Electron Transport Phenomena in NiS2−xSex Single Crystals

1996 ◽  
Vol 453 ◽  
Author(s):  
X. Yao ◽  
S. Ehrlich ◽  
G. Liedlb ◽  
T. Hogan ◽  
C. Kannewurf ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Single Crystals ◽  
Electron Correlation ◽  
Large Scale ◽  
Structural Changes ◽  
Dominant Role ◽  
Magnetic Ordering ◽  
Structural Studies ◽  
Complex Temperature

AbstractStructural studies, electrical resistivity, and Seebeck coefficient measurements are reported in the range 4.2 − 300 K for single crystals of NiS2−xSex (0 ≤ x ≤ 0.71) grown from a Te melt. Over the entire temperature and composition ranges there are no large scale structural changes concomitant to a variety of magnetic ordering phenomena, and to a changeover from insulating to metallic characteristics as x increases. Thus, the evolution in transport characteristics with x can be studied without interference from the lattice; moreover, the electron count is unaffected by substitution of Se for S. The existence of anomalous peaks in resistivity as a function of temperature is attributed to significant electron correlation phenomena which allow the entropy of charge carrier to play a dominant role. The complex temperature dependence of the Seebeck coefficient is attributed to the participation of both electrons and holes in charge transport.

PHONON-DRAG EFFECT OF ULTRA-THIN FeSi2 AND MnSi1.7/FeSi2 FILMS

2011 ◽  
Vol 25 (22) ◽  
pp. 1829-1838 ◽  
Author(s):  
Q. R. HOU ◽  
B. F. GU ◽  
Y. B. CHEN ◽  
Y. J. HE
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Single Crystals ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Low Temperatures ◽  
Room Temperature ◽  
Phonon Drag ◽  
Drag Effect ◽  
Thermoelectric Power Factor

Phonon-drag effect usually occurs in single crystals at very low temperatures (10–200 K). Strong phonon-drag effect is observed in ultra-thin β- FeSi 2 films at around room temperature. The Seebeck coefficient of a 23 nm-thick β- FeSi 2 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 MnSi 1.7 film with low electrical resistivity is grown on it, the thermoelectric power factor of the MnSi 1.7 film can reach 1.5×10-3 W/m-K2 at around room temperature. This value is larger than that of bulk MnSi 1.7 material in the same temperature range.

Electrical resistivity and Seebeck coefficient of La1?x M x MnO3 (M = Ca, Sr) single crystals

1988 ◽  
Vol 23 (3) ◽  
pp. 1102-1105 ◽  
Author(s):  
Tomotaka Hashimoto ◽  
Nobuo Ishizawa ◽  
Nobuyasu Mizutani ◽  
Masanori Kato
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Single Crystals

Cerium Doped Bismuth Antimony

2012 ◽  
Vol 1456 ◽  
Author(s):  
Kevin C. Lukas ◽  
Huaizhou Zhao ◽  
Ryan L. Stillwell ◽  
Zhifeng Ren ◽  
Cyril P. Opeil
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Single Crystals ◽  
Room Temperature ◽  
Zero Magnetic Field ◽  
Bismuth Antimony ◽  
Impurity Doping ◽  
Antimony Alloys

ABSTRACTBismuth-Antimony alloys have been shown to have high ZT values below room temperature, especially for single crystals. For polycrystalline samples, impurity doping and magnetic field have proven to be powerful tools in the search for understanding and improving thermoelectric performance. Nanopolycrystalline Bi0.88Sb0.12 doped with 0.05, 0.5 and 3 % Ce were prepared by ball milling and dc hot pressing techniques. Electrical resistivity, Seebeck coefficient, thermal conductivity, carrier concentration, mobility, and magnetization are measured in a temperature range of 5-350 K and in magnetic fields up to 9 Tesla. The effects of Ce doping on the thermoelectric properties of Bi0.88Sb0.12 in zero magnetic field are discussed.

Do Lower Foreign Flows and Higher Domestic Flows Reduce Indian Equity Market Volatility?

2021 ◽  
pp. 097226292199098
Author(s):  
Vaibhav Aggarwal ◽  
Adesh Doifode ◽  
Mrityunjay Kumar Tiwary
Keyword(s):  
Stock Market ◽  
Mutual Fund ◽  
Stock Markets ◽  
Large Scale ◽  
Structural Changes ◽  
Market Volatility ◽  
Stock Market Volatility ◽  
Equity Investments ◽  
Net Equity ◽  
Indian Stock Market

