Thermal transport through thin films: Mirage technique measurements on aluminum/titanium multilayers

2000 ◽  
Vol 15 (3) ◽  
pp. 764-771 ◽  
Author(s):  
E. J. Gonzalez ◽  
J. E. Bonevich ◽  
G. R. Stafford ◽  
G. White ◽  
D. Josell
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Thermal Transport ◽  
Multilayer Films ◽  
Multilayer Thin Films ◽  
Bilayer Thickness ◽  
Cu Films ◽  
Si Substrates ◽  
Electrical Conductances

Thermal transport properties of multilayer thin films both normal and parallel to the layers were measured. Al/Ti multilayer films 3 μm thick, with individual layers systematically varied from 2.5 to 40 nm, were studied on Si substrates. Layers of Al and Ti were nominally equal in thickness, with actual composition determined for each specimen using energy dispersive spectroscopy. The thermal diffusivity both in the plane and normal to the plane of the films (thermal conductivity divided by specific heat per volume) was found to decrease significantly with decreasing bilayer thickness. Pure Ti and Al films as well as Cu films from 0.1 to 5 μm thick were also studied. In-plane electrical conductances of the Al/Ti multilayers were also measured.

scholarly journals Comparative study of thermal transport in Zea mays straw and Zea mays heartwood (cork) boards

2010 ◽  
Vol 14 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Sunday Etuk ◽  
Louis Akpabio ◽  
Ita Akpan
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Zea Mays ◽  
Thermal Diffusivity ◽  
Comparative Study ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermal Transport ◽  
Insulation Material ◽  
Thermal Absorptivity

Thermal conductivity values at the temperature of 301-303K have been measured for Zea mays straw board as well as Zea mays heartwood (cork) board. Comparative study of the thermal conductivity values of the boards reveal that Zea mays heartwood board has a lower thermal conductivity value to that of the straw board. The study also shows that the straw board is denser than the heartwood board. Specific heat capacity value is less in value for the heartwood board than the straw board. These parameters also affect the thermal diffusivity as well as thermal absorptivity values for the two types of boards. The result favours the two boards as thermal insulators for thermal envelop but with heartwood board as a preferred insulation material than the straw board.

scholarly journals Effects of LaNiO3 Seed Layer on the Microstructure and Electrical Properties of Ferroelectric BZT/PZT/BZT Thin Films

2021 ◽  
Vol 8 ◽  
Author(s):  
Jinyu Ruan ◽  
Chao Yin ◽  
Tiandong Zhang ◽  
Hao Pan
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Surface Roughness ◽  
Electrical Properties ◽  
Seed Layer ◽  
Ferroelectric Properties ◽  
Lower Surface ◽  
Multilayer Films ◽  
Multilayer Thin Films ◽  
Orientation Growth

Ferroelectric multilayer films attract great attention for a wide variation of applications. The synergistic effect by combining different functional layers induces distinctive electrical properties. In this study, ferroelectric BaZr0.2Ti0.8O3/PbZr0.52Ti0.48O3/BaZr0.2Ti0.8O3 (BZT/PZT/BZT) multilayer thin films are designed and fabricated by using the magnetron sputtering method, and a LaNiO3 (LNO) seed layer is introduced. The microstructures and electrical properties of the BZT/PZT/BZT films with and without the LNO seed layer are systematically studied. The results show that the BZT/PZT/BZT/LNO thin film exhibits much lower surface roughness and a preferred (100)-orientation growth, with the growth template and tensile stress provided by the LNO layer. Moreover, an enhanced dielectric constant, decreased dielectric loss, and improved ferroelectric properties are achieved in BZT/PZT/BZT/LNO thin films. This work reveals that the seed layer can play an important role in improving the microstructure and properties of ferroelectric multilayer films.

Effects of thermal misfit strains on dielectric features of sandwich barium strontium titanate multilayer thin films on metal plates

2021 ◽  
pp. 2150030
Author(s):  
Hanting Dong ◽  
Liang Ke ◽  
Xiangjun Hui ◽  
Jiangfeng Mao ◽  
Haiqing Du ◽  
...  
Keyword(s):  
Thin Films ◽  
Dielectric Properties ◽  
Strontium Titanate ◽  
Barium Strontium Titanate ◽  
Composition Range ◽  
Multilayer Films ◽  
Multilayer Thin Films ◽  
Barium Strontium ◽  
Metal Plates ◽  
Bst Films

Effects of thermal misfit strains on dielectric features for sandwich structural barium strontium titanate (BST) thin films on metal plates were investigated via a modified thermodynamic model. When TEC of substrates is closer to that of BST, larger permittivity and tunability can be received. The tendency of permittivities and tunabilities of such films as a function of TEC of substrates agrees with that of single compositional BST films and compositionally graded BST multilayer films. The highest tunability reaches 60% at the biasing field of 300 kV/cm when the films are onto Ti metal. Moreover, Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3 structure can obtain higher tunability than Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3 structure, while Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3/Ba[Formula: see text]Sr[Formula: see text]TiO3 films show better compatible composition range for relatively larger tunability. Dielectric properties of sandwich-like BST films in some references can also be analyzed based on our calculated results.

