Seebeck coefficient of quasi-two-dimensional SnSxSe2−x crystals

1985 ◽  
Vol 63 (11) ◽  
pp. 1405-1408 ◽  
Author(s):  
Y. Frongillo ◽  
M. Aubin ◽  
S. Jandl
Keyword(s):  
Seebeck Coefficient ◽  
Single Crystals ◽  
Conduction Band ◽  
Hall Coefficient ◽  
Large Temperature ◽  
Two Dimensional ◽  
Bridgman Technique ◽  
Absolute Value ◽  
Conduction Mechanisms ◽  
Iodine Transport

We have measured the Seebeck coefficient of quasi-two-dimensional single crystals of SnSe2, SnS0.1Se1.9, and SnS0.3Se1.7, grown by the Bridgman technique, and SnSe2, grown by iodine transport, over a large temperature range varying from 15 (4.2 for SnSe2) to 300 K. To assist in the interpretation of these results, the Hall coefficient and resistivity were measured on SnSe2 and SnS0.1Se1.9 Bridgman samples. All these measurements were done in a plane perpendicular to the c axis. It was found that, as the temperature decreases, the absolute value of the Seebeck coefficient decreases slightly before a surprisingly large increase at the lowest temperatures. We interpret these results as the manifestation of two conduction mechanisms: electrons in the conduction band and hopping of electrons between impurities.

Precipitation of NiHfsi phase in NiAl single crystals containing Hf

1995 ◽  
Vol 53 ◽  
pp. 532-533
Author(s):  
A. Garg ◽  
R. D. Noebe ◽  
R. Darolia
Keyword(s):  
High Temperature ◽  
Single Crystals ◽  
High Temperature Strength ◽  
Bridgman Technique ◽  
Shell Mold ◽  
Third Phase ◽  
Unknown Phase ◽  
Transmission Electron ◽  
Two Phases ◽  
Nial Matrix

Small additions of Hf to NiAl produce a significant increase in the high-temperature strength of single crystals. Hf has a very limited solubility in NiAl and in the presence of Si, results in a high density of G-phase (Ni16Hf6Si7) cuboidal precipitates and some G-platelets in a NiAl matrix. These precipitates have a F.C.C structure and nucleate on {100}NiAl planes with almost perfect coherency and a cube-on-cube orientation-relationship (O.R.). However, G-phase is metastable and after prolonged aging at high temperature dissolves at the expense of a more stable Heusler (β'-Ni2AlHf) phase. In addition to these two phases, a third phase was shown to be present in a NiAl-0.3at. % Hf alloy, but was not previously identified (Fig. 4 of ref. 2 ). In this work, we report the morphology, crystal-structure, O.R., and stability of this unknown phase, which were determined using conventional and analytical transmission electron microscopy (TEM).Single crystals of NiAl containing 0.5at. % Hf were grown by a Bridgman technique. Chemical analysis indicated that these crystals also contained Si, which was not an intentional alloying addition but was picked up from the shell mold during directional solidification.

scholarly journals Strong Spin-Orbit Contribution to the Hall Coefficient of Two-Dimensional Hole Systems

2018 ◽  
Vol 121 (8) ◽  
Author(s):  
Hong Liu ◽  
E. Marcellina ◽  
A. R. Hamilton ◽  
Dimitrie Culcer
Keyword(s):  
Hall Coefficient ◽  
Spin Orbit ◽  
Two Dimensional ◽  
Strong Spin

N-type Ba0.2Co4Sb11.5Te0.5: Optimization of thermoelectric properties by different pressures

2019 ◽  
Vol 33 (03) ◽  
pp. 1950027 ◽  
Author(s):  
Jiaxiang Chen ◽  
Xiaopeng Jia ◽  
Yuewen Zhang ◽  
Haiqiang Liu ◽  
Baomin Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Seebeck Coefficient ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Absolute Value ◽  
X Ray ◽  
Coefficient Increase ◽  
Maximum Power Factor ◽  
Scanning Electron

The polycrystalline skutterudite [Formula: see text] were successfully synthesized from 1.5 GPa to 3.5 GPa by the high pressure and high temperature (HPHT) method. Negative Seebeck coefficient confirmed the n-type conductivity of all samples. The phase compositions of samples were investigated by X-ray diffraction (XRD) and the microstructures were observed by scanning electron microscopy (SEM). It was found that the grains appeared smaller and the grain boundaries became more abundant when pressures were higher. We measured the electrical properties from room temperature to 723 K. Both the electrical resistivity and absolute value of Seebeck coefficient increase with the increasing synthetic pressure. At 723 K, the maximum power factor of [Formula: see text] was obtained for the sample synthesized under 3 GPa. The maximum ZT value of 0.61 was reached by [Formula: see text] synthesized under 3 GPa and measured at 723 K.

scholarly journals Two-dimensional semiconductors pave the way towards dopant-based quantum computing

2018 ◽  
Vol 9 ◽  
pp. 2668-2673 ◽  
Author(s):  
José Carlos Abadillo-Uriel ◽  
Belita Koiller ◽  
María José Calderón
Keyword(s):  
Conduction Band ◽  
Quantum Computer ◽  
2D Materials ◽  
Exchange Interactions ◽  
Lattice Parameter ◽  
Oscillatory Behavior ◽  
Conduction Band Edge ◽  
Two Dimensional ◽  
Tunnel Coupling ◽  
Qubit Operations

