Zintl Phase as Thermoelectric Materials: Synthesis, Structure and Properties of Yb5Al2Sb6

2007 ◽  
Vol 1044 ◽  
Author(s):  
Iliya Todorov ◽  
Duck-Young Chung ◽  
Mercouri Kanatzidis
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Spectroscopic Properties ◽  
Structure Type ◽  
Structure And Properties ◽  
Materials Synthesis ◽  
Preliminary Assessment ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Doping Effects

AbstractWe present the synthesis, crystal structure, spectroscopic properties, and electronic structure of a new member of the Zintl family, Yb5Al2Sb6. The compound crystallizes in the Ba5Al2Bi6 structure type. A preliminary assessment of its thermoelectric properties including electrical conductivity, thermopower, and thermal conductivity are reported. Moreover, investigations of solid solutions of this phase, doping effects and chemical modifications will be presented. The room temperature conductivity, thermopower and thermal conductivity of Yb5Al2Sb6/0.5Ge were 1100 S/cm, 20 μV/K, and 3.8 W/m.K, respectively.

The thermal conductivity of germanium and silicon between 2 an d 300° K

1957 ◽  
Vol 238 (1215) ◽  
pp. 502-514 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Room Temperature ◽  
Energy Levels ◽  
Silicon Crystal ◽  
Lattice Vibrations ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Group Iii ◽  
Impurity Atoms ◽  
Type Silicon

The thermal conductivity of single crystals o f pure n -type germanium and of p -type germanium containing from 10 14 to 10 19 group III impurity atoms per cm 3 has been measured from 2 to 90° K . In some cases the readings have been extended up to room temperature. Whereas the low- temperature conductivity of the pure specimens is that which one would expect from a dielectric crystal, the addition of even very amounts of group III impurity decreases the conductivity very considerably and alters its temperature dependence. It is suggested that the extra thermal resistance introduced is due to the scattering of the lattice vibrations by the electrons or holes in the impurity energy levels. The theory of such scattering has been worked out by Ziman, and the experimental results are shown to be in fair agreement with this theory. A pure n -type silicon single crystal and a gold-doped p -type silicon crystal show a behaviour similar to the germanium. The room-temperature conductivity of germanium and silicon is 0⋅64 and 1⋅45 watt units respectively.

Thermal conductivity of AlN ceramic with a very low amount of grain boundary phase at 4 to 1000 K

2002 ◽  
Vol 17 (11) ◽  
pp. 2940-2944 ◽  
Author(s):  
Koji Watari ◽  
Hiromi Nakano ◽  
Kazuyori Urabe ◽  
Kozo Ishizaki ◽  
Shixun Cao ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Grain Boundary ◽  
Single Crystal ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Amorphous Film ◽  
Boundary Phase ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Significant Difference

An AlN ceramic fired at 2173 K for 100 h under a reduced N2 atmosphere with carbon possessed a room-temperature conductivity of 272 Wm−1K−1, slightly lower than the value for high-purity, single-crystal AlN. However, the thermal conductivity of the ceramic at temperatures below 100 K was much lower than that of single crystal. This is mainly due to phonon scattering by grain junctions that possess an amorphous film with a thickness of under 1 nm. At 500 to 1000 K, no significant difference in the conductivity was observed between the ceramic and the single crystal.

scholarly journals Old Donors for New Molecular Conductors: Combining TMTSF and BEDT-TTF with Anionic (TaF6)1−x/(PF6)x Alloys

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 386
Author(s):  
Magali Allain ◽  
Cécile Mézière ◽  
Pascale Auban-Senzier ◽  
Narcis Avarvari
Keyword(s):  
Single Crystal ◽  
Room Temperature ◽  
Density Wave ◽  
Spin Density Wave ◽  
Orthorhombic Phase ◽  
Molecular Conductors ◽  
Bechgaard Salts ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Resistivity Measurements

