scholarly journals Structure, Morphology, Heat Capacity, and Electrical Transport Properties of Ti3(Al,Si)C2 Materials

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3222
Author(s):  
Kamil Goc ◽  
Janusz Przewoźnik ◽  
Katarzyna Witulska ◽  
Leszek Chlubny ◽  
Waldemar Tokarz ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Heat Capacity ◽  
Specific Heat ◽  
Electrical Transport ◽  
Residual Resistivity ◽  
Max Phase ◽  
Electrical Transport Properties ◽  
Debye Temperatures ◽  
Si Content ◽  
Hot Pressing Sintering

A study of Ti3Al1−xSixC2 (x = 0 to x = 1) MAX-phase alloys is reported. The materials were obtained from mixtures of Ti3AlC2 and Ti3SiC2 powders with hot pressing sintering technique. They were characterised with X-ray diffraction, heat capacity, electrical resistivity, and magnetoresistance measurements. The results show a good quality crystal structure and metallic properties with high residual resistivity. The resistivity weakly varies with Si doping and shows a small, positive magnetoresistance effect. The magnetoresistance exhibits a quadratic dependence on the magnetic field, which indicates a dominant contribution from open electronic orbits. The Debye temperatures and Sommerfeld coefficient values derived from specific heat data show slight variations with Si content, with decreasing tendency for the former and an increase for the latter. Experimental results were supported by band structure calculations whose results are consistent with the experiment concerning specific heat, resistivity, and magnetoresistance measurements. In particular, they reveal that of the s-electrons at the Fermi level, those of Al and Si have prevailing density of states and, thus predominantly contribute to the metallic conductivity. This also shows that the high residual resistivity of the materials studied is an intrinsic effect, not due to defects of the crystal structure.

Electrical Transport Properties of Cu3Ge Thin Films

1993 ◽  
Vol 320 ◽  
Author(s):  
M. O. Aboelfotoh
Keyword(s):  
Crystal Structure ◽  
Thin Films ◽  
Electrical Transport ◽  
Pure Copper ◽  
Mean Free Path ◽  
Anomalous Behavior ◽  
Residual Resistivity ◽  
Electrical Transport Properties ◽  
Monoclinic Crystal ◽  
Monoclinic Crystal Structure

ABSTRACTWe present results of electrical transport studies performed on thin films of ε1-Cu3Ge in the temperature range 4.2 – 300 K. It is found that ε1-Cu3Ge which has a long-range ordered monoclinic crystal structure, exhibits a remarkably low metallic resistivity of σ 6 μΩ cm at room temperature. The density of charge carriers, which are predominantly holes, is σ 8 × 1022/cm3 and is independent of temperature and film thickness. The Hall mobility at 4.2 K is σ 132 cm2/V s, considerably higher than in pure copper. The elastic mean free path is found to be σ 1200Å, which is surprisingly large for a metallic compound film. The results show that the residual resistivity is dominated by surface scattering rather than grain-boundary scattering. It is also found that by varying the Ge concentration from 0 to 40 at. % the resistivity exhibits anomalous behavior. This behavior is correlated with changes observed in the crystal structure of the thin-film alloys as the Ge concentration is increased. The resistivity remains close to that of the ε1-Cu3Ge phase over a range of Ge concentration which extends from 25 to 35 at. %

Electrical Conductivity of Silicides

1993 ◽  
Vol 320 ◽  
Author(s):  
G. Ottaviani ◽  
F. Nava
Keyword(s):  
Electrical Transport ◽  
Temperature Limit ◽  
Residual Resistivity ◽  
Band Gaps ◽  
Structural Defects ◽  
Intrinsic Properties ◽  
Electrical Transport Properties ◽  
Fermi Surfaces ◽  
High Temperature Limit ◽  
Defects And Impurities