Impact of Deposition Rate on the Structural and Magnetic Properties of Sputtered Ni/Cu Multilayer Thin Films

2017 ◽  
Vol 73 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Ali Karpuz ◽  
Salih Colmekci ◽  
Hakan Kockar ◽  
Hilal Kuru ◽  
Mehmet Uckun
Keyword(s):  
Thin Films ◽  
Magnetic Properties ◽  
Deposition Rate ◽  
High Rate ◽  
Cubic Phase ◽  
High Deposition Rate ◽  
Multilayer Thin Films ◽  
Face Centered Cubic ◽  
Deposition Rates ◽  
Cu Films

AbstractThe structural and corresponding magnetic properties of Ni/Cu films sputtered at low and high deposition rates were investigated as there is a limited number of related studies in this field. 5[Ni(10 nm)/Cu(30 nm)] multilayer thin films were deposited using two DC sputtering sources at low (0.02 nm/s) and high (0.10 nm/s) deposition rates of Ni layers. A face centered cubic phase was detected for both films. The surface of the film sputtered at the low deposition rate has a lot of micro-grains distributed uniformly and with sizes from 0.1 to 0.4 μm. Also, it has a vertical acicular morphology. At high deposition rate, the number of micro-grains considerably decreased, and some of their sizes increased up to 1 μm. The surface of the Ni/Cu multilayer deposited at the low rate has a relatively more grainy and rugged structure, whereas the surface of the film deposited at the high rate has a relatively larger lateral size of surface grains with a relatively fine morphology. Saturation magnetisation, Ms, values were 90 and 138 emu/cm3 for deposition rates of 0.02 and 0.10 nm/s, respectively. Remanence, Mr, values were also found to be 48 and 71 emu/cm3 for the low and high deposition rates, respectively. The coercivity, Hc, values were 46 and 65 Oe for the low and high Ni deposition rates, respectively. The changes in the film surfaces provoked the changes in the Hc values. The Ms, Mr, and Hc values of the 5[Ni(10 nm)/Cu(30 nm)] films can be adjusted considering the surface morphologies and film contents caused by the different Ni deposition rates.

Tensile testing low density multilayers: Aluminum/titanium

1998 ◽  
Vol 13 (10) ◽  
pp. 2902-2909 ◽  
Author(s):  
D. Josell ◽  
D. van Heerden ◽  
D. Read ◽  
J. Bonevich ◽  
D. Shechtman
Keyword(s):  
Thin Films ◽  
Yield Stress ◽  
Tensile Testing ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Low Density ◽  
Multilayer Thin Films ◽  
Bilayer Thickness ◽  
Relationship Of ◽  
The Relationship

Yield stresses, ultimate tensile strengths, and specific strengths of aluminum/titanium multilayer thin films are determined from the results of uniaxial tensile tests. The plasticity in the stress-strain curves, the nature of the fracture surfaces, and the relationship of the yield stress and the bilayer thickness are discussed. Properties are compared with those of other multilayer materials published in the literature.

Anderson Localization of Phonons in Random Multilayer Thin Films

2012 ◽  
Vol 1404 ◽  
Author(s):  
Anthony Frachioni ◽  
Bruce White
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Thermoelectric Materials ◽  
Anderson Localization ◽  
Lattice Thermal Conductivity ◽  
Waste Heat ◽  
Mean Free Path ◽  
The United States ◽  
Energy Scavenging ◽  
Multilayer Thin Films

ABSTRACT1020 Joules of energy are generated by the United States each year; 60% of this energy is lost to waste heat [1]. Thermoelectric based energy scavenging has tremendous potential for the recovery of significant quantities of this waste heat. However, utilization of thermoelectric devices is limited due to relatively low energy conversion efficiency and the utilization of relatively scarce materials. This work focuses on generating sustainable and efficient thermoelectric materials through modifications to the lattice vibrations of materials with excellent thermoelectric electronic properties (Seebeck coefficients larger than 500 μV/K). In particular, Anderson localization of phonons in random multilayer thin films has been explored as a means for reducing lattice thermal conductivity to values approaching that of aerogels (∼10 mW/m-K). Silicon has been a sample of choice due to its high crust abundance and Seebeck coefficient. Reverse non-equilibrium molecular dynamics simulations have been utilized to determine the thermal conductivity of structures of interest. Simulations with pure Lennard-Jones argon solids have been performed to establish a methodology and to characterize the effect of different kinds of disorder prior to the examination of silicon. The simulation results indicate that mass disorder confined to randomly selected planes to be an effective way in which to reduce lattice thermal conductivity with the lattice thermal conductivity decreasing by a factor of thirty (to 4 mW/m-K) in the argon case and a factor of over ten thousand (to 15 mW/m-K) for silicon. Based on models in which the charge carrier mean free path is limited by scattering from the planes with mass disorder, the mobility of silicon is expected to reach values of 10 cm2/V-s. At this mobility the thermoelectric figure of merit, ZT, (utilizing the Wiedeman-Franz law to calculate the electronic thermal conductivity) varies between 4.5 and 11 as the mass ratio of the disordered planes is varied from 4 to 10 in 20% of the lattice planes. These results indicate that the pursuit of nanostructured thermoelectric materials in the form of random multilayers may provide a path to efficient and sustainable thermoelectric materials.

