Influence of Modulation Wavelength Induced Order on the Physical Properties of Nb/Rare Earth Superlattices

1984 ◽  
Vol 37 ◽  
Author(s):  
L. H. Greene ◽  
W. L. Feldmann ◽  
J. M. Rowell ◽  
B. Batlogg ◽  
R. Hull ◽  
...  
Keyword(s):  
Rare Earth ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Residual Resistance ◽  
Sapphire Substrates ◽  
Transmission Electron ◽  
Sputter Deposited ◽  
Residual Resistance Ratio ◽  
Temperature Resistivity ◽  
Modulation Wavelength

AbstractWe report the observation of a higher degree of preferred crystalline orientation in Nb/rare earth superlattices for modulation wavelengths in the range of 200 Å to 500 Å than that exhibited by single component films. All films and multilayers are sputter deposited onto room temperature sapphire substrates. Electronic transport measurements also show that the residual resistance ratio is higher and the room temperature resistivity is lower than for multilayers of either greater or lower periodicities. Transmission electron micrographs (TEM) showing excellent layering, grain size comparable to the layer thickness, and evidence of some degree of epitaxy are presented.

Deposition and characterization of crystalline conductive RuO2 thin films

1995 ◽  
Vol 10 (10) ◽  
pp. 2401-2403 ◽  
Author(s):  
Q.X. Jia ◽  
S.G. Song ◽  
S.R. Foltyn ◽  
X.D. Wu
Keyword(s):  
Thin Films ◽  
Room Temperature Resistivity ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
Residual Resistance ◽  
X Ray ◽  
Transmission Electron ◽  
Residual Resistance Ratio ◽  
Temperature Resistivity

Highly conductive metal-oxide RuO2 thin films have been successfully grown on yttria-stabilized zirconia (YSZ) substrates by pulsed laser deposition. Epitaxial growth of RuO2 thin films on YSZ and the atomically sharp interface between the RuO2 and the YSZ substrate are clearly evident from cross-sectional transmission electron microscopy. A diagonal-type epitaxy of RuO2 on YSZ is confirmed from x-ray diffraction measurements. The crystalline RuO2 thin films, deposited at temperatures in the range of 500 °C to 700 °C, have a room-temperature resistivity of 35 ± 2 μω-cm, and the residual resistance ratio (R300 k/R4.2 k) is around 5 for the crystalline RuO2 thin films.

High Resistivity AlxGa1−xN Layers Grown by MOCVD

1996 ◽  
Vol 1 ◽  
Author(s):  
A. Y. Polyakov ◽  
M. Shin ◽  
D. W. Greve ◽  
M. Skowronski ◽  
R. G. Wilson
Keyword(s):  
Optical Absorption ◽  
Electron Concentration ◽  
Room Temperature ◽  
High Resistivity ◽  
Room Temperature Resistivity ◽  
Active Centers ◽  
Electrical And Optical Properties ◽  
Sapphire Substrates ◽  
Good Surface ◽  
Temperature Resistivity

Undoped AlxGa1−xN layers with good surface morphology and very low electron concentration have been grown by MOCVD on sapphire substrates. The observed electrical and optical properties depend strongly on the growth temperature. Layers grown at 1000 °C exhibited low resistivity and strong optical absorption below the bandgap. In contrast,layers grown at 1050 °C had low carrier concentrations and good mobilities. Virtually no optical absorption near the band edge was observed as opposed to the usual situation in AlxGa1−xN. The electrical properties of these layers can be explained by the presence of donor centers whose energy increases with composition, and deeper lying compensating defects. The interaction of these centers renders the samples with x<0.2 highly resistive, with room temperature resistivity higher than 106 ohm-cm. SIMS data strongly suggest that the electrically active centers in our AlGaN layers are native defect-related. Implantation of Si ions into Al0.12Ga0.88N, and subsequent annealing at 1140 °C resulted in layers with electron concentration of 4.6 × 1017cm−3.

scholarly journals Computational Intelligence Approach for Estimating Superconducting Transition Temperature of Disordered MgB2Superconductors Using Room Temperature Resistivity

