Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “SnSe”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Three-dimensional superconductivity induced by an extremely small amount of Li in Li x ⁢SnSe 2

Unconventional superconductivity occurs often in materials with low dimensionality. Furthermore, we report superconductivity observed in layered Li x SnSe 2 with the superconducting transition temperature T c ~ 6 K. Through L⁢i + intercalation in semiconducting SnSe 2 via electrochemical process, Li x ⁢SnSe 2 is formed with an extremely small x value as estimated from the c-axis lattice parameter, carrier concentration, and first-principles calculations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Local Sn Dipolar-Character Displacements behind the Low Thermal Conductivity in SnSe Thermoelectric

The local atomic structure of SnSe was characterized across its orthorhmbic-to-orthorhombic structural phase transition using x-ray pair distribution function analysis. Substantial Sn displacements with a dipolar character persist in the high symmetry high temperature phase, albeit with a symmetry different from that of the ordered displacements below the transition. The analysis implies that the transition is neither order-disorder nor displacive, but rather a complex crossover. Robust ferro-coupled SnSe intra-layer distortions suggest a ferroelectric-like instability as the driving force. Furthermore, these local symmetry-lowering Sn displacements are likely integral to the ultra-low lattice thermal conductivity mechanism in SnSe.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnSe by Materials Project

SnSe crystallizes in the orthorhombic Cmcm space group. The structure is two-dimensional and consists of two SnSe sheets oriented in the (0, 1, 0) direction. Sn2+ is bonded to five equivalent Se2- atoms to form a mixture of corner and edge-sharing SnSe5 square pyramids. There are one shorter (2.74 Å) and four longer (3.04 Å) Sn–Se bond lengths. Se2- is bonded to five equivalent Sn2+ atoms to form a mixture of corner and edge-sharing SeSn5 square pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnSe by Materials Project

SnSe crystallizes in the orthorhombic Cmcm space group. The structure is two-dimensional and consists of two SnSe sheets oriented in the (0, 1, 0) direction. Sn2+ is bonded in a rectangular see-saw-like geometry to four equivalent Se2- atoms. There are two shorter (2.76 Å) and two longer (3.06 Å) Sn–Se bond lengths. Se2- is bonded in a rectangular see-saw-like geometry to four equivalent Sn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnSe by Materials Project

SnSe crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of two SnSe sheets oriented in the (0, 0, 1) direction. Sn2+ is bonded in a 5-coordinate geometry to three equivalent Se2- atoms. There are one shorter (2.78 Å) and two longer (2.84 Å) Sn–Se bond lengths. Se2- is bonded in a 3-coordinate geometry to three equivalent Sn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnSe by Materials Project

SnSe crystallizes in the tetragonal P4/nmm space group. The structure is two-dimensional and consists of one SnSe sheet oriented in the (0, 0, 1) direction. Sn2+ is bonded to five equivalent Se2- atoms to form a mixture of edge and corner-sharing SnSe5 square pyramids. There are one shorter (2.72 Å) and four longer (3.06 Å) Sn–Se bond lengths. Se2- is bonded in a single-bond geometry to five equivalent Sn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnSe by Materials Project

SnSe crystallizes in the orthorhombic Pmmn space group. The structure is one-dimensional and consists of two SnSe ribbons oriented in the (0, 1, 0) direction. Sn2+ is bonded in a T-shaped geometry to three equivalent Se2- atoms. There are one shorter (2.77 Å) and two longer (2.91 Å) Sn–Se bond lengths. Se2- is bonded in a 3-coordinate geometry to three equivalent Sn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnSe by Materials Project

SnSe crystallizes in the orthorhombic Pnma space group. The structure is two-dimensional and consists of two SnSe sheets oriented in the (0, 0, 1) direction. Sn2+ is bonded to five equivalent Se2- atoms to form a mixture of corner and edge-sharing SnSe5 square pyramids. There are a spread of Sn–Se bond distances ranging from 2.74–3.05 Å. Se2- is bonded to five equivalent Sn2+ atoms to form a mixture of corner and edge-sharing SeSn5 square pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on SnSe by Materials Project

