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.

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.

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.

Dielectric Properties and Raman Spectroscopy in Ca-Substituted Na0.5Bi0.5TiO3 Ferroelectric Ceramics

2011 ◽  
Vol 324 ◽  
pp. 298-301 ◽  
Author(s):  
Roy Jean Roukos ◽  
Olivier Bidault ◽  
Julien Pansiot ◽  
Ludivine Minier ◽  
Lucien Saviot
Keyword(s):  
Raman Spectroscopy ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Rhombohedral Phase ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
Ferroelectric Ceramics ◽  
Dielectric Measurements ◽  
X Ray Diffraction ◽  
X Ray

Lead free Na0.5Bi0.5TiO3 (NBT) and (Na0.5Bi0.5TiO3)1-x(CaTiO3)x (NBT-CT) piezoelectric ceramics with the perovskite structure were studied. The NBT and NBT-CT samples were synthesized using a solid-state reaction method and characterized with X-ray diffraction (XRD), Raman spectroscopy and dielectric measurements for several compositions (x = 0, 0.07, 0.15) at room temperature. The XRD analysis showed a stabilization of a rhombohedral phase at a low concentration of Ca (0 < x <0.15), whereas Raman spectra reveal a strong modification for the sample with x = 0.15. The dielectric properties of these ceramics were studied by measuring impedance in the 79-451K temperature range for unpoled and field cooling with an electric field (FC) conditions.

Sol-Gel Synthesis and Characterizations of LiCF3SO3-CeO2 Solid Composite Electrolytes

2010 ◽  
Vol 129-131 ◽  
pp. 506-510 ◽  
Author(s):  
N.A. Dzulkurnain ◽  
N.S. Mohamed
Keyword(s):  
Sol Gel ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
Lithium Triflate ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
X Ray ◽  
Composite Solid Electrolyte ◽  
Sol Gel Synthesis ◽  
Composite Solid

Composite solid electrolyte systems composed of different compositions of lithium triflate (LiCF3SO3) as host, and cerium oxide (CeO2) as dispersoid were prepared using sol-gel method. The electrical, structural and morphological properties of the composite solid electrolytes were investigated using impedance spectroscopy (IS), X-Ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM). Maximum room temperature conductivity was obtained for the system of 60 mol % LiCF3SO3 – 40 mol % CeO2.

scholarly journals Origin of Ultraviolet Luminescence from Bulk ZnO Thin Films Grown by Molecular Beam Epitaxy

2011 ◽  
Vol 1 ◽  
pp. 135-139 ◽  
Author(s):  
M. Asghar ◽  
Khalid Mahmood ◽  
Adnan Ali ◽  
M.A. Hasan ◽  
I. Hussain ◽  
...  
Keyword(s):  
Thin Films ◽  
Raman Spectroscopy ◽  
Molecular Beam Epitaxy ◽  
Room Temperature ◽  
Molecular Beam ◽  
Energy Dispersive ◽  
Zno Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uv Luminescence

Origin of ultraviolet (UV) luminescence from bulk ZnO has been investigated with the help of photoluminescence (PL) measurements. Thin films of ZnO having 52%, 53% and 54% of Zn-contents were prepared by means of molecular beam epitaxy (MBE). We observed a dominant UV line at 3.28 eV and a visible line centered at 2.5 eV in the PL spectrum performed at room temperature. The intensity of UV line has been found to depend upon the Zn percentage in the ZnO layers. Thereby, we correlate the UV line in our samples with the Zn-interstitials-bound exciton (Zni-X) recombination. The results obtained from, x-ray diffraction, the energy dispersive X-ray spectrum (EDAX) and Raman spectroscopy supported the PL results.

scholarly journals [HMIM][Br9]: a Room-temperature Ionic Liquid Based on a Polybromide Anion

2013 ◽  
Vol 68 (10) ◽  
pp. 1103-1107 ◽  
Author(s):  
Heike Haller ◽  
Michael Hog ◽  
Franziska Scholz ◽  
Harald Scherer ◽  
Ingo Krossing ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Raman Spectroscopy ◽  
Ionic Liquid ◽  
Nmr Spectroscopy ◽  
Single Crystal ◽  
Room Temperature ◽  
High Electrical Conductivity ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
X Ray

[HMIM][Br9] ([HMIM]=1-hexyl-3-methylimidazolium) has been investigated by Raman spectroscopy, single-crystal X-ray diffraction and NMR spectroscopy. Conductivity measurements show a high electrical conductivity like other polybromides.

