Research on Measuring Thermal Conductivity of Quartz and Sapphire Glass Using Rear-Side Photothermal Deflection Method

As the display industry continues to advance, various new materials are being developed for utilizing microtechnology and nanotechnology in display panels. Among these, transparent materials have been widely applied to the internal wiring of displays and flexible substrates, owing to their high optical transmittance, isotropy, and anisotropy. Thus, measurement of the thermophysical properties of various transparent materials is important. This study measured thermal conductivity by selecting quartz, a transparent isotropic material, and sapphire glass, a transparent anisotropic material, as measurement target materials using a rear-side photothermal deflection method. Measurements were made via a three-dimensional unsteady heat conduction equation, to which complex transformation was applied and numerically analyzed using COMSOL Multiphysics. Phase delays for a pump beam and a probe beam for a relative position were derived through a deflection analysis. From the derived phase delays between the numerical analysis and experimental result with optical alignment, the absolute and relative errors of quartz were appropriately confirmed to be 0.069 W/m-K and 5%, respectively, while those of the sapphire glass were likewise confirmed to be 0.55 W/m-K and 1.5%, respectively.

Download Full-text

Feasibility of Novel Rear-Side Mirage Deflection Method for Thermal Conductivity Measurements

Sensors ◽

10.3390/s21175971 ◽

2021 ◽

Vol 21 (17) ◽

pp. 5971

Author(s):

Gwantaek Kim ◽

Moojoong Kim ◽

Hyunjung Kim

Keyword(s):

Thermal Conductivity ◽

Copper Film ◽

Conductivity Measurement ◽

Measurement Methods ◽

Thermal Conductivity Measurement ◽

Photothermal Effect ◽

Rear Side ◽

Copper Aluminum ◽

Relative Errors ◽

Thin Copper Film

Among the noncontact measurement technologies used to acquire thermal property information, those that use the photothermal effect are attracting attention. However, it is difficult to perform measurements for new materials with different optical and thermal properties, owing to limitations of existing thermal conductivity measurement methods using the photothermal effect. To address this problem, this study aimed to develop a rear-side mirage deflection method capable of measuring thermal conductivity regardless of the material characteristics based on the photothermal effect. A thin copper film (of 20 µm thickness) was formed on the surfaces of the target materials so that measurements could not be affected by the characteristics of the target materials. In addition, phase delay signals were acquired from the rear sides of the target materials to exclude the influence of the pump beam, which is a problem in existing thermal conductivity measurement methods that use the photothermal effect. To verify the feasibility of the proposed measurement technique, thermal conductivity was measured for copper, aluminum, and stainless steel samples with a 250 µm thickness. The results were compared with literature values and showed good agreement with relative errors equal to or less than 0.2%.

Download Full-text

Structure and Thermoelectric Properties of New Quaternary Tin and Lead Bismuth Selenides, K1+xM4-2xBi7+xSe15 (M = Sn, Pb) and K1+xSn5-xBi11+xSe22

MRS Proceedings ◽

10.1557/proc-626-z8.4 ◽

2000 ◽

Vol 626 ◽

Author(s):

Antje Mrotzek ◽

Kyoung-Shin Choi ◽

Duck-Young Chung ◽

Melissa A. Lane ◽

John R. Ireland ◽

...

Keyword(s):

Thermal Conductivity ◽

Single Crystal ◽

Thermoelectric Properties ◽

Three Dimensional ◽

Structure Type ◽

Narrow Gap ◽

Low Thermal Conductivity ◽

Seebeck Coefficients ◽

Metal Atoms ◽

Anionic Framework

ABSTRACTWe present the structure and thermoelectric properties of the new quaternary selenides K1+xM4–2xBi7+xSe15 (M = Sn, Pb) and K1-xSn5-xBi11+xSe22. The compounds K1+xM4-2xBi7+xSe15 (M= Sn, Pb) crystallize isostructural to A1+xPb4-2xSb7+xSe15 with A = K, Rb, while K1-xSn5-xBi11+xSe22 reveals a new structure type. In both structure types fragments of the Bi2Te3-type and the NaCl-type are connected to a three-dimensional anionic framework with K+ ions filled tunnels. The two structures vary by the size of the NaCl-type rods and are closely related to β-K2Bi8Se13 and K2.5Bi8.5Se14. The thermoelectric properties of K1+xM4-2xBi7+xSe15 (M = Sn, Pb) and K1-xSn5-xBi11+xSe22 were explored on single crystal and ingot samples. These compounds are narrow gap semiconductors and show n-type behavior with moderate Seebeck coefficients. They have very low thermal conductivity due to an extensive disorder of the metal atoms and possible “rattling” K+ ions.

