scholarly journals Structural and Thermoelectric Properties of Cu Substituted Type I Clathrates Ba8CuxSi~32−xGa~14

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 237 ◽  
Author(s):  
Yue Dong ◽  
Xueyong Ding ◽  
Xinlin Yan ◽  
Long Zhang ◽  
Tianhua Ju ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electrical Resistivity ◽  
Thermoelectric Properties ◽  
Charge Carrier Concentration ◽  
Type I ◽  
X Ray Diffraction ◽  
Ring Plane ◽  
Principal Mechanism ◽  
X Ray ◽  
Cu Substitution

With an attempt to improve the thermoelectric properties of type I clathrates in the Ba-Ga-Si system, we introduce Cu into the framework of the crystal structure. Single crystals are prepared in Ga-flux and characterized by X-ray diffraction techniques and transport measurements for the structural and thermoelectric properties. Our composition analyses show that only a small amount of Cu is determined in the clathrates. The single crystal X-ray diffraction data refinements confirm that Ga atoms prefer the 6c and 24k sites and avoid the 16i sites in the crystal structure. The small amount of Cu affects the crystal structure by compressing the tetrakaidecahedral cage along the direction perpendicular to the six-atom-ring plane. This could be the reason for the high charge carrier concentration, and low electrical resistivity and Seebeck coefficient. We analyze the principal mechanism for our observation and conclude that the Cu substitution can adjust some subtle details of the structure, maintaining the Zintl rule in the type I clathrates.

Evolution of crystal structure of dual layered molecular conductor (ET)4ZnBr4(C6H4Cl2) with temperature

CrystEngComm ◽  
2021 ◽  
Author(s):  
Gennady V. Shilov ◽  
Elena I. Zhilyaeva ◽  
Sergey M. Aldoshin ◽  
Alexandra M Flakina ◽  
Rustem B. Lyubovskii ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electrical Resistivity ◽  
Single Crystal ◽  
Room Temperature ◽  
Organic Conductor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Resistivity Measurements ◽  
Molecular Conductor ◽  
Abrupt Changes

Electrical resistivity measurements of a dual layered organic conductor (ET)4ZnBr4(1,2-C6H4Cl2) above room temperature show abrupt changes in resistivity at 320 K. Single-crystal X-ray diffraction studies in the 100-350 K range...

Thermoelectric properties of Tl9BiTe6 / Tl9BiSe6 solid solutions

2000 ◽  
Vol 626 ◽  
Author(s):  
Bernd Wölfing ◽  
Christian Kloc ◽  
Ernst Bucher
Keyword(s):  
Electrical Resistivity ◽  
Electrical Properties ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
State Of The Art ◽  
High Resistivity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lattice Constants ◽  
Vegard’S Law

ABSTRACTThe compounds Tl9BiTe6 (TBT) and Tl9BiSe6 (TBS) crystallize in the tetragonal space group I4/mcm. Tl9BiTe6 has a thermopower of 185 μV/K and an electrical resistivity of 5.5 mΩcm at 300K, resulting in a power factor of S2/ρ = 0.6 mW/mK2. Compared to Bi2Te3 which is the state of the art material at this temperature this is about a factor of 7 lower. At 300 K TBS has a thermopower of 750 μV/K but a high resistivity of 130 Ωcm. To optimize the thermoelectric properties of TBT solid solutions have been formed with TBS. The resistivities and have been measured on Tl9BiTe1-xSex with x = 0.05, 0.08, 0.2 and 0.5. In addition to the electrical properties the lattice constants have been measured by X-ray diffraction. The dependence of the lattice constants on the Te/Se ratio clearly deviates from Vegard's law. Different affinities of Te and Se towards the two chalcogenide sites in the crystal can explain this behavior.

Thermoelectric Properties of InxCo4-yNiySb12 Skutterudite Compounds

2007 ◽  
Vol 1044 ◽  
Author(s):  
Veronique Da Ros ◽  
Juliusz Leszczynski ◽  
Bertrand Lenoir ◽  
Anne Dauscher ◽  
Christophe Candolfi ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermal Properties ◽  
Chemical Composition ◽  
Thermoelectric Power ◽  
Thermoelectric Properties ◽  
Electron Probe Microanalysis ◽  
Electron Probe ◽  
X Ray Diffraction ◽  
X Ray

AbstractThe preparation of partially filled n-type InxCo4Sb12 skutterudite compounds has been recently reported. The results were particularly promising, the materials exhibiting a ZT value far higher than one at moderated temperature. In this paper, we propose to investigate another way to tune the electrical and thermal properties by substituting Co atoms by Ni atoms in InxCo4Sb12. InxCo4-yNiySb12 polycrystalline samples have been prepared by a conventional metallurgical route. Structural analyses have been carried out by X-ray diffraction. The chemical composition and micro-homogeneity have been checked by electron probe microanalysis. Measurements of the electrical resistivity, thermoelectric power and thermal conductivity have been performed between 300 and 800 K. The influence of the presence of Ni on the thermoelectric properties of InxCo4Sb12 compounds is presented and discussed.

