu; Wang, Hui; Tian, Zhiting; Broido, David; Chen, Gang; Ren, Zhifeng

2013-08-30

168

Doping effects on thermoelectric properties of the off-stoichiometric Heusler compounds Fe{sub 2?x}V{sub 1+x}Al  

SciTech Connect

The thermoelectric properties of Heusler-type Fe{sub 2?x}V{sub 1+x}Al{sub 1?y}Si{sub y} and Fe{sub 2?x}V{sub 1+x?y}Ti{sub y}Al alloys have been investigated to clarify which off-stoichiometric alloy, i.e., V-rich (x?>?0) or V-poor (x?effective in enhancing the Seebeck coefficient when doped by Si and Ti, while retaining a low electrical resistivity. Large Seebeck coefficients of ?182??V/K and 110??V/K at 300?K are obtained for n-type Fe{sub 1.95}V{sub 1.05}Al{sub 0.97}Si{sub 0.03} and p-type Fe{sub 2.04}V{sub 0.93}Ti{sub 0.03}Al, respectively. When the Seebeck coefficient is plotted as a function of valence electron concentration (VEC), the VEC dependence for the doped off-stoichiometric alloys falls on characteristic curves depending on the off-stoichiometric composition x. It is concluded that a larger Seebeck coefficient with a negative sign can be obtained for the V-rich alloys rather than the V-poor alloys, whilst good p-type materials are always derived from the V-poor alloys. Substantial enhancements in the Seebeck coefficient for the off-stoichiometric alloys could be achieved by a favorable modification in the electronic structure around the Fermi level through the antisite V or Fe defect formation.

Nishino, Y., E-mail: nishino@nitech.ac.jp; Tamada, Y. [Department of Frontier Materials, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)

2014-03-28

169

On the Quantum Hall Effect in mono(bi)-layer graphene  

NASA Astrophysics Data System (ADS)

Based on a thermodynamic approach, we have calculated the specific resistivity of mono(bi)-layer graphene assumed dissipationless in quantizing magnetic field. The resistivity arises from combination of Peltier and Seebeck effects. The current I causes heating (cooling) at the first (second) sample contacts, due to the Peltier effect. The voltage measured across the sample is equal to the Seebeck thermoemf, and thus provides finite resistivity as I?0. The resistivity is a universal function of the magnetic field, e-h plasma density and temperature, expressed in fundamental units h/e2. At fixed magnetic field the magneto-transport problem is resolved in the vicinity of the Dirac point taking into account the splitting of zeroth Landau level. For mono(bi)- layer graphene the B-dependent splitting of zeroth Landau level is recovered from experimental data.

Cheremisin, M. V.

2014-11-01

170

Technische Department Walther-Meiner-Bayerische Universitat fur Institut fur Akademie der  

E-print Network

¨unchen Physik Tieftemperaturforschung Wissenschaften Spatially resolved spin Seebeck experiments Diploma Thesis . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.1 Seebeck effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 2.1.2 Nernst Seebeck effect . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3 Samples and materials 23 4

Gross, Rudolf

171

Compensation of voltage drops in solid-state switches used with thermoelectric generators  

NASA Technical Reports Server (NTRS)

Seebeck effect solid state switch was developed eliminating thermoelectric generator switch voltage drops. Semiconductor switches were fabricated from materials with large Seebeck coefficients, arranged such that Seebeck potential is generated with such polarity that current flow is aided.

Shimada, K.

1972-01-01

172

Synthetic conditions and their doping effect on {Beta}-K{sub 2}Bi{sub 8}Se{sub 13}.  

SciTech Connect

In this work the synthetic conditions for K{sub 2}Bi{sub 8}Se{sub 13} and their effect on its thermoelectric properties were investigated. K{sub 2}Bi{sub 8}Se{sub 13} was prepared as a single phase using K{sub 2}Se and Bi{sub 2}Se{sub 3} as starting materials in a furnace or via a reaction using direct flame, followed by remelting or annealing. Seebeck coefficient measurements showed that the doping level in the material is sensitive to the synthetic conditions. Higher synthesis temperatures as well as the flame reaction technique followed by annealing gave more homogenous samples with higher Seebeck coefficient. IR optical spectroscopic measurements showed a wide range of doping level achieved among the different synthetic conditions. These findings suggest that synthetic conditions can act as a useful tool for the optimization of the thermoelectric properties of these materials.

Kyratsi, Th.; Kika, I.; Hatzikraniotis, E.; Paraskevopoulos, K. M.; Chrissafis, K.; Kanatzidis, M. G. (Materials Science Division); (Univ. Cyprus); (Aristotle Univ. Thessaloniki); (Northwestern Univ.)

2009-04-01

173

Colossal enhancement in thermoelectric effect in a laterally coupled double-quantum-dot chain by the Coulomb interactions  

NASA Astrophysics Data System (ADS)

Thermoelectric effects, including Seebeck coefficient (S), thermal conductance (?), and figure of merit (ZT), in a laterally coupled double-quantum-dot (DQD) chain with two external nonmagnetic contacts are investigated theoretically by the nonequilibrium Green's function formalism. In this system, the DQD chain between two contacts forms a main channel for thermal electrons transporting, and each QD in the main chain couples laterally to a dangling one. The numerical calculations show that the Coulomb interactions not only lead to the splitting of the asymmetrical double-peak structure of the Seebeck coefficient, but also make the thermal spectrum show a strong violation of the Wiedemann-Franz law, leading to a colossal enhancement in ZT. These results indicate that the coupled DQD chain has potential applications in the thermoelectric devices with high thermal efficiency.

Xiong, Lun; Yi, Lin

2014-04-01

174

Anomalous effect of vanadium boride seeding on thermoelectric properties of YB{sub 22}C{sub 2}N  

SciTech Connect

Highlights: ? We doped YB{sub 22}C{sub 2}N; the long awaited n-type counterpart to p-type boron carbide. ? VB{sub 2} seeding of YB{sub 22}C{sub 2}N showed striking results. ? Thermal treatment effects led to VB{sub 2} being intrinsically doped. ? Large increase of both Seebeck coefficient and electrical conductivity was obtained. - Abstract: Vanadium boride seeded YB{sub 22}C{sub 2}N were synthesized and the thermoelectric properties investigated. YB{sub 22}C{sub 2}N is representative of the series of rare earth borocarbonitrides which is the potential long awaited n-type counterpart to p-type boron carbide. VB{sub 2} seeded samples of YB{sub 22}C{sub 2}N were prepared using VB{sub 2} directly as an initial additive and V{sub 2}O{sub 3} which also results in formation of vanadium diboride in the final product. The resistivity and Seebeck coefficient of samples were measured in the temperature range of 323 K to 1073 K. A dramatic effect of thermal treatment on the Seebeck coefficient of VB{sub 2} seeded samples was observed, and it is indicated that there is possible partial intrinsic doping of vanadium into YB{sub 22}C{sub 2}N. VB{sub 2} is revealed to be a promising additive to improve the thermoelectric properties of YB{sub 22}C{sub 2}N. An enhancement of more than 220% of the maximum absolute value of the Seebeck coefficient was obtained while the resistivity was also reduced considerably.

Prytuliak, A.; Maruyama, S. [International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba 305-0044 (Japan); Mori, T., E-mail: MORI.Takao@nims.go.jp [International Center for Materials Nanoarchitectonics (MANA), National Institute for Materials Science (NIMS), Namiki 1-1, Tsukuba 305-0044 (Japan)

2013-05-15

175

Impurity effects on electronic transport in ferropnictide superconductors  

NASA Astrophysics Data System (ADS)

Effects of impurities and disorder on transport properties by electronic quasiparticles in superconducting iron pnictides are theoretically considered. The most prominent new features compared to the case of pure material should appear at high enough impurity concentration when a specific narrow band of conducting quasiparticle states can develop within the superconducting gap, around the position of localized impurity level by a single impurity center. The predicted specific threshold effects in the frequency-dependent optical conductivity and temperature-dependent thermal conductivity and also in Seebeck and Peltier coefficients can have interesting potentialities for practical applications.

Pogorelov, Y. G.; Santos, M. C.; Loktev, V. M.

2013-12-01

176

Measuring Seebeck Coefficients With Large Thermal Gradients  

NASA Technical Reports Server (NTRS)

Apparatus takes measurements and analyzes data automatically. Cylindrical sample is pressed between heater and water-cooled baseplate. Thermocouples at opposite ends of sample provide both temperatures and Seeback voltages. Conveniently shaped samples used, and results calculated by microcomputer and printed out.

Wood, C.; Chmielewski, A.; Zoltan, L. D.

1986-01-01

177

Seebeck nanoantennas for solar energy harvesting  

NASA Astrophysics Data System (ADS)

We propose a mid-infrared device based on thermocouple optical antennas for light sensing and energy harvesting applications. We numerically demonstrate that antennas are able to generate low-power dc signals by beneficing of the thermoelectric properties of the metals that constitute them. We theoretically evaluate the optical-to-electrical conversion efficiency for harvesting applications and finally discuss strategies to increase its performance. Thermocouple optical antennas therefore open the route toward the design of photovoltaic devices.

Briones, E.; Briones, J.; Cuadrado, A.; Martinez-Anton, J. C.; McMurtry, S.; Hehn, M.; Montaigne, F.; Alda, J.; Gonzalez, F. J.

2014-09-01

178

Z .Sensors and Actuators 78 1999 180188 www.elsevier.nlrlocatersna  

E-print Network

of strain on the volume electrical resistiv- ity of the composite. The Seebeck effect has been reported w as temperature sensors. However, the use of the Seebeck effect for tem- perature measurement requires Seebeck are not included. This requirement makes it more complicated to make use of the Seebeck effect in a structure

Chung, Deborah D.L.

179

Numerical Calculation of Density of States and Band Structure A Thesis Submitted in Partial Satisfaction  

E-print Network

directly into electricity. One of the main components of thermoelectric effect, the Seebeck effect by a temperature differential via Seebeck effect is measured by Seebeck coefficient (S), also known as thermopower. The Seebeck coefficient has units of V/K, and in practice a material with several 100µV/K is considered a good

Belanger, David P.

180

Technische Universitt Mnchen Fakultt fr Physik  

E-print Network

Spatially and Temporally Resolved Spin Seebeck Experiments Orts- und Zeitaufgelöste Spin Seebeck Experimente.1 The Spin Seebeck effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Detection method: the inverse Spin Hall effect . . . . . . . . . . . . . . . 2 1.3 Spatially Resolved Spin Seebeck Effect: SRSSE

Gross, Rudolf

181

Anomalous and planar Nernst effects in thin films of the half-metallic ferromagnet La2/3Sr1/3MnO3  

NASA Astrophysics Data System (ADS)

We report the planar and anomalous Nernst effects in epitaxial thin films of spin polarized La2/3Sr1/3MnO3. The thermal counterpart of the anomalous Hall effect in this material (i.e., the anomalous Nernst effect) shows an extreme sensitivity to any parasitic thermal gradient, resulting in large asymmetric voltages under small temperature differences. This should be considered when interpreting the magnitude of the electrical response in nanostructures and devices that operate under high current densities. Finally, none of the observed magnetothermoelectric signals is related to the spin Seebeck effect in this material.

Bui, Cong Tinh; Rivadulla, F.

2014-09-01

182

Spin-dependent thermoelectric effects in graphene-based spin valves  

NASA Astrophysics Data System (ADS)

Using first-principles calculations combined with non-equilibrium Green's function (NEGF), we investigate spin-dependent thermoelectric effects in a spin valve which consists of zigzag graphene nanoribbon (ZGNR) electrodes with different magnetic configurations. We find that electron transport properties in the ZGNR-based spin valve are strongly dependent on the magnetic configurations. As a result, with a temperature bias, thermally-induced currents can be controlled by switching the magnetic configurations, indicating a thermal magnetoresistance (MR) effect. Moreover, based on the linear response assumption, our study shows that the remarkably different Seebeck coefficients in the various magnetic configurations lead to a very large and controllable magneto Seebeck ratio. In addition, we evaluate thermoelectric properties, such as the power factor, electron thermal conductance and figure of merit (ZT), of the ZGNR-based spin valve. Our results indicate that the power factor and the electron thermal conductance are strongly related to the transmission gap and electron-hole symmetry of the transmission spectrum. Moreover, the value of ZT can reach 0.15 at room temperature without considering phonon scattering. In addition, we investigate the thermally-controlled magnetic distributions in the ZGNR-based spin valve and find that the magnetic distribution, especially the local magnetic moment around the Ni atom, is strongly related to the thermal bias. The very large, multi-valued and controllable thermal magnetoresistance and Seebeck effects indicate the strong potential of ZGNR-based spin valves for extremely low-power consuming spin caloritronics applications. The thermally-controlled magnetic moment in the ZGNR-based spin valve indicates its possible applications for information storage.

Zeng, Minggang; Huang, Wen; Liang, Gengchiau

2012-12-01

183

Photo-controllable thermoelectric properties with reversibility and photo-thermoelectric effects of tungsten trioxide accompanied by its photochromic phenomenon  

NASA Astrophysics Data System (ADS)

The addition of photo-controllable properties to tungsten trioxide (WO3) is of interest for developing practical applications of WO3 as well as for interpreting such phenomena from scientific viewpoints. Here, a sputtered crystalline WO3 thin film generated thermoelectric power due to ultraviolet (UV) light-induced band-gap excitation and was accompanied by a photochromic reaction resulting from generating W5+ ions. The thermoelectric properties (electrical conductivity (?) and Seebeck coefficient (S)) and coloration of WO3 could be reversibly switched by alternating the external stimulus between UV light irradiation and dark storage. After irradiating the film with UV light, ? increased, whereas the absolute value of S decreased, and the photochromic (coloration) reaction was detected. Notably, the opposite behavior was exhibited by WO3 after dark storage, and this reversible cycle could be repeated at least three times. Moreover, photo-thermoelectric effects (photo-conductive effect (photo-conductivity, ?photo) and photo-Seebeck effect (photo-Seebeck coefficient, Sphoto)) were also detected in response to visible-light irradiation of the colored WO3 thin films. Under visible-light irradiation, ?photo and the absolute value of Sphoto increased and decreased, respectively. These effects are likely attributable to the excitation of electrons from the mid-gap visible light absorption band (W5+ state) to the conduction band of WO3. Our findings demonstrate that the simultaneous, reversible switching of multiple properties of WO3 thin film is achieved by the application of an external stimulus and that this material exhibits photo-thermoelectric effects when irradiated with visible-light.

Azuma, Chiori; Kawano, Takuto; Kakemoto, Hirofumi; Irie, Hiroshi

2014-11-01

184

Specific Salt Effects on Thermophoresis of Charged Colloids  

E-print Network

We study the Soret effect of charged polystyrene particles as a function of temperature and electrolyte composition. As a main result we find that the Soret coefficient is determined by charge effects, and that non-ionic contributions are small. In view of the well-kown electric-double layer interactions, our thermal field-flow fractionation data lead us to the conclusion that the Soret effect originates to a large extent from diffusiophoresis in the salt gradient and from the electrolyte Seebeck effect, both of which show strong specific-ion effects. Moreover, we find that thermophoresis of polystyrene beads is fundamentally different from proteins and aqueous polymer solutions, which show a strong non-ionic contribution.

Kyriakos A. Eslahian; Arghya Majee; Michael Maskos; Alois Würger

2014-01-28

185

Observation of the spin Peltier effect for magnetic insulators.  

PubMed

We report the observation of the spin Peltier effect (SPE) in the ferrimagnetic insulator yttrium iron garnet (YIG), i.e., a heat current generated by a spin current flowing through a platinum (Pt)|YIG interface. The effect can be explained by the spin transfer torque that transforms the spin current in the Pt into a magnon current in the YIG. Via magnon-phonon interactions the magnetic fluctuations modulate the phonon temperature that is detected by a thermopile close to the interface. By finite-element modeling we verify the reciprocity between the spin Peltier and spin Seebeck effect. The observed strong coupling between thermal magnons and phonons in YIG is attractive for nanoscale cooling techniques. PMID:25062233

Flipse, J; Dejene, F K; Wagenaar, D; Bauer, G E W; Ben Youssef, J; van Wees, B J

2014-07-11

186

Observation of the Spin Peltier Effect for Magnetic Insulators  

NASA Astrophysics Data System (ADS)

We report the observation of the spin Peltier effect (SPE) in the ferrimagnetic insulator yttrium iron garnet (YIG), i.e., a heat current generated by a spin current flowing through a platinum (Pt)|YIG interface. The effect can be explained by the spin transfer torque that transforms the spin current in the Pt into a magnon current in the YIG. Via magnon-phonon interactions the magnetic fluctuations modulate the phonon temperature that is detected by a thermopile close to the interface. By finite-element modeling we verify the reciprocity between the spin Peltier and spin Seebeck effect. The observed strong coupling between thermal magnons and phonons in YIG is attractive for nanoscale cooling techniques.

Flipse, J.; Dejene, F. K.; Wagenaar, D.; Bauer, G. E. W.; Youssef, J. Ben; van Wees, B. J.

2014-07-01

187

Effects of Ge Dopant on Thermoelectric Properties of Barium and Indium Double-Filled p-Type Skutterudites  

NASA Astrophysics Data System (ADS)

A series of Ge-doped and (Ba,In) double-filled p-type skutterudite materials with nominal composition Ba0.3In0.2FeCo3Sb12- x Ge x ( x = 0 to 0.4, ? x = 0.1) have been prepared by melting, quenching, annealing, and spark plasma sintering methods. The effects of Ge dopant on the phase composition, microstructure, and thermoelectric properties of these materials were investigated in this work. A single-phase skutterudite material was obtained in the samples with 0 < x ? 0.2, and trace Fe3Ge2 was detected in the samples with x ? 0.3. The electrical conductivity increased and Seebeck coefficient decreased with increasing x in the range of 0 to 0.2, while the inverse behaviors of electrical conductivity and Seebeck coefficient were observed in the samples with x ? 0.3. The variations of electrical conductivity and Seebeck coefficient are attributed to the significant increase in the carrier concentration in the x range of 0 to 0.2 and the intensive impact of Fe3Ge2 when x ? 0.3. The lattice thermal conductivity of all the Ge-doped samples was considerably reduced as compared with the undoped Ba0.3In0.2FeCo3Sb12 sample, and the lowest value of lattice thermal conductivity of the Ba0.3In0.2FeCo3Sb11.8Ge0.2 sample reached 1.0 W m-1 K-1 at 700 K. The highest ZT value of 0.54 was obtained at 800 K for the Ba0.3In0.2FeCo3Sb11.7Ge0.3 sample, increased by 10% as compared with that of Ba0.3In0.2FeCo3Sb12.

Yu, Jian; Zhao, Wen-Yu; Lei, Bing; Tang, Ding-Guo; Zhang, Qing-Jie

2013-07-01

188

Thermal Cycling Effects on the Thermoelectric Properties of n-Type In, Ce based Skutterudite Compounds  

SciTech Connect

N-type In-filled CoSb3 are known skutterudite compounds that have shown promising thermoelectric (TE) properties resulting in high dimensionless figure of merit values at elevated temperatures. Their use in various waste heat recovery applications will require that they survive and operate after exposure to harsh thermal cycling environments. This research focused on uncovering the thermal cycling effects on thermoelectric properties of n-type In0.2Co4Sb12 and In0.2Ce0.15Co4Sb12 skutterudite compositions as well as quantifying their temperature-dependent structural properties (elastic modulus, shear modulus, and Poisson's ratio). It was observed that the Seebeck coefficient and resistivity increased only slightly in the double-filled In,Ce skutterudite materials upon thermal cycling. In the In-filled skutterudites the Seebeck coefficient remained approximately the same on thermal cycling, while electrical resistivity increased significantly after thermal cycling. Results also show that thermal conductivity marginally decreases in the case of In-filled skutterudites, whereas the reduction is more pronounced in In, Ce-based skutterudite compounds. The possible reason for this kind of reduction can be attributed to grain pinning effects due to formation of nano inclusions. High temperature structural property measurements (i.e., Young's modulus and shear modulus) are also reported and the results show that these structural properties decrease slowly as temperature increases and the compounds are structurally stable after numerous thermal cycles.

Biswas, Krishnendu; Subramanian, Mas A.; Good, Morris S.; Roberts, Kamandi C.; Hendricks, Terry J.

2012-06-14

189

Influence of heat flow directions on Nernst effects in Py/Pt bilayers  

NASA Astrophysics Data System (ADS)

We investigated the voltages obtained in a thin Pt strip on a permalloy film which was subject to in-plane temperature gradients and magnetic fields. The voltages detected by thin W tips or bond wires showed a purely symmetric effect with respect to the external magnetic field which can be fully explained by the planar Nernst effect. To verify the influence of the contacts, measurements in vacuum and atmosphere were compared and gave similar results. We explain that a slightly in-plane tilted temperature gradient only shifts the field direction dependence but does not cancel out the observed effects. Additionally, the anomalous Nernst effect could be induced by using thick Au tips which generated a heat current perpendicular to the sample plane. The effect can be manipulated by varying the temperature of the Au tips. These measurements are discussed concerning their relevance in transverse spin Seebeck effect measurements.

Meier, D.; Reinhardt, D.; Schmid, M.; Back, C. H.; Schmalhorst, J.-M.; Kuschel, T.; Reiss, G.

2013-11-01

190

Effect of growth base pressure on the thermoelectric properties of indium antimonide nanowires  

NASA Astrophysics Data System (ADS)

We report a study of the effect of the growth base pressure on the thermoelectric (TE) properties of indium antimonide (InSb) nanowires (NWs) synthesized using a vapour-liquid-solid method at different base pressures varying from ambient to high vacuum. A suspended device was used to characterize the TE properties of the NWs, which are zinc-blende structure with lang1 1 0rang growth direction based on transmission electron microscopy (TEM) characterization of the same NWs assembled on the suspended device. The obtained Seebeck coefficient is negative, with the magnitude being smaller than the literature bulk values and increasing with decreasing growth base pressure. These results are attributed to the loss of In from the source materials due to oxidation by residual oxygen in the growth environment and the consequent formation of Sb-doped NWs. The electron mobility and lattice thermal conductivity in the NWs are lower than the corresponding bulk values because of both surface scattering and stronger dopant scattering in the Sb-doped NWs. Based on these findings, it is suggested that growth from In-rich source materials can be used to achieve composition stoichiometry in the NWs so as to increase the Seebeck coefficient and TE figure of merit.

Zhou, Feng; Moore, Arden L.; Pettes, Michael T.; Lee, Yong; Seol, Jae Hun; Ye, Qi Laura; Rabenberg, Lew; Shi, Li

2010-01-01

191

Influence of Thallium on the Shubnikov - de Haas effect and Thermoelectric Properties of Sb2Te3 and Bi2Se3  

NASA Astrophysics Data System (ADS)

Influence of Tl-doping on the Shubnikov de Haas effect (SdH) at T=4.2 K in magnetic field up to 38 T of p-Sb2-xTlxTe3 (x=0; 0.005; 0.015; 0.05) and n-Bi2-xTlxSe3 (x=0, 0.01; 0.02; 0.04; 0.06) single crystals has been investigated. By increasing the Tl content, the frequency of the SdH effect and hence the extremal cross-sections of the Fermi-surface decreases in both materials. The hole concentration decreases in Sb2-xTlxTe3 due to a donor effect of Tl and the electron concentration decreases in n-Bi2-xTlxSe3 due to an acceptor effect of Tl. Temperature dependence of the Seebeck coefficient S, electrical conductivity ?, thermal conductivity k and the figure of merit ZT single crystals were measured in the temperature range 77 K - 300 K. The values of k and ? decrease due to Tl doping in Sb2-xTlxTe3 and n-Bi2-xTlxSe3 and the Seebeck coefficient S for all compositions increases in the whole temperature range. The figure of merit ZT increases in both materials. The preferential scattering mechanism in Tl-doped samples changes from the acoustic phonon scattering to the ionized impurity scattering.

Kulbachinskii, V. A.; Kudryashov, A. A.; Kytin, V. G.

2014-12-01

192

Condensed Matter Theory Center Tuesday, July 19  

E-print Network

Sears, Texas A&M "Interpreting Spin-Seebeck Effect Measurements" Recent experiments seem to observe the spin-Seebeck effect, which is the production of a spin-current by a thermal gradient. A thermal(x/\\lambda). The thermal gradient along z yields a spin current along z (the spin-Seebeck effect), which in turn leads

Lathrop, Daniel P.

193

Belgirate, Italy, 28-30 September 2005 ULTRA-LOCAL TEMPERATURE MAPPING WITH AN INTRINSIC THERMOCOUPLE  

E-print Network

-known Seebeck effect through an intrinsic thermocouple made from an EFM conducting tip put in contact. The thermal measurement is related to the Seebeck junction effect: it will therefore not be sensitive contacting a metallic heating surface. The local probing is based on the Seebeck effect. Local investigation

194

Pyroelectric Nanogenerators for Harvesting Thermoelectric Energy Ken C. Pradel,  

E-print Network

Information ABSTRACT: Harvesting thermoelectric energy mainly relies on the Seebeck effect that utilizes contact, Seebeck effect Wasted heat is a rich source of energy that could be harvested. In 2010- technology. Harvesting thermoelectric energy mainly relies on the Seebeck effect that utilizes a temperature

Wang, Zhong L.

195

RAPID COMMUNICATIONS PHYSICAL REVIEW B 84, 020405(R) (2011)  

E-print Network

is the recent observation of the spin Seebeck effect in ferromagnets,4­6 where a spin voltage develops experimentally.7 Besides such practical implications, the spin Seebeck effect also raises theoretical puzzles the contribution of the conduction electrons to the spin Seebeck effect in a ferromagnetic metal. In particular, we

Nunner, Tamara

196

Graduate-level text published by Imperial College Press  

E-print Network

need to be employed to solve for the heat transport. · We describe the Seebeck effect here. #12;J. K, Aspen talk, 2008 Seebeck effect In the Seebeck effect, we isolate the device and work with an open=-aij[(L11)-1L12M-1]ijjQ, and the Seebeck coefficient is S=V/T= aij[(L11)-1L12M-1]ij/ijM-1 ij Note

Freericks, Jim

197

Competing spin pumping effects in magnetic hybrid structures  

SciTech Connect

Pure spin current can be detected by its conversion into charge current in nanometer thick nonmagnetic metal layer with large spin-orbit coupling by means of the inverse spin Hall effect (ISHE). Recently, it has been shown that the metallic ferromagnet Permalloy (Py) can also be used as spin current detector in experiments in which an ISHE voltage is created in a Py layer in contact with the insulating ferromagnet yttrium iron garnet (YIG) under a thermal gradient in the longitudinal spin Seebeck configuration. Here, we report experiments with microwave driven spin pumping in heterostructures made with single crystal YIG film and a nanometer thick Py or Pt layer that show that Py behaves differently than nonmagnetic metals as a spin current detector. The results are attributed to the competition between the spin currents generated by the dynamics of the magnetizations in YIG and in Py, which are exchange coupled at the interface.

Azevedo, A., E-mail: aac@df.ufpe.br; Alves Santos, O.; Fonseca Guerra, G. A.; Cunha, R. O.; Rezende, S. M. [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil); Rodríguez-Suárez, R. [Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago (Chile)

2014-02-03

198

Competing spin pumping effects in magnetic hybrid structures  

NASA Astrophysics Data System (ADS)

Pure spin current can be detected by its conversion into charge current in nanometer thick nonmagnetic metal layer with large spin-orbit coupling by means of the inverse spin Hall effect (ISHE). Recently, it has been shown that the metallic ferromagnet Permalloy (Py) can also be used as spin current detector in experiments in which an ISHE voltage is created in a Py layer in contact with the insulating ferromagnet yttrium iron garnet (YIG) under a thermal gradient in the longitudinal spin Seebeck configuration. Here, we report experiments with microwave driven spin pumping in heterostructures made with single crystal YIG film and a nanometer thick Py or Pt layer that show that Py behaves differently than nonmagnetic metals as a spin current detector. The results are attributed to the competition between the spin currents generated by the dynamics of the magnetizations in YIG and in Py, which are exchange coupled at the interface.

Azevedo, A.; Alves Santos, O.; Fonseca Guerra, G. A.; Cunha, R. O.; Rodríguez-Suárez, R.; Rezende, S. M.

2014-02-01

199

09:30~10:00 Reception 10:00~10:30 Opening Ceremony  

E-print Network

Matter theory 15:20~15:50 Break "New trend of condensed matter science in 21th Century" In the Seebeck. Since the Seebeck effect is due to the entropy carried by the electric current, the spin and orbital degrees of freedom of conducting electrons in the oxides may enhance the Seebeck effect [1]. In the first

Wu, Yih-Min

200

INTRODUCTION Developing materials which meet given specifications is a difficult process. For  

E-print Network

. A good thermoelectric material should have a high Seebeck coefficient (S), a high electrical conductivity. Thermoelectric effects were discovered early in the 19th century. Seebeck discovered the effect that bears his thermoelectric materials should possess large Seebeck coefficients, high electrical conductivity, and low thermal

Myles, Charles W.

201

PUBLISHED ONLINE: 12 FEBRUARY 2012 | DOI: 10.1038/NPHYS2219 Nonlinear detection of spin currents in graphene  

E-print Network

-yet-unexplored nonlinear interaction between spin and charge. In analogy to the Seebeck effect10 , where a heat current, this results in a built-up voltage V = -S(T2 -T1), with S the Seebeck coefficient of the conducting system Seebeck voltage Non-linear 'spin Seebeck' voltage 0 1 0 10 1 0 1f( ) s = ¬1/2 s = ±1/2 T1 EnergyEnergy f

Loss, Daniel

202

Improving efficiency of thermoelectric energy conversion devices is a major  

E-print Network

dimensionality increases the Seebeck coefficient of the device. · Decrease in nanofilm thickness leads dominates over increase in Seebeck coefficient leading to poor device performance. Thermoelectric figure Electron Scale Lattice Scale Device Models Nanoscale Effects on Seebeck Coefficient of Silicon Films

Walker, D. Greg

203

Seebeck nanoantennas for the detection and characterization of infrared radiation.  

PubMed

Arrays of metallic thermocouples in the shape of spiral nanoantennas are proposed as infrared detectors, which use the thermoelectric properties of the metallic interfaces to generate electrical DC signals. The responsivity of these types of antennas is evaluated from both theoretical and numerical perspectives pointing out its potential as infrared sensors. Moreover, the same structures can be used to characterize the state of polarization of the optical near fields with a spatial resolution comparable to the wavelength. PMID:25607310

Briones, Edgar; Cuadrado, Alexander; Briones, Joel; Díaz de León, Ramón; Martínez-Antón, Juan Carlos; McMurtry, Stefan; Hehn, Michel; Montaigne, François; Alda, Javier; González, Francisco Javier

2014-10-20

204

Giant Seebeck Coefficient in V-TCNE thin films  

NASA Astrophysics Data System (ADS)

The disordered structure of organic conductors results in a naturally low thermal conductivity (?) but their ZT is known to be low because of their low thermopower (S) and electrical conductivity (?). Here we report an exception, with results obtained from 220 to 320K for the thermopower of V-TCNEx (V-(C2(CN)4)x) thin films deposited on a Si wafer (111). At room temperature S=+21.8 mV/K and increases with decreasing temperature. Those values are matched only by very pure semiconductors such as Si at low temperature, Bi nanowires, or strongly correlated electron systems like FeSb2. The valence band of V-TCNE has a very high density of states over a very narrow energy range, ascribed mostly to vanadium 3d(t2g) orbitals,ootnotetextY-J Yoo et al., Nat. Mat. 9 638 2010 which is consistent with the exceptionally large value of S. The dependence of S and ? upon illumination will also be shown, alongside preliminary estimates for the ZT.