Download Full-text

Phase-field modeling of grain evolutions in additive manufacturing from nucleation, growth, to coarsening

npj Computational Materials ◽

10.1038/s41524-021-00524-6 ◽

2021 ◽

Vol 7 (1) ◽

Author(s):

Min Yang ◽

Lu Wang ◽

Wentao Yan

Keyword(s):

Additive Manufacturing ◽

Phase Field ◽

Field Model ◽

Three Dimensional ◽

Phase Field Model ◽

Nucleation Theory ◽

Experimental Result ◽

Classical Nucleation Theory ◽

Validation Experiment ◽

Powder Particles

AbstractA three-dimensional phase-field model is developed to simulate grain evolutions during powder-bed-fusion (PBF) additive manufacturing, while the physically-informed temperature profile is implemented from a thermal-fluid flow model. The phase-field model incorporates a nucleation model based on classical nucleation theory, as well as the initial grain structures of powder particles and substrate. The grain evolutions during the three-layer three-track PBF process are comprehensively reproduced, including grain nucleation and growth in molten pools, epitaxial growth from powder particles, substrate and previous tracks, grain re-melting and re-growth in overlapping zones, and grain coarsening in heat-affected zones. A validation experiment has been carried out, showing that the simulation results are consistent with the experimental results in the molten pool and grain morphologies. Furthermore, the grain refinement by adding nanoparticles is preliminarily reproduced and compared against the experimental result in literature.

Download Full-text

Preparation, microstructure and properties of three-dimensional carbon/carbon composites with high thermal conductivity

Carbon ◽

10.1016/j.carbon.2020.10.013 ◽

2021 ◽

Vol 174 ◽

pp. 758-759

Author(s):

Bao-liu Li ◽

Jian-guang Guo ◽

Bing Xu ◽

Hui-tao Xu ◽

Zhi-jun Dong ◽

...

Keyword(s):

Thermal Conductivity ◽

Three Dimensional ◽

High Thermal Conductivity ◽

Carbon Composites ◽

Microstructure And Properties

Download Full-text

Numerical simulation of variable thermal conductivity on 3D flow of nanofluid over a stretching sheet

Nonlinear Engineering ◽

10.1515/nleng-2020-0011 ◽

2020 ◽

Vol 9 (1) ◽

pp. 233-243 ◽

Cited By ~ 3

Author(s):

Nainaru Tarakaramu ◽

P.V. Satya Narayana ◽

Bhumarapu Venkateswarlu

Keyword(s):

Heat Transfer ◽

Thermal Conductivity ◽

Stretching Sheet ◽

Three Dimensional ◽

Variable Thermal Conductivity ◽

Normal Velocity ◽

Transfer Coefficients ◽

Similarity Transformations ◽

Frictional Coefficients ◽

The Impact

AbstractThe present investigation deals with the steady three-dimensional flow and heat transfer of nanofluids due to stretching sheet in the presence of magnetic field and heat source. Three types of water based nanoparticles namely, copper (Cu), aluminium oxide (Al2O3), and titanium dioxide (TiO2) are considered in this study. The temperature dependent variable thermal conductivity and thermal radiation has been introduced in the energy equation. Using suitable similarity transformations the dimensional non-linear expressions are converted into dimensionless system and are then solved numerically by Runge-Kutta-Fehlberg scheme along with well-known shooting technique. The impact of various flow parameters on axial and transverse velocities, temperature, surface frictional coefficients and rate of heat transfer coefficients are visualized both in qualitative and quantitative manners in the vicinity of stretching sheet. The results reviled that the temperature and velocity of the fluid rise with increasing values of variable thermal conductivity parameter. Also, the temperature and normal velocity of the fluid in case of Cu-water nanoparticles is more than that of Al2O3- water nanofluid. On the other hand, the axial velocity of the fluid in case of Al2O3- water nanofluid is more than that of TiO2nanoparticles. In addition, the current outcomes are matched with the previously published consequences and initiate to be a good contract as a limiting sense.