SnSe crystallizes in the orthorhombic Cmcm space group. The structure is one-dimensional and consists of four SnSe ribbons oriented in the (1, 0, 0) direction. Sn2+ is bonded in a bent 120 degrees geometry to two equivalent Se2- atoms. There are one shorter (2.58 Å) and one longer (2.59 Å) Sn–Se bond lengths. Se2- is bonded in a linear geometry to two equivalent Sn2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2024

High Mobility, High Carrier Density SnSe 2 Field‐Effect Transistors with Ultralow Subthreshold Swing and Gate‐Controlled Photoconductance Switching

2D and layered semiconductors are considered as promising electronic materials, particularly for applications that require high carrier mobility and efficient field-effect switching combined with mechanical flexibility. To date, however, the highest mobility has been realized primarily at low carrier concentration. Here, it is shown that few-layer/multilayer SnSe 2 gated by a solution top gate combines very high room-temperature electron mobility (up to 800 cm 2 V −1 s −1 ), along with large on-off current ratios (>10 5 ) and a subthreshold swing below the thermodynamic limit (50 mV per decade) in field-effect devices, at exceptionally large sheet carrier concentrations of ≈10 13 cm −2 . Observed mobility enhancements upon partial depletion of the channel point to near-surface defects or impurities as the mobility-limiting scattering centers. Under illumination, the resulting gap states give rise to gate-controlled switching between positive and negative photoconductance. The results qualify SnSe 2 as a promising layered semiconductor for flexible and wearable electronics, as well as for the realization of advanced approaches to photodetection.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Linear Dichroism of the Optical Properties of SnS and SnSe Van der Waals Crystals

Abstract Tin monochalcogenides SnS and SnSe, belonging to a family of Van der Waals crystals isoelectronic to black phosphorus, are known as environmentally friendly materials promising for thermoelectric conversion applications. However, they exhibit other desired functionalities, such as intrinsic linear dichroism of the optical and electronic properties originating from strongly anisotropic orthorhombic crystal structures. This property makes them perfect candidates for polarization‐sensitive photodetectors working in near‐infrared spectral range. A comprehensive study of the SnS and SnSe crystals is presented, performed by means of optical spectroscopy and photoemission spectroscopy, supported by ab initio calculations. The studies reveal the high sensitivity of the optical response of both materials to the incident light polarization, which is interpreted in terms of the electronic band dispersion and orbital composition of the electronic bands, dictating the selection rules. From the photoemission investigation the ionization potential, electron affinity and work function are determined, which are parameters crucial for the design of devices based on semiconductor heterostructures.

Chemistry↗
DOE OSTI2020

Materials Data on SnSe by Materials Project

SnSe is Halite, Rock Salt structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Sn2+ is bonded to six equivalent Se2- atoms to form a mixture of corner and edge-sharing SnSe6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Sn–Se bond lengths are 3.03 Å. Se2- is bonded to six equivalent Sn2+ atoms to form a mixture of corner and edge-sharing SeSn6 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Co2(SnSe)3 by Materials Project