Chamoire, Audrey; Jaworski, Christopher; Kao, Chi-Yueh; Heremans, Joseph; Epstein, Arthur

2011-03-01

205

Comment on "Unexpected size effect in the thermopower of thin-film stripes" [J. Appl. Phys. 110, 083709 (2011)  

NASA Astrophysics Data System (ADS)

In a recent article, Sun et al. [J. Appl. Phys. 110, 083709 (2011)] claim to measure a size-dependent thermoelectric effect in a micron-scale single-metal thermocouple. In this Comment, we demonstrate that the observed phenomenon is not due to a size-dependent Seebeck effect as claimed, but is rather wire-size-dependent heat transport that causes unequal heating at the bonding pads. As a result, the bonding pads are at two different temperatures, and the observed voltage corresponds to a thermoelectric effect of a parasitic thermocouple formed between their metal structure and the bonding-pad wires. We provide simulations and suggest a control experiment based on their structure that supports our contention that the observation depends on width-dependent heat transport in the wires.

Szakmany, Gergo P.; Orlov, Alexei O.; Bernstein, Gary H.; Porod, Wolfgang

2014-06-01

206

Spin-caloric transport properties of cobalt nanostructures: Spin disorder effects from first principles  

NASA Astrophysics Data System (ADS)

The fundamental aspects of spin-dependent transport processes and their interplay with temperature gradients, as given by the spin Seebeck coefficient, are still largely unexplored and a multitude of contributing factors must be considered. We used density functional theory together with a Monte-Carlo-based statistical method to simulate simple nanostructures, such as Co nanowires and films embedded in a Cu host or in vacuum, and investigated the influence of spin disorder scattering on electron transport at elevated temperatures. While we show that the spin-dependent scattering of electrons due to temperature-induced disorder of the local magnetic moments contributes significantly to the resistance, thermoelectric, and spin-caloric transport coefficients, we also conclude that the actual magnitude of these effects cannot be predicted, quantitatively or qualitatively, without such detailed calculations.

Ková?ik, Roman; Mavropoulos, Phivos; Wortmann, Daniel; Blügel, Stefan

2014-04-01

207

Ultraviolet fast-response photoelectric effect in tilted orientation SrTiO{sub 3} single crystals  

SciTech Connect

Ultraviolet photoelectricity based on the vicinal cut as-supplied SrTiO{sub 3} single crystals has been experimentally studied in the absence of an applied bias at room temperature. An open-circuit photovoltage of 130 ps rise time and 230 ps full width at half maximum was observed under the irradiation of a 355 nm pulsed laser of 25 ps in duration. The dependence of the photoelectric effect on the tilting angles was studied, and the optimum angle is 20.9 deg. . Seebeck effect is proposed to elucidate the tilting angle dependence of laser-induced photovoltage. This work demonstrates the potential of SrTiO{sub 3} single crystals in ultraviolet detection.

Zhao Kun; Jin Kuijuan; Huang Yanhong; Zhao Songqing; Lu Huibin; He Meng; Chen Zhenghao; Zhou Yueliang; Yang Guozhen [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China) and Department of Mathematics and Physics, China University of Petroleum, Beijing 102249 (China) and International Center for Materials Physics, Chinese Academy of Sciences, Shenyang 110016 (China); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080 (China)

2006-10-23

208

Effects of oxygen gas pressure on structural, electrical, and thermoelectric properties of (ZnO){sub 3}In{sub 2}O{sub 3} thin films deposited by rf magnetron sputtering  

SciTech Connect

Zinc indium oxide films were deposited by the rf magnetron sputtering method using a (ZnO){sub 3}In{sub 2}O{sub 3} target. The films were prepared at 573 K in various Ar/O{sub 2} sputtering gases (O{sub 2} content: 0%-25%). The effect of the oxygen gas content in the sputtering gas on the structural, optical, electrical, and thermoelectric properties of the films was investigated. The films had a c-axis oriented layer structure. The films deposited at 0%-3% oxygen gas contents exhibited a high electrical conductivity with a high carrier concentration, n{approx_equal}10{sup 20} cm{sup -3}, while the conductivity of the films significantly decreased above the 3% oxygen gas content, having a carrier concentration below 10{sup 18} cm{sup -3}. From the optical transmission measurement, the band gap of the films was estimated to be 3.01 eV. The films deposited at 3%-8% oxygen gas contents showed a high Seebeck coefficient, -300 {mu}V/K, while the maximum power factor, 4.78x10{sup -5} W/m K{sup 2}, was obtained at the 2% oxygen gas content. The Seebeck coefficient and the power factor were calculated on the basis of degenerate semiconductors. These results suggest that zinc indium oxide films have the possibility of being high performance thermoelectric materials.

Orikasa, Yuki; Hayashi, Naoaki; Muranaka, Shigetoshi [Department of Interdisciplinary Environment, Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto 606-8501 (Japan)

2008-06-01

209

The Effect of Multivalley Bandstructure on Thermoelectric Properties of Al x Ga1- x As  

NASA Astrophysics Data System (ADS)

We present the theoretical modeling of the thermoelectric properties of Al x Ga1- x As. It was shown that, contrary to the known good thermoelectric materials, the optimum composition happens far from the point at which the multiple bands meet. This unexpected optimum material composition is related to the detrimental effect of multivalley bandstructure. A semi-empirical model was employed to predict the thermoelectric properties versus alloy composition, temperature, and doping concentration. The electrical conductivity, Seebeck coefficient and figure-of-merit ( ZT) were calculated with consideration of the energy-dependent relaxation time and multivalley band structure for Al x Ga1- x As. The theoretical model was verified by comparison with different sets of experimental data on both electrical and thermal transport properties. It was shown that the multivalley bandstructure in Al x Ga1- x As affects the Seebeck coefficient in two counteracting processes; however, it always reduces the electrical conductivity and the electronic thermal conductivity. It was shown that the multivalley bandstructure also affects the lattice thermal conductivity. In contrast to several good thermoelectric materials in which their multivalley band structure enhances the ZT, in Al x Ga1- x As, the ZT reduces at the composition x at which the three bands of ?, X, and L meet each other. Therefore, the maximum ZT happens far from this point. The optimum x also depends on temperature and reduces with temperature. Therefore, the Al concentration must decrease across the thermoelectric leg from the cold to the hot side. At the optimum composition, the ZT of Al x Ga1- x As is predicted to be comparable to that of good thermoelectric materials at high temperatures.

Norouzzadeh, Payam; Vashaee, Daryoosh

2015-02-01

210

Effects of Fe substitution on the transport properties of the superconductor MgB2  

NASA Astrophysics Data System (ADS)

A systematic study has been made on the effect of Fe substitution by means of resistivity, thermal conductivity, and Seebeck coefficient of the Mg1-xFexB2 superconductor involving 0%, 0.3%, 0.6%, 1.2%, and 3.0% Fe content. The superconducting transition has been found to be very sharp (˜0.2K) for a pristine sample and substitution of Fe results in the decrease of TC with the increase in the transition width. Thermal conductivity is found to decrease with Fe content in general, such that the shoulder present in the pristine sample tends to fade away with increasing Fe. An analysis has been made on the normal state resistivity in terms of a two-band model, and of the thermal conductivity in terms of the Wiedemann-Franz law and the lattice thermal conductivity, and the information obtained on the basis of this analysis has been discussed. Besides, the electronic density of states (DOS) near the Fermi level remains nearly unaffected upon Fe substitution, as evidenced by the Seebeck coefficient measurements. When compared with Mn, Fe behaves like a nonmagnetic element with a modest variation in TC and on the other hand, the TC depression is much stronger when compared with other elements like Al, Cu, etc. Therefore, the observed variation in TC for the presently investigated concentrations of Fe is attributed to the specific nature of the given substituent element (Fe) in altering the phonon frequency and/or electron-phonon coupling strength rather than spin-flip scattering or change in DOS or disorder.

Gahtori, Bhasker; Lal, Ratan; Agarwal, S. K.; Kuo, Y. K.; Sivakumar, K. M.; Hsu, J. K.; Lin, J. Y.; Rao, Ashok; Chen, S. K.; MacManus-Driscoll, J. L.

2007-05-01

211

Phonon-Drag Effect of Ultra-Thin FeSi2 and MnSi1.7/FeSi2 Films  

NASA Astrophysics Data System (ADS)

Phonon-drag effect usually occurs in single crystals at very low temperatures (10-200 K). Strong phonon-drag effect is observed in ultra-thin ?-FeSi2 films at around room temperature. The Seebeck coefficient of a 23 nm-thick ?-FeSi2 film can reach -1.375 mV/K at 343 K. However, the thermoelectric power factor of the film is still small, only 0.42×10-3 W/m-K2, due to its large electrical resistivity. When a 27 nm-thick MnSi1.7 film with low electrical resistivity is grown on it, the thermoelectric power factor of the MnSi1.7 film can reach 1.5×10-3 W/m-K2 at around room temperature. This value is larger than that of bulk MnSi1.7 material in the same temperature range.

Hou, Q. R.; Gu, B. F.; Chen, Y. B.; He, Y. J.

212

Transport Magnetic Proximity Effects in Platinum  

NASA Astrophysics Data System (ADS)

Platinum (Pt) metal, being non-magnetic and having a strong spin-orbit coupling interaction, has been central in detecting pure spin current and establishing most of the recent spin-based phenomena. Thus, it is important to ascertain the transport and magnetic characteristics of thin Pt films in contact with a ferromagnet. In this work, we use both electric and thermal means to conclusively show the transport magnetic proximity effects (MPE) of thin Pt film in contact with ferromagnetic insulator YIG. At thicknesses comparable to, and less than, the spin diffusion length, the strong ferromagnetic characteristics in Pt films on YIG are indistinguishable from those of ferromagnetic permalloy on YIG. [1] The MPE occurs at the interface and decreases exponentially away from the interface, concentrating in only a few monolayers. As a result, the pure spin current detected by a thin Pt is tainted with a spin polarized current. The pure spin current phenomena, such as the inverse spin Hall effect and the spin Seebeck effect, have been contaminated with the anomalous Hall effect and the anomalous Nernst effect respectively. These results raise serious questions about the suitability, and the validity, of using Pt in establishing pure spin current phenomena; on the other hand, a much stronger spin-based effect can be induced by the MPE at the interface. This research is in collaboration with X. Fin, Y. P. Chen, J. Wu, and J. Q. Xiao (University of Delaware), T. Y. Chen (Arizona State University) and D. Qu, W. G. Wang, and C. L. Chien (The Johns Hopkins University).[4pt] [1] S. Y. Huang et al., Phys. Rev. Letts. 109, 107204 (2012).

Huang, Ssu-Yen

2013-03-01

213

Effects of partial substitution of Ni by Pd on the thermoelectric properties of ZrNiSn-based half-Heusler compounds  

NASA Astrophysics Data System (ADS)

We report on the effects of partial substitution of nickel by palladium on the thermoelectric properties of ZrNiSn-based half-Heusler compounds. It is shown that the substitution of palladium for nickel results in a significant, beneficial reduction of the thermal conductivity. The Seebeck coefficient also decreases, but only by a small amount. In the Hf0.5Zr0.5Ni0.8Pd0.2Sn0.99Sb0.01 compound, a power factor of 22.1 ?W K-2 cm-1 and a thermal conductivity as low as 4.5 W/m K are measured at room temperature. The dimensionless figure of merit ZT increases with increasing temperature and reaches a maximum value of 0.7 at about 800 K.

Shen, Q.; Chen, L.; Goto, T.; Hirai, T.; Yang, J.; Meisner, G. P.; Uher, C.

2001-12-01

214

Effects of Mn substitution on the thermoelectric properties of the electron-doped perovskite Sr1-xLaxTiO3  

NASA Astrophysics Data System (ADS)

We have tried to improve the n-type thermoelectric properties of the electron- doped Perovskite Sr1-xLaxTiO3 by a Mn substitution. The 1 ~ 2 % Mn substitution enhances the Seebeck coefficient (S) and reduces the thermal conductivity (?) by about 50 % at room temperature (RT) without largely increasing the resistivity for the 5 % electron-doped SrTiO3. Consequently, the power factor at RT keeps a large value comparable to that of Bi2Te3 and the dimensionless figure-of-merits at RT increases twofold by the slight Mn substitution. Such a large reduction of ? at RT is perhaps due to the effect of Jahn-Teller active Mn3+ ions, around which dynamical local lattice distortion may occur.

Okuda, T.; Hata, H.; Eto, T.; Nishina, K.; Kuwahara, H.; Nakamura, M.; Kajimoto, R.

2014-12-01

215

p s sbasic solid state physics www.pss-b.com  

E-print Network

Seebeck coefficients larger than 150 µV/K and effective electronic figures-of-merit ZT higher than 1. Our-hole symmetry. We show how one can achieve effective Seebeck coefficients larger than 150 µV/K and effective-of-merit of a multilayered nanostructure. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Seebeck

Freericks, Jim

216

Effects of Pd substitution on the thermoelectric and electronic properties of delafossite Cu1-xPdxFeO2 (x=0.01, 0.03 and 0.05)  

NASA Astrophysics Data System (ADS)

Cu(1-x)Pd(x)FeO2 (x=0.01, 0.03 and 005) delafossite was prepared by solid state reactions and was calcined/sintered at 1050 °C. The effect of Pd2+ substitution for the Cu1+ sites on the thermoelectric and electronic properties of Cu(1-x)Pd(x)FeO2 were investigated. The crystal structure, oxygen decomposition, thermoelectric and electronic properties were characterized by X-ray diffraction, thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), Seebeck coefficient, electrical conductivity and thermal conductivity measurements. The characterization showed that Cu(1-x)Pd(x)FeO2 formed a hexagonal delafossite structure with R3-m symmetry. The existence of Pd2+, Cu1+, Cu2+, Fe3+, Fe4+ and O was revealed from the XPS results. Confirmation of Pd2+ substitution for the Cu1+ sites occurred by increasing the c-axis in the lattice parameter with a Pd content. The O content intercalated at the center of the triangular Cu acted as a support to produce Cu2+ ions and was reduced with an increasing Pd content. The mixed valencies of Cu1+/Cu2+ and Cu1+/Pd2+ in the Cu layer changed the electrical conductivity and the Fe3+/Fe4+ mixed valencies in the FeO6 layer caused the Seebeck coefficient to increase. Both the electrical conductivity and Seebeck coefficient for Pd contents of x=0.01 and 0.03 were higher than that of non-doped CuFeO2. The low thermal conductivity of Cu(1-x)Pd(x)FeO2 resulted from the substitution of Pd, which has a large atomic mass, into structure. The Jonker plot indicated that the electronic properties displayed a degenerate density of states and that Cu(1-x)Pd(x)FeO2 was a semiconductor. A high ZT value of 0.055 was obtained for a Pd content of 0.03 at 950 K. The Pd2+ substitution for the Cu1+ sites influenced the thermoelectric and electronic properties of the delafossite Cu(1-x)Pd(x)FeO2 samples.

Ruttanapun, Chesta

2014-07-01

217

Thermoelectric effects and magnetic anisotropy of Ga1-xMnxAs thin films  

NASA Astrophysics Data System (ADS)

The transverse voltages generated in a Ga1-xMnxAs ferromagnetic semiconductor in planar Hall effect and transverse spin Seebeck effect configurations are systematically analyzed. The observed field dependences consist of symmetric and asymmetric contributions. The former is attributed to the planar Nernst effect in the magnetic film in the presence of an in-plane temperature gradient, while the latter is caused by the anomalous Nernst effect due to spurious out-of-plane temperature gradients with a coefficient as high as 500 ?V/K. We also report on the experimental observation of the planar Hall effect measured at different temperatures. Using a Stoner-Wohlfarth model for data analysis, the anisotropy constants Ku and Kc of superimposed uniaxial and cubic anisotropies in the magnetic film are determined. The temperature dependence of the Ku/Kc ratio reveals a gradual substitution of the cubic anisotropy dominating at low temperatures with the uniaxial anisotropy as the temperature rises. This behavior is confirmed by the simultaneous domain observation using Kerr microscopy, demonstrating different field evolutions of the domain structure at different temperatures.

Soldatov, I. V.; Panarina, N.; Hess, C.; Schultz, L.; Schäfer, R.

2014-09-01

218

Proximity effect on spin-dependent conductance and thermopower of correlated quantum dots  

NASA Astrophysics Data System (ADS)

We study the electric and thermoelectric transport properties of correlated quantum dots coupled to two ferromagnetic leads and one superconducting electrode. Transport through such hybrid devices depends on the interplay of ferromagnetic-contact-induced exchange field, superconducting proximity effect, and correlations leading to the Kondo effect. We consider the limit of large superconducting gap. The system can be then modeled by an effective Hamiltonian with a particle-nonconserving term describing the creation and annihilation of Cooper pairs. By means of the full density-matrix numerical renormalization group method, we analyze the behavior of electrical and thermal conductances, as well as the Seebeck coefficient as a function of temperature, dot level position, and strength of the coupling to the superconductor. We show that the exchange field may be considerably affected by the superconducting proximity effect and is generally a function of Andreev bound-state energies. Increasing the coupling to the superconductor may raise the Kondo temperature and partially restore the exchange-field-split Kondo resonance. The competition between ferromagnetic and superconducting proximity effects is reflected in the corresponding temperature and dot level dependence of both the linear conductance and the (spin) thermopower.

Wójcik, Krzysztof P.; Weymann, Ireneusz

2014-04-01

219

Spin transport and spin-caloric effects in (Cr,Zn)Te half-metallic nanostructures: Effect of spin disorder at elevated temperatures from first principles  

NASA Astrophysics Data System (ADS)

An important contribution to the thermoelectric and spin-caloric transport properties in magnetic materials at elevated temperatures is the formation of a spin-disordered state due to local moment fluctuations. This effect has not been largely investigated so far. We focus on various magnetic nanostructures of CrTe in the form of thin layers or nanowires embedded in ZnTe matrix, motivated by the miniaturization of spintronics devices and by recent suggestions that magnetic nanostructures can lead to extraordinary thermoelectric effects due to quantum confinement. The electronic structure of the studied systems is calculated within the multiple scattering screened Korringa-Kohn-Rostoker Green function (KKR-GF) framework. The Monte Carlo method is used to simulate the magnetization in the temperature induced spin disorder. The transport properties are evaluated from the transmission probability obtained using the Baranger-Stone approach within the KKR-GF framework. We find qualitative and quantitative changes in the thermoelectric and spin-caloric coefficients when spin disorder is included in the calculation. Furthermore, we show that substitutional impurities in CrTe nanowires could considerably enhance the Seebeck coefficient and the thermoelectric figure of merit.

Ková?ik, Roman; Mavropoulos, Phivos; Blügel, Stefan

2015-01-01

220

Effects of partial substitution of Co by Ni on the high-temperature thermoelectric properties of TiCoSb-based half-Heusler compounds  

Microsoft Academic Search

TiCoSb-based half-Heusler compounds were prepared by solid-state reaction and their thermoelectric properties were studied. The un-doped TiCoSb compound shows n-type conduction and demonstrates high Seebeck coefficient at high temperatures. The partial substitution of Co by Ni caused great increase in electron concentration and electrical conductivity, while the Seebeck coefficient and the thermal conductivity showed little change when Ni content (x)

Min Zhou; Chude Feng; Lidong Chen; Xiangyang Huang

2005-01-01

221

Photothermoelectric and photovoltaic effects both present in MoS2  

PubMed Central

As a finite-energy-bandgap alternative to graphene, semiconducting molybdenum disulfide (MoS2) has recently attracted extensive interest for energy and sensor applications. In particular for broad-spectral photodetectors, multilayer MoS2 is more appealing than its monolayer counterpart. However, little is understood regarding the physics underlying the photoresponse of multilayer MoS2. Here, we employ scanning photocurrent microscopy to identify the nature of photocurrent generated in multilayer MoS2 transistors. The generation and transport of photocurrent in multilayer MoS2 are found to differ from those in other low-dimensional materials that only contribute with either photovoltaic effect (PVE) or photothermoelectric effect (PTE). In multilayer MoS2, the PVE at the MoS2-metal interface dominates in the accumulation regime whereas the hot-carrier-assisted PTE prevails in the depletion regime. Besides, the anomalously large Seebeck coefficient observed in multilayer MoS2, which has also been reported by others, is caused by hot photo-excited carriers that are not in thermal equilibrium with the MoS2 lattice. PMID:25605348

Zhang, Youwei; Li, Hui; Wang, Lu; Wang, Haomin; Xie, Xiaomin; Zhang, Shi-Li; Liu, Ran; Qiu, Zhi-Jun

2015-01-01

222

Photothermoelectric and photovoltaic effects both present in MoS2  

NASA Astrophysics Data System (ADS)

As a finite-energy-bandgap alternative to graphene, semiconducting molybdenum disulfide (MoS2) has recently attracted extensive interest for energy and sensor applications. In particular for broad-spectral photodetectors, multilayer MoS2 is more appealing than its monolayer counterpart. However, little is understood regarding the physics underlying the photoresponse of multilayer MoS2. Here, we employ scanning photocurrent microscopy to identify the nature of photocurrent generated in multilayer MoS2 transistors. The generation and transport of photocurrent in multilayer MoS2 are found to differ from those in other low-dimensional materials that only contribute with either photovoltaic effect (PVE) or photothermoelectric effect (PTE). In multilayer MoS2, the PVE at the MoS2-metal interface dominates in the accumulation regime whereas the hot-carrier-assisted PTE prevails in the depletion regime. Besides, the anomalously large Seebeck coefficient observed in multilayer MoS2, which has also been reported by others, is caused by hot photo-excited carriers that are not in thermal equilibrium with the MoS2 lattice.

Zhang, Youwei; Li, Hui; Wang, Lu; Wang, Haomin; Xie, Xiaomin; Zhang, Shi-Li; Liu, Ran; Qiu, Zhi-Jun

2015-01-01

223

Photothermoelectric and photovoltaic effects both present in MoS2.  

PubMed

As a finite-energy-bandgap alternative to graphene, semiconducting molybdenum disulfide (MoS2) has recently attracted extensive interest for energy and sensor applications. In particular for broad-spectral photodetectors, multilayer MoS2 is more appealing than its monolayer counterpart. However, little is understood regarding the physics underlying the photoresponse of multilayer MoS2. Here, we employ scanning photocurrent microscopy to identify the nature of photocurrent generated in multilayer MoS2 transistors. The generation and transport of photocurrent in multilayer MoS2 are found to differ from those in other low-dimensional materials that only contribute with either photovoltaic effect (PVE) or photothermoelectric effect (PTE). In multilayer MoS2, the PVE at the MoS2-metal interface dominates in the accumulation regime whereas the hot-carrier-assisted PTE prevails in the depletion regime. Besides, the anomalously large Seebeck coefficient observed in multilayer MoS2, which has also been reported by others, is caused by hot photo-excited carriers that are not in thermal equilibrium with the MoS2 lattice. PMID:25605348

Zhang, Youwei; Li, Hui; Wang, Lu; Wang, Haomin; Xie, Xiaomin; Zhang, Shi-Li; Liu, Ran; Qiu, Zhi-Jun

2015-01-01

224

Effects of doping on transport properties in Cu-Bi-Se-based thermoelectric materials.  

PubMed

The thermoelectric properties of Zn-, In-, and I-doped Cu1.7Bi4.7Se8 pavonite homologues were investigated in the temperature range from 300 to 560 K. On the basis of the comprehensive structural analysis using Rietveld refinement of synchrotron radiation diffraction for Cu(x+y)Bi(5-y)Se8 compounds with the inherently disordered crystallographic sites, we demonstrate a doping strategy that provides a simultaneous control for enhanced electronic transport properties by the optimization of carrier concentration and exceptionally low lattice thermal conductivity by the formation of point defects. Substituted Zn or In ions on Cu site was found to be an effective phonon scattering center as well as an electron donor, while doping on Bi site showed a moderate effect for phonon scattering. In addition, we achieved largely enhanced power factor in small amount of In doping on Cu site by increased electrical conductivity and moderately decreased Seebeck coefficient. Coupled with a low lattice thermal conductivity originated from intensified point defect phonon scattering by substituted In ions with host Cu ions, a thermoelectric figure of merit ZT of 0.24 at 560 K for Cu1.6915In0.0085Bi4.7Se8 was achieved, yielding 30% enhancement compared with that of a pristine Cu1.7Bi4.7Se8 at the same temperature. PMID:25402498

Hwang, Jae-Yeol; Mun, Hyeon A; Kim, Sang Il; Lee, Ki Moon; Kim, Jungeun; Lee, Kyu Hyoung; Kim, Sung Wng

2014-12-15

225

Importance of relativistic effects in electronic structure and thermopower calculations for Mg2Si, Mg2Ge, and Mg2Sn  

NASA Astrophysics Data System (ADS)

We present a theoretical study of the influence of relativistic effects on the electronic band structure and thermopower of Mg2X (X = Si, Ge, Sn) semiconductors. The full potential Korringa-Kohn-Rostoker (KKR) method is used, and a detailed comparison between the fully relativistic and semirelativistic electronic structure features is done. We show that the spin-orbit (S-O) interaction splits the valence band at ? point in good agreement with the experimental data, and this effect strongly depends on X atom. The S-O modifications of the topology of the ?-centered holelike Fermi surface pockets lead to a change in electron transport properties, which are investigated using the Boltzmann approach. In addition, a simple and efficient method is presented for the calculation of density of states effective mass m*, and then used to examine the impact of relativistic effects on m*. It is found that the S-O coupling of the valence bands reduces the effective mass and therefore significantly lowers the thermopower, primarily in Mg2Sn, but also in Mg2Ge. A detrimental influence of the S-O interaction on the thermoelectric performance of p-type Mg2X is analyzed as a function of temperature (10-900 K) and carrier concentration (1018-1022 cm-3). Interestingly, similar calculations in n-type Mg2X, show a negligible effect of the S-O interaction on the lowest conduction bands and, consequently, also on the Seebeck coefficient.

Kutorasinski, K.; Wiendlocha, B.; Tobola, J.; Kaprzyk, S.

2014-03-01

226

Poole-Frenkel effect in sputter-deposited CuAlO2+x nanocrystals  

NASA Astrophysics Data System (ADS)

Field-assisted thermionic emission within a sputter-deposited, nanocrystalline thin film of CuAlO2.06 is observed for the first time, and explained in terms of the Poole-Frenkel model. The presence of adsorbed oxygen ions as trap-states at the grain boundary regions of the nanostructured thin film is considered to manifest this phenomenon. Under an applied field, the barrier of the trap potential is lowered and thermal emission of charge carriers takes place at different sample temperatures to induce nonlinearity in the current (I)-voltage (V) characteristics of the nanomaterial. Fitting of the Poole-Frenkel model with the I-V data shows that the nonlinearity is effective above 50 V under the operating conditions. Calculations of the energy of the trap level, acceptor level and Fermi level reveal the existence of deep level trap-states and a shallow acceptor level with acceptor concentration considerably higher than the trap-states. Hall measurements confirm the p-type semiconductivity of the film, with a hole concentration around 1018 cm-3. Thermopower measurements give a room-temperature Seebeck coefficient around 130 ?V K-1. This temperature-dependent conductivity enhancement within CuAlO2 nanomaterial may find interesting applications in transparent electronics and high-voltage applications for power supply networks.

Narayan Banerjee, Arghya; Joo, Sang Woo

2013-04-01

227

Poole-Frenkel effect in sputter-deposited CuAlO(2+x) nanocrystals.  

PubMed

Field-assisted thermionic emission within a sputter-deposited, nanocrystalline thin film of CuAlO2.06 is observed for the first time, and explained in terms of the Poole-Frenkel model. The presence of adsorbed oxygen ions as trap-states at the grain boundary regions of the nanostructured thin film is considered to manifest this phenomenon. Under an applied field, the barrier of the trap potential is lowered and thermal emission of charge carriers takes place at different sample temperatures to induce nonlinearity in the current (I)-voltage (V) characteristics of the nanomaterial. Fitting of the Poole-Frenkel model with the I-V data shows that the nonlinearity is effective above 50 V under the operating conditions. Calculations of the energy of the trap level, acceptor level and Fermi level reveal the existence of deep level trap-states and a shallow acceptor level with acceptor concentration considerably higher than the trap-states. Hall measurements confirm the p-type semiconductivity of the film, with a hole concentration around 10(18) cm(-3). Thermopower measurements give a room-temperature Seebeck coefficient around 130 ?V K(-1). This temperature-dependent conductivity enhancement within CuAlO2 nanomaterial may find interesting applications in transparent electronics and high-voltage applications for power supply networks. PMID:23535666

Banerjee, Arghya Narayan; Joo, Sang Woo

2013-04-26

228

Thermal Hall effect in YBCO: Probing Fermi-surface reconstruction inside the superconducting state  

NASA Astrophysics Data System (ADS)

The thermal Hall (Righi-Leduc) effect was measured in the cuprate superconductor YBCO at a doping p = 0.11, as a function of magnetic field H up to 29 T. At temperatures well below the zero-field superconducting Tc, the thermal Hall conductivity ?xy is positive at low field and then turns over to become negative at fields above 15 T. The negative ?xy is consistent with the negative Hall and Seebeck coefficients observed in the normal state above 25 T [1,2]. This further supports our interpretation: the Fermi surface of YBCO contains a small electron-like pocket [3] in that region of the phase diagram, the result of a Fermi-surface reconstruction attributed to stripe order [4]. In the T = 0 limit at H = 29 T, we find reasonable agreement with the Wiedemann-Franz law, ?xy/T=L0?xy. The fact that ?xy changes sign at H 15 T is consistent with a scenario of phase competition whereby stripe order emerges only at finite field, in agreement with recent NMR studies that detect the onset of charge-stripe order above 15 T [5]. [4pt] [1] LeBoeuf et al., PRB 83, 054056 (2011); [2] Lalibert'e et al., Nat. Commun. 2, 432 (2011); [3] LeBoeuf et al., Nature 450, 533 (2007); [4] Chang et al., PRL 104, 057005 (2010); [5] Wu et al., Nature 477, 191 (2011).

Cyr-Choinière, Olivier; Laliberté, Francis; Dufour-Beauséjour, Sophie; Grissonnanche, Gaël.; Gordon, Ryan T.; Doiron-Leyraud, Nicolas; Taillefer, Louis; Ramshaw, Brad J.; Liang, Ruixing; Bonn, Doug A.; Hardy, Walter N.; Proust, Cyril

2012-02-01

229

Compositional disorder and its effect on the thermoelectric performance of Zn?P? nanowire-copper nanoparticle composites.  