Thermal Transport Properties of Various Thin Films for MEMS Applications

2006 ◽  
Vol 326-328 ◽  
pp. 293-296
Author(s):  
Sun Rock Choi ◽  
Dong Sik Kim ◽  
Sung Hoon Choa
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Transport Properties ◽  
Thermal Transport ◽  
Metallic Thin Films ◽  
Micro Electro Mechanical Systems ◽  
Thermal Transport Properties ◽  
Atomic Force Microscope Measurement ◽  
Evaporation Technique ◽  
Thermal Diffusivities

The thermal properties of thin films, such as thermal conductivity and diffusivity, are important in design and analysis of MEMS (micro electro mechanical systems), particularly in microscale thermal systems and high-power electronic/optoelectronic devices. In the present study, the thermal conductivity and diffusivity of a variety of thin film materials, which are commonly used in MEMS applications, are measured. The samples include Au, Sn, Mo, Al/Ti alloy, AlN, and SiC. The Au sample is deposited by the e-beam evaporation technique while the rest of the metallic samples are deposited by sputtering processes. The AlN and SiC films are also prepared by sputtering processes. In the experiment, the thermal diffusivities of metallic thin films are measured by two independent methods — the AC calorimetric method and photothermal mirage technique. The thermal conductivities of dielectric thin films are measured by the 3 omega technique. The results show that the thermal transport properties of some of the films are significantly smaller than those of the same material in bulk form. Especially, the AlN and SiC thin films exhibit pronounced thermal conductivity reduction because of the size effect. The electrical conductivities of the metallic thin films are measured as well. The results for Au and Sn are consistent with the thermal conductivity, confirming the Wiedmann-Franz law. However, Al/Ti and Mo thin films show considerable deviation from the law. The results are analyzed based on the XRD (X-Ray diffraction) and AFM (Atomic Force Microscope) measurement.

Understanding of Growth Mechanism and Structure of Multilayer Thin Films via Layer-by-Layer Hydrogen Bonded Assembly from Polymer Brushes-Grafted Surface

2020 ◽  
Vol 12 (7) ◽  
pp. 890-900
Author(s):  
Hua Wei ◽  
Hua Zhang ◽  
Yang Zhou ◽  
Zongbao Wang ◽  
Rong Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Atom Transfer Radical Polymerization ◽  
Growth Mechanism ◽  
Polymer Brushes ◽  
Multilayer Films ◽  
Multilayer Thin Films ◽  
Layer By Layer ◽  
Deposition Technique ◽  
Layer Deposition ◽  
Hydrogen Bonded

This study demonstrated the feasibility of polymer brushes-modified plate substrate as template to construct multilayer thin films via layer-by-layer hydrogen bonded assembly. The anchored chains via controlled surface-initiated atom transfer radical polymerization (SI-ATRP). The anchored poly(4-vinylpyridine) brushes functions as a multivalent H-acceptor to regulate the following hydrogen bonded assembly with H-donors to construct multilayer thin films via layer-by-layer deposition technique. The growth mechanism and film natures of multilayer films mediated by hydrogen bonded assembly from a polymer brushes-grafted surface were fully investigated.

Thermal Transport in Few-Quintuple Bi2Te3 Thin Films and Nanoribbons

2011 ◽  
Author(s):  
Bo Qiu ◽  
Xiulin Ruan
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Temperature Dependence ◽  
Thermal Transport ◽  
Room Temperature ◽  
Phonon Scattering ◽  
Md Simulations ◽  
Boundary Scattering ◽  
Nanoporous Films

In this work, thermal conductivity of perfect and nanoporous few-quintuple Bi2Te3 thin films as well as nanoribbons with perfect and zig-zag edges is investigated using molecular dynamics (MD) simulations with Green-Kubo method. We find minimum thermal conductivity of perfect Bi2Te3 thin films with three quintuple layers (QLs) at room temperature, and we believe it originates from the interplay between inter-quintuple coupling and phonon boundary scattering. Nanoporous films and nanoribbons are studied for additional phonon scattering channels in suppressing thermal conductivity. With 5% porosity in Bi2Te3 thin films, the thermal conductivity is found to decrease by a factor of 4–6, depending on temperature, comparing to perfect single QL. For nanoribbons, width and edge shape are found to strongly affect the temperature dependence as well as values of thermal conductivity.

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