Co2(SnSe)3 is Hausmannite-derived structured and crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are two inequivalent Co sites. In the first Co site, Co is bonded to three Sn and three Se atoms to form CoSn3Se3 octahedra that share corners with six CoSn3Se3 octahedra, corners with four equivalent SnCo2Se2 tetrahedra, and corners with four equivalent SeCo2Sn2 tetrahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Co–Sn bond distances ranging from 2.51–2.54 Å. There are one shorter (2.39 Å) and two longer (2.42 Å) Co–Se bond lengths. In the second Co site, Co is bonded to three equivalent Sn and three equivalent Se atoms to form corner-sharing CoSn3Se3 octahedra. The corner-sharing octahedra tilt angles range from 51–56°. All Co–Sn bond lengths are 2.52 Å. All Co–Se bond lengths are 2.40 Å. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded to two Co and two equivalent Se atoms to form distorted SnCo2Se2 tetrahedra that share corners with four equivalent CoSn3Se3 octahedra, corners with two equivalent SnCo2Se2 tetrahedra, corners with four equivalent SeCo2Sn2 tetrahedra, and an edgeedge with one SnCo2Se2 tetrahedra. The corner-sharing octahedra tilt angles range from 69–74°. There are one shorter (2.75 Å) and one longer (2.94 Å) Sn–Se bond lengths. In the second Sn site, Sn is bonded in a 4-coordinate geometry to two equivalent Co and two equivalent Se atoms. There are one shorter (2.76 Å) and one longer (2.93 Å) Sn–Se bond lengths. There are two inequivalent Se sites. In the first Se site, Se is bonded in a 4-coordinate geometry to two equivalent Co and two equivalent Sn atoms. In the second Se site, Se is bonded to two Co and two equivalent Sn atoms to form distorted SeCo2Sn2 tetrahedra that share corners with four equivalent CoSn3Se3 octahedra, corners with two equivalent SeCo2Sn2 tetrahedra, corners with four equivalent SnCo2Se2 tetrahedra, and an edgeedge with one SeCo2Sn2 tetrahedra. The corner-sharing octahedra tilt angles range from 68–75°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba(SnSe)32 by Materials Project