PubMed

Recent studies indicated that nanowire format of materials is ideal for enhancing the thermoelectric performance of materials. Most of these studies were performed using individual nanowires as the test elements. It is not currently clear whether bulk assemblies of nanowires replicate this enhanced thermoelectric performance of individual nanowires. Therefore, it is imperative to understand whether enhanced thermoelectric performance exhibited by individual nanowires can be extended to bulk assemblies of nanowires. It is also imperative to know whether the addition of metal nanoparticle to semiconductor nanowires can be employed for enhancing their thermoelectric performance further. Specifically, it is important to understand the effect of microstructure and composition on the thermoelectric performance on bulk compound semiconductor nanowire-metal nanoparticle composites. In this study, bulk composites composed of mixtures of copper nanoparticles with either unfunctionalized or 1,4-benzenedithiol (BDT) functionalized Zn?P? nanowires were fabricated and analyzed for their thermoelectric performance. The results indicated that use of BDT functionalized nanowires for the fabrication of composites leads to interface-engineered composites that have uniform composition all across their cross-section. The interface engineering allows for increasing their Seebeck coefficients and electrical conductivities, relative to the Zn?P? nanowire pellets. In contrast, the use of unfunctionalized Zn?P? nanowires for the fabrication of composite leads to the formation of composites that are non-uniform in composition across their cross-section. Ultimately, the composites were found to have Zn?P? nanowires interspersed with metal alloy nanoparticles. Such non-uniform composites exhibited very high electrical conductivities, but slightly lower Seebeck coefficients, relative to Zn?P? nanowire pellets. These composites were found to show a very high zT of 0.23 at 770 K, orders of magnitude higher than either interface-engineered composites or Zn?P? nanowire pellets. The results indicate that microstructural composition of semiconductor nanowire-metal nanoparticle composites plays a major role in determining their thermoelectric performance, and such composites exhibit enhanced thermoelectric performance. PMID:24577096

Brockway, Lance; Vasiraju, Venkata; Vaddiraju, Sreeram

2014-03-28

230

Optical band gap and the Burstein-Moss effect in iodine doped PbTe using diffuse reflectance infrared Fourier transform spectroscopy  

NASA Astrophysics Data System (ADS)

Optical absorption edge measurements are performed on I doped PbTe using diffuse reflectance infrared Fourier transform spectroscopy. The Burstein-Moss shift, an increase in the absorption edge (optical band gap) with increasing doping level, is explored. The optical gap increases on the order of 0.1 eV for doping levels ranging from 3 × 1018 to 2 × 1020 cm-3, relevant doping levels for good thermoelectric materials. Chemical potential is estimated from transport measurements—specifically, Hall effect and Seebeck coefficient—using a single band Kane model. In heavily doped semiconductors, it is well-known that the band gap shrinks with increasing doping level. This effect, known as band gap renormalization, is fit here using an n1/3 scaling law which reflects an electron-electron exchange interaction. The renormalization effect in these samples is shown to be more than 0.1 eV, on the same order of magnitude as the band gap itself. Existing models do not explain such large relative changes in band gap and are not entirely self-consistent. An improved theory for the renormalization in narrow gap semiconductors is required.

Gibbs, Zachary M.; LaLonde, Aaron; Snyder, G. Jeffrey

2013-07-01

231

Grundlagen-Untersuchungen des Seebeck Koeffizienten der Clathrate Ba8ZnxGe46-x.  

E-print Network

??Themoelektrische Materialien gewinnen immer mehr an Bedeutung auf Grund ihrer Eigenschaft, umweltfreundlich Strom zu produzieren. Deswegen wurde die Erforschung vielversprechender thermoelektrischer Materialien auch ein wichtiges… (more)

Moser, Rene

2011-01-01

232

Using first principles Destiny Functional Theory methods to model the Seebeck coefficient of bulk silicon  

E-print Network

Thermoelectrics are gaining significant amounts of attention considering their relevance today in the areas of sustainable energy generation and energy efficiency. In this thesis, the thermoelectric properties of bulk ...

Mehra, Saahil

2008-01-01

233

Ribosomal Synthesis of Dehydroalanine-Containing Peptides Florian P. Seebeck and Jack W. Szostak*  

E-print Network

February 9, 2006; E-mail: szostak@molbio.mgh.harvard.edu The nonribosomal peptides (NRP) feature backbone residues remains a challenging,8-10 yet indispensable step toward the production of NRP might undergo oxidative elimination to expose Ala in a post-translational manner (Scheme 1). To test

Heller, Eric

234

Seebeck Enhancement Through Miniband Conduction in IIIV Semiconductor Superlattices at Low Temperatures  

E-print Network

theoretically improved thermoelectric power factors in low- dimensional materials such as quantum wells in 1993. Boltzmann transport in the relaxa- tion-time approximation is used to calculate the thermoelectric transport thermoelectric transport properties are also calculated and discussed to fur- ther enhance the thermoelectric

235

Effects of Heavy Element Substitution on Electronic Structure and Lattice Thermal Conductivity of Fe2VAl Thermoelectric Material  

NASA Astrophysics Data System (ADS)

By using first-principles cluster calculations, we identified that Ta or W substitution for V is useful for decreasing the lattice thermal conductivity of the Fe2VAl Heusler alloy without greatly affecting the electron transport properties. It was clearly confirmed that the Fe2(V1- x Ta x )Al0.95Si0.05 ( x = 0, 0.025, 0.05), Fe2(V0.9- x Ta x Ti0.1)Al ( x = 0, 0.10, 0.20), and Fe2(V0.9-2 x W x Ti0.1+ x )Al ( x = 0, 0.05, 0.10) alloys indeed possessed large Seebeck coefficient regardless of the amounts of substituted elements, while their lattice thermal conductivity was effectively reduced. As a result of partial substitution of Ta for V, we succeeded in increasing the magnitude of the dimensionless figure of merit of the Heusler phase up to 0.2, which is five times as large as the Ta-free compound.

Terazawa, Yuichi; Mikami, Masashi; Itoh, Takashi; Takeuchi, Tsunehiro

2012-06-01

236

Effect of Sn Doping on the Thermoelectric Properties of n-type Bi2(Te,Se)3 Alloys  

NASA Astrophysics Data System (ADS)

In the present work, 0.01-0.05wt.% Sn-doped Bi2(Te0.9Se0.1)3 alloys were prepared by mechanical deformation followed by hot pressing, and their thermoelectric properties were studied. We observed that the Sn element is a very effective dopant as an acceptor to control the carrier concentration in the n-type Bi2(Te0.9Se0.1)3 alloys to optimize their thermoelectric property. The n-type carrier concentration can be controlled from 4.2 × 1019/cm3 to 2.4 × 1019/cm3 by 0.05wt.% Sn-doping. While the Seebeck coefficient and the electrical resistivity are both increased with doping, the power factor remains the same. Therefore, we found that the thermoelectric figure-of-merit becomes maximized at 0.75 when the thermal conductivity has a minimum value for the 0.03wt.% Sn-doped sample.

Lee, Jae-Uk; Lee, Deuk-Hee; Kwon, Beomjin; Hyun, Dow-Bin; Nahm, Sahn; Baek, Seung-Hyub; Kim, Jin-Sang

2015-01-01

237

Effects of impurity-band conduction on thermoelectric properties of lightly doped p-type CoSb3  

NASA Astrophysics Data System (ADS)

Experimental data on the thermoelectric properties of lightly doped p-type CoSb3 reported by Mandrus et al. [Phys. Rev. B 52, 4926 (1995)], Arushanov et al. [Phys. Rev. B 56, 1911 (1997)], and Dyck et al. [Phys. Rev. B 65, 115204 (2002)] have been analyzed, incorporating both the impurity-band conduction and the nonparabolicity of the valence band. The concentrations of a resonant acceptor, a deep acceptor, and a compensating donor level have been considerably corrected from those obtained in the original studies by Arushanov et al. and Dyck et al. The impurity-band conduction in the deep acceptor level has been proved to be the dominant conduction mechanism at low temperatures in the sample of Dyck et al. while that in the resonant acceptor level has been proved to be the dominant one in the other samples. Especially, the impurity-band conduction has been proved to be predominant up to as high as 400 K in the sample of Mandrus et al. As a result of incorporating the effects of both the impurity-band conduction and the nonparabolicity, the agreement of the simulated Seebeck coefficient with the experimental one has been excellently improved.

Kajikawa, Y.

2014-10-01

238

Oxide based thermoelectric materials for large scale power generation  

E-print Network

The thermoelectric (TE) devices are based on the Seebeck and Peltier effects, which describe the conversion between temperature gradient and electricity. The effectiveness of the material performance can be described by ...

Song, Yang, M. Eng. Massachusetts Institute of Technology

2008-01-01

239

Thermoelectric Effect across the Metal-Insulator Domain Walls in VO2  

E-print Network

-performance thermoelectric materials are currently one of the focuses in materials research for energy conversion technologies.1-4 A good thermoelectric material should have a relatively high thermopower (Seebeck coefficient perpendicular to the current and heat flow direction. This offers a material platform where the thermoelectric

Wu, Junqiao

240

Spray pyrolysis of tin selenide thin-film semiconductors: the effect of selenium concentration on the properties of the thin films  

NASA Astrophysics Data System (ADS)

Thin films of tin selenide (SnxSey) with an atomic ratio of , 1 and 1.5 were prepared on a glass substrate at T = 470°C using a spray pyrolysis technique. The initial materials for the preparation of the thin films were an alcoholic solution consisting of tin chloride (SnCl4· 5H2O) and selenide acide (H2SeO3). The prepared thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy, scanning tunneling microscopy, scanning helium ion microscopy, and UV-vis spectroscopy. The photoconductivity and thermoelectric effects of the SnxSey thin films were then studied. The SnxSey thin films had a polycrystalline structure with an almost uniform surface and cluster type growth. The increasing atomic ratio of r in the films, the optical gap, photosensitivity and Seebeck coefficient were changed from 1.6 to 1.37 eV, 0.01 to 0.31 and -26.2 to -42.7 mV/K (at T = 350 K), respectively. In addition, the XRD patterns indicated intensity peaks in r = 1 that corresponded to the increase in the SnSe and SnSe2 phases.

Fadavieslam, M. R.; Bagheri-Mohagheghi, M. M.

2013-08-01

241

Effect of ceramic dispersion on thermoelectric properties of nano-ZrO{sub 2}/CoSb{sub 3} composites  

SciTech Connect

In the present work, nano-ZrO{sub 2}/CoSb{sub 3} composites were fabricated by milling ZrO{sub 2} and CoSb{sub 3} powders and hot pressing at different sintering temperatures. For the prepared compacts, the phase purity, microstructure, and temperature-dependent thermoelectric properties were characterized. The effect of nano-ZrO{sub 2} dispersion on composite electrical conductivity and thermal conductivity is strictly clarified by comparing the transport properties of the nondispersed and dispersed CoSb{sub 3} at identical porosity, so that the effect of porosity on thermoelectric parameters could be eliminated. The effect of the insulating inclusion itself on transport properties is also considered and eliminated using effective media theories. It is clearly verified that charge carrier scattering and phonon scattering occur simultaneously to lower the electrical conductivity and the thermal conductivity of CoSb{sub 3} due to the introduction of nano-ZrO{sub 2} inclusions. The investigated composites show higher electrical conductivity due to existence of metallic Sb and lower thermal conductivity because of nanodispersion. At the ranges of high measuring temperature (673-723 K) and low porosity (6%-9%), the ratio of electrical conductivity to thermal conductivity of the dispersed CoSb{sub 3} is higher than that of nondispersed CoSb{sub 3}, and the dimensionless figure of merit (ZT) of the composite could probably be improved at these ranges with the enhanced ratio of electrical conductivity to thermal conductivity and Seebeck coefficient, which is assumed to be increased by a potential barrier scattering.

He, Zeming; Stiewe, Christian; Platzek, Dieter; Karpinski, Gabriele; Mueller, Eckhard; Li, Shanghua; Toprak, Muhammet; Muhammed, Mamoun [Institute of Materials Research, German Aerospace Center (DLR), D-51170 Cologne (Germany); Materials Chemistry Division, Royal Institute of Technology (KTH), SE-10044 Stockholm (Sweden)

2007-02-15

242

The effects of the size and the doping concentration on the power factor of n-type lead telluride nanocrystals for thermoelectric energy conversion.  

PubMed

For the first time, we demonstrate a successful synthesis of colloidal n-type lead telluride nanocrystals doped with iodine. By tuning the reaction time and iodine concentration in the precursor solution, nanocrystals with different sizes and doping concentrations are synthesized. The Seebeck coefficient and electrical conductivity of the nanocrystals are measured on nanocrystal thin films fabricated by dip-coating glass substrates in the nanocrystals solution. Investigations on the influence of size and doping concentration on the electrical properties have been performed. The results show that the size of the nanocrystals significantly influences the electrical conductivity but not the Seebeck coefficient of nanocrystal films, while higher doping concentration leads to lower Seebeck coefficient but higher electrical conductivity in the nanocrystal films. Proof-of-concept thin-film thermoelectric modules are also fabricated using both p-type and n-type PbTe nanocrystals for the conversion of thermal energy into electrical energy. PMID:24527850

Fang, Haiyu; Luo, Zhiqiang; Yang, Haoran; Wu, Yue

2014-03-12

243

Band Structure Engineering in Geometry-Modulated Nanostructures for Thermoelectric Efficiency Enhancement  

NASA Astrophysics Data System (ADS)

The energy subband structure of nanowires with periodically modulated cross-section has been calculated within a continuum model and the effective mass approximation. A characteristic structure of minibands and resonances has been found. This leads to a remarkable enhancement of the Seebeck coefficient compared with that of nonmodulated nanowires of the same dimensions. The Seebeck coefficient enhancement depends on the interplay between the thermal broadening and the quantum confinement. It is pointed out here that the modulation geometry and material parameters can provide design tools for Seebeck coefficient enhancement in nanowires.

Zianni, Xanthippi

2014-10-01

244

Modeling of solar thermal selective surfaces and thermoelectric generators  

E-print Network

A thermoelectric generator is a solid-state device that converts a heat flux into electrical power via the Seebeck effect. When a thermoelectric generator is inserted between a solar-absorbing surface and a heat sink, a ...

McEnaney, Kenneth

2010-01-01

245

Effects of Ge doping on the thermoelectric properties of TiCoSb-based p-type half-Heusler compounds  

Microsoft Academic Search

Ge-doped TiCoSb-based half-Heusler compounds, TiCoGexSb1?x (x=0–0.2), were prepared by arc melting and spark plasma sintering (SPS). The electrical conductivity, Seebeck coefficient and thermal conductivity were measured from room temperature to 850K. The Seebeck coefficient changed from negative to positive by Ge doping, and the electrical conductivity increased with increasing Ge content. The lattice thermal conductivity for TiCoGexSb1?x is considerably reduced,

Ting Wu; Wan Jiang; Xiaoya Li; Shengqiang Bai; Shengcong Liufu; Lidong Chen

2009-01-01

246

A study of transport properties in Cu and P doped ZnSb  

NASA Astrophysics Data System (ADS)

ZnSb samples have been doped with copper and phosphorus and sintered at 798 K. Electronic transport properties are interpreted as being influenced by an impurity band close to the valence band. At low Cu dopant concentrations, this impurity band degrades the thermoelectric properties as the Seebeck coefficient and effective mass are reduced. At carrier concentrations above 1 × 1019 cm-3, the Seebeck coefficient in Cu doped samples can be described by a single parabolic band.

Valset, K.; Song, X.; Finstad, T. G.

2015-01-01

247

Effect of ruthenium substitution in layered sodium cobaltate Na{sub x}CoO{sub 2}: Synthesis, structural and physical properties  

SciTech Connect

Solid-state synthesis of Na{sub 0.71}Co{sub 1-x}Ru{sub x}O{sub 2} compositions shows that ruthenium can be substituted for cobalt in the hexagonal Na{sub 0.71}CoO{sub 2} phase up to x=0.5. The cell expands continuously with increasing ruthenium content. All mixed Co-Ru phases show a Curie-Weiss behaviour with no evidence of magnetic ordering down to 2 K. Unlike the parent phase Na{sub 0.71}CoO{sub 2}, ruthenium-substituted phases are all semiconducting. They exhibit high thermoelectric power, with a maximum of 165 muV/K at 300 K for x=0.3. The Curie constant C and Seebeck coefficient S show a non-monotonic evolution as a function of ruthenium content, demonstrating a remarkable interplay between magnetic properties and thermoelectricity. The presence of ruthenium has a detrimental effect on water intercalation and superconductivity in this system. Applying to Ru-substituted phases the oxidative intercalation of water known to lead to superconductivity in the Na{sub x}CoO{sub 2} system yields a 2-water layer hydrate only for x=0.1, and this phase is not superconducting down to 2 K. - Graphical Abstract: Effect of ruthenium substitution on thermoelectric power in Na{sub 0.71}Co{sub 1-x}Ru{sub x}O{sub 2} (left) and on low-temperature ac susceptibility in hydrated derivative (right).

Strobel, Pierre, E-mail: pierre.strobel@grenoble.cnrs.f [Institut Neel, CNRS, and Universite Joseph Fourier, B.P. 166, 38042 Grenoble, Cedex 9 (France); Muguerra, Herve [Institut Neel, CNRS, and Universite Joseph Fourier, B.P. 166, 38042 Grenoble, Cedex 9 (France); Hebert, Sylvie [CRISMAT (UMR CNRS 6508), ENSI-Caen, F-14050 Caen Cedex (France); Pachoud, Elise [Institut Neel, CNRS, and Universite Joseph Fourier, B.P. 166, 38042 Grenoble, Cedex 9 (France); CRISMAT (UMR CNRS 6508), ENSI-Caen, F-14050 Caen Cedex (France); Colin, Claire [Institut Neel, CNRS, and Universite Joseph Fourier, B.P. 166, 38042 Grenoble, Cedex 9 (France); Julien, Marc-Henri [Laboratoire de Spectrometrie Physique, UMR CNRS 5588 and Universite Joseph Fourier, 38402 Saint Martin d'Heres (France)

2009-07-15

248

Temperature gradient measurements by using thermoelectric effect in CNTs-silicone adhesive composite.  

PubMed

This work presents the fabrication and investigation of thermoelectric cells based on composite of carbon nanotubes (CNT) and silicone adhesive. The composite contains CNT and silicon adhesive 1?1 by weight. The current-voltage characteristics and dependences of voltage, current and Seebeck coefficient on the temperature gradient of cell were studied. It was observed that with increase in temperature gradient the open circuit voltage, short circuit current and the Seebeck coefficient of the cells increase. Approximately 7 times increase in temperature gradient increases the open circuit voltage and short circuit current up to 40 and 5 times, respectively. The simulation of experimental results is also carried out; the simulated results are well matched with experimental results. PMID:24748375

Chani, Muhammad Tariq Saeed; Karimov, Kh S; Asiri, Abdullah M; Ahmed, Nisar; Bashir, Muhammad Mehran; Khan, Sher Bahadar; Rub, Malik Abdul; Azum, Naved

2014-01-01

249

Micro-thermoelectric cooler: interfacial effects on thermal and electrical transport  

Microsoft Academic Search

The flows of heat and electricity in a column-type micro-thermoelectric cooler are analyzed by modeling the various interfacial resistances. Electron (barrier tunneling) and phonon (diffuse mismatch) boundary resistances at the thermoelectric\\/metal interface, and thermal non-equilibrium between electrons and phonons adjacent to this interface (cooling length), increase the thermal conduction resistance and decrease the Seebeck coefficient of the thermoelectric elements. These

Luciana W. da Silva; Massoud Kaviany

2004-01-01

250

Doppler Effect  

NSDL National Science Digital Library

This site offers information on the classical doppler effect, the relativistic doppler effect, aberration, and the transverse doppler effect. It also discusses wave fronts, first-order and second order effect, light-time correction, Galilean transformation, and parallax.

Calvert, J. B.

2010-08-19

251

Effect of boundary scattering on the thermal conductivity of TiNiSn-based half-Heusler alloys  

Microsoft Academic Search

TiNiSn-based half-Heusler alloys have been of significant interest for their potential as thermoelectric materials. They exhibit promising electronic transport properties as revealed through high Seebeck coefficient and moderate electrical resistivity values. The chief disadvantage of these materials is a comparatively high lattice thermal conductivity. Attempts to ``tune'' the lattice thermal conductivity (kappaL) in these materials have led to the comparison

S. Bhattacharya; M. J. Skove; M. Russell; T. M. Tritt; Y. Xia; V. Ponnambalam; S. J. Poon; N. Thadhani

2008-01-01

252

Effect of Heat Treatment on the Thermoelectric Properties of Bismuth-Antimony-Telluride Prepared by Mechanical Deformation and Mechanical Alloying  

NASA Astrophysics Data System (ADS)

In this work, p-type 20%Bi2Te3-80%Sb2Te3 bulk thermoelectric (TE) materials were prepared by mechanical deformation (MD) of pre-melted ingot and by mechanical alloying (MA) of elemental Bi, Sb, and Te granules followed by cold-pressing. The dependence on annealing time of changes of microstructure and TE properties of the prepared samples, including Seebeck coefficient, electrical resistivity, thermal conductivity, and figure-of-merit, was investigated. For both samples, saturation of the Seebeck coefficient and electrical resistivity were observed after annealing for 1 h at 380°C. It is suggested that energy stored in samples prepared by both MA and MD facilitated their recrystallization within short annealing times. The 20%Bi2Te3-80%Sb2Te3 sample prepared by MA followed by heat treatment had higher a Seebeck coefficient and electrical resistivity than specimens fabricated by MD. Maximum figures-of-merit of 3.00 × 10-3/K and 2.85 × 10-3/K were achieved for samples prepared by MA and MD, respectively.

Lee, Deuk-Hee; Lee, Jae-Uk; Jung, Sung-Jin; Baek, Seung-Hyub; Kim, Ju-Heon; Kim, Dong-Ik; Hyun, Dow-Bin; Kim, Jin-Sang

2014-06-01

253

High temperature experimental characterization of microscale thermoelectric effects  

NASA Astrophysics Data System (ADS)

Thermoelectric devices have been employed for many years as a reliable energy conversion technology for applications ranging from the cooling of sensors or charge coupled devices to the direct conversion of heat into electricity for remote power generation. However, its relatively low conversion efficiency has limited the implementation of thermoelectric materials for large scale cooling and waste heat recovery applications. Recent advances in semiconductor growth technology have enabled the precise and selective engineering of material properties to improve the thermoelectric figure of merit and thus the efficiency of thermoelectric devices. Accurate characterization at the intended operational temperature of novel thermoelectric materials is a crucial component of the optimization process in order to fundamentally understand material behavior and evaluate performance. The objective of this work is to provide the tools necessary to characterize high efficiency bulk and thin-film materials for thermoelectric energy conversion. The techniques developed here are not bound to specific material or devices, but can be generalized to any material system. Thermoreflectance imaging microscopy has proven to be invaluable for device thermometry owing to its high spatial and temporal resolutions. It has been utilized in this work to create two-dimensional temperature profiles of thermoelectric devices during operation used for performance analysis of novel materials, identification of defects, and visualization of high speed transients in a high-temperature imaging thermostat. We report the development of a high temperature imaging thermostat capable of high speed transient thermoelectric characterization. In addition, we present a noninvasive method for thermoreflectance coefficient calibration ideally suited for vacuum and thus high temperature employment. This is the first analysis of the thermoreflectance coefficient of commonly used metals at high-temperatures. High temperature vacuum thermostats are designed and fabricated with optical imaging capability and interchangeable measurement stages for various electrical and thermoelectric characterizations. We demonstrate the simultaneous measurement of in-plane electrical conductivity and Seebeck coefficient of thin-film or bulk thermoelectric materials. Furthermore, we utilize high-speed circuitry to implement the transient Harman technique and directly determine the cross-plane figure of merit of thin film thermoelectric materials at high temperatures. Transient measurements on thin film devices are subject to complications from the growth substrate, non-ideal contacts and other detrimental thermal and electrical effects. A strategy is presented for optimizing device geometry to mitigate the impact of these parasitics. This design enabled us to determine the cross-plane thermoelectric material properties in a single high temperature measurement of a 25mum InGaAs thin film with embedded ErAs (0.2%) nanoparticles using the bipolar transient Harman technique in conjunction with thermoreflectance thermal imaging. This approach eliminates discrepancies and potential device degradation from the multiple measurements necessary to obtain individual material parameters. Finite element method simulations are used to analyze non-uniform current and temperature distributions over the device area and determine the three dimensional current path for accurate extraction of material properties from the thermal images. Results match with independent measurements of thermoelectric material properties for the same material composition, validating this approach. We apply high magnification thermoreflectance imaging to create temperature maps of vanadium dioxide nanobeams and examine electro-thermal energy conversion along the nanobeam length. The metal to insulator transition of strongly correlated materials is subject to strong lattice coupling which brings about the unique one-dimensional alignment of metal-insulator domains along nanobeams. Many studies have investigated the effects of stress o

Favaloro, Tela

254

Ballistic thermoelectric transport in structured nanowires  

NASA Astrophysics Data System (ADS)

Thermoelectric (TE) devices are solid-state energy converters that can be used for power generation through the Seebeck effect and TE cooling through the Peltier effect. Nanostructures give great opportunities to engineer TE energy conversion efficiency. In this work, we investigate TE transport properties in structured nanowires (NWs) in the ballistic transport regime, where the NWs are bent, kinked, stubbed and segmented like a superlattice nanowire using the Green’s function method and the Landauer-Büttiker formula. A large Seebeck coefficient is found when the transmission gap appears due to the quantum interference effect of electrons. The sign of the Seebeck coefficient can be controlled by the geometries of these structured NWs. This finding is helpful for the design of nanoscale TE devices, such as thermocouple, with the same type of material doping rather than those comprised of n-type and p-type materials.

Wang, Biao; Zhou, Jun; Yang, Ronggui; Li, Baowen

2014-06-01

255

Synthesis and thermoelectric properties of RuO{sub 2} nanorods  

SciTech Connect

We have explored the effect of the O/Ru ratio on the morphology and the Seebeck coefficient of RuO{sub 2} nanorods (space group P4{sub 2}/mnm) synthesized by reactive sputtering. At an O/Ru ratio of 1.69, a faceted surface is observed, while nanorod formation occurs at O/Ru ratios of 2.03 and 2.24. Using classical molecular dynamics with the potential parameters derived in this work, we show that volatile species enable nanorod formation. Based on ab initio calculations, two effects of the nanorod formation on the Seebeck coefficient are observed: (i) increase due to additional states in the vicinity of the Fermi level and (ii) decrease due to oxygen point defects (volatile species). These two competing effects give rise to a moderate increase in the Seebeck coefficient upon nanorod formation.

Music, Denis; Basse, Felix H.-U.; Schneider, Jochen M. [Materials Chemistry, RWTH Aachen University, D-52056 Aachen (Germany); Hassdorf, Ralf [Institute of Materials Research, German Aerospace Centre (DLR), D-51147 Cologne (Germany)

2010-07-15

256

Spin density wave order and fluctuations in Mn3Si : A transport study  

NASA Astrophysics Data System (ADS)

We present a comprehensive transport investigation of the itinerant antiferromagnet Mn3Si which undergoes a spin density wave (SDW) order below TN˜21.3K. The electrical resistivity, the thermal conductivity, and the Hall, Seebeck, and Nernst effects exhibit pronounced anomalies at the SDW transition. At temperatures higher than TN our data provide strong evidence for a large fluctuation regime which extends up to ˜200K in the resistivity, the Seebeck effect, and the Nernst effect. From the comparison of our results with other prototype SDW materials, viz., LaFeAsO and chromium, we conclude that many of the observed features are of generic character.

Steckel, Frank; Rodan, Steven; Hermann, Regina; Blum, Christian G. F.; Wurmehl, Sabine; Büchner, Bernd; Hess, Christian

2014-10-01

257

Doppler Effect  

NSDL National Science Digital Library

Doppler effect followed from water waves to sound waves to light waves. Red shift of the universe is also explored. What is doppler effect? It is the change in frequency of a wave for an observer moving relative to the source of the wave. What does that mean? Watch this: moving doppler effect video What does the doppler effect look like in a stationary and moving object? dooppler effect views What does doppler effect have to do with stars and galaxies??? View the following ...

Clemons, Mrs.

2010-11-10

258

Doppler Effect  

NSDL National Science Digital Library

Doppler effect followed from water waves to sound waves to light waves. Red shift of the universe is also explored. What is doppler effect? It is the change in frequency of a wave for an observer moving relative to the source of the wave. What does that mean? Watch this: moving doppler effect video What does the doppler effect look like in a stationary and moving object? dooppler effect views What does doppler effect have to do with stars and galaxies??? View the following ...

Brown, Mrs.

2010-10-26

259

Low effective mass and carrier concentration optimization for high performance p-type Mg2(1-x)Li2xSi0.3Sn0.7 solid solutions.  

PubMed

Mg2Si1-xSnx solid solutions are promising thermoelectric materials for power generation applications in the 500-800 K range. Outstanding n-type forms of these solid solutions have been developed in the past few years with the thermoelectric figure of merit ZT as high as 1.4. Unfortunately, no comparable performance has been achieved so far with p-type forms of the structure. In this work, we use Li doping on Mg sites in an attempt to enhance and control the concentration of hole carriers. We show that Li as well as Ga is a far more effective p-type dopant in comparison to Na or K. With the increasing content of Li, the electrical conductivity rises rapidly on account of a significantly enhanced density of holes. While the Seebeck coefficient decreases concomitantly, the power factor retains robust values supported by a rather high mobility of holes. Theoretical calculations indicate that Mg2Si0.3Sn0.7 intrinsically possesses the almost convergent double valence band structure (the light and heavy band), and Li doping retains a low density of states (DOS) on the top of the valence band, contrary to the Ga doping at the sites of Si/Sn. Low temperature specific heat capacity studies attest to a low DOS effective mass in Li-doped samples and consequently their larger hole mobility. The overall effect is a large power factor of Li-doped solid solutions. Although the thermal conductivity increases as more Li is incorporated in the structure, the enhanced carrier density effectively shifts the onset of intrinsic excitations (bipolar effect) to higher temperatures, and the beneficial role of phonon Umklapp processes as the primary limiting factor to the lattice thermal conductivity is thus extended. The final outcome is the figure of merit ZT ? 0.5 at 750 K for x = 0.07. This represents a 30% improvement in the figure of merit of p-type Mg2Si1-xSnx solid solutions over the literature values. Hence, designing low DOS near Fermi level EF for given carrier pockets can serve as an effective approach to optimize the PF and thus ZT value. PMID:25178356

Zhang, Qiang; Cheng, Long; Liu, Wei; Zheng, Yun; Su, Xianli; Chi, Hang; Liu, Huijun; Yan, Yonggao; Tang, Xinfeng; Uher, Ctirad

2014-11-21

260

Greenhouse Effect  

NSDL National Science Digital Library

This activity is a greenhouse-effect-in-a-bottle experiment. The lesson includes readings from NEED.org and an inquiry lab measuring the effect of carbon dioxide and temperature change in an enclosed environment.