Since the proposal in 1998 to build a quantum computer using dopants in silicon as qubits, much progress has been made in the nanofabrication of semiconductors and the control of charge and spins in single dopants. However, an important problem remains unsolved, namely the control over exchange interactions and tunneling between two donors, which presents a peculiar oscillatory behavior as the dopants relative positions vary at the scale of the lattice parameter. Such behavior is due to the valley degeneracy in the conduction band of silicon, and does not occur when the conduction-band edge is at k = 0. We investigate the possibility of circumventing this problem by using two-dimensional (2D) materials as hosts. Dopants in 2D systems are more tightly bound and potentially easier to position and manipulate. Moreover, many of them present the conduction band minimum at k = 0, thus no exchange or tunnel coupling oscillations. Considering the properties of currently available 2D semiconductor materials, we access the feasibility of such a proposal in terms of quantum manipulability of isolated dopants (for single qubit operations) and dopant pairs (for two-qubit operations). Our results indicate that a wide variety of 2D materials may perform at least as well as, and possibly better, than the currently studied bulk host materials for donor qubits.

scholarly journals The Layered Structure of Cu2(H2O)4[C4H4N2][C6H2(COO)4]·2H2O

2019 ◽  
Author(s):  
Roberto Köferstein
Keyword(s):  
Nitrogen Atom ◽  
Single Crystals ◽  
Silica Gel ◽  
Layered Structure ◽  
Water Molecules ◽  
Two Dimensional ◽  
Space Group ◽  
Distorted Octahedral ◽  
Oxygen Atoms

Triclinic single crystals of Cu2(H2O)4[C4H4N2][C6H2(COO)4]·2H2O have been grown in anaqueous silica gel. Space group P-1 (Nr. 2), a = 723.94(7) pm, b = 813.38(14) pm, c = 931.0(2) pm, α = 74.24(2)°, β = 79.24(2)°, γ = 65.451(10)°, V = 0.47819(14) nm3, Z = 1. Cu2+ is coordinated in a distorted, octahedral manner by two water molecules, three oxygen atoms ofthe pyromellitate anions and one nitrogen atom of pyrazine (Cu—O 194.1(2)–229.3(3) pm;Cu–N 202.0(2) pm). The connection of Cu2+ and [C6H2(COO)4)]4− yields infinite strands,which are linked by pyrazine molecules to form a two-dimensional coordination polymer.Thermogravimetric analysis in air showed that the dehydrated compound was stable between175 and 248 °C. Further heating yielded CuO.

Crystal Structure of Eu2PdSi3

2003 ◽  
Vol 58 (10) ◽  
pp. 971-974 ◽  
Author(s):  
U. Ch. Rodewald ◽  
R.-D. Hoffmann ◽  
R. Pöttgen ◽  
E.V. Sampathkumaran
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
Single Crystals ◽  
Two Dimensional ◽  
Silica Tube ◽  
Variable Parameters ◽  
X Ray

Single crystals of Eu2PdSi3 were obtained from an arc-melted sample that was further annealed at 1020 K for seven days in a silica tube. The structure of Eu2PdSi3 was refined from single crystal X-ray diffractometer data: P6/mmm, a = 831.88(12), c = 435.88(9) pm, wR2 = 0.1175, 265 F2 values, and 13 variable parameters. It crystallizes with the U2RuSi3 structure, a superstructure of the AlB2 type. The palladium and silicon atoms form a planar two-dimensional [PdSi3] network. The two crystallographically different europium atoms have hexagonal prismatic coordinations Eu1Si12 and Eu2Pd4Si8. The Pd-Si and Si-Si distances within the [PdSi3] network are 244 and 236 pm, respectively.

Scalable printing of two-dimensional single crystals of organic semiconductors towards high-end device applications

2021 ◽  
Author(s):  
Shohei Kumagai ◽  
Tatsuyuki Makita ◽  
Shun Watanabe ◽  
Jun Takeya
Keyword(s):  
Single Crystals ◽  
Organic Semiconductors ◽  
Materials Science ◽  
Printed Electronics ◽  
Human Society ◽  
Two Dimensional ◽  
Organic Thin Film ◽  
Device Applications ◽  
High Carrier Mobility ◽  
High Carrier

Abstract The past several decades have witnessed a vast array of developments in printable organic semiconductors, where successes both in synthetic chemistry and in printing technology constituted a key step forward to realization of printed electronics. In this review, we highlight specifically on materials science, charge transport, and device engineering of —two-dimensional single crystals—. Defect-free organic single-crystalline wafers manufactured via a one-shot printing process allows remarkably reliable implementations of organic thin-film transistors with decently high carrier mobility up to 10 cm2 V-1 s-1, which has revolutionized the current printing electronics to be able to meet looming IoT challenges. This review focuses on the perspective of printing two-dimensional single crystals with reasonable areal coverage, showing their promising applications for practical devices and future human society, particularly based on our recent contributions.

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