Ba(SnSe)32 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Ba is bonded in a 6-coordinate geometry to two equivalent Sn and seven Se atoms. Both Ba–Sn bond lengths are 3.58 Å. There are a spread of Ba–Se bond distances ranging from 3.31–3.64 Å. There are twenty inequivalent Sn sites. In the first Sn site, Sn is bonded in a 3-coordinate geometry to three Se atoms. There are a spread of Sn–Se bond distances ranging from 2.79–2.86 Å. In the second Sn site, Sn is bonded in a rectangular see-saw-like geometry to four Se atoms. There are a spread of Sn–Se bond distances ranging from 2.80–3.07 Å. In the third Sn site, Sn is bonded in a 3-coordinate geometry to three Se atoms. There are a spread of Sn–Se bond distances ranging from 2.75–2.84 Å. In the fourth Sn site, Sn is bonded in a 3-coordinate geometry to three Se atoms. There are a spread of Sn–Se bond distances ranging from 2.72–3.08 Å. In the fifth Sn site, Sn is bonded in a distorted T-shaped geometry to three Se atoms. There are one shorter (2.78 Å) and two longer (2.85 Å) Sn–Se bond lengths. In the sixth Sn site, Sn is bonded in a distorted rectangular see-saw-like geometry to four Se atoms. There are a spread of Sn–Se bond distances ranging from 2.81–3.11 Å. In the seventh Sn site, Sn is bonded in a 3-coordinate geometry to three Se atoms. There are one shorter (2.79 Å) and two longer (2.83 Å) Sn–Se bond lengths. In the eighth Sn site, Sn is bonded in a distorted T-shaped geometry to three Se atoms. There are a spread of Sn–Se bond distances ranging from 2.78–2.85 Å. In the ninth Sn site, Sn is bonded in a 4-coordinate geometry to four Se atoms. There are a spread of Sn–Se bond distances ranging from 2.79–3.05 Å. In the tenth Sn site, Sn is bonded in a 4-coordinate geometry to three Se atoms. There are two shorter (2.81 Å) and one longer (2.91 Å) Sn–Se bond lengths. In the eleventh Sn site, Sn is bonded in a distorted T-shaped geometry to three Se atoms. There are one shorter (2.79 Å) and two longer (2.84 Å) Sn–Se bond lengths. In the twelfth Sn site, Sn is bonded in a distorted T-shaped geometry to three Se atoms. There are a spread of Sn–Se bond distances ranging from 2.80–2.87 Å. In the thirteenth Sn site, Sn is bonded in a distorted rectangular see-saw-like geometry to four Se atoms. There are a spread of Sn–Se bond distances ranging from 2.80–3.21 Å. In the fourteenth Sn site, Sn is bonded in a 5-coordinate geometry to one Ba and three Se atoms. There are a spread of Sn–Se bond distances ranging from 2.71–2.93 Å. In the fifteenth Sn site, Sn is bonded in a distorted T-shaped geometry to three Se atoms. All Sn–Se bond lengths are 2.81 Å. In the sixteenth Sn site, Sn is bonded in a 3-coordinate geometry to three Se atoms. There are a spread of Sn–Se bond distances ranging from 2.78–2.91 Å. In the seventeenth Sn site, Sn is bonded in a distorted T-shaped geometry to three Se atoms. There are one shorter (2.81 Å) and two longer (2.84 Å) Sn–Se bond lengths. In the eighteenth Sn site, Sn is bonded in a distorted T-shaped geometry to three Se atoms. There are one shorter (2.80 Å) and two longer (2.85 Å) Sn–Se bond lengths. In the nineteenth Sn site, Sn is bonded in a distorted octahedral geometry to six Se atoms. There are a spread of Sn–Se bond distances ranging from 2.85–3.30 Å. In the twentieth Sn site, Sn is bonded in a distorted T-shaped geometry to three Se atoms. There are one shorter (2.77 Å) and two longer (2.86 Å) Sn–Se bond lengths. There are twenty inequivalent Se sites. In the first Se site, Se is bonded in a 3-coordinate geometry to three Sn atoms. In the second Se site, Se is bonded in a distorted trigonal non-coplanar geometry to three Sn atoms. In the third Se site, Se is bonded in a distorted trigonal non-coplanar geometry to three Sn atoms. In the fourth Se site, Se is bonded to four Sn atoms to form distorted SeSn4 tetrahedra that share corners with two SeSn5 trigonal bipyramids and corners with two SeBaSn3 trigonal pyramids. In the fifth Se site, Se is bonded to one Ba and three Sn atoms to form distorted SeBaSn3 trigonal pyramids that share corners with three SeSn4 tetrahedra, a cornercorner with one SeSn5 trigonal bipyramid, and edges with two equivalent SeBaSn4 trigonal bipyramids. In the sixth Se site, Se is bonded to five Sn atoms to form distorted SeSn5 trigonal bipyramids that share corners with two equivalent SeSn4 tetrahedra, corners with two equivalent SeBaSn4 trigonal bipyramids, and corners with three SeBaSn3 trigonal pyramids. In the seventh Se site, Se is bonded in a distorted trigonal non-coplanar geometry to three Sn atoms. In the eighth Se site, Se is bonded in a 3-coordinate geometry to three Sn atoms. In the ninth Se site, Se is bonded in a see-saw-like geometry to one Ba and three Sn atoms. In the tenth Se site, Se is bonded to one Ba and four Sn atoms to form distorted SeBaSn4 trigonal bipyramids that share a cornercorner with one SeSn4 tetrahedra, a cornercorner with one SeSn5 trigonal bipyramid, a cornercorner with one SeSn4 trigonal pyramid, an edgeedge with one SeBaSn3 tetrahedra, an edgeedge with one SeBaSn4 trigonal bipyramid, and an edgeedge with one SeBaSn3 trigonal pyramid. In the eleventh Se site, Se is bonded in a trigonal non-coplanar geometry to three Sn atoms. In the twelfth Se site, Se is bonded in a distorted trigonal non-coplanar geometry to three Sn atoms. In the thirteenth Se site, Se is bonded in a distorted trigonal non-coplanar geometry to three Sn atoms. In the fourteenth Se site, Se is bonded in a 4-coordinate geometry to one Ba and three Sn atoms. In the fifteenth Se site, Se is bonded in a 3-coordinate geometry to three Sn atoms. In the sixteenth Se site, Se is bonded to one Ba and three Sn atoms to form distorted SeBaSn3 tetrahedra that share corners with three SeBaSn3 trigonal pyramids and edges with two equivalent SeBaSn4 trigonal bipyramids. In the seventeenth Se site, Se is bonded in a 4-coordinate geometry to four Sn atoms. In the eighteenth Se site, Se is bonded in a 3-coordinate geometry to three Sn atoms. In the nineteenth Se site, Se is bonded to four Sn atoms to form distorted SeSn4 trigonal pyramids that share corners with two SeSn4 tetrahedra, corners with two SeSn5 trigonal bipyramids, and a cornercorner with one SeSn4 trigonal pyramid. In the twentieth Se site, Se is bonded in a distorted trigonal non-coplanar geometry to three Sn atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Suppressing Charged Cation Antisites via Se Vapor Annealing Enables p-Type Dopability in AgBiSe 2 –SnSe Thermoelectrics