Connecticut Energy Education

261

Thermoelectric properties of Yb-filled CoSb3 skutterudites  

NASA Astrophysics Data System (ADS)

Yb-filled skutterudites Yb z Co4Sb12 (z = 0, 0.1, 0.2, 0.3, 0.4) were prepared by encapsulated melting and hot pressing. The filling effects of Yb on the transport and the thermoelectric properties of the skutterudites were examined. In the case of z ? 0.3, a secondary phase (YbSb2) was formed, indicating that the filling fraction limit of Yb was z = 0.2 - 0.3. The intrinsic CoSb3 had a high positive Seebeck coefficient, but Yb-filled CoSb3 exhibited a negative Seebeck coefficient. In the case of z ? 0.1, the maximum absolute value of the Seebeck coefficient was | -231| ?VK-1, and in the case of z ? 0.2, the absolute value of the Seebeck coefficient increased with increasing temperature. The electrical conductivity increased and the Seebeck coefficient decreased with increasing Yb filling content due to the increased carrier concentration. The thermal conductivity was reduced significantly by Yb filling, mainly due to a decrease in the lattice thermal conductivity. Also, the lattice thermal conductivity decreased with increasing Yb filling content, indicating that the phonon scattering was caused by the rattling of Yb fillers in the voids of the skutterudite structure. Yb0.2Co4Sb12 showed the highest figure of merit of 1.0 at 823 K.

Park, Kwan-Ho; Seo, Won-Seon; Shin, Dong-Kil; Kim, Il-Ho

2014-08-01

262

Anomalous enhancement of the thermoelectric power in gallium-doped p-(Bi{sub 1-x}Sb{sub x}){sub 2}Te{sub 3} single crystals  

SciTech Connect

The effect of gallium on the temperature dependences (5 K {<=} T {<=} 300 K) of Seebeck coefficient {alpha}, electrical conductivity {sigma}, thermal conductivity k, and thermoelectric efficiency Z of mixed p-(Bi{sub 0.5}Sb{sub 0.5}){sub 2}Te{sub 3} semiconductor single crystals is studied. The hole concentration decreases upon gallium doping; that is, gallium causes a donor effect. The Seebeck coefficient increases anomalously, i.e., much higher than it should be at the detected decrease in the hole concentration. This leads to an enhancement of the thermoelectric power. The observed changes in the Seebeck coefficient indicate a noticeable gallium-induced change in the density of states in the valence band.

Kulbachinskii, V. A., E-mail: kulb@mig.phys.msu.ru; Kytin, V. G.; Tarasov, P. M. [Moscow State University (Russian Federation)

2010-04-15

263

Thermoelectricity and disorder of FeCo/MgO/FeCo magnetic tunnel junctions  

NASA Astrophysics Data System (ADS)

We compute the thermoelectric transport parameterized by the Seebeck coefficient and thermal/electric conductance of random-alloy FeCo/MgO/FeCo(001) magnetic tunnel junctions (MTJs) from first principles using a generalized Landauer-Büttiker formalism. The thermopower is found to be typically smaller than those of Fe/MgO/Fe(001) MTJs. The (magneto-)Seebeck effect is sensitive to the details of the FeCo/MgO interfaces. Interfacial can greatly enhance the thermoelectric effects in MTJs. We also compute angular-dependent Seebeck coefficients that provide additional information about the transport physics. We report large deviations from the Wiedemann-Franz law at room temperature.

Wang, Shi-Zhuo; Xia, Ke; Bauer, Gerrit E. W.

2014-12-01

264

Photo-transport properties of Pb2CrO5 single crystals  

NASA Astrophysics Data System (ADS)

We report photo-thermoelectric transport phenomena in Pb2CrO5 single crystals. Without illumination, this material exhibits an insulating behavior characterized by an activation-type temperature variation of the electrical conductivity. The Seebeck coefficient contrastingly shows a crossover from high-temperature insulating to low-temperature metallic behavior, which is attributed to degenerate carriers in a donor level. We have found that under illumination, both the conductivity and the Seebeck coefficient increase in magnitude with increasing photon flux density in the degenerate-conduction regime. This result is difficult to understand within a simple photo-doping effect, which usually leads to a decrease in the Seebeck coefficient under illumination. The observed phenomenon is discussed in terms of a two-carrier contribution to the transport properties.

Mondal, P. S.; Okazaki, R.; Taniguchi, H.; Terasaki, I.

2014-11-01

265

Doppler Effect  

NSDL National Science Digital Library

In this activity, learners use a tuning fork to explore how the Doppler effect works. They strike the tuning fork to produce a sound, then observe as the tone changes as the fork is swung back and forth. Learners also explore applications of the Doppler effect in technology.

Cosi

2009-01-01

266

Gauging Effectiveness  

ERIC Educational Resources Information Center

Books by education experts and speakers at national professional conferences have inspired many school leaders to initiate professional learning communities (PLCs). Sustaining them effectively to raise student achievement is another matter. How can one know whether a PLC is moving toward a desired outcome? Measuring effectiveness requires an…

Foord, Kathleen A.; Haar, Jean M.

2012-01-01

267

Modern Thermocouple Experiment.  

ERIC Educational Resources Information Center

Describes a thermocouple circuit used to measure Joule heating as well as Peltier heating and cooling for a copper-Constantan metallic junction. Shows how the Seebeck effect from a thermocouple can monitor the temperature condition of a junction with regard to input power and Peltier effect. (Author/GA)

Chang, K. N.; And Others

1978-01-01

268

Thermoelectric Devices: Solid-State Refrigerators and Electrical Generators in the Classroom  

Microsoft Academic Search

Thermoelectric devices are solid-state devices that convert thermal energy from a temperature gradient into electrical energy (the Seebeck effect) or convert electrical energy into a temperature gradient (the Peltier effect). The first application is used most notably in spacecraft power generation systems (for example, in Voyager I and II) and in thermocouples for temperature measurement, while the second application is

Edmund J. Winder; Arthur B. Ellis; George C. Lisensky

1996-01-01

269

Tuning the Thermal Properties of Magnetic Tunnel Junctions  

E-print Network

study of this effect in MgO-based MTJs with spin-orbit coupling. We present theoretical calculations of the Tunneling Anisotropic Magneto-Seebeck effect using realistic band structures, and show that the thermal properties of MTJs are tunable via...

Amin, Vivek Pravin

2014-04-18

270

PHYSICAL REVIEW B 88, 085426 (2013) Nonlinear thermoelectric transport: A class of nanodevices for high efficiency  

E-print Network

I. INTRODUCTION Thermoelectric materials1 can convert unused waste heat to electricity (Seebeck effect) or use electricity for refrigeration (Peltier effect). A good thermoelectric material needs charge. As a result it has not yet been possible to find bulk thermoelectric materials efficient enough

Muttalib, Khandker

271

A study of piezoelectric properties of carbon fiber reinforced concrete and plain cement paste during dynamic loading  

Microsoft Academic Search

Carbon fiber reinforced concrete (CFRC) is an intrinsically smart material, which can be used to realize the self-monitoring of concrete structures based on its piezoresistance effect and the Seebeck effect. An experimental study was made to examine the piezoelectric properties of CFRC and plain cement paste. The results show that both CFRC and plain cement paste exhibit piezoelectric behavior, which

Mingqing Sun; Qingping Liu; Zhuoqiu Li; Yaozu Hu

2000-01-01

272

High thermoelectric figure of merit in nanocrystalline polyaniline at low temperatures  

NASA Astrophysics Data System (ADS)

Thermoelectric coolers with figure of merit (ZT) close to unity at low temperatures are the need of the hour with new advances in high temperature superconductors, superconducting microelectronic circuits, quantum computers, and photonics. Here, we demonstrate that the conducting polymer polyaniline (Pani) doped with camphor sulfonic acid synthesized in semi-crystalline nanostructures, possesses a giant Seebeck effect at low temperatures. The resulting enormously large Seebeck coefficient (up to 0.6 V/K) combined with an intrinsically low electrical conductivity and thermal conductivity give rise to a ZT = 0.77 at 45 K and ZT = 2.17 at 17 K.

Nath, Chandrani; Kumar, Ashok; Kuo, Yung-Kang; Okram, Gunadhor Singh

2014-09-01

273

Implications of nanostructuring on the thermoelectric properties in half-Heusler alloys  

NASA Astrophysics Data System (ADS)

High energy ball milled Zr0.25Hf0.75NiSn alloys subjected to spark plasma sintering show an enhanced thermoelectric figure of merit in comparison with its normal bulk material synthesized by arc-melting process. The enhancement is due to increase in Seebeck coefficient with simultaneous decrease in thermal conductivity which follows due to increase in the cell volume. Theoretical calculations find that volume expansion facilitates band narrowing effects leading to high Seebeck coefficient and that decreasing orbital overlap which results in weak bonding leads to dampening the phonon propagation in addition to the interface scattering of phonons from phase boundaries.

Bhardwaj, A.; Misra, D. K.; Pulikkotil, J. J.; Auluck, S.; Dhar, A.; Budhani, R. C.

2012-09-01

274

Psychopharmaceuticals: effects and side effects  

PubMed Central

Drugs which affect psychological behaviour are being used in vast amounts nowadays, with, in all too many cases, but scant regard for their exact uses or possible side effects. This article contains a clinical classification of these drugs, followed by an account of their principal side effects and the means of obviating them. PMID:14409889

Kline, Nathan S.

1959-01-01

275

Effective Teachers in Effective Schools.  

ERIC Educational Resources Information Center

While effective schools research has inspired new efforts toward improving education for all students, it is flawed by offering simplistic prescriptions based on correlational studies focusing on basic skills achievement. Effective school research and theory can be upgraded by a more careful definition of the goals of learning and a systematic…

Hathaway, Walter E.

276

Doppler Effect  

NSDL National Science Digital Library

- The Doppler Effect explains why we hear a sonic boom when an airplane flies faster than the speed of sound. - Applying the Doppler Effect is how we have Doppler Radar used to track weather. - The Doppler Effect can be applied to outerspace and it evidence that the universe is expanding. Sound is energy traveling through a medium. A medium can be a gas, liquid, or solid. Therefore sound can not travel in outerspace since it is a vacuum which means there is nothing not even air. Energy traveling through a medium or even a vacuum is considered a wave. ...

Mr. Leet

2008-03-16

277

The Effect of Structural Vacancies on the Thermoelectric Properties of (Cu2Te)1-x(Ga2Te3)x  

SciTech Connect

We have studied the effects of structural vacancies on the thermoelectric properties of the ternary compounds (Cu2Te)1-x(Ga2Te3)x (x = 0.5, 0.55, 0.571, 0.6, 0.625, 0.667 and 0.75), which are solid solutions found in the pseudo-binary phase diagram for Cu2Te and Ga2Te3. This system possesses tunable structural vacancy concentrations. The x= 0.5 phase, CuGaTe2, is nominally devoid of structural vacancies, while the rest of the compounds contain varying amounts of these features, and the volume density of vacancies increases with Ga2Te3 content. The sample with x = 0.5, 0.55, 0.571, 0.6, 0.625 crystallize in the chalcopyrite structure while the x = 0.667 and 0.75 adopt the Ga2Te3 defect zinc blende structure. Strong scattering of heat carrying phonons by structural defects, leads to the reduction of thermal conductivity, which is beneficial to the thermoelectric performance of materials. On the other hand, these defects also scatter charge carriers and reduce the electrical conductivity. All the samples investigated are p-type semiconductors as inferred by the signs of their respective Hall (RH) and Seebeck (S) coefficients. The structural vacancies were found to scatter phonons strongly, while a combination of increased carrier concentration, and vacancies decreases the Hall mobility ( H), degrading the overall thermoelectric performance. The room temperature H drops from 90 cm2/V s for CuGaTe2 to 13 cm2/V s in Cu9Ga11Te21 and 4.6 cm2/V s in CuGa3Te5. The low temperature thermal conductivity decreases significantly with higher Ga2Te3 concentrations (higher vacancy concentration) due to increased point defect scattering which dominate thermal resistance terms. At high temperatures, the dependence of thermal conductivity on the Ga2Te3 content is less significant. The presence of strong Umklapp scattering leads to low thermal conductivity at high temperatures for all samples investigated. The highest ZT among the samples in this study was found for the defect-free CuGaTe2 with ZT ~ 1.0 at 840K.

Ye, Zuxin [GM Research and Development Center; Cho, Jung Y [GM R& D and Planning, Warren, Michigan; Tessema, Misle [GM Research and Development Center; Salvador, James R. [GM R& D and Planning, Warren, Michigan; Waldo, Richard [GM R& D and Planning, Warren, Michigan; Wang, Hsin [ORNL; Cai, Wei [ORNL

2013-01-01

278

Doppler Effect  

NSDL National Science Digital Library

Control the velocity of two sound sources in which the wave crests are visually represented. As the sound sources move, interference patterns and evidence of the Doppler effect can be observed and measured.

2007-12-12

279

Health Effects  

MedlinePLUS

... Chapter . Additional information regarding the health effects of climate change and references to supporting literature can be found ... http://nca2014.globalchange.gov/report/sectors/human-health . Climate change, together with other natural and human-made health ...

280

Seismomagnetic effects  

NASA Astrophysics Data System (ADS)

Local changes in the earth's magnetic field that are associated with active faults have long been viewed as offering a potential method of analyzing earthquakes. Considerable efforts have been made to determine the effects theoretically and, in the field, to develop a sensitive method of identifying characteristic stress patterns. In particular, if related magnetic changes can be identified before an earthquake, the so-called seismomagnetic effect could be useful in earthquake prediction. After several years of observing magnetic changes whose magnitudes seem to have been constantly reevaluated in the light of more sensitive measurements, Hao, Hastie, and Stacey (Physics of Earth and Planetary Interiors, 28, 129, 1982) recently examined the theory and concluded that actual effects are probably a lot weaker than had been previously thought.

Bell, Peter M.

281

Ripple Effects  

E-print Network

policies and practices might have on producers? incomes and water savings, as well as the ripple effects on the regional economy. Drs. Steve Amosson of Texas Cooperative Extension in Amarillo, Lal K. Almas of West Texas A&M University, Jeff Peterson...-region and in particular crop production costs. Finally, they input the initial effects on farmers? incomes gained from the opti- mization models into the socio-economic modeling program. The results give an idea of what specific policies or technological advances...

Wythe, Kathy

2006-01-01

282

Slingshot Effect  

NSDL National Science Digital Library

This web page demonstrates the slingshot effect through a Flash simulation. The user places an object at some distance from Jupiter, sets up its initial velocity, then choose the appropriate time to lunch it. Once the simulation begins, the path of the projectile and its speed are shown.

Fowler, Michael; Ching, Jacquie H.

2008-09-20

283

Energy-Harvesting Thermoelectric Sensing for Unobtrusive Water and Appliance Metering  

E-print Network

Energy-Harvesting Thermoelectric Sensing for Unobtrusive Water and Appliance Metering Bradford that meters using the same thermoelectric generator with which it powers itself. In short, the rate at which be harvested with a thermoelectric generator (TEG) to power a sensor node. TEGs utilize the Seebeck effect

Dutta, Prabal

284

System Effectiveness  

SciTech Connect

An effective risk assessment system is needed to address the threat posed by an active or passive insider who, acting alone or in collusion, could attempt diversion or theft of nuclear material. It is critical that a nuclear facility conduct a thorough self-assessment of the material protection, control, and accountability (MPC&A) system to evaluate system effectiveness. Self-assessment involves vulnerability analysis and performance testing of the MPC&A system. The process should lead to confirmation that mitigating features of the system effectively minimize the threat, or it could lead to the conclusion that system improvements or upgrades are necessary to achieve acceptable protection against the threat. Analysis of the MPC&A system is necessary to understand the limits and vulnerabilities of the system to internal threats. Self-assessment helps the facility be prepared to respond to internal threats and reduce the risk of theft or diversion of nuclear material. MSET is a self-assessment or inspection tool utilizing probabilistic risk assessment (PRA) methodology to calculate the system effectiveness of a nuclear facility's MPC&A system. MSET analyzes the effectiveness of an MPC&A system based on defined performance metrics for MPC&A functions based on U.S. and international best practices and regulations. A facility's MC&A system can be evaluated at a point in time and reevaluated after upgrades are implemented or after other system changes occur. The total system or specific subareas within the system can be evaluated. Areas of potential performance improvement or system upgrade can be assessed to determine where the most beneficial and cost-effective improvements should be made. Analyses of risk importance factors show that sustainability is essential for optimal performance. The analyses reveal where performance degradation has the greatest detrimental impact on total system risk and where performance improvements have the greatest reduction in system risk. The risk importance factors show the amount of risk reduction achievable with potential upgrades and the amount of risk reduction actually achieved after upgrades are completed. Applying the risk assessment tool gives support to budget prioritization by showing where budget support levels must be sustained for MC&A functions most important to risk. Results of the risk assessment are also useful in supporting funding justifications for system improvements that significantly reduce system risk.

Powell, Danny H [ORNL] [ORNL; Elwood Jr, Robert H [ORNL] [ORNL

2011-01-01

285

Blazhko Effect  

NASA Technical Reports Server (NTRS)

The cause of the Blazhko effect, the long-term modulation of the light and radial velocity curves of some RR Lyr stars, is still not understood. The observational characteristics of the Blazhko effect are discussed. Some preliminary results are presented from two recent campaigns to observe RR Lyr, using the International Ultraviolet Explorer along with ground-based spectroscopy and photometry, throughout a pulsation cycle, at a variety of Blazhko phases. A set of ultraviolet light curves have been generated from low dispersion IUE spectra. In addition, the (visual) light curves from IUE's Fine Error Sensor are analyzed using the Fourier decomposition technique. The values of the parameters Psi(sub 21) and R(sub 21) at different Blazhko phases of RR Lyr span the range of values found for non-Blazhko variables of similar period.

Teays, Terry

1996-01-01

286

1-4244-0154-2/06/$20.00 2006 IEEE 232 22nd IEEE SEMI-THERM Symposium Optimization of Doping Concentration for Three-Dimensional Bulk Silicon Microrefrigerators  

E-print Network

, hot spots, on-chip thermal management, doping concentration, Seebeck coefficient, electrical the expression of, S: Seebeck coefficient; , electrical conductivity; , thermal conductivity. The difficulty in increasing ZT lies in the fact that Seebeck coefficient (S), electrical conductivity

287

THERMOELECTRIC PROPERTIES OF ULTRASCALED SILICON NANOWIRES Edwin Bosco Ramayya  

E-print Network

Thermal Conductivity . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 3.5 The Seebeck Coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 3.5.1 Electronic Seebeck Coefficient . . . . . . . . . . . . . . . . . . . . . . . . 61 3.5.2 Phononic Seebeck Coefficient : Phonon Drag . . . . . . . . . . . . . . . . 61 3.6 ZT Dependence

Knezevic, Irena

288

Simultaneous Determination of Conductance and Thermopower of Single Molecule Junctions  

E-print Network

molecular orbital (LUMO), respectively. We find that the Seebeck coefficient is negative for pyridine the accessible temperature gradients (Seebeck coefficient on temperature. From histograms of thousands of junctions, we use the most probable Seebeck

Venkataraman, Latha

289

Quantum Simulation of Si/Ge Nanostructured Thermoelectrics Introduction  

E-print Network

thermoelectric devices. · Thermoelectric Figure of Merit · SLs' have limited Seebeck performance for more than 4 Seebeck than homogeneous Si device · Optimization of NCC thermoelectric devices is possible · Seebeck

Walker, D. Greg

290

A nonequilibrium Green's function study of thermoelectric properties in single-walled carbon nanotubes  

E-print Network

of enhanced Seebeck coefficient. ZT is smaller in the armchair SWCNT, where Seebeck coefficient is small due conductance, S is the Seebeck coefficient or thermopower , and is the thermal conductance. Higher value of ZT

Li, Baowen

291

Atomic-level control of the thermoelectric properties in polytypoid nanowires Sean C. Andrews,ab  

E-print Network

the Seebeck coefficient, electrical conductivity, absolute temperature, and thermal conductivity, respectively, limiting the efficiency.2 Specifically, the Seebeck coefficient's inverse depen- dence on carrier to two factors: electronic band structure changes (increasing the Seebeck coef- ficient) and enhanced

Yang, Peidong

292

Compton Effect  

NSDL National Science Digital Library

The Compton Effect model simulates the the scattering of light off of an electron, the Compton effect. Compton used the idea that light behaves like a particle to explain light-electron (photon-electron) scattering. He used the relation for the energy and momentum of the photon and the relativistic expression for the energy of the electron, and applied relativistic energy and momentum conservation for the collision. The wavelength shift of the light depend on the angle of the scattered photon (and the electron). By changing the scattering angle in the simulation, the angle of the scattered photon changes according to Compton's equation. The panel on the left shows the experimental set up, while the panel on the right shows the resulting photon wavelength from the scattering. In a typical Compton experiment, light is scattered off of the electrons in an atom, and there is little scattering due to the more tightly held electrons while there is more scattering due to the less tightly held electrons. This is what is responsible for the two peak distribution shown. The Compton Effect model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_qm_compton.jar file will run the program if Java is installed.

Palop, Jose I.

2010-12-12

293

Piezoelectric Effect  

NSDL National Science Digital Library

In this activity, by the Concord Consortium's Molecular Literacy project, students explore the piezoelectric effect, which is the conversion between electricity and mechanical motion. The model used in this activity shows this conversion and users can manipulate the model to change the voltage and observe changes to a crystal. The activity itself is a java-based interactive resource built upon the free, open source Molecular Workbench software. In these activities, students are allowed to explore at their own pace in a digital environment full of demonstrations, illustrations, and models they can manipulate. In addition to the activity, visitors will find an overview of the activity and central and key concepts.

2008-10-23

294

Erosion Effects  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site]

The impact crater in this THEMIS image is a model illustration to the effects of erosion on Mars. The degraded crater rim and several landslides observed in crater walls is evidence to the mass wasting of materials. Layering in crater walls also suggests the presence of materials that erode at varying rates.

Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

Image information: VIS instrument. Latitude 31.6, Longitude 44.3 East (315.7 West). 19 meter/pixel resolution.

2003-01-01

295

University of California Year 2006 Paper 2242  

E-print Network

the quantum mechanical electron transmission show that the Seebeck coefficient can be in- creased the quantum mechanical electron transmission show that the Seebeck coefficient can be increased significantly

296

Study effectively.  

PubMed

As a busy healthcare practitioner with a desire to maintain and update professional skills and knowledge, perhaps the study skills you acquired as an undergraduate may need to be updated and refined too. Issues of time management take on a different meaning with the increased pressures of juggling a busy career, home life and continuing professional development. As an undergraduate, your focus was very much on learning the volume of material that was delivered in the medical curriculum but was the idea of learning how to learn ever considered? This article is aimed at identifying some of the strategies that might be helpful in enabling you to make the most effective use of the time available to you for study and thereby ensuring that your learning opportunities are maximised. PMID:19583907

Pugsley, Lesley

2009-05-01

297

Effect of TeI 4 content on the thermoelectric properties of n-type Bi–Te–Se crystals prepared by zone melting  

Microsoft Academic Search

n-Type (Bi2Te3)0.93(Bi2Se3)0.07 thermoelectric materials doped with various content of TeI4 (0, 0.05, 0.10, 0.13, and 0.15wt.%) have been fabricated through the zone melting method. Electrical conductivity (?), Seebeck coefficient (?) and thermal conductivity (?) were measured along the crystal growth direction in the temperature range of 300–500K. The influence of the variations of TeI4 content on thermoelectric properties was studied.

Jun Jiang; Lidong Chen; Qin Yao; Shengqiang Bai; Qun Wang

2005-01-01

298

Effect of substitution for Ni by Co and\\/or Cu on the thermoelectric properties of half-Heusler ZrNiSn  

Microsoft Academic Search

We have synthesized the half-Heusler ZrNiSn alloys where the Ni is partially substituted by Co and\\/or Cu. Such substitution much affects the thermoelectric properties of ZrNiSn by changing the valence electron count (VEC) of the material. The behaviors in the Seebeck coefficient and electrical resistivity for ZrNi1?xCoxSn or ZrNi1?yCuySn system can be understood as the result of the increase in

S. Katsuyama; H. Matsushima; M. Ito

2004-01-01

299

Thermoelectric properties and electronic structure of substituted Heusler compounds: NiTi0.3-xScxZr0.35Hf0.35Sn  

NASA Astrophysics Data System (ADS)

The effect of Ti substitution by Sc on the thermoelectric properties of the Heusler compounds NiTi0.3-xScxZr0.35Hf0.35Sn (where 0Seebeck coefficient, and thermal conductivity. A reduction of the thermal conductivity by a factor of 2 was obtained by substitution of Ti by Sc. The pure compound NiTi0.3Zr0.35Hf0.35Sn showed n-type conductivity with a Seebeck coefficient of -288 ?V/K at 350 K, while under Sc substitution the system switched to p-type behavior. A maximum Seebeck coefficient of +230 ?V/K (350 K) was obtained by 4% Sc substitution, which is the highest value for p-type thermoelectric compounds based on Heusler alloys. The electronic structure was studied by photoelectron spectroscopy excited by hard x-ray synchrotron radiation. Massive in gap states are observed for the parent compound. This proves that the electronic states close to the Fermi energy play a key role on the behavior of the transport properties. Especially, they are responsible for the high, negative Seebeck coefficient of the parent compound.

Ouardi, Siham; Fecher, Gerhard H.; Balke, Benjamin; Schwall, Michael; Kozina, Xeniya; Stryganyuk, Gregory; Felser, Claudia; Ikenaga, Eiji; Yamashita, Yoshiyuki; Ueda, Shigenori; Kobayashi, Keisuke

2010-12-01

300

Effectiveness Update: Academic Programs Transfer Effectiveness Measures.  

ERIC Educational Resources Information Center

This document is a compilation of reports that outline various institutional effectiveness measures and present assessment results and data at Austin Community College (ACC) (Texas). The College Effectiveness Update reports include Academic Programs Transfer Effectiveness Measures, Workforce Education Effectiveness Measures, Developmental…

Austin Community Coll., TX.

301

Effect of hydrostatic pressure on the thermoelectric properties of Bi2Te3  

NASA Astrophysics Data System (ADS)

We use first-principles calculations to understand the behavior of the Seebeck coefficient (S ) in Bi2Te3 as a function of isotropic pressure. We perform calculations up to 5 GPa using density functional theory and with thermoelectric properties extracted using Boltzmann transport equations. We find that with the increase in pressure the system becomes more metallic, in agreement with previous calculations on Sb2Te3 . For p -type doping the overall behavior is a decrease in S with an increase in pressure. At small values of hole doping (p =1.8 ×1018cm-3 ), we obtain an anomalous variation of S under 2 GPa, which is an indication of the electronic topological transition. For n -type doping, S slightly increases with pressure.

Ibarra-Hernández, Wilfredo; Verstraete, Matthieu J.; Raty, Jean-Yves

2014-12-01

302

Fizeau effect for neutrons  

SciTech Connect

It is shown that local-field effects in the neutron optical potential produce a nonvanishing Fizeau effect and that the magnitude of the effect is particularly large for cold neutrons with wavelengths lambda> or approx. =13 A. .AE

Sears, V.F.

1985-10-01

303

RAPID COMMUNICATIONS PHYSICAL REVIEW B 90, 121403(R) (2014)  

E-print Network

. Generally, spin Seebeck coefficient (Ss) is shown to increase linearly with the spin gap. Specifically = S - S is spin Seebeck coefficient, G (S ) is the spin-dependent electric conductance (Seebeck coefficient Seebeck coefficient is found to increase linearly with the increasing spin gap. Besides this key spin

Simons, Jack

304

PHYSICAL REVIEW B 85, 085117 (2012) Spin thermopower in interacting quantum dots  

E-print Network

, but of the same order of magnitude, the spin-Seebeck coefficient is large, of the order of kB /|e|. Via a mapping, we relate the spin-Seebeck coefficient to the charge-Seebeck coefficient of a negative-U quantum dot, the dependence of the spin-Seebeck coefficient on the temperature and the magnetic field is explained in terms

Ramsak, Anton

305

A composite high-pressure cell with sintered diamond insets for study of thermoelectric and thermomagnetic properties in a range up to 30 GPa: Application to Pr and PbTe  

Microsoft Academic Search

A composite high-pressure cell with the sintered diamond insets is reported to be an effective tool for investigation of transport properties of solids under pressure as high as ?30GPa. The temperature distribution inside the cell was calculated. Using this cell, the pressure-driven phase transitions in praseodymium (Pr) have been studied by the thermopower technique (Seebeck effect). The results have shown

Vladimir V. Shchennikov; Sergey V. Ovsyannikov; Anatoly V. Bazhenov

2008-01-01

306

LETTER TO THE EDITOR: Observation of a new high-pressure semimetal phase of GaAs from pressure dependence of the thermopower  

Microsoft Academic Search

We report the use of the thermopower technique (Seebeck effect) as an effective tool for discovery of 'hidden' (for standard techniques, like x-ray, synchrotron, Raman, etc) phases of substances. Applying the thermopower technique to a set of GaAs single crystals pressurized in a sintered diamond anvil cell, we found an unknown high-pressure semimetal phase with the electron type of conductivity,

Sergey V. Ovsyannikov; Vladimir V. Shchennikov

2006-01-01

307

Small-polaron versus band conduction in some transition-metal oxides  

Microsoft Academic Search

In this paper an attempt is made to establish the nature of free charge carriers and of charge carriers bound to centres in p-type NiO, CoO and MnO and in n-type MnO and ?-Fe2O3.For free charge carriers, d.c. conductivity, Seebeck coefficient and Hall effect are considered. Effects arising from inhomogeneous conduction and impurity conduction are discussed. Impurity conduction appears to

A. J. Bosman; H. J. van Daal

1970-01-01

308

Quantum and classical thermoelectric transport in quantum dot nanocomposites  

Microsoft Academic Search

Quantum dot nanocomposites are potentially high-efficiency thermoelectric materials, which could outperform superlattices and random nanocomposites in terms of manufacturing cost-effectiveness and material properties because of the reduction of thermal conductivity due to the phonon-interface scattering, the enhancement of Seebeck coefficient due to the formation of minibands, and the enhancement of electrical conductivity due to the phonon-bottleneck effect in electron-phonon scattering

Jun Zhou; Ronggui Yang

2011-01-01

309

Sokolov Effect Conclusions  

E-print Network

Dysprosium Nathan Leefer #12;Background Sokolov Effect Conclusions Outline 1 Background Neutral Hydrogen Stark Effect Hydrogen Atom Interferometer 2 Sokolov Effect Pamir Broken Theories Summary Dysprosium 3 Sokolov Effect Conclusions Pamir Broken Theories Summary Dysprosium Measurement of Lamb Shift Pamir Nathan

Budker, Dmitry

310

On Effect Size  

Microsoft Academic Search

The call for researchers to report and interpret effect sizes and their corresponding confidence intervals has never been stronger. However, there is confusion in the literature on the definition of effect size, and consequently the term is used inconsistently. We propose a definition for effect size, discuss 3 facets of effect size (dimension, measure\\/index, and value), outline 10 corollaries that

Ken Kelley; Kristopher J. Preacher

2012-01-01

311

Dimensional Analysis of Thermoelectric Modules Under Constant Heat Flux  

NASA Astrophysics Data System (ADS)

Thermoelectric power generation is examined in the case of radiative heating. A constant heat flux is assumed in addition to consideration of the Seebeck effect, Peltier effect, and Joule heating with temperature-dependent material properties. Numerical evaluations are conducted using a combination of the finite-volume method and an original simultaneous solver for the heat transfer, thermoelectric, and electric transportation phenomena. Comparison with experimental results shows that the new solver could work well in the numerical calculations. The calculations predict that the Seebeck effect becomes larger for longer thermoelectric elements because of the larger temperature difference. The heat transfer to the cold surface is critical to determine the junction temperatures under a constant heat flux from the hot surface. The negative contribution from Peltier cooling and heating can be minimized when the current is smaller for longer elements. Therefore, a thicker TE module can generate more electric power even under a constant heat flux.