This study examines the relationship that both domestic and foreign institutional net equity flows have with the India stock markets. The motivation behind is the study to examine whether increased net equity investments from domestic institutional investors has reduced the influence of foreign equity flows on the Indian stock market volatility. Our results indicate that only during periods in which domestic equity inflows surpass foreign flows by a significant margin, as seen during 2015–2018, is the Indian stock market volatility not significantly influenced by foreign equity investments. However, during periods of re-emergence of strong foreign net inflows, the Indian market volatility is still being impacted significantly, as has been observed since 2019. Furthermore, we find that both large-scale net buying and net selling by domestic funds increased the stock market volatility as observed during 2015–2018 and COVID-impacted year 2020 respectively. The implications of this study are multi-fold. First, the regulators should discuss with industry bodies before enforcing major structural changes like reconstituting of mutual fund investment mandate in 2017 which forced domestic funds to quickly change portfolio allocation amongst large-cap, mid-cap and small-cap stocks resulting in higher stock market volatility. Second, adequate investor educational and awareness programmes need to be conducted regularly for retail investors to minimize herd behaviour of investing during market rise and heavy redemptions at times of fall. Third, the economic policies should be stable and forward-looking to ensure foreign investors remain attracted to the Indian stock markets at all times.

Structural Changes in Thalamic Nuclei Across Prodromal and Clinical Alzheimer’s Disease

2021 ◽  
pp. 1-11
Author(s):  
Adam S. Bernstein ◽  
Steven Z. Rapcsak ◽  
Michael Hornberger ◽  
Manojkumar Saranathan ◽  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Large Scale ◽  
Structural Changes ◽  
Thalamic Nuclei ◽  
Medial Temporal Lobes ◽  
Cognitive Changes ◽  
Temporal Lobes ◽  
Medial Geniculate ◽  
Healthy Control

Background: Increasing evidence suggests that thalamic nuclei may atrophy in Alzheimer’s disease (AD). We hypothesized that there will be significant atrophy of limbic thalamic nuclei associated with declining memory and cognition across the AD continuum. Objective: The objective of this work was to characterize volume differences in thalamic nuclei in subjects with early and late mild cognitive impairment (MCI) as well as AD when compared to healthy control (HC) subjects using a novel MRI-based thalamic segmentation technique (THOMAS). Methods: MPRAGE data from the ADNI database were used in this study (n = 540). Healthy control (n = 125), early MCI (n = 212), late MCI (n = 114), and AD subjects (n = 89) were selected, and their MRI data were parcellated to determine the volumes of 11 thalamic nuclei for each subject. Volumes across the different clinical subgroups were compared using ANCOVA. Results: There were significant differences in thalamic nuclei volumes between HC, late MCI, and AD subjects. The anteroventral, mediodorsal, pulvinar, medial geniculate, and centromedian nuclei were significantly smaller in subjects with late MCI and AD when compared to HC subjects. Furthermore, the mediodorsal, pulvinar, and medial geniculate nuclei were significantly smaller in early MCI when compared to HC subjects. Conclusion: This work highlights nucleus specific atrophy within the thalamus in subjects with early and late MCI and AD. This is consistent with the hypothesis that memory and cognitive changes in AD are mediated by damage to a large-scale integrated neural network that extends beyond the medial temporal lobes.

Growth of Large-Scale Silver Lithium Niobate Single Crystals and Their Piezoelectric Properties

2006 ◽  
Vol 45 (9B) ◽  
pp. 7389-7396 ◽  
Author(s):  
Satoshi Wada ◽  
Akiko Saito ◽  
Takuya Hoshina ◽  
Hirofumi Kakemoto ◽  
Takaaki Tsurumi ◽  
...  
Keyword(s):  
Lithium Niobate ◽  
Single Crystals ◽  
Large Scale ◽  
Piezoelectric Properties

scholarly journals Metastable Intermediates as Stepping Stones on the Maturation Pathways of Viral Capsids

mBio ◽  
2014 ◽  
Vol 5 (6) ◽  
Author(s):  
Giovanni Cardone ◽  
Robert L. Duda ◽  
Naiqian Cheng ◽  
Lili You ◽  
James F. Conway ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Large Scale ◽  
Structural Changes ◽  
Energy Landscape ◽  
Potential Hazard ◽  
Stepping Stones ◽  
Scanning Calorimetry ◽  
Conformational Effects ◽  
Capsid Maturation ◽  
Capsid Integrity