Tetramethyl-tetraselenafulvalene (TMTSF) and bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) are flagship precursors in the field of molecular (super)conductors. The electrocrystallization of these donors in the presence of (n-Bu4N)TaF6 or mixtures of (n-Bu4N)TaF6 and (n-Bu4N)PF6 provided Bechgaard salts formulated as (TMTSF)2(TaF6)0.84(PF6)0.16, (TMTSF)2(TaF6)0.56(PF6)0.44, (TMTSF)2(TaF6)0.44(PF6)0.56 and (TMTSF)2(TaF6)0.12(PF6)0.88, together with the monoclinic and orthorhombic phases δm-(BEDT-TTF)2(TaF6)0.94(PF6)0.06 and δo-(BEDT-TTF)2(TaF6)0.43(PF6)0.57, respectively. The use of BEDT-TTF and a mixture of (n-Bu4N)TaF6/TaF5 afforded the 1:1 phase (BEDT-TTF)2(TaF6)2·CH2Cl2. The precise Ta/P ratio in the alloys has been determined by an accurate single crystal X-ray data analysis and was corroborated with solution 19F NMR measurements. In the previously unknown crystalline phase (BEDT-TTF)2(TaF6)2·CH2Cl2 the donors organize in dimers interacting laterally yet no organic-inorganic segregation is observed. Single crystal resistivity measurements on the TMTSF based materials show typical behavior of the Bechgaard phases with room temperature conductivity σ ≈ 100 S/cm and localization below 12 K indicative of a spin density wave transition. The orthorhombic phase δo-(BEDT-TTF)2(TaF6)0.43(PF6)0.57 is semiconducting with the room temperature conductivity estimated to be σ ≈ 0.16–0.5 S/cm while the compound (BEDT-TTF)2(TaF6)2·CH2Cl2 is also a semiconductor, yet with a much lower room temperature conductivity value of 0.001 to 0.0025 S/cm, in agreement with the +1 oxidation state and strong dimerization of the donors.

scholarly journals Synthesis and Characterization of Lithium-Ion Conductive LATP-LaPO4 Composites Using La2O3 Nano-Powder

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3502
Author(s):  
Fangzhou Song ◽  
Masayoshi Uematsu ◽  
Takeshi Yabutsuka ◽  
Takeshi Yao ◽  
Shigeomi Takai
Keyword(s):  
Room Temperature ◽  
Conduction Mechanism ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
X Ray ◽  
Nano Powder ◽  
Powder Addition

LATP-based composite electrolytes were prepared by sintering the mixtures of LATP precursor and La2O3 nano-powder. Powder X-ray diffraction and scanning electron microscopy suggest that La2O3 can react with LATP during sintering to form fine LaPO4 particles that are dispersed in the LATP matrix. The room temperature conductivity initially increases with La2O3 nano-powder addition showing the maximum of 0.69 mS∙cm−1 at 6 wt.%, above which, conductivity decreases with the introduction of La2O3. The activation energy of conductivity is not largely varied with the La2O3 content, suggesting that the conduction mechanism is essentially preserved despite LaPO4 dispersion. In comparison with the previously reported LATP-LLTO system, although some unidentified impurity slightly reduces the conductivity maximum, the fine dispersion of LaPO4 particles can be achieved in the LATP–La2O3 system.

Structure and Conductivity of Iodine-Doped C60 Thin Films

1994 ◽  
Vol 359 ◽  
Author(s):  
Jun Chen ◽  
Haiyan Zhang ◽  
Baoqiong Chen ◽  
Shaoqi Peng ◽  
Ning Ke ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Room Temperature ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
X Ray ◽  
Thermally Activated ◽  
Order Of Magnitude

ABSTRACTWe report here the results of our study on the properties of iodine-doped C60 thin films by IR and optical absorption, X-ray diffraction, and electrical conductivity measurements. The results show that there is no apparent structural change in the iodine-doped samples at room temperature in comparison with that of the undoped films. However, in the electrical conductivity measurements, an increase of more that one order of magnitude in the room temperature conductivity has been observed in the iodine-doped samples. In addition, while the conductivity of the undoped films shows thermally activated temperature dependence, the conductivity of the iodine-doped films was found to be constant over a fairly wide temperature range (from 20°C to 70°C) exhibiting a metallic feature.

A comparative study of Li10.35Ge1.35P1.65S12 and Li10.5Ge1.5P1.5S12 superionic conductors

2020 ◽  
Vol 13 (06) ◽  
pp. 2050031
Author(s):  
Yue Jiang ◽  
Zhiwei Hu ◽  
Ming’en Ling ◽  
Xiaohong Zhu
Keyword(s):  
Ionic Conductivity ◽  
Room Temperature ◽  
Ionic Conductivities ◽  
Lithium Ion ◽  
Lattice Parameter ◽  
Superionic Conductors ◽  
Chemical Compositions ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Ion Conductor