Suzuki, Ryosuke O.; Fujisaka, Takeyuki; Ito, Keita O.; Meng, Xiangning; Sui, Hong-Tao

2015-01-01

312

A random effects model for effect sizes  

Microsoft Academic Search

Recent interest in quantitative research synthesis has led to the development of rigorous statistical theory for some of the methods used in meta-analysis. Statistical theory proposed previously has stressed the estimation of fixed but unknown population effect sizes (standardized mean differences). Theoretical considerations often suggest that treatment effects are not fixed but vary across different implementations of a treatment. The

Larry V. Hedges

1983-01-01

313

Effect of antisite defects on band structure and thermoelectric performance of ZrNiSn half-Heusler alloys  

NASA Astrophysics Data System (ADS)

Band structures for ZrNiSn with Zr/Sn antisite defects are calculated with ab initio methods. Antisite defects shrink the band gap and enhance the density of states slope near the Fermi level, which are favorable to electrical transport properties for intrinsic semiconductors. The degree of Zr/Sn antisite defects are controlled by annealing time experimentally, and measurements show low electrical resistivity and high Seebeck coefficient for unannealed ZrNiSn, which benefits from the modified electronic structure caused by antisite defects. The maximum ZT is 0.64 at 800 K for unannealed ZrNiSn, which is the highest value for ZrNiSn systems without exterior doping.

Qiu, Pengfei; Yang, Jiong; Huang, Xiangyang; Chen, Xihong; Chen, Lidong

2010-04-01

314

Effect of sintering in ball-milled K2Bi8Se13 thermoelectric nano-composites  

NASA Astrophysics Data System (ADS)

K2Bi8Se13 has many attractive features for thermoelectric applications. Recently, K2Bi8Se13-based nanocomposite materials, consisting of nano-crystalline, micro-crystalline and amorphous phases, have been fabricated based on powder technology techniques. The Seebeck coefficient has been enhanced while the thermal conductivity has been decreased presenting, thus, interesting behavior. The behavior of the materials under heat treatment conditions is now of interest, as the application of sintering process is necessary for the development of thermoelectric modules. In this work, the crystallization of the K2Bi8Se13-based nano-composites is studied using Differential Scanning Calorimetry. The results show that crystallization follows a multiple-step process with different activation energies. The thermoelectric properties are also discussed in the range that crystallization occurs.

Hatzikraniotis, E.; Ioannou, M.; Chrissafis, K.; Chung, D. Y.; Paraskevopoulos, K. M.; Kyratsi, Th.

2012-09-01

315

Regulation with placebo effects.  

PubMed

A growing scientific literature supports the existence of placebo effects from a wide range of health interventions and for a range of medical conditions. This Article reviews this literature, examines the implications for law and policy, and suggests future areas for research on placebo effects. In particular, it makes the case for altering the drug approval process to account for, if not credit, placebo effects. It recommends that evidence of placebo effects be permitted as a defense in cases alleging violations of informed consent or false advertising. Finally, it finds that tort law already has doctrines such as joint and several liability to account for placebo effects. Future research on placebo effects should focus on whether awareness of placebo effects can disable these effects and whether subjects can control their own placebo effects. PMID:19353835

Malani, Anup

2008-12-01

316

Kite Pseudo Effect Algebras  

NASA Astrophysics Data System (ADS)

We define a new class of pseudo effect algebras, called kite pseudo effect algebras, which is connected with partially ordered groups not necessarily with strong unit. In such a case, starting even with an Abelian po-group, we can obtain a noncommutative pseudo effect algebra. We show how such kite pseudo effect algebras are tied with different types of the Riesz Decomposition Properties. Kites are so-called perfect pseudo effect algebras, and we define conditions when kite pseudo effect algebras have the least non-trivial normal ideal.

Dvure?enskij, Anatolij

2013-11-01

317

Peltier Cooling and Onsager Reciprocity in Ferromagnetic Thin Films  

NASA Astrophysics Data System (ADS)

We present direct measurements of the Peltier effect as a function of temperature from 77 to 325 K in Ni, Ni80Fe20, and Fe thin films made using a suspended Si-N membrane structure. Measurement of the Seebeck effect in the same films allows us to directly test predictions of Onsager reciprocity between the Peltier and Seebeck effects. The Peltier coefficient ? is negative for both Ni and Ni80Fe20 films and positive for the Fe film. The Fe film also exhibits a peak associated with the magnon drag Peltier effect. The observation of magnon drag in the Fe film verifies that the coupling between the phonon, magnon, and electron systems in the film is the same whether driven by heat current or charge current. The excellent agreement between ? values predicted using the experimentally determined Seebeck coefficient for these films and measured values offers direct experimental confirmation of the Onsager reciprocity between these thermoelectric effects in ferromagnetic thin films near room temperature.

Avery, A. D.; Zink, B. L.

2013-09-01

318

Kondo behavior in superconducting NpPd5Al2  

NASA Astrophysics Data System (ADS)

The unconventional superconductor NpPd5Al2 , crystallizing in the tetragonal ZrNi2Al5 -type structure, was studied by means of N237p Mössbauer spectroscopy, heat capacity, electrical resistivity, magnetoresistivity, and thermoelectric power measurements. The superconductivity is clearly observed below Tc=5K . The Mössbauer studies confirm the absence of ordered magnetic Np moments in both the superconducting and normal phases. The value of the isomer shift suggests that the 5f -electron count is close to n5f=4 , in agreement with electron band structure calculations. Above Tc the electronic specific heat, the magnetic contribution to the electrical resistivity, the magnetoresistivity, and the Seebeck coefficient are governed by the interplay of Kondo and crystal-field effects. The Seebeck coefficient, negative in the whole temperature range, indicates electronlike conductivity. This perfectly agrees with the Hall effect data as well as with theoretical predictions.

Gofryk, K.; Griveau, J.-C.; Colineau, E.; Sanchez, J. P.; Rebizant, J.; Caciuffo, R.

2009-04-01

319

Theoretical and experimental investigation of magnetotransport in iron chalcogenides  

NASA Astrophysics Data System (ADS)

We explore the electronic, transport and thermoelectric properties of Fe1+ySexTe1-x compounds to clarify the mechanisms of superconductivity in Fe-based compounds. We carry out first-principles density functional theory (DFT) calculations of structural, electronic, magnetic and transport properties and measure resistivity, Hall resistance and Seebeck effect curves. All the transport properties exhibit signatures of the structural/magnetic transitions, such as discontinuities and sign changes of the Seebeck coefficient and of the Hall resistance. These features are reproduced by calculations provided that antiferromagnetic correlations are taken into account and experimental values of lattice constants are considered in DFT calculations. On the other hand, the temperature dependences of the transport properties can not be fully reproduced, and to improve the agreement between experiment and DFT calculations it is necessary to go beyond the constant relaxation time approximation and take into account correlation effects.

Caglieris, Federico; Ricci, Fabio; Lamura, Gianrico; Martinelli, Albert; Palenzona, A.; Pallecchi, Ilaria; Sala, Alberto; Profeta, Gianni; Putti, Marina

2012-10-01

320

Nanocubes  

NASA Astrophysics Data System (ADS)

A giant Seebeck coefficient of -890 ?V/K at 500 °C has been observed in Y0.2Sr0.8TiO3 prepared using nanocubes. Doping rare earth elements, RE, has revealed that small RE is effective to enhance the Seebeck coefficient. Through soft mode observations by Raman spectroscopy and structural calculations based on density functional theory, it has been found that the breakdown of inversion symmetry of the perovskite structure near the surface of nanocubes can be recovered by doping with small RE. Because the dielectric constant is strongly related to the surface structure in this compound, we suggest that RE doping modulates the potential barrier at the grain boundary, resulting in a pronounced energy filtering effect in Y doped SrTiO3.

Kinemuchi, Yoshiaki; Mimura, Ken-ichi; Towata, Atsuya; Kato, Kazumi

2014-06-01

321

Thermoelectric properties of magnesium silicide fabricated using vacuum plasma thermal spray  

NASA Astrophysics Data System (ADS)

The thermoelectric properties of magnesium silicide samples prepared by Vacuum Plasma Spray (VPS) are compared with those made from the conventional hot press method using the same feedstock powder. Thermal conductivity, electrical conductivity, Seebeck coefficient, and figure of merit are characterized from room temperature to 700 K. X-ray diffraction and scanning electron microscopy of the samples are obtained to assess how phase and microstructure influence the thermoelectric properties. Carrier concentration and Hall mobility are obtained from Hall Effect measurements, which provide further insight into the electrical conductivity and Seebeck coefficient mechanisms. Low-temperature electrical conductivity measurements suggest a 3D variable range hopping effect in the samples. VPS samples achieved a maximum ZT = 0.16 at 700 K, which is around 30% of the hot press sample ZT = 0.55 at 700 K using the same raw powder. The results suggest that thermal spray is a potential deposition technique for thermoelectric materials.

Fu, Gaosheng; Zuo, Lei; Longtin, Jon; Nie, Chao; Gambino, Richard

2013-10-01

322

Spin current generation from sputtered Y3Fe5O12 films  

NASA Astrophysics Data System (ADS)

Spin current injection from sputtered yttrium iron garnet (YIG) films into an adjacent platinum layer has been investigated by means of the spin pumping and the spin Seebeck effects. Films with a thickness of 83 and 96 nanometers were fabricated by on-axis magnetron rf sputtering at room temperature and subsequent post-annealing. From the frequency dependence of the ferromagnetic resonance linewidth, the damping constant has been estimated to be (7.0 ± 1.0) × 10-4. Magnitudes of the spin current generated by the spin pumping and the spin Seebeck effect are of the same order as values for YIG films prepared by liquid phase epitaxy. The efficient spin current injection can be ascribed to a good YIG|Pt interface, which is confirmed by the large spin-mixing conductance (2.0 ± 0.2) × 1018 m-2.

Lustikova, J.; Shiomi, Y.; Qiu, Z.; Kikkawa, T.; Iguchi, R.; Uchida, K.; Saitoh, E.

2014-10-01

323

Thermoelectric properties of tungsten-substituted Heusler Fe2VAl alloy  

NASA Astrophysics Data System (ADS)

A Heusler Fe2V1-xWxAl sintered alloy was synthesized to evaluate the effect of W substitution on thermoelectric properties of the Heusler alloy. The Seebeck coefficient and the electrical conductivity are simultaneously enhanced through electron injection resulting from the W substitution. Comparison with the Si-substituted Fe2VAl alloy reveals that the additional electronic states derived from W 5d orbital in the vicinity of pseudogap are likely to degrade the Seebeck coefficient. Thermal conductivity is effectively reduced by the W substitution because of the large atomic mass and volume of W compared to the constituent elements of Fe2VAl alloy. The appreciable reduction of thermal conductivity, without a serious deterioration in electrical conduction, enhances the thermoelectric figure of merit in the Heusler alloy.

Mikami, M.; Kinemuchi, Y.; Ozaki, K.; Terazawa, Y.; Takeuchi, T.

2012-05-01

324

Effective 4-H Meetings  

E-print Network

As a 4-H volunteer, you will have different functions. An especially important task is to prepare interesting and effective meetings where youth can obtain the greatest educational benefit while having fun. This publication outlines effective...

Howard, Jeff W.

2005-05-10

325

Managing Physical Effects  

Cancer.gov

Browse a list of common side effects of cancer or cancer treatment with links to practical information for preventing or relieving these effects. Also find information on maintaining proper nutrition during cancer treatment.

326

Effective College Teaching.  

ERIC Educational Resources Information Center

The author discusses other writings on effective college teaching and then presents his list of necessary characteristics for the effective teacher, stressing the interpersonal dimension of the teaching-learning situation. (MF)

Caraway, James E.

1978-01-01

327

The Hydrophobic Effect.  

ERIC Educational Resources Information Center

Discusses the physical basis and current understanding of hydrophobic effects. The thermodynamic background of the effects, hydrophobic hydration, and hydrophobic interactions are described. Four existing controversies are outlined. (YP)

Huque, Entazul M.

1989-01-01

328

Skin Effect in Semiconductors  

Microsoft Academic Search

This paper deals with the theory of skin effect in semiconductor materials including the effect of displacement currents, which are generally neglected in the skin-effect theory for metallic conductors. In the case of flat plates, formulas are derived for the field distribution, the impedance and the eddy-current power losses, considering symmetrical electric as well as magnetic fields. Impedance as a

A. H. Frei; M. J. O. Strutt

1960-01-01

329

Mercury: Health Effects  

MedlinePLUS

... in rats and mice, and methylmercury has caused kidney tumors in male mice. Scientists only observed these health effects at extremely high doses, above levels that produced other effects. When ... may be kidney effects, respiratory failure and death. People concerned about ...

330

Special Effects Activity Guide.  

ERIC Educational Resources Information Center

This guide accompanies "Special Effects," a 40-minute IMAX film and "Special Effects II", a multimedia, interactive traveling exhibit designed by the California Museum of Science and Industry. The exhibit focuses on the underlying scientific and technical processes of special effects from the earliest motion picture to state-of-the-art digital…

Boxer, Jennifer; Valenta, Carol

331

Effective Schools Research.  

ERIC Educational Resources Information Center

Research studies that have focused on identifying the characteristics or correlates of elementary and secondary schools that are unusually effective are reviewed, concentrating on the "effective schools" movement. Research on effective schools supports the conclusion that they rank high on certain characteristics frequently referred to as…

Levine, Daniel U.; Lezotte, Lawrence W.

332

Effects of Nuclear Weapons.  

ERIC Educational Resources Information Center

Fundamental principles governing nuclear explosions and their effects are discussed, including three components of a nuclear explosion (thermal radiation, shock wave, nuclear radiation). Describes how effects of these components depend on the weapon's yield, its height of burst, and distance of detonation point. Includes effects of three…

Sartori, Leo

1983-01-01

333

Influence of the rare-earth element on the effects of the structural and magnetic phase transitions in CeFeAsO, PrFeAsO, and NdFeAsO  

SciTech Connect

We present results of transport and magnetic properties and heat capacity measurements on polycrystalline CeFeAsO, PrFeAsO and NdFeAsO. These materials undergo structural phase transitions, spin density wave-like magnetic ordering of small moments on iron and antiferromagnetic ordering of rare-earth moments. The temperature dependence of the electrical resistivity, Seebeck coefficient, thermal conductivity, Hall coefficient and magnetoresistance are reported. The magnetic behavior of the materials have been investigated using Moessbauer spectroscopy and magnetization measurements. Transport and magnetic properties are affected strongly by the structural and magnetic transitions, suggesting significant changes in the band structure and/or carrier mobilities occur, and phonon-phonon scattering is reduced upon transformation to the low-temperature structure. Results are compared with recent reports for LaFeAsO, and systematic variations in properties as the identity of Ln is changed are observed and discussed. As Ln progresses across the rare-earth series from La to Nd, an increase in the hole contributions to the Seebeck coefficient and increases in magnetoresistance and the Hall coefficient are observed in the low-temperature phase. Analysis of hyperfine fields at the iron nuclei determined from Moessbauer spectra indicates that the moment on Fe in the orthorhombic phase is nearly independent of the identity of Ln, in apparent contrast to reports of powder neutron diffraction refinements.

McGuire, Michael A [ORNL; Hermann, Raphael P. [Forschungszentrum Julich, Julich, Germany; Safa-Sefat, Athena [ORNL; Sales, Brian C [ORNL; Jin, Rongying [ORNL; Mandrus, David [ORNL; Grandjean, F. [University of Liege, Belgium; Long, Gary J. [University of Missouri, Rolla

2009-01-01

334

A nano-stripe based sensor for temperature measurement at the submicrometer and nano scales.  

PubMed

Submicrometer dual-stripe temperature sensors made from a single piece of metal thin film (e.g., Pd) are developed. With the narrowest sensor being 900 nm in width, they show sensitivity of 1-2 ?V/K for the full range of 10-300 K. The results confirm the size effect in Seebeck coefficient previously observed in microstripe sensors of the same device configuration. PMID:24888901

Huo, Xiaoye; Liu, Haixiao; Liang, Yiran; Fu, Mengqi; Sun, Weiqiang; Chen, Qing; Xu, Shengyong

2014-10-15

335

Disordered electronic systems. III. Thermoelectric power in alloys with phase separation  

Microsoft Academic Search

Applying effective medium theory and the Boltzmann transport equation, a formula is derived for calculation of the Seebeck coefficient alpha (thermoelectric power) of alloys with phase separation (composite) under especial consideration of the electrochemical potential mu and its change with temperature T,dmu\\/dT . dmu\\/dT is essentially determined by the electronic structure, carrier densities, and electron-electron-interaction in the phases. For metal-metal

Joachim Sonntag

2006-01-01

336

Thermoelectric Properties of Lanthanum Sulfide  

NASA Technical Reports Server (NTRS)

Report describes measurement of Seebeck coefficient, electrical resistivity, thermal conductivity, and Hall effect in gamma-phase lanthanum sulfide with composition of La3-x S4. Results of study, part of search for high-temperature thermoelectric energy-conversion materials, indicate this sulfide behaves like extrinsic semiconductor over temperature range of 300 to 1,400 K, with degenerate carrier concentration controlled by stoichiometric ratio of La to S.

Wood, C.; Lockwood, R.; Parker, J. B.; Zoltan, A.; Zoltan, L. D.; Danielson, L.; Raag, V.

1987-01-01

337

Global fault localization using induced voltage alteration  

Microsoft Academic Search

Advances in integrated circuit technology have made failure site localization extremely challenging. Charge-induced voltage alteration (CIVA), low energy CIVA (LECIVA), light-induced voltage alteration (LIVA), Seebeck effect imaging (SEI) and thermally-induced voltage alteration (TIVA) are five recently developed failure analysis techniques which meet the challenge by rapidly and non-destructively localizing interconnection defects on ICs. The techniques take advantage of voltage fluctuations

Edward I. Cole Jr.

2001-01-01

338

Conduction mechanism in boron carbide  

NASA Technical Reports Server (NTRS)

Electrical conductivity, Seebeck-coefficient, and Hall-effect measurements have been made on single-phase boron carbides, B(1-x)C(x), in the compositional range from 0.1 to 0.2 X, and between room temperature and 1273 K. The results indicate that the predominant conduction mechanism is small-polaron hopping between carbon atoms at geometrically inequivalent sites.

Wood, C.; Emin, D.

1984-01-01

339

Design of a Concentration Solar Thermoelectric Generator  

Microsoft Academic Search

Thermoelectric technology can be another direct way to convert solar radiation into electricity, using the Seebeck effect.\\u000a Herein, a prototype concentration solar thermoelectric generator (CTG) and a discrete numerical model for the evaluation of\\u000a the whole system are presented. The model takes into account the temperature dependence of the thermoelectric material properties\\u000a by dividing the thermoelectric leg into finite elements

Peng Li; Lanlan Cai; Pengcheng Zhai; Xinfeng Tang; Qingjie Zhang; M. Niino

2010-01-01

340

Thermoelectric properties of constantan\\/spherical SiO 2 and Al 2O 3 particles composite  

Microsoft Academic Search

The thermoelectric properties of the composite, spherical SiO2 or Al2O3 particles dispersed in a 45Ni55Cu matrix, were measured in the temperature range from room temperature to 1073 K. The dispersed particles decrease the electrical and thermal conductivity according to an effective media theory. The Seebeck coefficient is slightly increased and differences between SiO2 and Al2O3 are not observed. The dimensionless

Hiroaki Muta; Ken Kurosaki; Masayoshi Uno; Shinsuke Yamanaka

2003-01-01

341

Thermoelectric Microconverter for Energy Harvesting Systems  

Microsoft Academic Search

This paper presents a solution for energy microgeneration through energy harvesting by taking advantage of temperature differences that are converted into electrical energy using the Seebeck effect. A thermoelectric microconverter for energy scavenging systems that can supply low-power electronics was fabricated using thin films of bismuth and antimony tellurides. Thin films of n-type bismuth (Bi2Te3) and p-type antimony (Sb2Te3) tellurides

João Paulo Carmo; Luis Miguel Goncalves; José Higino Correia

2010-01-01

342

Thermally Driven Josephson Effect  

NASA Technical Reports Server (NTRS)

A concept is proposed of the thermally driven Josephson effect in superfluid helium. Heretofore, the Josephson effect in a superfluid has been recognized as an oscillatory flow that arises in response to a steady pressure difference between two superfluid reservoirs separated by an array of submicron-sized orifices, which act in unison as a single Josephson junction. Analogously, the thermally driven Josephson effect is an oscillatory flow that arises in response to a steady temperature difference. The thermally driven Josephson effect is partly a consequence of a quantum- mechanical effect known as the fountain effect, in which a temperature difference in a superfluid is accompanied by a pressure difference. The thermally driven Josephson effect may have significance for the development of a high-resolution gyroscope based on the Josephson effect in a superfluid: If the pressure-driven Josephson effect were used, then the fluid on the high-pressure side would become depleted, necessitating periodic interruption of operation to reverse the pressure difference. If the thermally driven Josephson effect were used, there would be no net flow and so the oscillatory flow could be maintained indefinitely by maintaining the required slightly different temperatures on both sides of the junction.

Penanen, Konstantin; Chui, Talso

2008-01-01

343

The central role of the Peltier coefficient in thermoelectric cooling  

NASA Astrophysics Data System (ADS)

This paper discusses the special role that the Peltier effect plays in thermoelectric cooling. From a particular energy balance for a thermocouple, we can conclude that the Peltier component pumps out the energy of all other terms: Joule, Fourier, Seebeck, and thermoelectric cooling. We emphasize also that in this energy balance, there is a need to include a new contribution, named after Seebeck that usually is not considered in the literature. We discuss a new method to evaluate the Peltier coefficient using measurements of the two temperature gradients at the junction of a thermocouple. An arrangement has been built to explore this method. A precise value for the Peltier coefficient of a thermocouple has been obtained but which deviates from the Kelvin relation. A better design of the experimental device is needed.

Garrido, J.; Casanovas, A.

2014-03-01

344

Thermoelectricity of Nanocomposites Containing TiO2–CoO Coaxial Nanocables  

SciTech Connect

TiO{sub 2}-CoO coaxial nanocables were deposited into anodic aluminum oxide (AAO) nanoporous templates to form nanocomposite materials. Electron microscopic analysis was conducted to reveal their structures. Seebeck coefficients of the composites were measured. The highest absolute value of Seebeck coefficient is 393 {micro}V K{sup -1} for the TiO{sub 2} nanotube-filled AAO. The TiO{sub 2}-CoO coaxial nanocable-filled AAO has a lower absolute value of 300 {micro}V K{sup -1}. Both composites showed n-type behavior. The effect of Ag nanoparticles addition on the thermoelectric behavior was also examined.

Su, L.; Zhang, L.; Gana, Y.X.

2011-04-01

345

Measurement of Thermopower and Current-Voltage Characteristics of Molecular Junctions to Identify Orbital Alignment  

SciTech Connect

We report an experimental technique that concurrently measures the Seebeck coefficient and the current-voltage (I-V) characteristics of a molecular junction to determine the identity and the effective energetic separation of the molecular orbital closest to the electrodes’ Fermi level. Junctions created by contacting a gold-coated atomic force microscope tip with a monolayer of molecules assembled on a gold substrate were found to have a Seebeck coefficient of (+16.9±1.4) ?V/K. This positive value unambiguously shows that the highest occupied molecular orbital (HOMO) dominates charge transport. Further, by analyzing the (I-V) characteristics, the HOMO level is estimated to be ? 0.69?eV with respect to the Fermi level.

Tan, Aaron; Sadat, Seid; Reddy, Pramod

2010-01-01

346

Thermoelectric Properties and n- to p-Type Conversion of Co-Doped ZrNiSn-Based Half-Heusler Alloys  

NASA Astrophysics Data System (ADS)

Half-Heulser thermoelectric materials ZrNi1- y Co y Sn ( y = 0, 0.02, 0.04, 0.08, 0.12) were prepared by a time-efficient levitation melting and spark plasma sintering procedure. X-ray diffraction analysis and electron probe microanalysis showed that single-phase half-Heusler compounds without compositional segregation have been obtained. The effects of Co doping on the electrical conductivity, Seebeck coefficient, and thermal conductivity of ZrNiSn-based half-Heusler alloys have been investigated from 300 K to 900 K. The Seebeck coefficient displayed a change from negative to positive values above nominal Co doping content of y = 0.02, indicating a transition in the conduction behavior from n-type to p-type. The maximum dimensionless figure of merit ZT of undoped ZrNiSn sample reached 0.5 at 870 K.

Xie, Han-Hui; Yu, Cui; He, Bin; Zhu, Tie-Jun; Zhao, Xin-Bing

2012-06-01

347

High temperature transport properties of thermoelectric CaMnO{sub 3??} — Indication of strongly interacting small polarons  

SciTech Connect

The conductivity and Seebeck coefficient of CaMnO{sub 3??} have been studied at temperatures up to 1000?°C and in atmospheres with controlled oxygen partial pressure. Both transport coefficients were varied in situ by the reversible formation of oxygen vacancies up to ??=?0.15. The charge carrier concentration was calculated using a defect chemical model. The Seebeck coefficient could be approximated by Heikes' formula, while the conductivity shows a maximum at a molar charge carrier concentration of 0.25. These results were interpreted as a signature of strong electronic correlation effects, and it was concluded that charge transport in CaMnO{sub 3??} occurs via strongly interacting small polarons. General prospects for strongly correlated materials as potential candidates for high temperature thermoelectric power generation were discussed.

Schrade, M., E-mail: matthias.schrade@smn.uio.no; Finstad, T. G. [Centre for Materials Science and Nanotechnology, Department of Physics, University of Oslo, Sem Sælandsvei 24, 0371 Oslo (Norway); Kabir, R.; Li, S. [School of Materials Science and Engineering, University of New South Wales, Sydney, New South Wales 2052 (Australia); Norby, T. [Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, FERMiO, Gaustadalléen 21, 0349 Oslo (Norway)

2014-03-14

348

Effective Strategies Brief  

NSDL National Science Digital Library

In this research brief the authors detail effective teaching strategies for teaching students with difficulties in math. The brief summarizes the work of over fifty research studies and details the practices that were seen as consistently effective across many of them. The brief details six instructional strategies and presents data describing the effectiveness of each on special education students and low-achieving students. The brief can be viewed on the webpage or downloaded as a PDF.

Gersten, Russell; Clarke, Benjamin S.

2007-01-01

349

Dynamic ground effects  

NASA Technical Reports Server (NTRS)

A research program is underway at the NASA Langley Research Center to study the effect of rate of descent on ground effects. A series of powered models were tested in the Vortex Research Facility under conditions with rate of descent and in the 14 x 22 Foot Subsonic Tunnel under identical conditions but without rate of descent. These results indicate that the rate of descent can have a significant impact on ground effects particularly if vectored or reversed thrust is used.

Paulson, John W., Jr.; Kemmerly, Guy T.; Gilbert, William P.

1990-01-01

350

The Atomic Lighthouse Effect  

E-print Network

We investigate the deflection of light by a cold atomic cloud when the light-matter interaction is locally tuned via the Zeeman effect using magnetic field gradients. This "lighthouse" effect is strongest in the single-scattering regime, where deviation of the incident field is largest. For optically dense samples, the deviation is reduced by collective effects, as the increase in linewidth leads to a decrease of the magnetic field efficiency.

Máximo, C E; Courteille, Ph W; Bachelard, R

2014-01-01

351

Atomic lighthouse effect.  

PubMed

We investigate the deflection of light by a cold atomic cloud when the light-matter interaction is locally tuned via the Zeeman effect using magnetic field gradients. This "lighthouse" effect is strongest in the single-scattering regime, where deviation of the incident field is largest. For optically dense samples, the deviation is reduced by collective effects, as the increase in linewidth leads to a decrease in magnetic field efficiency. PMID:25401364

Máximo, C E; Kaiser, R; Courteille, Ph W; Bachelard, R

2014-11-01

352

[Effects and side effects of hormonal contraceptives].  

PubMed

A discussion of the side effects of hormonal oral contraceptive (OC) use is presented. Studies show that the estrogen component of OCs works to suppress the release of GRH (gonadotropin-releasing hormone), reducing the serum FSH level. The gestagen component desensitizes the frontal lobe of the pituitary gland to the effect of GRH and suppresses the preovulatory LH peak. OCs can cause subjective side effects such as nausea, headache, depression, which can also be observed during placebo use. Breakthrough bleeding, spotting, silent menstruation, and post-pill amenorrhea are menstrual irregularities which can be linked to OC use; 98% of those who discontinue OC use show normal biphasic menstrual cycles 3 cycles after discontinuation. A constant increase in serum triglyceride levels, small increases in cholesterol and phospholipid levels are observed among OC users. Minor cases of hyperinsulinism are observed among OC users with no history of diabetes; glucose tolerance tests should be regularly administered to OC users who have a risk of diabetes or a history of pregnancy diabetes. Serum levels of proteins are affected by OC use, probably due to the effects of OC use on liver function. Studies have shown an increased risk of thromboembolism and circulatory disorders among OC users, especially those who are over 30 years of age or who smoke. OC use has been linked to development of benign tumors of the liver and the cervix. Gestagens appear to reduce the frequency of endometrial mitosis. Other medications, e.g. analgesics, barbituates, can reduce the effectiveness of OCs. For adolescents, sequence preparations are preferred and should be administered only after a 1 year period of regular menstruation. Thorough check-ups should be performed on OC users twice yearly, and contraindications should be scrupulously observed. PMID:7415248

Carol, W; Göretzlehner, G

1980-02-01

353

Volcanic effects on climate  

NASA Technical Reports Server (NTRS)

Volcanic eruptions which inject large amounts of sulfur-rich gas into the stratosphere produce dust veils which last years and cool the earth's surface. At the same time, these dust veils absorb enough solar radiation to warm the stratosphere. Since these temperature changes at the earth's surface and in the stratosphere are both in the opposite direction of hypothesized effects from greenhouse gases, they act to delay and mask the detection of greenhouse effects on the climate system. Tantalizing recent research results have suggested regional effects of volcanic eruptions, including effects on El Nino/Southern Oscillation (ENSO). In addition, a large portion of the global climate change of the past 100 years may be due to the effects of volcanoes, but a definite answer is not yet clear. While effects of several years were demonstrated with both data studies and numerical models, long-term effects, while found in climate model calculations, await confirmation with more realistic models. Extremely large explosive prehistoric eruptions may have produced severe weather and climate effects, sometimes called a 'volcanic winter'. Complete understanding of the above effects of volcanoes is hampered by inadequacies of data sets on volcanic dust veils and on climate change. Space observations can play an increasingly important role in an observing program in the future. The effects of volcanoes are not adequately separated from ENSO events, and climate modeling of the effects of volcanoes is in its infancy. Specific suggestions are made for future work to improve the knowledge of this important component of the climate system.