ABSTRACT As they mature, many capsids undergo massive conformational changes that transform their stability, reactivity, and capacity for DNA. In some cases, maturation proceeds via one or more intermediate states. These structures represent local minima in a rich energy landscape that combines contributions from subunit folding, association of subunits into capsomers, and intercapsomer interactions. We have used scanning calorimetry and cryo-electron microscopy to explore the range of capsid conformations accessible to bacteriophage HK97. To separate conformational effects from those associated with covalent cross-linking (a stabilization mechanism of HK97), a cross-link-incompetent mutant was used. The mature capsid Head I undergoes an endothermic phase transition at 60°C in which it shrinks by 7%, primarily through changes in its hexamer conformation. The transition is reversible, with a half-life of ~3 min; however, >50% of reverted capsids are severely distorted or ruptured. This observation implies that such damage is a potential hazard of large-scale structural changes such as those involved in maturation. Assuming that the risk is lower for smaller changes, this suggests a rationalization for the existence of metastable intermediates: that they serve as stepping stones that preserve capsid integrity as it switches between the radically different conformations of its precursor and mature states. IMPORTANCE Large-scale conformational changes are widespread in virus maturation and infection processes. These changes are accompanied by the release of conformational free energy as the virion (or fusogenic glycoprotein) switches from a precursor state to its mature state. Each state corresponds to a local minimum in an energy landscape. The conformational changes in capsid maturation are so radical that the question arises of how maturing capsids avoid being torn apart. Offering proof of principle, severe damage is inflicted when a bacteriophage HK97 capsid reverts from the (nonphysiological) state that it enters when heated past 60°C. We suggest that capsid proteins have been selected in part by the criterion of being able to avoid sustaining collateral damage as they mature. One way of achieving this—as with the HK97 capsid—involves breaking the overall transition down into several smaller steps in which the risk of damage is reduced.

Magnetic ordering in relaxor ferroelectric (1 − x)Pb(Fe2/3W1/3)O3–xPbTiO3 single crystals

2007 ◽  
Vol 22 (8) ◽  
pp. 2116-2124 ◽  
Author(s):  
Li Feng ◽  
Haiyan Guo ◽  
Zuo-Guang Ye
Keyword(s):  
Single Crystals ◽  
Magnetic Measurements ◽  
Ferroelectric Properties ◽  
Magnetic Ordering ◽  
Magnetic Behavior ◽  
Relaxor Ferroelectric ◽  
X Ray Diffraction ◽  
Ferroelectric State ◽  
Temperature Changes ◽  
Temperature Solution

Single crystals of the perovskite solid solution (1 − x)Pb(Fe2/3W1/3)O3–xPbTiO3, with x = 0, 0.07, 0.27, and 0.75, have been synthesized by the high-temperature solution growth using PbO as flux and characterized by x-ray diffraction and dielectric and magnetic measurements. The crystal structure at room temperature changes from a pseudocubic to a tetragonal phase with the PbTiO3 (PT) content increasing to x ⩾ 0.27. As the amount of PT increases, the relaxor ferroelectric behavior of Pb(Fe2/3W1/3)O3 (PFW) is transformed toward a normal ferroelectric state with sharp and nondispersive peaks of dielectric permittivity at TC. Two types of magnetic orderings are observed on the temperature dependence of the magnetization in the crystals with x ⩽ 0.27. This behavior is explained based on the relationships among the magnetic ordering, perovskite structure, composition, and relaxor ferroelectric properties. Furthermore, the macroscopic magnetization of the system was measured under the application of a magnetic field, which demonstrates different magnetic behavior associated with the weakly ferromagnetic, antiferromagnetic, and paramagnetic ordering in the temperature range of 2 to 390 K. Interestingly, the low-temperature ferromagnetism is enhanced by the addition of ferroelectric PT up to x = 0.27.

Thermoelectric Properties of Semiconducting Intermetallic Compounds: FeGa3and RuGa3

2003 ◽  
Vol 793 ◽  
Author(s):  
Y. Amagai ◽  
A. Yamamoto ◽  
C. H. Lee ◽  
H. Takazawa ◽  
T. Noguchi ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Seebeck Coefficient ◽  
Transport Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
High Seebeck Coefficient

ABSTRACTWe report transport properties of polycrystalline TMGa3(TM = Fe and Ru) compounds in the temperature range 313K<T<973K. These compounds exhibit semiconductorlike behavior with relatively high Seebeck coefficient, electrical resistivity, and Hall carrier concentrations at room temperature in the range of 1017- 1018cm−3. Seebeck coefficient measurements reveal that FeGa3isn-type material, while the Seebeck coefficient of RuGa3changes signs rapidly from large positive values to large negative values around 450K. The thermal conductivity of these compounds is estimated to be 3.5Wm−1K−1at room temperature and decreased to 2.5Wm−1K−1for FeGa3and 2.0Wm−1K−1for RuGa3at high temperature. The resulting thermoelectric figure of merit,ZT, at 945K for RuGa3reaches 0.18.

Cu Doping Effect on Electrical Resistivity and Seebeck Coefficient of Perovskite-Type LaFeO 3 Ceramics

2009 ◽  
Vol 26 (10) ◽  
pp. 107301 ◽  
Author(s):  
Wang Hong-Chao ◽  
Wang Chun-Lei ◽  
Zhang Jia-Liang ◽  
Zhao Ming-Lei ◽  
Liu Jian ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Doping Effect ◽  
Cu Doping ◽  
Perovskite Type
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