Cation disordering is commonly found in multinary cubic compounds, but its effect on electronic properties has been neglected because of difficulties in determining the ordered structure and defect energetics. An absence of rational understanding of the point defects present has led to poor reproducibility and uncontrolled conduction type. AgBiSe 2 is a representative compound that suffers from poor reproducibility of thermoelectric properties, while the origins of its intrinsic n-type conductivity remain speculative. Here, it is demonstrated that cation disordering is facilitated by Bi Ag charged antisite defects in cubic AgBiSe 2 which also act as a principal donor defect that greatly controls the electronic properties. Using density functional theory calculations and in situ Raman spectroscopy, how saturation annealing with selenium vapor can stabilize p-type conductivity in cubic AgBiSe 2 alloyed with SnSe at high temperatures is elucidated. With stable and controlled hole concentration, a peak is observed in the weighted mobility and the density-of-states effective mass in AgBiSnSe 3 , implying an increased valley degeneracy in this system. These findings corroborate the importance of considering the defect energetics for exploring the dopability of ternary thermoelectric chalcogenides and engineering electronic bands by controlling self-doping.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Microscopic Manipulation of Ferroelectric Domains in SnSe Monolayers at Room Temperature

Two-dimensional (2D) van der Waals ferroelectrics provide an unprecedented architectural freedom for the creation of artificial multiferroics and nonvolatile electronic devices based on vertical and coplanar heterojunctions of 2D ferroic materials. Nevertheless, controlled microscopic manipulation of ferroelectric domains is still rare in monolayer-thick 2D ferroelectrics with in-plane polarization. Here we report the discovery of robust ferroelectricity with a critical temperature close to 400 K in SnSe monolayer plates grown on graphene and the demonstration of controlled room-temperature ferroelectric domain manipulation by applying appropriate bias voltage pulses to the tip of a scanning tunneling microscope (STM). This study shows that STM is a powerful tool for detecting and manipulating the microscopic domain structures in 2D ferroelectric monolayers, which are difficult for conventional approaches such as piezoresponse force microscopy, thus facilitating the hunt for other 2D ferroelectric monolayers with in-plane polarization with important technological applications.

2D ferroelectric↗
DOE OSTI2020

Extended anharmonic collapse of phonon dispersions in SnS and SnSe

The lattice dynamics and high-temperature structural transition in SnS and SnSe are investigated via inelastic neutron scattering, high-resolution Raman spectroscopy and anharmonic first-principles simulations. We uncover a spectacular, extreme softening and reconstruction of an entire manifold of low-energy acoustic and optic branches across a structural transition, reflecting strong directionality in bonding strength and anharmonicity. Further, our results solve a prior controversy by revealing the soft-mode mechanism of the phase transition that impacts thermal transport and thermoelectric efficiency. Our simulations of anharmonic phonon renormalization go beyond low-order perturbation theory and capture these striking effects, showing that the large phonon shifts directly affect the thermal conductivity by altering both the phonon scattering phase space and the group velocities. These results provide a detailed microscopic understanding of phase stability and thermal transport in technologically important materials, providing further insights on ways to control phonon propagation in thermoelectrics, photovoltaics, and other materials requiring thermal management.

36 MATERIALS SCIENCE↗