Robock, Alan

1991-01-01

354

The Kaye Effect  

ERIC Educational Resources Information Center

The International Young Physicists' Tournament (IYPT) is a worldwide, annual competition for secondary school students. This is our solution to problem number 10, "The Kaye effect", as presented in the final round of the 21st IYPT in Trogir, Croatia. The Kaye effect occurs when a thin stream of shampoo or a different adequate non-Newtonian liquid…

Binder, J. M.; Landig, A. J.

2009-01-01

355

effectively tax treaty?  

E-print Network

Is income effectively connected to US trade/ business? Is this exempt under the tax treaty? Does- employee comp? Is income "effectively connected"? Is payment subject to a lower tax rate? Is payment for rent or royalty? Individual completes IRS form 1001. Payment will not be taxed. (Code "N") Taxes

Krovi, Venkat

356

Comparative Effectiveness Research  

Cancer.gov

Comparative Effectiveness Research (CER) is the conduct and synthesis of systematic research comparing different interventions and strategies to prevent, diagnose, treat and monitor health conditions. The purpose of this research is to inform patients, providers, and decision-makers about which interventions are most effective for which patients under specific circumstances.

357

Earthquake Effects and Experiences  

NSDL National Science Digital Library

This portion of the United States Geological Survey's (USGS) frequently-asked-questions feature on earthquakes addresses what individuals might actually experience during an earthquake. Topics include earthquake motion (rolling or shaking), earthquake effects (ground shaking, surface faulting, ground failure, etc.), earthquake magnitude, what an earthquake feels like, and others. There are also links to additional resources on earthquake effects and experiences.

358

JPL Radiation Effects Facilities  

NASA Technical Reports Server (NTRS)

Radiation Effects Group investigates the effects of space radiation on present and future microelectronic and optoelectronic technologies, evaluate the risk of using them in specific space missions, and recommend component and design techniques for JPL and NASA programs to reduce reliability risk from space radiation.

Thorbourn, Dennis

2013-01-01

359

On Effective Topological Spaces  

Microsoft Academic Search

Starting with D. Scott's work on the mathematical foundations of programming language semantics, interest in topology has grown up in theoretical computer science, under the slogan `open sets are semidecidable properties'. But whereas on effectively given Scott domains all such properties are also open, this is no longer true in general. In this paper a characterization of effectively given topological

Dieter Spreen

1998-01-01

360

Polaronic Effects in Ferroelectrics  

Microsoft Academic Search

We studied polaronic effects due to the interaction of an electron with optical phonons in ferroelectric materials with a layered crystal structure. We evaluated the polaron self-energy part using the effective T-matrix approach. It has been shown that transition from the large radius polaron to the small radius polaron is controlled by the interlayer interaction or interlayer spacing. We have

Y. M. Malozovsky; J. D. Fan; D. Bagayoko; J. T. Wang

2000-01-01

361

The greenhouse effect  

Microsoft Academic Search

The greenhouse effect on the Earth is identified by the difference between the effective radiating temperature of the planet and its surface temperature. The difference between the energy emitted by the surface and that emitted upward to space by the upper atmosphere quantifies it; it can therefore be defined as the long wave energy trapped in the atmosphere. Climate forcing

A. Berger; Ch. Tricot

1992-01-01

362

The Greenhouse Effect  

Microsoft Academic Search

The Greenhouse Effect is getting a lot of publicity as concern grows about trends in weather and pollution. The midwestern states of the US suffered a drought during 1988 coupled with an unsually hot summer throughout the country. Many people attributed this to the Greenhouse Effect. Palmer and Brankovic (Nature, Vol. 338, page 54, March 2, 1989) tied the drought

2009-01-01

363

Effects of Drug Abuse  

MedlinePLUS

Listen to this page Effects of Drug Abuse Drug abuse hurts the people who take drugs AND the people around them, including families , kids , and babies who ... HIV/AIDS Click here to learn more about effects of specific drugs . VIDEO: Why Are Drugs So Hard to Quit? ...

364

Photorefractive Effects and Materials  

Microsoft Academic Search

As mentioned in the preface: `This book is a collection of many of the most recent developments in photorefractive effects and materials'. The readers, who, according to the title, would expect to find a broad coverage of the field will be somewhat disappointed. A more appropriate title of this volume would be: `Recent Developments in Photorefractive Effects and Materials'. Within

1996-01-01

365

Generalized gravitomagnetic clock effect  

NASA Astrophysics Data System (ADS)

In general relativity, the rotation of a gravitating body like the Earth influences the motion of orbiting test particles or satellites in a non-Newtonian way. This causes, e.g., a precession of the orbital plane known as the Lense-Thirring effect and a precession of the spin of a gyroscope known as the Schiff effect. Here, we discuss a third effect first introduced by Cohen and Mashhoon called the gravitomagnetic clock effect. It describes the difference in proper time of counterrevolving clocks after a revolution of 2?. For two clocks on counterrotating equatorial circular orbits around the Earth, the effect is about 10-7 s per revolution, which is quite large. We introduce a general relativistic definition of the gravitomagnetic clock effect which is valid for arbitrary pairs of orbits. This includes rotations in the same direction and different initial conditions, which are crucial if the effect can be detected with existing satellites or with payloads on nondedicated missions. We also derive the post-Newtonian expansion of the general relativistic expression and calculate the effect for the example of a satellite of a global navigation satellite system compared to a geostationary satellite.

Hackmann, Eva; Lämmerzahl, Claus

2014-08-01

366

Radiation effects in space  

SciTech Connect

As more people spend more time in space, and the return to the moon and exploratory missions are considered, the risks require continuing examination. The effects of microgravity and radiation are two potential risks in space. These risks increase with increasing mission duration. This document considers the risk of radiation effects in space workers and explorers. 17 refs., 1 fig., 4 tabs.

Fry, R.J.M.

1987-07-01

367

Side effects from amiodarone.  

PubMed

Amiodarone causes many side effects involving all organ systems. Although most of the side effects are mild and do not limit the use of the drug, there are several that are serious. Since many of these toxic reactions develop only after a prolonged period of therapy, careful follow-up on a regular basis is essential. PMID:1985357

Wilson, J S; Podrid, P J

1991-01-01

368

Earthquake Effects and Experiences  

NSDL National Science Digital Library

This portion of the United States Geological Survey's (USGS) frequently-asked-questions feature on earthquakes addresses what individuals might actually experience during an earthquake. Topics include earthquake motion (rolling or shaking), earthquake effects (ground shaking, surface faulting, ground failure, etc.), earthquake magnitude, what an earthquake feels like, and others. There are also links to additional resources on earthquake effects and experiences.

2010-11-23

369

Effects of acid precipitation  

Microsoft Academic Search

A growing body of evidence suggests that acid rain is responsible for substantial adverse effects on the public welfare. Such effects include: the acidification of lakes and rivers, with resultant damage to fish and other components of aquatic ecosystems; acidification and demineralization of soils; and possible reductions in crop and forest productivity. Affected areas include Canada and the northeastern US.

Norman R. Glass; Gary E. Glass; Peter J. Rennie

1979-01-01

370

Handbook of radiation effects  

Microsoft Academic Search

This book emphasizes radiation effects on solid state devices from exposure to the types of radiation found outside the atmosphere (in space, or in the vicinity of an exploding nuclear device). It contains a basic study of radiation shielding of payload components for payloads in space and specifically covers radiation effects on minority and majority carriers, optical media and organic

A. Holmes-Siedle; L. Adams

1993-01-01

371

Developing Effective Managers.  

ERIC Educational Resources Information Center

In this introductory work, the main principles on which British companies are basing management development programs are presented, and stages in assuring a supply of effective managerial talent are set forth: stages in assuring a supply of effective managerial t"lent are set forth: program planning based on clear objectives and communication;…

Roberts, T.J.

372

Dimensions of Teacher Effectiveness  

ERIC Educational Resources Information Center

Describes a study of teacher effectiveness in college departments of sociology, anthropology, and social work. Five types of teacher effectiveness were found to be potentially useful for student, faculty, and administrative purposes. They include teacher task responsiveness, respect for students, teacher capability, student development, and…

Wimberly, Ronald C.; And Others

1978-01-01

373

Generalized gravitomagnetic clock effect  

E-print Network

In General Relativity, the rotation of a gravitating body like the Earth influences the motion of orbiting test particles or satellites in a non-Newtonian way. This causes, e.g., a precession of the orbital plane known as the Lense-Thirring effect and a precession of the spin of a gyroscope known as the Schiff effect. Here, we discuss a third effect first introduced by Cohen and Mashhoon called the gravitomagnetic clock effect. It describes the difference in proper time of counterrevolving clocks after a revolution of $2\\pi$. For two clocks on counterrotating equatorial circular orbits around the Earth, the effect is about $10^{-7}$ seconds per revolution, which is quite large. We introduce a general relativistic definition of the gravitomagnetic clock effect which is valid for arbitrary pairs of orbits. This includes rotations in the same direction and different initial conditions, which are crucial if the effect can be detected with existing satellites or with payloads on nondedicated missions. We also derive the post-Newtonian expansion of the general relativistic expression and calculate the effect for the example of a satellite of a Global Navigation Satellite System compared to a geostationary satellite.

Eva Hackmann; Claus Lämmerzahl

2014-08-28

374

Thermoelectric Properties of Magnesium Silicide Deposited by Use of an Atmospheric Plasma Thermal Spray  

NASA Astrophysics Data System (ADS)

The thermoelectric properties of magnesium silicide (Mg2Si) samples prepared by use of an atmospheric plasma spray (APS) were compared with those of samples prepared from the same feedstock powder by use of the conventional hot-pressing method. The characterization performed included measurement of thermal conductivity, electrical conductivity, Seebeck coefficient, and figure of merit, ZT. X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive x-ray spectroscopy (EDX) were used to assess how phase and microstructure affected the thermoelectric properties of the samples. Hall effect measurements furnished carrier concentration, and measurement of Hall mobility provided further insight into electrical conductivity and Seebeck coefficient. Low temperature and high velocity APS using an internal-powder distribution system achieved a phase of composition similar to that of the feedstock powder. Thermal spraying was demonstrated in this work to be an effective means of reducing the thermal conductivity of Mg2Si; this may be because of pores and cracks in the sprayed sample. Vacuum-annealed APS samples were found to have very high Seebeck coefficients. To further improve the figure of merit, carrier concentration must be adjusted and carrier mobility must be enhanced.

Fu, Gaosheng; Zuo, Lei; Longtin, Jon; Nie, Chao; Chen, Yikai; Tewolde, Mahder; Sampath, Sanjay

2014-07-01

375

Analysis of high-temperature thermoelectric properties of p-type CoSb3 within a two-valence-band and two-conduction-band model  

NASA Astrophysics Data System (ADS)

Experimental data on the thermoelectric properties of p-type CoSb3 reported by Caillat et al. [J. Appl. Phys. 80, 4442 (1996)] have been analyzed, assuming not only a pair of the first valence (v1) and the first conduction (c1) bands but also the second valence (v2) and the second conduction (c2) bands. By taking into account the excitation of carriers into the v2 and the c2 bands, the behavior of the Hall coefficient as well as that of the Seebeck coefficient at high temperatures is well explained. By taking into account the nonparabolicity of the v1 band, the temperature dependence of mobility is well explained with assuming scattering due to acoustic phonons, nonpolar and polar optical phonons, and ionized impurities. Furthermore, various material parameters of CoSb3, such as the band-gap energy, effective masses, and deformation potentials, have been deduced from fitting the calculation to the experimental data on the temperature dependences of the Hall coefficient, the mobility, and the Seebeck coefficient. Among them, the band-gap energy and the effective mass of the v1 band have been corrected from the original values estimated by Caillat et al. In addition, it is shown that the experimental data on the hole-concentration dependences of both the room-temperature Seebeck coefficient and the cyclotron mass are well reproduced by the theoretical calculation using the deduced values for the nonparabolic v1 band.

Kajikawa, Y.

2014-05-01

376

Electromagnetic field effects and mechanisms  

Microsoft Academic Search

The author discusses the following topics: exposure vs. dose; known mechanisms; thermal effects vs. nonthermal effects; membrane excitation; electric fields (charge interactions; permanent dipole interactions; induced dipole interactions); magnetic field effects; free radical effects; human perception of 60 Hz magnetic fields; cyclotron resonance; microwave auditory effect; blood-brain barrier effects

K. R. Foster

1996-01-01

377

Greenhouse effect of NOX.  

PubMed

Through various processes the nitrogen oxides (NOX) interact with trace gases in the troposphere and stratosphere which do absorb in the spectral range relevant to the greenhouse effect (infrared wavelengths). The net effect is an enhancement of the greenhouse effect. The catalytic role of NOX in the production of tropospheric ozone provides the most prominent contribution. The global waming potential is estimated as GWP (NOX = 30 - 33 and 7 - 10 for the respective time horizons of 20 and 100 years, and is thereby comparable to that of methane. NOX emissions in rural areas of anthropogenically influenced regions, or those in the vicinity of the txopopause caused by air traffic, cause the greenhouse effectivity to be substantially more intense. We estimate an additional 5-23 % for Germany's contribution to the anthropogenic greenhouse effect as a result of the indirect greenhouse effects stemming from NOX. Furthermore, a small and still inaccurately defined amount of the deposited NOX which has primarily been converted into nitrates is again released from the soil into the atmosphere in the form of the long-lived greenhouse gas nitrous oxide (N2O). Thus, anthropogenically induced NOX emissions contribute to enhanced greenhouse effect and to stratospheric ozone depletion in the time scale of more than a century. PMID:24234471

Lammel, G; Graßl, H

1995-07-01

378

Bystander effects and radiotherapy.  

PubMed

Radiation-induced bystander effects are defined as biological effects expressed after irradiation by cells whose nuclei have not been directly irradiated. These effects include DNA damage, chromosomal instability, mutation, and apoptosis. There is considerable evidence that ionizing radiation affects cells located near the site of irradiation, which respond individually and collectively as part of a large interconnected web. These bystander signals can alter the dynamic equilibrium between proliferation, apoptosis, quiescence or differentiation. The aim of this review is to examine the most important biological effects of this phenomenon with regard to areas of major interest in radiotherapy. Such aspects include radiation-induced bystander effects during the cell cycle under hypoxic conditions when administering fractionated modalities or combined radio-chemotherapy. Other relevant aspects include individual variation and genetics in toxicity of bystander factors and normal tissue collateral damage. In advanced radiotherapy techniques, such as intensity-modulated radiation therapy (IMRT), the high degree of dose conformity to the target volume reduces the dose and, therefore, the risk of complications, to normal tissues. However, significant doses can accumulate out-of-field due to photon scattering and this may impact cellular response in these regions. Protons may offer a solution to reduce out-of-field doses. The bystander effect has numerous associated phenomena, including adaptive response, genomic instability, and abscopal effects. Also, the bystander effect can influence radiation protection and oxidative stress. It is essential that we understand the mechanisms underlying the bystander effect in order to more accurately assess radiation risk and to evaluate protocols for cancer radiotherapy. PMID:25535579

Marín, Alicia; Martín, Margarita; Liñán, Olga; Alvarenga, Felipe; López, Mario; Fernández, Laura; Büchser, David; Cerezo, Laura

2015-01-01

379

Finite Temperature Effective Actions  

E-print Network

We present, from first principles, a direct method for evaluating the exact fermion propagator in the presence of a general background field at finite temperature, which can be used to determine the finite temperature effective action for the system. As applications, we determine the complete one loop finite temperature effective actions for 0+1 dimensional QED as well as the Schwinger model. These effective actions, which are derived in the real time (closed time path) formalism, generate systematically all the Feynman amplitudes calculated in thermal perturbation theory and also show that the retarded (advanced) amplitudes vanish in these theories.

Ashok Das; J. Frenkel

2009-07-30

380

Measuring Study Effectiveness  

NSDL National Science Digital Library

This model-eliciting activity challenges students to operationally define a construct (study effectiveness). Students are given a survey to review that rates different aspects of study behaviors. They are then given a set of data for a few students and asked to use their scores to determine an index of study effectiveness. After determining a method, they are then asked to use this index to put five students in rank order according to their scores on study effectiveness. Students write a report explaining the method they used to determine these scores and how they produced their ratings.

This page was authored by the CATALST Group at the University of Minnesota, based on an original activity by Richard Lesh at Purdue University.

381

Bustling argon: biological effect.  

PubMed

Argon is a noble gas in group 18 of the periodic table. Certificated to exist in air atmosphere merely one century ago, discovery of argon shows interesting stories of researching and exploring. It was assumed to have no chemical activity. However, argon indeed present its biological effect on mammals. Narcotic effect of argon in diving operation and neur-protective function of argon in cerebral injury demonstrate that argon has crucial effect and be concentrated on is necessary. Furthermore, consider to be harmless to human, argon clinical application in therapy would be another option. PMID:24088583

Ye, Zhouheng; Zhang, Rongjia; Sun, Xuejun

2013-01-01

382

Improving engineering effectiveness  

NASA Technical Reports Server (NTRS)

Methodologies to improve engineering productivity were investigated. The rocky road to improving engineering effectiveness is reviewed utilizing a specific semiconductor engineering organization as a case study. The organization had a performance problem regarding new product introductions. With the help of this consultant as a change agent the engineering team used a systems approach to through variables that were effecting their output significantly. Critical factors for improving this engineering organization's effectiveness and the roles/responsibilities of management, the individual engineers and the internal consultant are discussed.

Fiero, J. D.

1985-01-01

383

Effects of ocular decongestants.  

PubMed

Eight widely used commercially available ocular decongestants were compared on the basis of vasoconstrictive effectiveness. The ability of these preparations to counteract histamine-induced erythema and to block its recurrence when rechallenged after one hour was evaluated in six human subjects in seven sessions. All vasoconstrictors tested were effective. No preparation was statistically different from 0.02% naphazoline hydrochloride in vasoconstrictive effect. In fact, this intermediate concentration of naphazoline (0.02%) was found to be significantly better that the other nonprescription decongestant preparations tested as a group and not significantly different from a group of higher concentrations of naphazoline. PMID:7378008

Abelson, M B; Yamamoto, G K; Allansmith, M R

1980-05-01

384

[Reporting a side effect].  

PubMed

Encountering a side-effect when practicing aesthetic dermatology must lead French practitioners to a double report: to VigiDEC medical network, and to the French agency for sanitary security of health products. PMID:19931702

Roos, N; Vigan, M

2009-10-01

385

Chesapeake Bay Impact Effects  

NSDL National Science Digital Library

This PowerPoint show depicts the effects (blast, heat, etc.) of the Chesapeake Bay impact. To emphasize the human consequences of asteroid and comet impacts, the slides show what would happen to East Coast communities if an identical object hit the same place today. (The impact actually happened roughly 35 million years ago.) Impact effects were estimated with the Earth Impact Effects Program (www.lpl.arizona.edu/impacteffects/). Effects shown on these slides are at best very approximate, and, consequently, these slides should only be used to stimulate discussions about impact hazards. Satellite images were obtained through the NASA Earth Observing System Higher Education Alliance (GeoBrain) which provided funding for this work. Graphics were created with the Environmental Systems Research Institute (ESRI) family of geographic information system (GIS) products.

Abolins, Mark; Univiversity, Middle T.

386

[Genetic effects of radiation].  

PubMed

This paper is a short review of genetic effect of radiation. This includes methods and results of a large-scale genetic study on specific loci in mice and of various studies in the offspring of atomic-bomb survivors. As for the latter, there is no results obtained which suggest the effect of parental exposure to radiation. Further, in recent years, studies are conducted to the offspring born to parents who were survivors of childhood cancers. In several reports, the mean gonad dose is quite large whereas in most instances, the results do not indicate genetic effect following parental exposure to radiation. Possible reasons for the difficulties in detecting genetic effect of radiation are discussed. PMID:22514926

Nakamura, Nori

2012-03-01

387

Radiation effects in space  

SciTech Connect

The paper discusses the radiation environment in space that astronauts are likely to be exposed to. Emphasis is on proton and HZE particle effects. Recommendations for radiation protection guidelines are presented. (ACR)

Fry, R.J.M.

1986-01-01

388

Magnetoplastic effects in solids  

NASA Astrophysics Data System (ADS)

This paper is an overview of the studies into the effect of weak magnetic fields on the structure and mechanical properties of nonmagnetic solids of various nature (ionic, covalent, molecular, and metallic crystals, polymers, etc.). The various effects and aftereffects initiated by static, pulsed, and microwave magnetic fields that have been discovered over the past 15 years are classified and critically analyzed. The thermodynamic and kinetic aspects of the magnetic-field sensitivity of real solids with structural defects containing paramagnetic centers (electrons, holes, radicals, excitons, etc.) are discussed. Possible mechanisms for the effect of a weak magnetic field on the defect structure of crystals are considered. Special attention is given to the most developed chemical-physical theory of spin-dependent reactions between mobile particles and unpaired electrons. Interpretation of magnetoplastic effects is proposed in terms of the spin, electron, molecular, and dislocation dynamics of the complex multistage processes initiated by a magnetic field in a system of metastable structural defects.

Golovin, Yu. I.

2004-05-01

389

PATHWAYS TO EFFECTIVE APPLICATIONS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Effective agricultural irrigation involves applying irrigation water efficiently and with water management techniques that insure profitable crop production. The purpose of this paper is to briefly outline choices for irrigation application technology and irrigation water management that can lead t...

390

Thermoelectric power factor enhancement with gate-all-around silicon nanowires  

SciTech Connect

The thermoelectric properties of gate-all-around silicon nanowires (Si NWs) are calculated to determine the potential for significant power factor enhancement. The Boltzmann transport equation and relaxation time approximation are employed to develop an electron transport model used to determine the field-effect mobility, electrical conductivity, Seebeck coefficient, and power factor for Si NWs with cross-sectional areas between 4?nm?×?4?nm and 12?nm?×?12?nm and a range of gate biases. Electrical conductivity for the gated Si NWs was much higher than that of doped Si due to the lack of ionized impurities and correspondingly greater carrier mobility. A significant increase in electrical conductivity with decreasing Si NW cross-sectional area was also observed due to a large increase in the average carrier density. For all Si NWs, the Seebeck coefficient was lower than that of doped bulk Si due to the different energy dependence between ionized impurity and phonon-mediated scattering processes. This decrease was also confirmed with Seebeck coefficient measurements of multigated Si NWs and n-type Si thin-films. Quantum confinement was also found to increase the Seebeck coefficient for <8?nm?×?8?nm Si NWs and also at high charge densities. A maximum power factor of 6.8?×?10{sup ?3}?W m{sup ?1} K{sup ?2} was calculated for the 6?nm?×?6?nm Si NWs with typical Si/SiO{sub 2} interface roughness, which is 2–3?×?those obtained experimentally for bulk Si. The power factor was also found to greatly depend on surface roughness, with a root-mean-square roughness of <0.8?nm necessary for power factor enhancement. An increase in ZT may also be possible if a low thermal conductivity can be obtained with minimal surface roughness.

Curtin, Benjamin M., E-mail: bcurtin@ece.ucsb.edu [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Bowers, John E. [Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States); Materials Department, University of California, Santa Barbara, California 93106 (United States)

2014-04-14

391

Nocturnal aircraft noise effects.  

PubMed

Noise protection associated with the construction and extension of airports in the Federal Republic of Germany has been regulated by the law for protection against aircraft noise since 1971. This legislation is due for revision because of different aspects. One aspect is the growth of air traffic which has led many airports to the limits of their capacity and in search of new ways of adaptation to the increasing demand for flight services. Another aspect is the increasing concern of the population about noise effects which has to be addressed by better protection against the effects of aircraft noise. The framework conditions of policy in terms of society as a whole, its health and economic environment need to be put into effect by political action. Science can contribute to this goal by performing noise effects research and by providing recommendations to the political body. However, it remains controversial, what measures are necessary or adequate to assure effective protection of the population against aircraft noise. This is particularly true for the protection of rest and sleep at night. The problem of finding a common basis for adequate recommendations is associated with (1) the low number of primary studies, which also exhibited highly variable results and assessments, (2) the handling of acoustic or psycho-acoustic dimensions for quantifying psychological or physiological reactions, and (3) the conception of how far preventive measures have to go to prove effective. With this in mind, the DLR Institute for Aerospace Medicine is conducting a large-scale, multi-stage study for investigating the acute effects of nocturnal aircraft noise on human sleep. This enterprise is implemented in the framework of the HGF/DLR project "Quiet Air Traffic" for developing sustainable assessment criteria for human-specific effects of aircraft noise at night. PMID:15070533

Basner, M; Samel, A

2004-01-01

392

Effects of periodic discharges  

NASA Technical Reports Server (NTRS)

Periodic capacity checks are assessed as well as the effects of periodic discharges on the cycle life and the performance of cells during the cycle life. Topics discussed include the effect of the amount of electrolyte on cell capacity at 35 C; battery design for spacecraft; electrolyte starvation theory; battery separator degradation; negative electrode stability; voltage regulation; operating temperatures; and integration of reconditioning systems using microprocessors.

Ford, F. E.

1977-01-01

393

The Doppler Effect  

NSDL National Science Digital Library

This Flash animation provides a simulation of the Doppler effect. The user can change the speed of the wave source and can move a microphone to detect the wave frequency at different points relative to the moving source. The resulting wave pattern can be both observed and heard. Instructional notes outlining the details of the Doppler effect are provided. This material is part of a web site for a second semester physics course for majors covering gravity, fluids, waves, and thermodynamics.

Fowler, Michael; Welch, Heather

2008-07-31

394

Acid Rain Effects  

NSDL National Science Digital Library

Learners conduct a simple experiment to model and explore the harmful effects of acid rain (vinegar) on living (green leaf and eggshell) and non-living (paper clip) objects. Learners observe the effects over a period of days. This activity has links to other activities which can be combined to make a larger lesson. Resource contains vocabulary definitions and suggestions for assessment, extensions, and scaling for different levels of learners.

Kolenbrander, Amy; Yowell, Janet; Mach, Natalie; Zarske, Malinda S.; Carlson, Denise

2004-01-01

395

Correlational Effect Size Benchmarks.  

PubMed

Effect size information is essential for the scientific enterprise and plays an increasingly central role in the scientific process. We extracted 147,328 correlations and developed a hierarchical taxonomy of variables reported in Journal of Applied Psychology and Personnel Psychology from 1980 to 2010 to produce empirical effect size benchmarks at the omnibus level, for 20 common research domains, and for an even finer grained level of generality. Results indicate that the usual interpretation and classification of effect sizes as small, medium, and large bear almost no resemblance to findings in the field, because distributions of effect sizes exhibit tertile partitions at values approximately one-half to one-third those intuited by Cohen (1988). Our results offer information that can be used for research planning and design purposes, such as producing better informed non-nil hypotheses and estimating statistical power and planning sample size accordingly. We also offer information useful for understanding the relative importance of the effect sizes found in a particular study in relationship to others and which research domains have advanced more or less, given that larger effect sizes indicate a better understanding of a phenomenon. Also, our study offers information about research domains for which the investigation of moderating effects may be more fruitful and provide information that is likely to facilitate the implementation of Bayesian analysis. Finally, our study offers information that practitioners can use to evaluate the relative effectiveness of various types of interventions. (PsycINFO Database Record (c) 2014 APA, all rights reserved). PMID:25314367

Bosco, Frank A; Aguinis, Herman; Singh, Kulraj; Field, James G; Pierce, Charles A

2014-10-13

396

Doppler Effect JS Model  

NSDL National Science Digital Library

The Doppler Effect JS Model shows five different animations with different combinations of moving/stationary sources/detectors. The final animation shows what happens when a source exceeds the speed of sound. The Doppler Effect JS Model was developed using the Easy Java Simulations (EJS) version 5. It is distributed as a ready-to-run html page and requires only a browser with JavaScript support. It is also distributed as an ePub.

Kennedy, Matt; Dixon, Rachel

2014-07-02

397

Demonstration of electron filtering to increase the Seebeck coefficient in In0.53Ga0.47As/In0.53Ga0.28Al0.19As superlattices  

E-print Network

and the thermoelectric power factor of heterostructured materials over that of the bulk. We present a theoretical model.50.Lw, 73.21. b Traditionally, research on thermoelectric materials has fo- cused on finding, is electrical conductivity, is thermal conductivity, and T is temperature. Good thermoelectric materials have

398

Barriers to effective teaching.  

PubMed

Medical school faculty members are charged with the critical responsibility of preparing the future physician and medical scientist workforce. Recent reports suggest that medical school curricula have not kept pace with societal needs and that medical schools are graduating students who lack the knowledge and skills needed to practice effectively in the 21st century. The majority of faculty members want to be effective teachers and graduate well-prepared medical students, but multiple and complex factors-curricular, cultural, environmental, and financial-impede their efforts. Curricular impediments to effective teaching include unclear definitions of and disagreement on learning needs, misunderstood or unstated goals and objectives, and curriculum sequencing challenges. Student and faculty attitudes, too few faculty development opportunities, and the lack of an award system for teaching all are major culture-based barriers. Environmental barriers, such as time limitations, the setting, and the physical space in which medical education takes place, and financial barriers, such as limited education budgets, also pose serious challenges to even the most committed teachers. This article delineates the barriers to effective teaching as noted in the literature and recommends action items, some of which are incremental whereas others represent major change. Physicians-in-training, medical faculty, and society are depending on medical education leaders to address these barriers to effect the changes needed to enhance teaching and learning. PMID:21346500

DaRosa, Debra A; Skeff, Kelley; Friedland, Joan A; Coburn, Michael; Cox, Susan; Pollart, Susan; O'connell, Mark; Smith, Sandy

2011-04-01

399

The real butterfly effect  

NASA Astrophysics Data System (ADS)

Historical evidence is reviewed to show that what Ed Lorenz meant by the iconic phrase ‘the butterfly effect’ is not at all captured by the notion of sensitive dependence on initial conditions in low-order chaos. Rather, as presented in his 1969 Tellus paper, Lorenz intended the phrase to describe the existence of an absolute finite-time predicability barrier in certain multi-scale fluid systems, implying a breakdown of continuous dependence on initial conditions for large enough forecast lead times. To distinguish from ‘mere’ sensitive dependence, the effect discussed in Lorenz's Tellus paper is referred to as ‘the real butterfly effect’. Theoretical evidence for such a predictability barrier in a fluid described by the three-dimensional Navier-Stokes equations is discussed. Whilst it is still an open question whether the Navier-Stokes equation has this property, evidence from both idealized atmospheric simulators and analysis of operational weather forecasts suggests that the real butterfly effect exists in an asymptotic sense, i.e. for initial-time atmospheric perturbations that are small in scale and amplitude compared with (weather) scales of interest, but still large in scale and amplitude compared with variability in the viscous subrange. Despite this, the real butterfly effect is an intermittent phenomenon in the atmosphere, and its presence can be signalled a priori, and hence mitigated, by ensemble forecast methods.