Thermoelectric properties of InxPbxCo4Sb12 prepared by HPHT

2016 ◽  
Vol 09 (01) ◽  
pp. 1650008 ◽  
Author(s):  
Le Deng ◽  
Li Bin Wang ◽  
Jie Ming Qin ◽  
Xiao Peng Jia ◽  
Hong An Ma
Keyword(s):  
Thermal Conductivity ◽  
High Pressure ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Substantial Reduction ◽  
X Ray Diffraction ◽  
X Ray

We prepared InxPbxCo4Sb[Formula: see text] by high-pressure and high-temperature (HPHT) method. Samples were characterized by X-ray diffraction (XRD), electron microprobe analysis and thermoelectric properties measurements. The Seebeck coefficient, electrical resistivity and thermal conductivity of InxPbxCo4Sb[Formula: see text] samples were all performed in the temperature range of 323–723[Formula: see text]K. With the increasing synthetic pressure, the Seebeck coefficient of In[Formula: see text]Pb[Formula: see text]Co4Sb[Formula: see text] samples, which synthesized between 1.5 GPa–2.3 GPa, showed an obvious increase while the thermal conductivity exhibited a substantial reduction.

ELECTRICAL CONDUCTING AND THERMOELECTRIC PROPERTIES OF Ba4Na2Nb10O30−Ba3NaLaNb10O30 SYSTEM

1990 ◽  
Vol 04 (10) ◽  
pp. 681-688
Author(s):  
MASAYUKI TSUKIOKA ◽  
YASUO TANOKURA ◽  
MASAZI SHIMAZU ◽  
SHINICHIRO KUROIWA ◽  
SADAO TSUTSUMI
Keyword(s):  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Solid Solutions ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ceramic Samples ◽  
Electrical Conducting ◽  
P Type

Ceramic samples of BNN-BNLN ( Ba 4 Na 2 Nb 10 O 30− Ba 3 NaLaNb 10 O 30) system were prepared in flowing N 2 gas at about 1410°C, which has been confirmed to have continuous solid solutions over the whole range of BNN-BNLN system by X-ray diffraction measurement. Electrical resistivity and Seebeck coefficient measurements were carried out at temperatures from 77 K to 773 K and from 60 K to 200 K, respectively for the samples of different composition belonging to the BNN-BNLN system. These experiments revealed that all these materials were extrinsic semiconductors and change from p-type semiconductors to n-type during the process of rising temperature.

Structural complexity in minerals: twinning, polytypism and disorder in the crystal structure of polybasite, (Ag,Cu)16(Sb,As)2S11

2006 ◽  
Vol 62 (3) ◽  
pp. 447-456 ◽  
Author(s):  
Michel Evain ◽  
Luca Bindi ◽  
Silvio Menchetti
Keyword(s):  
Crystal Structure ◽  
Diffraction Data ◽  
Structural Complexity ◽  
X Ray Diffraction ◽  
Monoclinic Symmetry ◽  
X Ray ◽  
System A ◽  
Cu Substitution ◽  
A Cell ◽  
Linear Coordination

The crystal structures of 222- and 221-polybasite [(Ag,Cu)16(Sb,As)2S11] crystals have been solved and refined by means of X-ray diffraction data (collected at 100 and 120 K, respectively) from twinned crystals. Both structures consist of the stacking of [(Ag,Cu)6Sb2S7]2− and [Ag9CuS4]2+ module layers in which Sb forms isolated SbS3 pyramids typically occurring in sulfosalts; copper links two S atoms in a linear coordination and silver occupies sites with coordination ranging from quasi-linear to almost tetrahedral. An Ag → Cu substitution in the [(Ag,Cu)6Sb2S7]2− module layer is observed in both structures, the substitution amount being larger in the 221- than in the 222-polybasite. A pattern of the possible mechanism regulating the type of unit cell that is stabilized is proposed: starting from the hypothetical stoichiometric and fully ordered Ag15CuSb2S11 222-polybasite structure, with a low C2/c monoclinic symmetry and a large 222 supercell, the disorder introduced by the substitution of Cu for Ag increases the symmetry with a cell reduction along the c axis yielding the 221 supercell and a trigonal crystal system. A further increase of the substitution gives rise to a folding of the cell along the a and b axes and the 111-pearceite structure, space group P\bar3m1.