ABSTRACTElectrical transport properties of thin film and single crystal silicides will be reviewed and discussed. The presentation will be made by considering that most of the compounds behave as metals, with the resistivity which increases with the temperature, and few of them are semiconductors. Semiconductor silicides have band-gaps which span between 0.1 and 1.2 eV for ReSi2 and IrSil.75, respectively. Several metallic silicides show, expecially in the high-temperature limit, a resistivity-temperature dependence different from the classical linearity. The deviation, related to the intrinsic properties of the compound, can be affected by the presence of structural defects and impurities. The role played of such defects on the residual resistivity at low temperature will also be considered. Anisotropic effects will be discussed in relation with the shape of the Fermi surfaces.

scholarly journals Electrical Transport Properties and Magnetoresistance of Pr0.67Sr0.33MnO3-NiO Composites

2017 ◽  
Vol 268 ◽  
pp. 292-296
Author(s):  
Kean Pah Lim ◽  
Abdul Halim Shaari ◽  
Soo Kien Chen ◽  
Hassan Jumiah ◽  
Siau Wei Ng ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Crystal Structure ◽  
Solid State ◽  
Electrical Transport ◽  
Magnetic Field Dependence ◽  
Single Phase ◽  
Parent Compound ◽  
Secondary Phase ◽  
Electrical Transport Properties ◽  
X Ray

A series of polycrystalline bulk samples (Pr0.67Sr0.33MnO3)1-x/ (NiO)x were prepared by solid state reaction, and its structure, electrical transport and magnetoresistance properties were investigated. X-ray analysis showed that parent compound of Pr0.67Sr0.33MnO3 (PSMO) formed in single phase with crystal structure of orthorhombic while secondary phase of NiO can be detected with the addition of composite. The electrical properties showed that the resistivity increased with the addition of NiO due to enhancement of spin dependent-tunneling scattering across the artificial grain boundaries of NiO layer. Magnetic field dependence MR curve at various temperatures clearly indicates that extrinsic magnetoresistance had been enhanced due to addition of NiO as the artificial grain boundary.

Structural and thermal properties of the monoclinic Lu2SiO5single crystal: evaluation as a new laser matrix

2009 ◽  
Vol 42 (2) ◽  
pp. 284-294 ◽  
Author(s):  
Hengjiang Cong ◽  
Huaijin Zhang ◽  
Jiyang Wang ◽  
Wentao Yu ◽  
Jiandong Fan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Specific Heat ◽  
Linear Thermal Expansion ◽  
Cell Parameters ◽  
Thermal Expansion Tensor ◽  
Anisotropic Thermal Conductivity

The crystal structure of monoclinic Lu2SiO5(LSO) crystals, grown by the Czochralski method, was determined at room temperature by X-ray diffraction. The unit-cell parameters area= 10.2550 (2),b= 6.6465 (2),c= 12.3626 (4) Å, β = 102.422 (1)° in space groupI2/a. The linear thermal expansion tensor was determined along thea,b,candc* directions over the temperature range from 303.15 to 768.15 K, and the principal coefficients of the thermal expansion tensor are found to be αI= −1.0235 × 10−6 K, αII= 4.9119 × 10−6 K and αIII= 10.1105 × 10−6 K. The temperature dependence of the cell volume and monoclinic angle were also evaluated. In addition, the specific heat and the thermal diffusivity were measured over the temperature ranges from 293.15 to 673.15 K and from 303.15 to 572.45 K, respectively. As a result, the anisotropic thermal conductivity could be calculated and is reported for the first time, to the best of the authors' knowledge. The specific heat capacity of LSO is 139.54 J mol−1 K−1, and the principal components of the thermal conductivity arekI= 2.26 W m−1 K−1,kII= 3.14 W m−1 K−1andkII= 3.67 W m−1 K−1at 303.15 K. A new structure model was proposed to better understand the relationships between the crystal structure and anisotropic thermal properties. In comparison with other laser matrix crystals, it is found that LSO possesses relatively large anisotropic thermal properties, and owing to its small heat capacity it has a moderate thermal conductivity, which is similar to those of the tungstates but lower than those of the vanadates.

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