Palmer, T. N.; Döring, A.; Seregin, G.

2014-09-01

400

Knowledge of Contraceptive Effectiveness  

PubMed Central

Objectives To determine women's knowledge of contraceptive effectiveness. Study Design We performed a cross-sectional analysis of a contraceptive knowledge questionnaire completed by 4,144 women enrolled in the Contraceptive CHOICE Project prior to receiving comprehensive contraceptive counseling and choosing their method. For each contraceptive method, women were asked “what percentage would get pregnant in a year: <1%, 1-5%, 6-10%, >10%, don't know.” Results Overall, 86% of subjects knew the annual risk of pregnancy was >10% if no contraception is used. More than 45% of women overestimate the effectiveness of depo-medroxyprogesterone acetate, pills, patch, ring, and condoms. After adjusting for age, education and contraceptive history, women who chose the intrauterine device (IUD) [RRadj=6.9, 95% CI: 5.6-8.5] or implant [RRadj = 5.9, 95% CI 4.7-7.3] were significantly more likely to accurately identify the effectiveness of their method compared to women who chose either the pill, patch, or ring. Conclusions This cohort demonstrated significant knowledge gaps regarding contraceptive effectiveness and over-estimated the effectiveness of pills, patch, ring, DMPA, and condoms. PMID:22521458

EISENBERG, David L.; SECURA, Gina M.; MADDEN, Tessa E.; ALLSWORTH, Jenifer E.; ZHAO, Qiuhong; PEIPERT, Jeffrey F.

2014-01-01

401

New type of thermoelectric conversion of energy by semiconducting liquid anisotropic media  

E-print Network

The paper describes preliminary investigations of a new effect in conducting anisotropic liquids, which leads to thermoelectric conversion of energy. Nematic liquid crystals with semiconducting dopes are used. A thermoelectric figure of merit ZT = 0.2 is obtained in experiments. The effect can be explained by assuming that the thermocurrent in semiconducting nematics, in contrast to the Seebeck effect, is a nonlinear function of the temperature gradient and of the temperature itself. Though the discovered effect has to be further investigated, the data obtained suggest that it can be effectively used in alternative energy engineering.

Sergey I. Trashkeev; Alexey N. Kudryavtsev

2013-08-01

402

Effective Documentation Tools  

NASA Technical Reports Server (NTRS)

Quality assurance programs provide a very effective means to monitor and evaluate medical care. Quality assurance involves: (1) Identify a problem; (2) Determine the source and nature of the problem; (3) Develop policies and methods to effect improvement; (4) Implement those polices; (5) Monitor the methods applied; and (6) Evaluate their effectiveness. Because this definition of quality assurance so closely resembles the Nursing Process, the health unit staff was able to use their knowledge of the nursing process to develop many forms which improve the quality of patient care. These forms include the NASA DFRC Service Report, the occupational injury form (Incident Report), the patient survey (Pre-hospital Evaluation/Care Report), the Laboratory Log Sheet, the 911 Run Sheet, and the Patient Assessment Stamp. Examples and steps which are followed to generate these reports are described.

Sleboda, Claire

1997-01-01

403

Applications of effective Lagrangians  

SciTech Connect

Effective Lagrangians were originally used only at the tree level as so-called phenomenological Lagrangians since they were in general non-renormalizable. Today they are treated as effective field theories valid below a characteristic energy scale. Quantum corrections can then be calculated in a consistent way as for any renormalizable theory. A few applications of the Euler-Heisenberg Lagrangian for interacting photons at low energies are presented together with recent developments in the use of QED for non-relativistic systems. Finally, the ingredients of an effective theory for the electroweak sector of the Standard Model are discussed in the case of a non-linear realization of the Higgs mechanism using the Stueckelberg formalism.

Ravndal, Finn [Institute of Physics, University of Oslo, N-0316 Oslo (Norway)

1997-06-15

404

Transgenerational genetic effects  

PubMed Central

Since Mendel, studies of phenotypic variation and disease risk have emphasized associations between genotype and phenotype among affected individuals in families and populations. Although this paradigm has led to important insights into the molecular basis for many traits and diseases, most of the genetic variants that control the inheritance of these conditions continue to elude detection. Recent studies suggest an alternative mode of inheritance where genetic variants that are present in one generation affect phenotypes in subsequent generations, thereby decoupling the conventional relations between genotype and phenotype, and perhaps, contributing to ‘missing heritability’. Under some conditions, these transgenerational genetic effects can be as frequent and strong as conventional inheritance, and can persist for multiple generations. Growing evidence suggests that RNA mediates these heritable epigenetic changes. The primary challenge now is to identify the molecular basis for these effects, characterize mechanisms and determine whether transgenerational genetic effects occur in humans. PMID:22122083

Nelson, Vicki R; Nadeau, Joseph H

2012-01-01

405

Effective Nutritional Supplement Combinations  

NASA Astrophysics Data System (ADS)

Few supplement combinations that are marketed to athletes are supported by scientific evidence of their effectiveness. Quite often, under the rigor of scientific investigation, the patented combination fails to provide any greater benefit than a group given the active (generic) ingredient. The focus of this chapter is supplement combinations and dosing strategies that are effective at promoting an acute physiological response that may improve/enhance exercise performance or influence chronic adaptations desired from training. In recent years, there has been a particular focus on two nutritional ergogenic aids—creatine monohydrate and protein/amino acids—in combination with specific nutrients in an effort to augment or add to their already established independent ergogenic effects. These combinations and others are discussed in this chapter.

Cooke, Matt; Cribb, Paul J.

406

Disentangling the EMC effect  

NASA Astrophysics Data System (ADS)

The deep inelastic scattering cross section for scattering from bound nucleons differs from that of free nucleons. This phenomena, first discovered 30 years ago, is known as the EMC effect and is still not fully understood. Recent analysis of world data showed that the strength of the EMC effect is linearly correlated with the relative amount of Two-Nucleon Short Range Correlated pairs (2N-SRC) in nuclei. The latter are pairs of nucleons whose wave functions overlap, giving them large relative momentum and low center of mass momentum, where high and low is relative to the Fermi momentum of the nucleus. The observed correlation indicates that the EMC effect, like 2N-SRC pairs, is related to high momentum nucleons in the nucleus. This paper reviews previous studies of the EMC-SRC correlation and studies its robustness. It also presents a planned experiment aimed at studying the origin of this EMC-SRC correlation.

Piasetzky, E.; Hen, O.; Weinstein, L. B.

2013-10-01

407

Giant Thermoelectric Effect in Graphene-Based Topological Insulators with Heavy Adatoms and Nanopores  

NASA Astrophysics Data System (ADS)

Designing thermoelectric materials with high figure of merit $ZT=S^2 G T/\\kappa$ requires fulfilling three often irreconcilable conditions, i.e., the high electrical conductance $G$, small thermal conductance $\\kappa$ and high Seebeck coefficient $S$. Nanostructuring is one of the promising ways to achieve this goal as it can substantially suppress lattice contribution to $\\kappa$. However, it may also unfavorably influence the electronic transport in an uncontrollable way. Here we theoretically demonstrate that this issue can be ideally solved by fabricating graphene nanoribbons with heavy adatoms and nanopores. These systems, acting as a two-dimensional topological insulator with robust helical edge states carrying electrical current, yield a highly optimized power factor $S^2G$ per helical conducting channel. Concurrently, their array of nanopores impedes the lattice thermal conduction through the bulk. Using quantum transport simulations coupled with first-principles electronic and phononic band structure calculations, the thermoelectric figure of merit is found to reach its maximum $ZT \\simeq 3$ at $T \\simeq 40$ K. This paves a way to design high-$ZT$ materials by exploiting the nontrivial topology of electronic states through nanostructuring.

Chang, Po-Hao; Bahramy, Mohammad Saeed; Nagaosa, Naoto; Nikoli?, Branislav K.

2014-07-01

408

Effect of assisted hopping on thermopower in an interacting quantum dot  

NASA Astrophysics Data System (ADS)

We investigate the electrical conductance and thermopower of a quantum dot tunnel coupled to external leads described by an extension of the Anderson impurity model which takes into account the assisted hopping processes, i.e., the occupancy-dependence of the tunneling amplitudes. We provide analytical understanding based on scaling arguments and the Schrieffer-Wolff transformation, corroborated by detailed numerical calculations using the numerical renormalization group method. The assisted hopping modifies the coupling to the two-particle state, which shifts the Kondo exchange coupling constant and exponentially reduces or enhances the Kondo temperature, breaks the particle-hole symmetry, and strongly affects the thermopower. We discuss the gate-voltage and temperature dependence of the transport properties in various regimes. For a particular value of the assisted hopping parameter we find peculiar discontinuous behaviour in the mixed-valence regime. Near this value, we find very high Seebeck coefficient. We show that, quite generally, the thermopower is a highly sensitive probe of assisted hopping and Kondo correlations.

Tooski, S. B.; Ramšak, A.; Bu?ka, B. R.; Žitko, R.

2014-05-01

409

Giant thermoelectric effect in graphene-based topological insulators with heavy adatoms and nanopores.  

PubMed

Designing thermoelectric materials with high figure of merit ZT = S(2)GT/Ktot requires fulfilling three often irreconcilable conditions, that is, the high electrical conductance G, small thermal conductance Ktot, and high Seebeck coefficient S. Nanostructuring is one of the promising ways to achieve this goal as it can substantially suppress lattice contribution to Ktot. However, it may also unfavorably influence the electronic transport in an uncontrollable way. Here, we theoretically demonstrate that this issue can be ideally solved by fabricating graphene nanoribbons with heavy adatoms and nanopores. The adatoms locally enhance spin-orbit coupling in graphene thereby converting it into a two-dimensional topological insulator with a band gap in the bulk and robust helical edge states, which carry electrical current and generate a highly optimized power factor S(2)G per helical conducting channel due to narrow boxcar-function-shaped electronic transmission (surpassing even the Mahan-Sofo limit obtained for delta-function-shaped electronic transmission). Concurrently, the array of nanopores impedes the lattice thermal conduction through the bulk. Using quantum transport simulations coupled with first-principles electronic and phononic band structure calculations, the thermoelectric figure of merit is found to reach its maximum ZT ? 3 at low temperatures T ? 40 K. This paves a way to design high-ZT materials by exploiting the nontrivial topology of electronic states through nanostructuring. PMID:24932511

Chang, Po-Hao; Bahramy, Mohammad Saeed; Nagaosa, Naoto; Nikoli?, Branislav K

2014-07-01

410

Health Effects of Air Pollution  

MedlinePLUS

... Health effects of air pollution Health effects of air pollution Breathing air that is not clean can hurt ... important to know about the health effects that air pollution can have on you and others. Once you ...

411

Side Effects of Hormone Therapy  

MedlinePLUS

... PCF Spotlight Glossary African American Men Living with Prostate Cancer Side Effects of Hormone Therapy Side Effects Urinary ... to evaluate its use in men with advanced prostate cancer. If the approach proves to be as effective ...

412

Habituation of reinforcer effectiveness  

PubMed Central

In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral- and neural-based explanations of reinforcement. We argue that HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009; Rankin etal., 2009). We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow) normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect “accelerated-HRE.” Consideration of HRE is important for the development of effective reinforcement-based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior. PMID:24409128

Lloyd, David R.; Medina, Douglas J.; Hawk, Larry W.; Fosco, Whitney D.; Richards, Jerry B.

2014-01-01

413

Quantum Spin Hall Effect  

SciTech Connect

The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of 2 e/4{pi}. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.

Bernevig, B.Andrei; Zhang, Shou-Cheng; /Stanford U., Phys. Dept.

2010-01-15

414

Anticancer effects of fucoidan.  

PubMed

Recently, there has been an increased interest in the pharmacologically active natural compounds isolated and used for remedies of various kinds of diseases, including cancer. The great deal of interest has been developed to isolate bioactive compounds from marine resources because of their numerous health beneficial effects. Among marine resources, marine algae are valuable sources of structurally diverse bioactive compounds. Fucoidan is a sulfated polysaccharide derived from brown seaweeds and has been used as an ingredient in some dietary supplement products. Fucoidan has various biological activities including antibacterial, antioxidant, anti-inflammatory, anticoagulant, and antitumor activities. So this chapter deals with anticancer effects of fucoidan. PMID:25081084

Senthilkumar, Kalimuthu; Kim, Se-Kwon

2014-01-01

415

ENVIRONMENTAL RESIDUE EFFECTS DATABASE (ERED)  

EPA Science Inventory

US Army Corps of Engineers public web site for the "Environmental Residue Effects Database", a searchable database of adverse biological effects associated with tissue concentrations of various contaminants....

416

Physiological effects of hypnosis  

Microsoft Academic Search

There are many studies indicating that sensory, circulatory, gastrointestinal, and cutaneous functions can be altered by means of hypnosis. There also are many studies indicating that similar physiological effects can be produced by symbolic stimulation without hypnosis. The assumption that hypnotic behavior is a function of the trance state is open to question. From Psyc Abstracts 36:01:3II90B.

Theodore Xenophon Barber

1961-01-01

417

Economic effects of echinococcosis  

Microsoft Academic Search

Cystic echinococcosis (CE) has a number of important economic effects. The most tangible of these is the cost of expensive medical treatment for human cases. Each confirmed case of CE can cost the health services or individual several thousand dollars. In addition to these costs, the additional cost of loss of edible offal from agricultural animals is well known. This

P. R Torgerson

2003-01-01

418

Towards Hall effect spintronics  

Microsoft Academic Search

Major efforts in the current exploration of spintronics are focused on the giant magnetoresistance (GMR) phenomenon in metallic, semiconducting and tunnel junction magnetic heterostructures. I wish to present a different approach based on the extraordinary Hall effect (EHE). Since its discovery more than a century ago, the EHE was not considered seriously for technological applications because of its relatively small

A. Gerber

2007-01-01

419

Case 26: Somogyi effect  

Technology Transfer Automated Retrieval System (TEKTRAN)

This individual has a classic manifestation of the Somogyi effect, which is fasting morning hyperglycemia in response to hypoglycemia in the early morning and late night hours. The danger is that if night-time blood glucose levels are not measured, the physician may interpret the patient as having h...

420

FIELD DISPERSANT EFFECTIVENESS TEST  

EPA Science Inventory

The EPA's OHMSETT facility has developed a rapid field test that includes some of the theoretical aspects and conditions of dispersion at sea. This Field Dispersant Effectiveness Test (FDET) has been used to evaluate the dispersibility of various commonly-transported oils and mak...

421

Cutaneous Effects of Smoking  

Microsoft Academic Search

Background: Cigarette smoking is the single biggest preventable cause of death and disability in developed countries and is a significant public health concern. While known to be strongly associated with a number of cardiovascular and pulmonary diseases and cancers, smoking also leads to a variety of cutaneous manifestations. Objective: This article reviews the effects of cigarette smoking on the skin

Anatoli Freiman; Garrett Bird; Andrei I. Metelitsa; Benjamin Barankin; Gilles J. Lauzon

2004-01-01

422

Effective Thinking Outdoors.  

ERIC Educational Resources Information Center

Effective Thinking Outdoors (ETO) is an organization that teaches thinking skills and strategies via significant outdoor experiences. Identifies the three elements of thinking as creativity, play, and persistence; presents a graphic depiction of the problem-solving process and aims; and describes an ETO exercise, determining old routes of travel…

Hyde, Rod

1997-01-01

423

Effectively Communicating Qualitative Research  

ERIC Educational Resources Information Center

This article is a guide for counseling researchers wishing to communicate the methods and results of their qualitative research to varied audiences. The authors posit that the first step in effectively communicating qualitative research is the development of strong qualitative research skills. To this end, the authors review a process model for…

Ponterotto, Joseph G.; Grieger, Ingrid

2007-01-01

424

Effects of nuclear war  

SciTech Connect

The author reviews the subject rising the following topics and subtopics: I. Nuclear explosions: heat, nuclear radiation, and radioactive fallout; II. Effects: radiation sickness, burns, blast injuries, and equivalent areas of death; III. Nuclear war: battlefield, regional, intercontinental - counterforce, and intercontinental - counter-city and industry. There are two appendices. 34 references, 32 figures.

von Hippel, F.

1983-01-01

425

Effective Presentations Organization  

E-print Network

· Qualities of great speakers · Other information Content · Be faithful to your audience Organization I1 Pericles Effective Presentations · Content · Organization · Delivery · Visual aids and graphics. Intent E. Payoff Body II. Body A. Points organized as described in "Intent" B. Make transitions clear

Shull, David H.

426

EFFECTS ON SALTWATER ORGANISMS  

EPA Science Inventory

The literature review summarizes current data on the effects of pesticides and metals on marine organisms, aquatic environmental research methods, bioaccumulation of pollutants by estuarine and marine organisms and in water/sediment residues and biota. Results of studies of the e...

427

Effectiveness of Smokeless Ashtrays  

Microsoft Academic Search

Most environmental tobacco smoke (ETS) issues from the tips of smoldering cigarettes between puffs. Smokeless ashtrays are designed to reduce ETS exposure by removing particulate and\\/or gas-phase contaminants from this plume. This paper describes an experimental investigation of the effectiveness of four smokeless ashtrays: two commercial devices and two prototypes constructed by the authors. In the basic experimental protocol, one

David A. Wampler; Shelly Miller-Leiden; William W. Nazaroff; Ashok J. Gadgil; Andres Litvak; K. R. R. Mahanama; Matty Nematollahi

1995-01-01

428

Space Environmental Effects Knowledgebase  

NASA Technical Reports Server (NTRS)

This report describes the results of an NRA funded program entitled Space Environmental Effects Knowledgebase that received funding through a NASA NRA (NRA8-31) and was monitored by personnel in the NASA Space Environmental Effects (SEE) Program. The NASA Project number was 02029. The Satellite Contamination and Materials Outgassing Knowledgebase (SCMOK) was created as a part of the earlier NRA8-20. One of the previous tasks and part of the previously developed Knowledgebase was to accumulate data from facilities using QCMs to measure the outgassing data for satellite materials. The main object of this current program was to increase the number of material outgassing datasets from 250 up to approximately 500. As a part of this effort, a round-robin series of materials outgassing measurements program was also executed that allowed comparison of the results for the same materials tested in 10 different test facilities. Other programs tasks included obtaining datasets or information packages for 1) optical effects of contaminants on optical surfaces, thermal radiators, and sensor systems and 2) space environmental effects data and incorporating these data into the already existing NASA/SEE Knowledgebase.

Wood, B. E.

2007-01-01

429

Designing Effective Posters  

NSDL National Science Digital Library

This website presents an online tutorial about creating effective poster presentations. The site guides users through the basics of poster design, which should free the presenter to focus on discussion of essential elements of the work. Decisions about poster format and design which contribute to efficient and accurate transfer of information using this medium are also discussed.

Radel, Jeff; Center, Ku M.

430

Building Effective Afterschool Programs.  

ERIC Educational Resources Information Center

Through a comprehensive review of various afterschool programs across the United States, this resource provides a practical overview of the research and best practices that can be easily adapted and applied in the development of highly effective afterschool programs. chapters focus on: (1) "Why Afterschool Programs?" (benefits, challenges, and…

Fashola, Olatokunbo S.

431

Microcircuit radiation effects databank  

NASA Technical Reports Server (NTRS)

Radiation test data submitted by many testers is collated to serve as a reference for engineers who are concerned with and have some knowledge of the effects of the natural radiation environment on microcircuits. Total dose damage information and single event upset cross sections, i.e., the probability of a soft error (bit flip) or of a hard error (latchup) are presented.

1983-01-01

432

Explaining Charter School Effectiveness  

ERIC Educational Resources Information Center

This study uses entrance lotteries to explore heterogeneity in the achievement effects of charter schools across demographic groups and between urban and non-urban areas in Massachusetts. The authors develop a framework for interpreting this heterogeneity using both student- and school-level explanatory variables. (Contains 4 tables.)

Angrist, Joshua D.; Pathak, Parag A.; Walters, Christopher R.

2012-01-01

433

Effects of Induced Astigmatism.  

ERIC Educational Resources Information Center

The relationship of astigmatism to reading and the possible detrimental effects it might have on reading were investigated. The greatest incidence of astigmatism was for the with-the-rule type ranging from .50 to 1.00 diopter. This type of astigmatism was induced in 35 seniors from the Los Angeles College of Optometry by placing cylindrical lenses…

Schubert, Delwyn G.; Walton, Howard N.

1968-01-01

434

The Effectiveness of DISCOVER.  

ERIC Educational Resources Information Center

Computer assisted career guidance (CACG) systems have been around for at least the past 20 years in career guidance centers. There are two types of systems: information retrieval and guidance interaction. This study investigated the effectiveness of DISCOVER in facilitating career decisions among college students. DISCOVER is a systematic career…

Engel, Elaine Frances

435

Side Effects of Chemotherapy  

MedlinePLUS

... a way to relax—listening to music, doing yoga or stretching exercises, taking a walk in the woods or on the beach, or watching a movie marathon on television. Effectively relieving stress will help contribute to the ultimate goal of ...

436

Exploring the Lotus Effect  

NSDL National Science Digital Library

Students test and observe the "self-cleaning" lotus effect using a lotus leaf and cloth treated with a synthetic lotus-like superhydrophobic coating. They also observe the Wenzel and Cassie Baxter wetting states by creating and manipulating condensation droplets on the leaf surface. They consider the real-life engineering applications for these amazing water-repellent and self-cleaning properties.

NSF CAREER Award and RET Program, Mechanical Engineering and Material Science,

437

Minnesota Educational Effectiveness Program.  

ERIC Educational Resources Information Center

Goals and implementation of the Minnesota Educational Effectiveness Program (MEEP), a school-based improvement program, are presented in this document. The program's mission is to enhance learning and instruction through planned change based upon research facilitated by staff development. The first section examines program components, specifically…

Minnesota State Dept. of Education, St. Paul. Instructional Design Section.

438

The Anrep Effect Reconsidered  

PubMed Central

Evidence is presented supporting the hypothesis that the positive inotropic effect after an abrupt increase in systolic pressure (Anrep effect) is the recovery from subendocardial ischemia induced by the increase and subsequently corrected by vascular autoregulation of the coronary bed. Major evidence consists of data obtained from an isolated heart preparation showing that the Anrep effect can be abolished with coronary vasodilation, and that with an abrupt increase in systolic pressure there is a significant reduction in the distribution of coronary flow to subendocardial layers of the ventricle. Furthermore, the intracardiac electrocardiogram shows S-T segment and T wave changes after an abrupt increase in ventricular pressure similar to that noted after coronary constriction. Major implications are that normally there may be ischemia of the subendocardial layers tending to reduce myocardial contractility which may account, in part, for the positive inotropic effect of various coronary vasodilators; that with an abrupt increase in ventricular pressure the subendocardium is rendered temporarily ischemic, placing the heart in jeopardy from arrhythmias until this is corrected; and that end-diastolic pressure and the intracardiac electrocardiogram may provide a means of evaluating the adequacy of circulation to subendocardial layers in diseased ventricles when systolic pressure is abruptly increased. PMID:5056656

Monroe, R. G.; Gamble, W. J.; Lafarge, C. G.; Kumar, A. E.; Stark, J.; Sanders, G. L.; Phornphutkul, C.; Davis, M.

1972-01-01

439

What Effective Schools Do  

ERIC Educational Resources Information Center

Research has been showing that the most important development in K-12 education over the past decade has been the emergence of a growing number of urban schools that have been convincingly shown to have dramatic positive effects on the achievement of disadvantaged students. Those with the strongest evidence of success are oversubscribed charter…

West, Martin R.; Gabrieli, Christopher F. O.; Finn, Amy S.; Kraft, Matthew A.; Gabrieli, John D. E.

2014-01-01

440

Tacrolimus effect on rosacea  

Microsoft Academic Search

Twenty-four patients with erythrotelangiectatic or papulopustular rosacea were treated with 0.1% tacrolimus topical ointment in a 12-week open-label trial. Erythema was significantly improved in both rosacea subtypes (P < .05). There was no decrease in the number of papulopustular lesions. Side effects were consistent with those on the tacrolimus topical ointment labeling.

Joel T. M Bamford; Barbara A Elliott; Irina V Haller

2004-01-01

441

Documentation: Effective AND Literate  

Microsoft Academic Search

The purpose of this paper is to show how documentation can be literate, in a stylistic sense, and still be effective. Literate prose is a powerful tool that, when properly used in computer documentation, can take advantage of the full power of the English language. This does not mean that all computer documentation must or can read like a Nobel

Paul S. Burdett Jr.

1985-01-01

442

EFFECTIVE USE OF PHEROMONES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Effective integrated pest management programs are needed for food processing and storage facilities and this requires improvements in our ability to monitor pest populations and use this information to target management tactics in both time and space. The use of pheromone traps to detect pests is i...

443

Simple Adaptive Mosaic Effects  

Microsoft Academic Search

We present an algorithm that creates a mosaic effect for an image in an adaptive and automatic fashion. The algo- rithm is automatic because it does not need user interven- tion, except for the choice of a couple of parameters. The algorithm is adaptive because it creates tiles whose sizes are adapted to the features of the image. This is

Geisa Martins Faustino; Luiz Henrique De Figueiredo

2005-01-01

444

Effects of Acid Rain  

NSDL National Science Digital Library

This portal provides links to information on the potential damage caused to the environment by acid rain. An introductory paragraph briefly describes the damage to lakes and streams, building materials, and monuments. Each link access additional information on these topics: surface waters and aquatic animals, forests, automotive coatings, soluble building materials such as marble or limestone, atmospheric haze, and human health effects.

445

Reporting Research Results Effectively  

ERIC Educational Resources Information Center

Assessment research is at its best when it packages research results and data so that they can be digested by multiple audiences. Too many assessment researchers spend all their efforts planning and executing the research project with little attention to closing the loop at the end. If assessment findings are not communicated effectively, the…

Volkwein, J. Fredericks

2010-01-01

446

Alcohol's Effects on Adolescents  

Microsoft Academic Search

uring adolescence, many people begin to experi­ ment with alcohol, yet relatively little is known about alcohol's effects on this critical stage of development. We do know that early initiation of alcohol use remains one of the most powerful predictors of later alcohol abuse (Grant 1998). We also know that during adolescence changes occur in the regions of the brain

Linda Patia Spear

2002-01-01

447

Effective Group Counseling.  

ERIC Educational Resources Information Center

This book focuses on the essential elements of leading effective groups in group counseling. Chapter 1 concentrates on the rationale behind using groups and their myths, advantages, and limitations. Chapter 2 discusses different types of groups, especially those that are therapeutic and task-oriented, and their theory and ethics. Chapter 3 delves…

Gladding, Samuel T.

448

Lorenz Attractor -- Butterfly Effect  

NSDL National Science Digital Library

The "Butterfly Effect", or more technically the "sensitive dependence on initial conditions", is the essence of chaos. This is illustrated an applet of the Lorenz Attractor. The demonstration shows a graphical representation of the time variation of three variables X(t),Y(t) and Z(t), coupled by non-linear evolution equations.

Michael Cross, Cal T.

449

Conditional Effects in Graphplan  

Microsoft Academic Search

Graphplan has attracted considerable interest because of its extremely high performance, but the algorithm's inability to handle action representations more expressive than STRIPS is a major limitation. In particular, extending Graphplan to handle conditional effects is a surprisingly subtle enterprise. In this paper, we describe the space of possible alternatives, and then concentrate on one particular approach we call factored

Corin R. Anderson; David E. Smith; Daniel S. Weld

1998-01-01

450

Cost Effective Prototyping  

NASA Technical Reports Server (NTRS)

This laboratory exercise seeks to develop a cost effective prototype development. The exercise has the potential of linking part design, CAD, mold development, quality control, metrology, mold flow, materials testing, fixture design, automation, limited parts production and other issues as related to plastics manufacturing.

Wickman, Jerry L.; Kundu, Nikhil K.

1996-01-01

451

Nitrogen effects on cantaloupes  

Microsoft Academic Search

The NO3 levels in cantaloupe (Cucumis melo L.) petioles relate closely to N treatment and reflect the N status of the cantaloupe plant. Suggested levels of petiole NO3 in cantaloupes grown in Arizona are presented. Nitrogen treatment had little effect on melon size, earliness, or most storage quality factors that were evaluated except that deficiencies resulted in lower netting, poor

W. D. Pew; B. R. Gardner

1972-01-01

452

Interactive Pi Bonding Effects  

NSDL National Science Digital Library

This application demonstrates the effect of pi bonding on the one-electron ligand field splitting in an octahedral. By clicking on the appropriate buttons students can see how D changes when you move from ligands with no pi bonding capability to pi donor and pi acceptor ligands.

453

Strongly nonlinear thermovoltage and heat dissipation in interacting quantum dots  

NASA Astrophysics Data System (ADS)

We investigate the nonlinear regime of charge and energy transport through Coulomb-blockaded quantum dots. We discuss crossed effects that arise when electrons move in response to thermal gradients (Seebeck effect) or energy flows in reaction to voltage differences (Peltier effect). We find that the differential thermoelectric conductance shows a characteristic Coulomb butterfly structure due to charging effects. Importantly, we show that experimentally observed thermovoltage zeros are caused by the activation of Coulomb resonances at large thermal shifts. Furthermore, the power dissipation asymmetry between the two attached electrodes can be manipulated with the applied voltage, which has implications for the efficient design of nanoscale coolers.

Sierra, Miguel A.; Sánchez, David

2014-09-01

454

Unintended Effects of Program Evaluation.  

ERIC Educational Resources Information Center

Unintended effects of evaluation are discussed, with reference to the Hawthorne Effect, where unintended effects overshadow the manipulations controlled by researchers. Unintended effects are categorized as (1) affective reactions; (2) political dimensions; (3) importance of individual differences; and (4) expectations concerning evaluation.…

Welch, Wayne W.; Sternhagen, Fred

1991-01-01

455

Evolution of Earth's Greenhouse Effect  

Microsoft Academic Search

The major factors contributing to Earth's greenhouse effect are discussed along with various quantitative methods for determining the greenhouse effect. Earth's greenhouse effect has evolved over geologic time scales and continues to evolve. The magnitude of Earth's greenhouse effect is explored for particular time periods of Earth's evolution from the Neoproterozoic to present. Coupled climate model simulations for these various

J. T. Kiehl

2003-01-01

456

SOLAR EFFECTS ON BUILDING DESIGN.  

ERIC Educational Resources Information Center

A REPORT OF A PROGRAM HELD AS PART OF THE BUILDING RESEARCH INSTITUTE 1962 SPRING CONFERENCE ON THE SOLAR EFFECTS ON BUILDING DESIGN. TOPICS DISCUSSED ARE--(1) SOLAR ENERGY DATA APPLICABLE TO BUILDING DESIGN, (2) THERMAL EFFECTS OF SOLAR RADIATION ON MAN, (3) SOLAR EFFECTS ON ARCHITECTURE, (4) SOLAR EFFECTS ON BUILDING COSTS, (5) SELECTION OF…

Building Research Inst., Inc., Washington, DC.