BEDT-TTF-Salze mit quadratischen Platinaten(II) als Gegenionen: [BEDT-TTF]4[Pt(CN)4] / BEDT-TTF-Salts with Square Platinates(II) as Counter Ions: [BEDT-TTF]4[Pt(CN)4]

1990 ◽  
Vol 45 (6) ◽  
pp. 763-774 ◽  
Author(s):  
Stephan Gärtner ◽  
Ilsabe Heinen ◽  
Heimo J. Keller ◽  
Roland Niebl ◽  
Bernhard Nuber ◽  
...  
Keyword(s):  
Structure Elucidation ◽  
Room Temperature ◽  
Specific Resistance ◽  
Structural Phase ◽  
Antiferromagnetic Coupling ◽  
Neutral Donor ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
X Ray ◽  
Counter Ions

The compound [BEDT-TTF]4[Pt(CN)4], BEDT-TTF = Bis(4.5-ethylendithiolo)tetrathiafulvalen = C10H8S8, stoichiometry C44H32N4S32Pt, Mr = 1837.9 (g/mol), was obtained by electrocrystallization in at least three different modifications. Two of them could be identified by single crystal X-ray structure elucidation. 1 = β-modification, is isolated in black, lustrous platelets: triclinic, P 1̄, Z = 1, α = 9.7280(30) Å, b = 10.9237(27) Å, c = 16.5432(60) Å, a = 95.820(25)°, β = 98.296(26)°, γ = 115.215(24)°, V = 1547.56 A3, dc = 2.0 (g/cm3), room temperature, Rw = 0.082 for 7322 observed reflections. 2 = y-modification, is isolated in black not very regular crystals: monoclinic, C 2/c, Z = 4, a = 11.163(6) Å, b = 33.56(2) Å, c = 16.56(1) Å, β = 91.39(4)°, V = 6202.04 A3, dc = 1.97 (g/cm3), room temperature, Rw = 0.053 for 1404 observed independent reflections. Both solids contain sheets of BEDT-TTF cations separated by sheets of the counter anions. 1 contains two crystallographically independent BEDT-TTF moieties while 2 contains four independent donor units per cell. Of interest are the very different lengths of the central C=C bonds of the BEDT-TTF moieties which are assumed to reflect the charge density on these ions. In 1 these distances are 1.350(14) Å and 1.306(14) A, respectively, for the two different BEDT-TTF cations in the lattice, in 2 they are 1.372(34) A, 1.401(42) A and 1.289(54) Å respectively. The remarkable differences in these bond lengths indicate, according to published concepts, quite different charges on the different BEDT-TTF units. Two of the distances are shorter than in the neutral donor. Measurements of the specific resistance and the thermopower show that 1 is a metal with a room temperature conductivity of 10 S/cm. At around 200 K 1 becomes semiconducting. 2 turns out to be a semiconductor with a room temperature conductivity of 1—2 S/cm. Around 225 K a structural phase transition occurs. ESR measurements show an antiferromagnetic coupling between the spins in the solid. A third modification (δ) (semiconducting with a room temperature conductivity around 2 × 10-2 S/cm) was identified by ESR investigations.

scholarly journals Thermal Annealing and Phase Transformation of Serpentine-Like Garnierite

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 188
Author(s):  
Arun Kumar ◽  
Michele Cassetta ◽  
Marco Giarola ◽  
Marco Zanatta ◽  
Monique Le Guen ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Raman Spectroscopy ◽  
Phase Transformation ◽  
Differential Thermal Analysis ◽  
Thermal Treatment ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Thermally Induced ◽  
X Ray ◽  
Micro Raman Spectroscopy

This study is focused on the vibrational and microstructural aspects of the thermally induced transformation of serpentine-like garnierite into quartz, forsterite, and enstatite occurring at about 620 °C. Powder specimens of garnierite were annealed in static air between room temperature and 1000 °C. The kinetic of the transformation was investigated by means of thermogravimetric and differential thermal analysis, and the final product was extensively characterized via micro-Raman spectroscopy and X-ray diffraction. Our study shows that serpentine-like garnierite consists of a mixture of different mineral species. Furthermore, these garnierites and their composition can provide details based on the mineralogy and the crystalline phases resulting from the thermal treatment.

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