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Taoreed O. Owolabi ◽  
Kabiru O. Akande ◽  
Sunday O. Olatunji
Keyword(s):  
Transition Temperature ◽  
Superconducting Transition Temperature ◽  
Room Temperature ◽  
Optimization Technique ◽  
Support Vector ◽  
Measuring Instruments ◽  
Room Temperature Resistivity ◽  
Superconducting Transition ◽  
Experimental Values ◽  
Temperature Resistivity

Doping and fabrication conditions bring about disorder in MgB2superconductor and further influence its room temperature resistivity as well as its superconducting transition temperature (TC). Existence of a model that directly estimatesTCof any doped MgB2superconductor from the room temperature resistivity would have immense significance since room temperature resistivity is easily measured using conventional resistivity measuring instrument and the experimental measurement ofTCwastes valuable resources and is confined to low temperature regime. This work develops a model, superconducting transition temperature estimator (STTE), that directly estimatesTCof disordered MgB2superconductors using room temperature resistivity as input to the model. STTE was developed through training and testing support vector regression (SVR) with ten experimental values of room temperature resistivity and their correspondingTCusing the best performance parameters obtained through test-set cross validation optimization technique. The developed STTE was used to estimateTCof different disordered MgB2superconductors and the obtained results show excellent agreement with the reported experimental data. STTE can therefore be incorporated into resistivity measuring instruments for quick and direct estimation ofTCof disordered MgB2superconductors with high degree of accuracy.

Magnetic Properties and Crystallography of Selected Co/Pt Multilayers with Rare-Earth Additions

1993 ◽  
Vol 313 ◽  
Author(s):  
G.A. Bertero ◽  
R.L. White ◽  
R. Sinclair
Keyword(s):  
Magnetic Properties ◽  
Rare Earth ◽  
Cross Section ◽  
Uniaxial Anisotropy ◽  
Amorphous Film ◽  
Perpendicular Anisotropy ◽  
Grain Sizes ◽  
Transmission Electron ◽  
Rare Earth Additions ◽  
Sputter Deposited

ABSTRACTWe have sputter-deposited a series of Pt/CO Multilayers with differing amounts of rare-earth (RE) in an effort to improve the uniaxial perpendicular anisotropy in these structures. The present work investigates the influence on the magnetic properties of Tb and Ho incorporated both at the interfaces of Pt/CO Multilayers and into the Co layers. The uniaxial anisotropy improved significantly only for those multilayers that showed poor perpendicular anisotropy in the undoped state, in particular, those with large (∼30 Å) bilayer periods. High resolution transmission electron microscopy was used to study these multilayers in cross-section. The Multilayer structures present strong [111] texture with grain sizes ranging from 200 to 600 Å. It is found that the RE does not produce a significant change in the growth texture of the multilayers until a critical amount is introduced beyond which the multilayer structure amorphizes resulting in a compositionally modulated amorphous film.

scholarly journals Formation of Metastable Disordered Ni3Al by Pulsed Laser Induced Rapid Solidification

1990 ◽  
Vol 213 ◽  
Author(s):  
Jeffrey A. West ◽  
James T. Manos ◽  
Michael J. Aziz
Keyword(s):  
Rapid Solidification ◽  
Room Temperature ◽  
Interface Velocity ◽  
Phase Changes ◽  
Fast Time ◽  
Room Temperature Resistivity ◽  
X Ray Diffraction ◽  
Resistivity Measurements ◽  
Disordered Lattice ◽  
Transmission Electron

ABSTRACTThin films of Ni3Al formed by co-evaporation onto insulating substrates form a single phase fcc disordered lattice upon rapid solidification following excimer laserinduced melting with an interface velocity of ~4 m/s. Transmission Electron Microscopy (TEM) and x-ray diffraction (XRD) analyses exhibit no superlattice diffraction at room temperature. Resistivity measurements, indicating that the disordered phase has a higher resistivity and much smaller temperature coefficient at room temperature than the stable ordered (L12) phase, permit us to monitor phase changes and ordering on a fast time-scale. Subsequent annealing recovers long-range order, with resistivity measurements indicating that reordering begins just below 300°C.