scholarly journals X-ray diffraction studies of enkephalins. Crystal structure of [(4′-bromo) Phe4,Leu5]enkephalin

1984 ◽  
Vol 218 (3) ◽  
pp. 677-689 ◽  
Author(s):  
T Ishida ◽  
M Kenmotsu ◽  
Y Mino ◽  
M Inoue ◽  
T Fujiwara ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Least Squares Method ◽  
Heavy Atom ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Biologically Active ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relationship Of

In order to investigate the structure-activity relationship of [Leu5]- and [Met5]enkephalins, [(4′-bromo)Phe4, Leu5]-, [(4′-bromo)Phe4, Met5]- and [Met5] enkephalins were synthesized and crystallized. The crystal structure of [(4′-bromo) Phe4, Leu5]- enkephalin was determined by X-ray diffraction method using the heavy atom method and refined to R = 0.092 by the least-squares method. The molecule in this crystal took essentially the same type I' beta-turn conformation found in [Leu5]enkephalin [Smith & Griffin (1978) Science 199, 1214-1216). On the other hand, the preliminary three-dimensional Patterson analyses showed that the most probable conformations of [(4′-bromo)Phe4,Met5]- and [Met5]enkephalins are both the dimeric extended forms. Based on these insights, the biologically active conformation of enkephalin was discussed in relation to the mu- and delta-receptors.

Structure of vanadocene in the temperature interval 108–357 K and the nature of the ring disorder

1996 ◽  
Vol 52 (2) ◽  
pp. 314-322 ◽  
Author(s):  
M. Yu. Antipin ◽  
R. Boese
Keyword(s):  
Crystal Structure ◽  
Careful Analysis ◽  
Similar Data ◽  
X Ray Diffraction ◽  
Ring Plane ◽  
Temperature Dependent ◽  
X Ray ◽  
Ring Rotation ◽  
Anisotropic Displacement Parameters ◽  
Rotation Motion

The crystal structure of vanadocene, bis(π5–2,4-cyclopentadien-1-yl)vanadium, Cp2V, has been studied at the four temperatures 108, 170, 297 and 357 K by X-ray diffraction in order to elucidate the nature of the Cp-ring disorder and compare the results obtained with similar data for formally isostructural ferrocene, cobaltocene and nickelocene. A careful analysis of the anisotropic displacement parameters (ADP's) for Cp2V showed that at 108 K the crystal structure is ordered (staggered Cp2V molecules occupy centres of symmetry in the space group P21/n, Z = 2), which distinguishes vanadocene from its formal analogues and some Cp-ring disorder starts at ca 170 K. A model of this disorder has been proposed with two distinct orientations of the ring, differing in temperature-dependent occupancy factors and by a rotation in the ring plane of almost 36°. The fractional contributions of the second (minor) ring orientation are 0.05, 0.17 and 0.35, respectively, at 170, 297 and 357 K. The energetic characteristics of the ring rotation motion in the Cp2V crystal were estimated from ADP analysis and compared with similar data for other 3d-metallocenes.

Effects of Homogenization Treatment on Thermoelectric Properties of Ba8Al16Si30

2007 ◽  
Vol 544-545 ◽  
pp. 275-278 ◽  
Author(s):  
Joo Ho Lee ◽  
Jung Il Lee ◽  
Young Ho Kim ◽  
Il Ho Kim ◽  
Kyung Wook Jang ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Phase Transformations ◽  
Thermoelectric Properties ◽  
Treatment Time ◽  
Type I ◽  
X Ray Diffraction ◽  
Homogenization Treatment ◽  
X Ray ◽  
Arc Melting ◽  
Melting Technique

The Arc melting technique was employed to synthesize the type I clathrate of Ba8Al16Si30 compound. Phase transformations during synthesis and homogenization treatment were investigated using X-ray diffraction (XRD) and thermal analysis (TG/DSC). Thermoelectric properties as functions of temperature and homogenization treatment time were evaluated in this study. Maximum ZT was 0.14 at 590K for homogenized at 1173 K for 168hrs specimen and it is strongly expected to show higher value above 600K.

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