457

Calculating and Synthesizing Effect Sizes  

Microsoft Academic Search

The effect size is a standardized, scale-free measure of the relative size of the effect of an interven- tion, and it has important and practical implications for clinicians in the speech and hearing field who are interested in estimating the effects of interventions. This article develops a conceptual interpretation of the effect size, makes explicit assumptions for its proper use

Herbert M. Turner; Robert M. Bernard

2006-01-01

458

Thermochimica Acta 457 (2007) 1119 Chimie douce synthesis and thermochemical characterization  

E-print Network

-called Figure of Merit, ZT (where Z = S2/, S is the Seebeck coefficient, and are the electrical and thermal conductivities, respectively) [7]. Large Seebeck coefficients and high electrical conductivities are observed

459

PSPICE-Compatible Equivalent Circuit of Thermoelectric Coolers Simon Lineykin and Sam Ben-Yaakov*  

E-print Network

, Joule heating, Peltier cooling/heating, Seebeck power generation and the Thompson phenomenon. All electrical resistance of the couple, Seebeck coefficient, and T=(Te-Ta). It is conventional to leave out

460

IEEE POWER ELECTRONICS LETTERS, VOL. 3, NO. 2, JUNE 2005 63 Analysis of Thermoelectric Coolers by a  

E-print Network

/heating, Seebeck power generation and the Thompson Manuscript received November 7, 2004; revised November 19, 2004, R is the electrical resistance of the couple, Seebeck coefficient, and . It is conventional to leave

461

Doppler Effect Model  

NSDL National Science Digital Library

The Doppler Effect model demonstrates the shift in frequency of a wave that is produced by the motion of either the wave source or the observer of the wave (or both). In this simulation, you can explore the change in the wave that is produced by source and/or observer motion, and you can even view what the situation looks like from the perspective of the medium (the standard reference frame), the source, or the observer. The Doppler Effect model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_bu_Doppler.jar file will run the program if Java is installed.

Duffy, Andrew

2010-04-25

462

Fire Effects Information System  

NSDL National Science Digital Library

The Fire Effects Information System (FEIS) provides up-to-date information about fire effects on plants and animals. It was developed at the USDA Forest Service Rocky Mountain Research Station's Fire Sciences Laboratory in Missoula, Montana. The FEIS database contains synoptic descriptions, taken from current English-language literature of almost 900 plant species, about 100 animal species, and 16 Kuchler plant communities found on the North American continent. The emphasis of each synopsis is fire and how it affects each species. Background information on taxonomy, distribution, basic biology and ecology of each species is also included. Synopses are thoroughly documented, and each contains a complete bibliography. Personnel from several land management agencies (USDA Forest Service, USDI-BIA, NPS, BLM, F&WS) identified the species to be included in the database. Those agencies funded the original work and continue to support maintenance and updating of the database.

1995-12-12

463

Fatigue and Barkhausen effect  

NASA Astrophysics Data System (ADS)

Piezomagnetism designates a change in the magnetization of materials induced by mechanical actions such as tension or compression. The type of Barkhausen effect that occurs in this work consists of sudden, discontinuous jumps in a material's magnetization that appear in response to smooth (continuous) stress variations. A series of strain controlled fatigue tests with an alternating sinusoidal waveform were carried out to study the relationship between the endurance limit and the Barkhausen effect. Results of fatigue tests on steel specimens exhibiting Barkhausen pulses at various stages are reported and a threshold-crossing analysis is applied to the test results. These studies show that when the fatigue limit is approached, the Barkhausen pulses become, in general, more intense in amplitude and quantity than at other stress levels. A hypothetical mechanism is proposed that relates the intensity of the Barkhausen response to the inception of micro-cracking and rearrangements of the mechanical lattice at the microscopic level.

Tong, Wei

464

Phytoestrogens and their effects.  

PubMed

The chemical structure, classification, source, metabolism, physiological and health effects of plant phytoestrogens and mechanisms of their action are reviewed. The available knowledge suggests that phytoestrogens can affect a number of physiological and pathological processes related to reproduction, bone remodeling, skin, cardiovascular, nervous, immune systems and metabolism. Due to these effects, phytoestrogens and phytoestrogen-containing diet can be useful for the prevention and treatment of menopausal symptoms, skin aging, osteoporosis, cancer, cardiovascular, neurodegenerative, immune and metabolic diseases. Possible problems in understanding and application of phytoestrogens (multiple targets and multiple estrogen receptor -dependent and -independent mechanisms of action, the discrepancy between the results of experimental and clinical studies, adequate source of phytoestrogen) have been discussed. PMID:25160742

Sirotkin, Alexander V; Harrath, Abdel Halim

2014-10-15

465

Nanocarpet effect induced superhydrophobicity.  

PubMed

By coating a fluorocarbon monolayer on a bundled Si nanorod array substrate, a superhydrophobic surface with contact angle approximately 167 degrees and sliding angle approximately 2 degrees is created due to the nanocarpet effect. Without forming the nanocarpet, we can only obtain a moderately hydrophobic surface with contact angle <151 degrees and sliding angle >17 degrees. Comparison between nanocarpets formed from nanorods with low and high densities confirms that the main reason for the superhydrophobicity is the formation of sharp pyramidal bundles, which effectively reduces the area of solid-liquid contact. Video recording and analysis of millimeter-sized water droplets bouncing on the solid surface are used to ascertain the superhydrophobicity, and the energy dissipation during a low speed impact is estimated to be several nanojoules. PMID:20218548

Fan, Jianguo; Zhao, Yiping

2010-06-01

466

Ground Effect in Flight  

NASA Astrophysics Data System (ADS)

The present paper aims to analyze the propulsion of birds and fishes undergoing the ground effect as well as the lift of high-speed ground vehicle. Applying the analytical method which was developed for flutter of a soft plate placed at an arbitrary position in subsonic channel flows, calculations are carried out first for non-oscillatory case in compressible flow and then for oscillating cases of birds and fishes in incompressible flow. The results obtained show that the ground effect acts to increase not only the lift in steady flight but also the thrust and propulsive efficiency in oscillating modes. This method holds not only in the case of very close proximity to the ground but also in compressible flow case, so it would be applicable to the flutter analysis of high-speed ground vehicle with wings.

Tanida, Yoshimichi

467

The Kaye effect  

NASA Astrophysics Data System (ADS)

The International Young Physicists' Tournament (IYPT) is a worldwide, annual competition for secondary school students. This is our solution to problem number 10, The Kaye effect, as presented in the final round of the 21st IYPT in Trogir, Croatia. The Kaye effect occurs when a thin stream of shampoo or a different adequate non-Newtonian liquid is poured onto a surface. Suddenly, a jet leaves the heap that is formed by the shampoo and begins to 'dance' around the primary jet like a lasso. The phenomenon ends when the 'dancing' jet hits the primary jet and subsequently collapses. We started our investigations based on available literature (Kaye 1963 Nature 197 1001, Versluis et al 2006 J. Stat. Mech., Collyer and Fischer 1976 Nature 261 682). We made experiments with a similar experimental set-up in which we could determine the velocities of both shampoo streams as well as the angle of the 'dancing' stream. From there on, we developed a theoretical model for the energy loss of the jet in the heap. We discovered that the air layer between the jet and the heap is a necessity for the Kaye effect to occur. At this point, our observations differ from the aforementioned literature. This also accounts for the shampoo beam acting as a light guide. Further experiments concerning the viscoelasticity of the shampoo revealed that the elastic property of the shampoo is necessary for the effect to occur. This article is a written version of the oral contribution of the German team to the 21st IYPT competition, which was awarded first prize by an international jury. The article has been edited by European Journal of Physics.

Binder, J. M.; Landig, A. J.

2009-11-01

468

Writing Effective TAFs  

NSDL National Science Digital Library

This module provides an overview of some of the applicable TAF Amendment and Conditional Group usage rules, as presented in the latest version of the National Weather Service Instruction 10-813 on TAF directives. It also presents a methodology for TAF writing and development that will lead to an effective and user-friendly product. The focus is on the ceiling and visibility aspects of the TAF. This module is part of the Distance Learning Course 1: Forecasting Fog and Low Stratus.

Comet

2003-06-28

469

Mössbauer Effect  

NSDL National Science Digital Library

This website provides current and historical information on Rudolf L. Mössbauer and Mössbauer spectroscopy (a type of nuclear gamma resonant spectroscopy). Mössbauer spectroscopy can be used to study a variety of phenomena dealing with shift and splitting of nuclear energy levels. Instruments, labs, and sources for the use and/or study of the Mössbauer effect are provided.

Center, Mã¶ssbauer E.

2008-06-25

470

Magnetic effects on thermocouples  

NASA Astrophysics Data System (ADS)

Thermometers in laboratory environment and industrial applications are often subject to extraneous, usually unwanted and uncontrolled magnetic fields. Magnetic field influence can be minimized, but cannot be fully cancelled out. Even more, in most cases, there is no awareness of the existence of magnetic fields, let alone their effect on measurement instrumentation. In the past, sensitivity to high dc magnetic fields has been investigated in cryogenics and at high temperatures. More recently, the magnetic effect on weak dc magnetic fields was presented. The goal of this paper was to analyse and empirically and experimentally prove the magnetic sensitivity of thermocouples exposed to low magnetic fields: both dc and ac. Precision and uniform alternating and direct magnetic flux densities were generated by means of permanent magnets and power amplifiers with air-cored coils. The magnetic effect on ferromagnetic and non-ferromagnetic thermocouples at liquid-nitrogen-boiling point (-196 °C), ice point (0 °C), in water (17 °C) and at melting point of gallium fixed point cell (29.7646 °C) was investigated. Magnetic-field-dependent temperature errors of up to 700 mK (at 5.3 mT: dc) and up to 1 °C (at 10 mT: ac 50 Hz magnetic fields) were detected. From the results, it can be concluded that, ideally for temperature measurements of the highest accuracy in the above-cryogenic temperature range, magnetic sensitivity should be estimated and taken into account either as the correction of an error and/or as an additional source of measurement uncertainty. Special consideration should be given to thermocouple orientation relative to the magnetic field direction, influence of metal enclosures and magnetization effects on ferromagnetic components of thermocouples.

Beguš, Samo; Bojkovski, Jovan; Drnovšek, Janko; Geršak, Gregor

2014-03-01

471

Hall Effect Measurements  

NSDL National Science Digital Library

The objective of this Web site is twofold: (1) to describe the Hall measurement technique for determining the carrier density and mobility in semiconductor materials and (2) to initiate an electronic interaction forum where workers interested in the Hall effect can exchange ideas and information. It includes an introductory description of the Hall measurement technique and covers basic principles, equipment, and recommended procedures. Keywords: Conductance, conductivity, resistance, resistivity

2012-07-26

472

Optimizing the boron effect  

Microsoft Academic Search

The effects of boron content varying from 0.0001 to 0.0110 wt pct were studied to determine the optimum boron range for commercially desirable combinations of hardenability and notch toughness in 11\\/4 in. thick steel plate made from grade ASTM A514-J. Increasing boron content up to 0.0025 pct resulted in a gradually increasing boron hardenability factor which reached a maximum value

G. F. Melloy; P. R. Summon; P. P. Podgursky

1973-01-01

473

Optimizing the boron effect  

Microsoft Academic Search

The effects of boron content varying from 0.0001 to 0.0110 wt pct were studied to determine the optimum boron range for commercially\\u000a desirable combinations of hardenability and notch toughness in 11\\/4 in. thick steel plate made from grade ASTM A514-J. Increasing\\u000a boron content up to 0.0025 pct resulted in a gradually increasing boron hardenability factor which reached a maximum value

G. F. Melloy; P. R. Summon; P. P. Podgursky

1973-01-01

474

[Therapeutic effectiveness of Crataegus].  

PubMed

Hawthorn (crataegus) has been used since antiquity for medicinal purposes. More recent research suggests it to be useful in congestive heart failure. Rigorous clinical trials show benefit concerning objective signs and subjective symptoms of congestive heart failure stage NYHA-II. No adverse drug reactions have been reported. It is therefore concluded that crataegus is an effective and safe therapeutic alternative for this indication. PMID:8647566

Weihmayr, T; Ernst, E

1996-01-20

475

Doppler-Effect Omnirange  

Microsoft Academic Search

This paper describes an omnirange of a new design in which the transmitting antenna is caused either to move, or to appear to move along a circular path to produce low-deviation FM by Doppler effect. The FM envelope phase of the transmitted signal is directionally characterized. Deviation-expansion and selective-degeneration in an AFC circuit are used at the receiver to detect

Paul Hansel

1953-01-01

476

Neuroprotective effects of creatine  

Microsoft Academic Search

There is a substantial body of literature, which has demonstrated that creatine has neuroprotective effects both in vitro\\u000a and in vivo. Creatine can protect against excitotoxicity as well as against ?-amyloid toxicity in vitro. We carried out studies\\u000a examining the efficacy of creatine as a neuroprotective agent in vivo. We demonstrated that creatine can protect against excitotoxic\\u000a lesions produced by

M. Flint Beal

2011-01-01

477

Extra Housepayments Effect  

NSDL National Science Digital Library

How financial institutions use the monthly mortgage payment and mortgage amortization formulas can be a confusing concept to grasp. This lesson asks students to find a current interest mortgage rate for their city and state. This rate is then applied to an Internet based mortgage calculator to discover the effect that paying extra on a monthly house payment has on total interest paid and length of the loan. A student worksheet is included in the document.

2011-01-05

478

Side effects of benoxaprofen  

Microsoft Academic Search

A study was made of adverse dermatological reactions to the non-steroidal anti-inflammatory agent benoxaprofen. Photosensitivity was seen in several patients, confined to wavelengths less than 340 nm. Other cutaneous side effects were erythema multiforme, the Stevens-Johnson syndrome, milia, and onycholysis. One case of pancytopenia and toxic epidermal necrolysis was reported. patients were not rechallenged with the drug, but these reactions

Brian Diffey; Colin Hindson; F Lawlor

1982-01-01

479

Dark Matter Effective Theory  

E-print Network

We organize the effective (self)interaction terms for complex scalar dark matter candidates which are either an isosinglet, isodoublet or an isotriplet with respect to the weak interactions. The classification has been performed ordering the operators in inverse powers of the dark matter cutoff scale. We assume Lorentz invariance, color and charge neutrality. We also introduce potentially interesting dark matter induced flavor-changing operators. Our general framework allows for model independent investigations of dark matter properties.

Eugenio Del Nobile; Francesco Sannino

2012-04-18

480

Botany: floral fluorescence effect.  

PubMed

The way flowers appear to insects is crucial for pollination. Here we describe an internal light-filtering effect in the flowers of Mirabilis jalapa, in which the visible fluorescence emitted by one pigment, a yellow betaxanthin, is absorbed by another, a violet betacyanin, to create a contrasting fluorescent pattern on the flower's petals. This finding opens up new possibilities for pollinator perception as fluorescence has not previously been considered as a potential signal in flowers. PMID:16163341

Gandía-Herrero, Fernando; García-Carmona, Francisco; Escribano, Josefa

2005-09-15

481

Ejs Doppler Effect Model  

NSDL National Science Digital Library

The Ejs Doppler Effect model displays the detection of sound waves from a moving source and the change in frequency of the detected wave via the Doppler effect. In addition to the wave fronts from the source a graph depicting the time of emission and time of detection of each of the wave fronts is given. The speed of sound, the velocity of the source and the position and velocity of the detector can be changed via text boxes. You can modify this simulation if you have Ejs installed by right-clicking within the plot and selecting âOpen Ejs Modelâ from the pop-up menu item. Ejs Doppler Effect model was created using the Easy Java Simulations (Ejs) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_ehu_waves_doppler.jar file will run the program if Java is installed. Ejs is a part of the Open Source Physics Project and is designed to make it easier to access, modify, and generate computer models. Additional Ejs models for wave optics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Ejs.

Aguirregabiria, Juan

2008-08-20

482

SAD effects on grantmanship  

E-print Network

Seasonal affective disorder (SAD) is a state of depression induced by a lack of sufficient sunlight that occurs at high latitudes during the fall and winter. One effect of SAD is that causes people to be more risk-adverse, an effect that should be considered by granting agencies of high latitude countries. Funding agencies often have programmes aimed at high-risk, innovative research. However, the time of the year during which these purposefully high-risk proposals are evaluated usually does not take into consideration the effects of SAD. In high-latitude countries (e.g., Canada, UK, Nordic and Baltic countries), evaluating proposals for high-risk programmes during the late fall might significantly detract from the very purpose of such programmes. At this time of the year, grant evaluators might be in a darkness-induced state of mild depression. As such, evaluators might be more likely to opt for safe investments, more of the same, the well established, which is the antithesis of innovative research.

Lozano, George A

2014-01-01

483

The Giant Magnetocaloric Effect  

NASA Astrophysics Data System (ADS)

Since the discovery of the magnetocaloric effect in pure iron by E.Warburg in 1881, it has been measured experimentally on many magnetic metals and compounds. The majority of the materials studied order magnetically undergoing a second order phase transformation. The magnetocaloric effect, typically peaking near the Curie or the Néel temperature, generally ranges from 0.5 to 2 K (in terms of adiabatic temperature change) or at 1 to 4 J/kg K (in terms of isothermal magnetic entropy change) per 1 T magnetic field change. The giant magnetocaloric effect recently discovered in Gd_5(Si_xGe_1-x)4 alloys, where x <= 0.5, is associated with a first order magnetic phase transition and it reaches values of 3 to 4 K and 6 to 10 J/kg K per 1 T field change, respectively. The refrigerant capacity, which is the measure of how much heat can be transferred from a cold to a hot reservoir in one ideal thermodynamic cycle, is larger than that of the best second order phase transition materials by 25 to 100%. When the Gd_5(Si_xGe_1-x)4 alloys are compared with other known materials, which show first order magnetic phase transition, such as Dy, Ho, Er, HoCo_2, NdMn_2Si_2, Fe_0.49Rh_0.51, and (Hf_0.83Ta_0.17)Fe_2+x, only Fe_0.49Rh_0.51 has comparable magnetocaloric properties. However, the first order magnetic phase transition in Fe_0.49Rh_0.51 is irreversible, and the magnetocaloric effect disappears after one magnetizing/demagnetizing cycle. A study of the crystal structure, thermodynamics, and magnetism of the Gd_5(Si_xGe_1-x)4 alloys, where 0 <= x <= 1 allowed us to obtain a qualitative understanding of the basic relations between the composition, the crystal structure, and the change in thermodynamics and magnetocaloric properties, which occur in the Gd_5(Si_xGe_1-x)4 system, and which brings about the giant magnetocaloric effect when x <= 0.5.

Pecharsky, Vitalij K.

1998-03-01

484

Causal diagrams, the placebo effect, and the expectation effect  

PubMed Central

Using causal diagrams, a formal research methodology, we analyzed several definitions of placebo and the placebo effect. We conclude that placebo is an ambiguous, redundant term and that the so-called placebo effect conceals far more interesting effects that are attributed to the patient’s expectation. Biomedical research will benefit from abandoning the term placebo effect and focusing instead on a deeper understanding of the expectation variable, including its causes, effects, and effect modifiers. This avenue of research should be pursued by observational cohorts that are nested within clinical trials. PMID:24101881

Shahar, Eyal; Shahar, Doron J

2013-01-01

485

'The Kesterson effect'  

USGS Publications Warehouse

Hypothesized to be derived from Cretaceous marine sedimentary rocks, selenium contamination of the Kesterson National Wildlife Refuge is traced through irrigation drainage to the source bedrock of the California Coast Ranges. This biogeochemical pathway of selenium is defined here as the 'Kesterson effect.' At the refuge ponds, this effect culminated in 1983 in a 64% rate of deformity and death of embryos and hatchlings of wild aquatic birds. From the previous companion paper on irrigation drainage, the Kesterson effect has been implicated in nine of 11 reconnaissance areas studied in the western United States. Deformities have resulted in at least five of these sites. Climatic, geologic, hydrologic, and soil conditions in these reconnaissance areas are similar to those in the area surrounding Kesterson National Wildlife Refuge in the west-central San Joaquin Valley of California, in California, selenium as selenate, was ultimately found weathered with sulfur from marine sources in soluble sodium and magnesium sulfate salts, which are concentrated by evaporation on farmland soils. The Se, mobilized by irrigation drainage, is bioaccumulated to toxic levels in refuge wetland ponds that are located mainly in hydrologically closed basins and thus act as concentrating disposal points. The depositional environment of the ponds may be similar to that of the nutrient-rich continental shelf edge and slope in which Cretaceous, Eocene, and Miocene sediments found to be seleniferous in the California Coast Ranges were deposited. Bioaccumulation may be therefore a primary mechanism of selenium enrichment in ancient sediments in addition to that of the formerly suggested Cretaceous volcanic pathway.

Presser, T.S.

1994-01-01

486

Quantum Effects in Biology  

NASA Astrophysics Data System (ADS)

List of contributors; Preface; Part I. Introduction: 1. Quantum biology: introduction Graham R. Fleming and Gregory D. Scholes; 2. Open quantum system approaches to biological systems Alireza Shabani, Masoud Mohseni, Seogjoo Jang, Akihito Ishizaki, Martin Plenio, Patrick Rebentrost, Alàn Aspuru-Guzik, Jianshu Cao, Seth Lloyd and Robert Silbey; 3. Generalized Förster resonance energy transfer Seogjoo Jang, Hoda Hossein-Nejad and Gregory D. Scholes; 4. Multidimensional electronic spectroscopy Tomáš Man?al; Part II. Quantum Effects in Bacterial Photosynthetic Energy Transfer: 5. Structure, function, and quantum dynamics of pigment protein complexes Ioan Kosztin and Klaus Schulten; 6. Direct observation of quantum coherence Gregory S. Engel; 7. Environment-assisted quantum transport Masoud Mohseni, Alàn Aspuru-Guzik, Patrick Rebentrost, Alireza Shabani, Seth Lloyd, Susana F. Huelga and Martin B. Plenio; Part III. Quantum Effects in Higher Organisms and Applications: 8. Excitation energy transfer in higher plants Elisabet Romero, Vladimir I. Novoderezhkin and Rienk van Grondelle; 9. Electron transfer in proteins Spiros S. Skourtis; 10. A chemical compass for bird navigation Ilia A. Solov'yov, Thorsten Ritz, Klaus Schulten and Peter J. Hore; 11. Quantum biology of retinal Klaus Schulten and Shigehiko Hayashi; 12. Quantum vibrational effects on sense of smell A. M. Stoneham, L. Turin, J. C. Brookes and A. P. Horsfield; 13. A perspective on possible manifestations of entanglement in biological systems Hans J. Briegel and Sandu Popescu; 14. Design and applications of bio-inspired quantum materials Mohan Sarovar, Dörthe M. Eisele and K. Birgitta Whaley; 15. Coherent excitons in carbon nanotubes Leonas Valkunas and Darius Abramavicius; Glossary; References; Index.

Mohseni, Masoud; Omar, Yasser; Engel, Gregory S.; Plenio, Martin B.

2014-08-01

487

Effectiveness Review Analysis (Insert Effectiveness Review Name) Root Cause  

E-print Network

Effectiveness Review Analysis ­ (Insert Effectiveness Review Name) 1 of 1 Root Cause: Corrective action address the root cause? 2. Does the corrective action prevent recurrence of similar conditions due

488

On nature's scaling effects  

NASA Astrophysics Data System (ADS)

This presentation afforded the opportunity to look back in the literature to discover scaling effects in nature that might be relevant to composites. Numerous examples were found in nature's approaches to wood, teeth, horns, leaves, eggs, feathers, etc. Nature transmits tensile forces rigidly with cohesive bonds, while dealing with compression forces usually through noncompressible hydraulics. The optimum design scaling approaches for aircraft were also reviewed for comparison with similitude laws. Finally, some historical evidence for the use of Weibull scaling in composites was reviewed.

Wilkins, Dick J.

1994-07-01

489

On nature's scaling effects  

NASA Technical Reports Server (NTRS)

This presentation afforded the opportunity to look back in the literature to discover scaling effects in nature that might be relevant to composites. Numerous examples were found in nature's approaches to wood, teeth, horns, leaves, eggs, feathers, etc. Nature transmits tensile forces rigidly with cohesive bonds, while dealing with compression forces usually through noncompressible hydraulics. The optimum design scaling approaches for aircraft were also reviewed for comparison with similitude laws. Finally, some historical evidence for the use of Weibull scaling in composites was reviewed.

Wilkins, Dick J.

1994-01-01

490

Earthquake occurrence and effects.  

PubMed

Although earthquakes are mainly concentrated in zones close to boundaries of tectonic plates of the Earth's lithosphere, infrequent events away from the main seismic regions can cause major disasters. The major cause of damage and injury following earthquakes is elastic vibration, rather than fault displacement. This vibration at a particular site will depend not only on the size and distance of the earthquake but also on the local soil conditions. Earthquake prediction is not yet generally fruitful in avoiding earthquake disasters, but much useful planning to reduce earthquake effects can be done by studying the general earthquake hazard in an area, and taking some simple precautions. PMID:2347628

Adams, R D

1990-01-01

491

Effective string theory simplified  

NASA Astrophysics Data System (ADS)

In this note we simplify the formulation of the Poincaré-invariant effective string theory in D dimensions by adding an intrinsic metric and embedding its dynamics into the Polyakov formalism. We use this formalism to classify operators order-by-order in the inverse physical length of the string, in a fully gauge-invariant framework. We then use this classification to analyze the universality and nonuniversality of observables, up to and including the second sub-leading order in the long string expansion.

Hellerman, Simeon; Maeda, Shunsuke; Maltz, Jonathan; Swanson, Ian

2014-09-01

492

[Genotoxic effects of tonarol].  

PubMed

Genotoxic effects of 2,6-di-tret-butyl-4-methylphenol (tonarol) were studied using four test systems: the Ames test, the SOS chromotest, the cytogenetic test with rootlets of onion (Allium cepa), and the in vivo micronucleus test. Tonarol did not affect gene mutation induction in Salmonella typhimurium tester strains, the SOS response in the Escherichia coli strain PQ37, chromosomal aberrations in cells of onion (Allium cepa) rootlets, and micronuclei in erythrocytes of peripheral blood of CBA x C5713 L/G mice. Tonarol induced cell division in A. PMID:9445825

Karamova, N S; Il'inskaia, O N; Ivanchenko, O B; Ermolaev, A I; Gil'mutdinov, G Z; Gershanov, F B; Khamitov, B R

1997-09-01

493

Vibration by relativistic effects  

E-print Network

Relativity, time reversal invariance in mechanics and principle of causality can be in the bases of a type of vibration of the extensive objects. It is because, the detailed analysis of the relativistic movement of an extensive body entail that all the objects must have inherent a vibratory movement to their own size. Such effect does not happen when it works with point particles thus is not stranger who happens unnoticed in the traditional studies. Also we can find relation between the form of vibration of the extensive objects and the energy that calculates by quantum considerations.

Enrique Oradaz Romay

2005-12-23

494

Greenhouse Effect Lab  

NSDL National Science Digital Library

In this simple lab, students collect data to demonstrate basic atmospheric science concepts. Groups of students measure the effect of carbon dioxide on temperature using soda bottles with thermometers inserted. One bottle is filled with air and capped. The second bottle is filled with carbon dioxide using a specific procedure. To conduct the experiment, both bottles are placed under a lamp while students record the increase in temperature over five minutes. The bottle containing carbon dioxide has a greater increase in temperature than the bottle containing air. This lab demonstrates the fundamental concept that underlies climate change science by providing data that are easy for students to interpret.

Krista Larsen

495

Assessments of astronaut effectiveness  

NASA Technical Reports Server (NTRS)

This study examined the reliability and convergent validity of three methods of peer and supervisory ratings of the effectiveness of individual NASA astronauts and their relationships with flight assignments. These two techniques were found to be reliable and relatively convergent. Seniority and a peer-rated Performance and Competence factor proved to be most closely associated with flight assignments, while supervisor ratings and a peer-rated Group Living and Personality factor were found to be unrelated. Results have implications for the selection and training of astronauts.

Rose, Robert M.; Helmreich, Robert L.; Fogg, Louis; Mcfadden, Terry J.

1993-01-01

496

Microcircuit radiation effects databank  

NASA Technical Reports Server (NTRS)

This databank is the collation of radiation test data submitted by many testers and serves as a reference for engineers who are concerned with and have some knowledge of the effects of the natural radiation environment on microcircuits. It contains radiation sensitivity results from ground tests and is divided into two sections. Section A lists total dose damage information, and section B lists single event upset cross sections, I.E., the probability of a soft error (bit flip) or of a hard error (latchup).

1983-01-01

497

Effectiveness of vasectomy techniques.  

PubMed

The effectiveness of various vasectomy techniques is reviewed, with a focus on methods used for vas occlusion. Spontaneous recanalization of the vas is more common than generally recognized and is often transient. Simple ligation and excision has an unacceptably high risk for failure. Techniques that include cautery seem to have a lower risk for failure than techniques that do not include cautery. There is insufficient evidence to recommend a particular standardized cautery technique, but adding fascial interposition to cautery seems to be associated with the lowest risk for failure. PMID:19643234

Sokal, David C; Labrecque, Michel

2009-08-01

498

Direct effects protection  

NASA Technical Reports Server (NTRS)

Protection of an aircraft and each of its various systems against the direct effects of lightning were analyzed. Components located in different sections of the aircraft were individually examined since they are likely to experience different degrees of susceptibility to lightning, and may be vulnerable to different components of the lightning flash. The basic steps to be followed in establishing lightning protection were presented by discussing the varieties of arc entry and current flow-through damage. The lightning-strike zones and lightning current environments are established, since environmental conditions in the zones are those under which specific protective measures must perform. Airworthiness regulations which apply to lightning protection are cited.

1977-01-01

499

Genotoxic effect of alkaloids.  

PubMed

Because of the increased use of alkaloids in general medical practice in recent years, it is of interest to determine genotoxic, mutagenic and recombinogenic response to different groups of alkaloids in prokaryotic and eucaryotic organisms. Reserpine, boldine and chelerythrine did not show genotoxicity response in the SOS-Chromotest whereas skimmianine showed genotoxicity in the presence of a metabolic activation mixture. Voacristine isolated from the leaves of Ervatamia coronaria shows in vivo cytostatic and mutagenic effects in Saccharomyces cerevisiae hapioids cells. The Rauwolfia alkaloid (reserpine) was not able to induce reverse mutation and recombinational mitotic events (crossing-over and gene conversion) in yeast diploid strain XS2316. PMID:1842017

Henriques, J A; Moreno, P R; Von Poser, G L; Querol, C C; Henriques, A T

1991-01-01

500

A quantitative analysis of the thermoelectric power measurements on composite Al-Ge films  

NASA Astrophysics Data System (ADS)

Thermoelectric power (Seebeck coefficient) measurements at room temperature have been made on composite Al-Ge films for aluminum volume fractions ranging from 20% to 100%. The critical metallic concentration ? c at the metal-insulator transition is about ? c?55%. These measurements were motivated to test theoretical predictions recently suggested by Bergman and Levy. The electrical conductivity, a variable in their equation, was obtained both by direct measurements and by an effective media equation, while the thermal conductivity was obtained from two different effective media equations. The agreement between the theoretical and experimental results support the correctness both of their theory and the effective media equations used.

Hurvits, G.; Rosenbaum, R.; McLachlan, D. S.

1994-06-01