Preparation of Ni/BaTiO3 Composites and PTC Effect

2007 ◽  
Vol 280-283 ◽  
pp. 341-344
Author(s):  
Xiao Lei Li ◽  
Yuan Fang Qu ◽  
Wei Bing Ma ◽  
Zhan Shen Zheng
Keyword(s):  
Heat Treatment ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Ptc Effect ◽  
Reducing Atmosphere ◽  
Prepared Composite ◽  
Temperature Resistivity ◽  
Ntc Effect

Ni/BaTiO3 composite was prepared by decomposition of NiC2O4·2H2O/BaTiO3 precursor, which was prepared by precipitating of nickel in the form of oxalate into the BaTiO3 slurry. The composite must be sintered in reducing atmosphere. Otherwise NTC effect would be introduced. The prepared composite almost had no PTC effect. But PTC effect of the Ni/BaTiO3 composite can be effectively renewed by heat-treatment in air. Under a proper composition and method, the composite shows low room-temperature resistivity (ρRT=6.0 Ω·cm) and obvious PTC effect (ρmax/ρmin=102).

The Influence of Sintering Atmosphere and Reoxidation Temperature on the Electrical Properties of the Chip-Type Ba1-xSmxTiO3 Based Ceramics

2014 ◽  
Vol 900 ◽  
pp. 134-137
Author(s):  
Xu Xin Cheng ◽  
Dong Xiang Zhou ◽  
Qi Jun Xiao ◽  
Zhao Xiong Zhao
Keyword(s):  
Electrical Properties ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Sintering Atmosphere ◽  
Reducing Atmosphere ◽  
Chip Type ◽  
Ptcr Effect ◽  
Temperature Resistivity

The PTCR characteristics of (Ba1-xSmx)TiO3(BSMT) with different donor-doped concentration (x) sintered in a reducing atmosphere and reoxidized in air are investigated. The results reveal that the room temperature resistivity (ρRT) of the semiconducting BSMT ceramics first decreases and then increases with increasing of thexvalues, especially whenxis 0.004, the semiconducting BSMT ceramics reoxidized at 850oC for 1 h after sintering at 1300 °C for 30 min in a reducing atmosphere achieve a lower room temperature resisitivity of 82.6 Ωcm. in addition, the doped 0.1 mol% Sm3+BSMT samples fired at 1300 °C for 30 min in air exhibit remarkable PTCR effect with a resistance jumping ratio of 3.4 orders magnitude; moreover, a lower ρRTof the BSMT specimens sintered in a reducing atmosphere is obtained.

Transport Studies in Single-Crystal Films of Cosi2 and Nisi2

1983 ◽  
Vol 25 ◽  
Author(s):  
J. C. Hensel ◽  
R. T. Tung ◽  
J. M. Poate ◽  
F. C. Unterwald ◽  
D. C. Jacobson
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Transport Studies ◽  
Single Crystal Films ◽  
Crystal Films ◽  
The Difference ◽  
Temperature Resistivity

ABSTRACTTransport studies have been performed on thin films of CoSi 2 and NiSis2 in the temperature range 1 to 300 K. The conductivities are metallic with essentially the same temperature dependence; however, the residual resistivities are markedly different even though the two silicides are structurally similar (the room temperature resistivity of NiSi2 being at least twice that of CoSi2 of 15 μΩ cm). The difference is attributed to intrinsic defects in NiSi2. This defect has been simulated by ion bombardment of the film where it is also shown that Matthiesen's rule is obeyed over a remarkable range of bombardment doses.

Enhanced thermoelectric properties in PbTe Nanocomposites

2009 ◽  
Vol 1166 ◽  
Author(s):  
Hillary Kirby ◽  
Joshua Martin ◽  
Anuja Datta ◽  
Lidong Chen ◽  
George S. Nolas
Keyword(s):  
Thermoelectric Properties ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Phase Reaction ◽  
Conductivity Measurements ◽  
Temperature Dependent ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Temperature Dependent Thermal Conductivity ◽  
Temperature Resistivity

AbstractDimensional nanocomposites of PbTe with varying carrier concentrations were prepared from undoped and Ag doped PbTe nanocrystals synthesized utilizing an alkaline aqueous solution-phase reaction. The nanocrystals were densified by Spark Plasma Sintering (SPS) for room temperature resistivity, Hall, Seebeck coefficient, and temperature dependent thermal conductivity measurements. The nanocomposites show an enhancement in the thermoelectric properties compared to bulk PbTe with similar carrier concentrations, thus demonstrating a promising approach for enhanced thermoelectric performance.

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