Since the lithium-ion conductor Li[Formula: see text]GeP2S[Formula: see text] (LGPS) with a super high room-temperature conductivity of 12[Formula: see text]mS/cm was first reported in 2011, sulfide-type solid electrolytes have been paid much attention. It was suggested by Kwon et al. [J. Mater. Chem. A 3, 438 (2015)] that some excess lithium ions in LGPS, namely, Li[Formula: see text]Ge[Formula: see text] P[Formula: see text]S[Formula: see text], could further improve their ionic conductivities, and the highest conductivity of 14.2[Formula: see text]mS/cm was obtained at [Formula: see text] though a larger lattice parameter that occurred at [Formula: see text]. In this study, we focus on these two different chemical compositions of LGPS with [Formula: see text] and [Formula: see text], respectively. Both samples were prepared using the same experimental process. Their lattice parameter, microstructure and room-temperature ionic conductivity were compared in detail. The results show that the main phase is the tetragonal LGPS phase but with a nearly identical amount of orthorhombic LGPS phase coexisting in both samples. Bigger lattice parameters, larger grain sizes and higher ionic conductivities are simultaneously achieved in Li[Formula: see text]Ge[Formula: see text]P[Formula: see text]S[Formula: see text] ([Formula: see text]), exhibiting an ultrahigh room-temperature ionic conductivity of 18.8[Formula: see text]mS/cm.

Intercalation of Acceptors and Donors in Highly Ordered Graphite Fibers

1982 ◽  
Vol 20 ◽  
Author(s):  
T.C. Chieu ◽  
G. Timp ◽  
M.S. Dresselhaus
Keyword(s):  
Raman Spectroscopy ◽  
Room Temperature ◽  
Skin Depth ◽  
X Ray Diffraction ◽  
Repeat Distance ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
X Ray ◽  
Order Of Magnitude ◽  
Graphite Fibers

ABSTRACTThe intercalation of various acceptors and donors into graphite fibers, prepared from benzene-derived precursor materials is investigated by Raman spectroscopy, x-ray diffraction, electron diffraction, lattice fringing, and electrical resistivity measurements. Evidence for formation of well-staged acceptor compounds is provided by Debye-Scherrer x-ray diffraction which probes the bulk fiber and by Raman spectroscopy which probes an optical skin depth (< 0.1 μm). Lattice fringing measurements provide direct observation of large regions (up to 50 Aring; × 400 Aring;) of defectfree single-staged regions. Values for the c-axis repeat distance Ic are obtained by indexing (00l) lines of the x-ray diffraction pattern. Raman results show characteristic upshifted modes for stage 1 acceptor compounds with a sharpening in linewidth as compared to the E2g2 mode of the pristine fiber. The room temperature electrical conductivity is increased about an order of magnitude upon intercalation and exhibits a metallic dependence on temperature. The highest air-stable room temperature conductivity 1.4 × 105 (Ω-cm)−l ever reported for an intercalated fiber has been achieved.

Hydrogenation of B and P Implanted LPCVD Amorphous Silicon

1992 ◽  
Vol 258 ◽  
Author(s):  
Stanislaw M. Pietruszko
Keyword(s):  
Ion Implantation ◽  
Amorphous Silicon ◽  
Room Temperature ◽  
Silicon Films ◽  
Conductivity Measurements ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
B Doping ◽  
Doping Range

ABSTRACTThe results of the investigation of doping by B and P ion implantation into LPCVD amorphous silicon films in the range from 2*1015 to 2*1021 atoms/cm3 are presented. The room temperature conductivity increases to 10-2 Ω-1 cm-1 and to 10-2 Ω-1 cm-1 for the highest B and P doping, respectively. The subsequent hydrogenation (2.5 and 5 at%) by ion implantation increases the doping efficiency for P doping. For B doping efficiency increases at the low and decreases for the high doping range. The results of conductivity measurements vs temperature of doped and hydrogenated films are presented.

Synthesis, Electrical and Humidity Sensing Properties of BaTiO3 Nanofibers via Electrospinning

2011 ◽  
Vol 418-420 ◽  
pp. 684-687 ◽  
Author(s):  
Hong Di Zhang ◽  
Yun Ze Long ◽  
Zhao Jian Li ◽  
Bin Sun ◽  
Chen Hao Sheng
Keyword(s):  
Room Temperature ◽  
Humidity Sensor ◽  
Annealing Process ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
Humidity Sensing ◽  
P Type ◽  
Application Prospects ◽  
Humidity Sensing Properties ◽  
Scanning Electron

Barium titanate (BTO, BaTiO3) nanofiber was prepared via electrospinning and followed annealing process. The as-spun and calcined BTO nanofibers were characterized by a scanning electron microscope (SEM). After annealing at 800 °C in air for 3 h, polycrystalline BTO nanofibers with 120-200 nm in diameter were successfully obtained. I-V characteristic curves of single BTO nanofiber were measured. The p-type semiconducting fiber shows a room-temperature conductivity of about 0.3 S/cm. In addition, the small humidity hysteresis demonstrates the application prospects of electrospun BTO nanofibers in the fabrication of a high-sensitive humidity sensor.

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