Download Full-text

Advances in Liquid Crystalline Epoxy Resins for High Thermal Conductivity

Polymers ◽

10.3390/polym13081302 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1302

Author(s):

Younggi Hong ◽

Munju Goh

Keyword(s):

Thermal Conductivity ◽

Network Structure ◽

Epoxy Resins ◽

Liquid Crystalline ◽

Random Network ◽

Three Dimensional ◽

Heat Insulator ◽

Liquid Crystalline Epoxy ◽

Thermally Conductive ◽

Substantial Interest

Epoxy resin (EP) is one of the most famous thermoset materials. In general, because EP has a three-dimensional random network, it possesses thermal properties similar to those of a typical heat insulator. Recently, there has been substantial interest in controlling the network structure of EP to create new functionalities. Indeed, the modified EP, represented as liquid crystalline epoxy (LCE), is considered promising for producing novel functionalities, which cannot be obtained from conventional EPs, by replacing the random network structure with an oriented one. In this paper, we review the current progress in the field of LCEs and their application to highly thermally conductive composite materials.

Download Full-text

Performance of GaN-Based LEDs with Nanopatterned Indium Tin Oxide Electrode

Journal of Nanomaterials ◽

10.1155/2016/8202405 ◽

2016 ◽

Vol 2016 ◽

pp. 1-7

Author(s):

Zhanxu Chen ◽

Wenjie Liu ◽

Wei Wan ◽

Gengyan Chen ◽

Yongzhu Chen ◽

...

Keyword(s):

Tin Oxide ◽

Indium Tin Oxide ◽

Ohmic Contacts ◽

Three Dimensional ◽

Light Output ◽

Light Extraction Efficiency ◽

Experimental Result ◽

Indium Tin Oxide Electrode ◽

Light Emitting ◽

Ito Electrode

The indium tin oxide (ITO) has been widely applied in light emitting diodes (LEDs) as the transparent current spreading layer. In this work, the performance of GaN-based blue light LEDs with nanopatterned ITO electrode is investigated. Periodic nanopillar ITO arrays are fabricated by inductive coupled plasma etching with the mask of polystyrene nanosphere. The light extraction efficiency (LEE) of LEDs can be improved by nanopatterned ITO ohmic contacts. The light output intensity of the fabricated LEDs with nanopatterned ITO electrode is 17% higher than that of the conventional LEDs at an injection current of 100 mA. Three-dimensional finite difference time domain simulation matches well with the experimental result. This method may serve as a practical approach to improving the LEE of the LEDs.

Download Full-text

Thermal Design of Highly-Efficient Thermoelectric Materials With Atomic-Scale Three-Dimensional Phononic Crystals

Volume 10: Mechanics of Solids and Structures, Parts A and B ◽

10.1115/imece2007-43538 ◽

2007 ◽

Author(s):

Jean-Numa Gillet ◽

Yann Chalopin ◽

Sebastian Volz

Keyword(s):

Thermal Conductivity ◽

Bulk Material ◽

Phononic Crystal ◽

Three Dimensional ◽

Mean Free Path ◽

Dispersion Curves ◽

Phononic Crystals ◽

Thermal Design ◽

Atomic Scale ◽

Thermal Insulating

Owing to their thermal insulating properties, superlattices have been extensively studied. A breakthrough in the performance of thermoelectric devices was achieved by using superlattice materials. The problem of those nanostructured materials is that they mainly affect heat transfer in only one direction. In this paper, the concept of canceling heat conduction in the three spatial directions by using atomic-scale three-dimensional (3D) phononic crystals is explored. A period of our atomic-scale 3D phononic crystal is made up of a large number of diamond-like cells of silicon atoms, which form a square supercell. At the center of each supercell, we substitute a smaller number of Si diamond-like cells by other diamond-like cells, which are composed of germanium atoms. This elementary heterostructure is periodically repeated to form a Si/Ge 3D nanostructure. To obtain different atomic configurations of the phononic crystal, the number of Ge diamond-like cells at the center of each supercell can be varied by substitution of Si diamond-like cells. The dispersion curves of those atomic configurations can be computed by lattice dynamics. With a general equation, the thermal conductivity of our atomic-scale 3D phononic crystal can be derived from the dispersion curves. The thermal conductivity can be reduced by at least one order of magnitude in an atomic-scale 3D phononic crystal compared to a bulk material. This reduction is due to the decrease of the phonon group velocities without taking into account that of the phonon average mean free path.

Download Full-text