Thermally Stable Two-Dimensional Photonic Crystal for Selective Emitters

2013 ◽  
Vol 1497 ◽  
Author(s):  
Heon J. Lee ◽  
Stephen P. Bathurst ◽  
Sang-Gook Kim
Keyword(s):  
Thermal Stability ◽  
Photonic Crystal ◽  
Structural Integrity ◽  
Electrical Energy ◽  
Crystallization Surface ◽  
Thermal Emitters ◽  
Spectral Control ◽  
Experimental Validations ◽  
Selective Emitters ◽  
Thermal Stability Of

ABSTRACTA fundamental challenge in solar-thermal-electrical energy conversion is the thermal stability of materials and devices at high operational temperatures. This study focuses on the thermal stability of selective emitters for solar thermophotovoltaic (STPV) systems to enhance the conversion efficiency. 2-D photonic crystals are periodic micro/nano-scale structures that are designed to affect the motion of photons at certain wavelengths. The structured patterns, however, lose their structural integrity at high temperature, which disrupts the tight tolerances required for spectral control of the thermal emitters. Through analytical studies and experimental observations, the four major mechanisms of thermal degradation of 2-D photonic crystal are identified: oxidation, grain growth and re-crystallization, surface diffusion, and evaporation and re-condensation. In this work, the design of a flat surface photonic crystal (FSPC) is proposed and experimental validations are performed.

Structural integrity and thermal stability of TiN/CoSi2 used as local interconnect in a self-aligned CoSi2 process

1991 ◽  
Vol 52 (1-2) ◽  
pp. 59-69 ◽  
Author(s):  
Rama I. Hegde ◽  
Robert E. Jones ◽  
Vidya S. Kaushik ◽  
Philip J. Tobin
Keyword(s):  
Thermal Stability ◽  
Structural Integrity ◽  
Thermal Stability Of

scholarly journals Improved Thermal Emitters for Thermophotovoltaic Energy Conversion

2016 ◽  
Author(s):  
Veronika Stelmakh ◽  
Walker R. Chan ◽  
John D. Joannopoulos ◽  
Marin Soljacic ◽  
Ivan Celanovic ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Photonic Crystal ◽  
Energy Conversion ◽  
Temperature Stability ◽  
Square Lattice ◽  
Natural Material ◽  
Efficiency Gain ◽  
High Temperature Stability ◽  
Selective Emitter ◽  
Thermal Emitters

Thermophotovoltaic (TPV) energy conversion enables millimeter scale power generation required for portable microelectronics, robotics, etc. In a TPV system, a heat source heats a selective emitter to incandescence, the radiation from which is incident on a low bandgap TPV cell. The selective emitter tailors the photonic density of states to produce spectrally confined selective emission of light matching the bandgap of the photovoltaic cell, enabling high heat-to-electricity conversion efficiency. The selective emitter requires: thermal stability at high-temperatures for long operational lifetimes, simple and relatively low-cost fabrication, as well as spectrally selective emission over a large uniform area. Generally, the selective emission can either originate from the natural material properties, such as in ytterbia or erbia emitters, or can be engineered through microstructuring. Our approach, the 2D photonic crystal fabricated in refractory metals, offers high spectral selectivity and high-temperature stability while being fabricated by standard semiconductor processes. In this work, we present a brief comparison of TPV system efficiencies using these different emitter technologies. We then focus on the design, fabrication, and characterization of our current 2D photonic crystal, which is a square lattice of cylindrical holes fabricated in a refractory metal substrate. The spectral performance and thermal stability of the fabricated photonic crystal thermal emitters are demonstrated and the efficiency gain of our model TPV system is characterized.

Hafnia-plugged microcavities for thermal stability of selective emitters

2013 ◽  
Vol 102 (24) ◽  
pp. 241904 ◽  
Author(s):  
Heon-Ju Lee ◽  
Katherine Smyth ◽  
Stephen Bathurst ◽  
Jeffrey Chou ◽  
Michael Ghebrebrhan ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Selective Emitters ◽  
Thermal Stability Of

scholarly journals Structure, Morphology and Thermal Stability of Porous Carbon Nanofibers Loaded with Cobalt Nanoparticles

2011 ◽  
Vol 6 (4) ◽  
pp. 155892501100600
Author(s):  
Dawei Gao ◽  
Hui Qiao ◽  
Qingqing Wang ◽  
Yibing Cai ◽  
Qufu Wei
Keyword(s):  
Thermal Stability ◽  
Carbon Nanofibers ◽  
Porous Carbon ◽  
Composite Nanofibers ◽  
Structural Integrity ◽  
Cobalt Nanoparticles ◽  
Structure Morphology ◽  
Bet Analysis ◽  
Fibrous Morphology ◽  
Thermal Stability Of

Porous carbon/cobalt (C/Co) composite nanofibers with diameters of 200–300 nm were prepared by electrospinning and subsequent carbonization processes. Two polymer solutions of polyacrylonitrile (PAN), polyvinyl pyrrolidone (PVP), and Co (CH3COOH) 2 (Co (OAc) 2) were used as C/Co composite nanofiber precursors. The study revealed that C/Co composite nanofibers were successfully prepared and cobalt particles with diameters of 20–30 nm were uniformly scattered in the carbon nanofibers. It was also observed that clear fibrous morphology with grainlike particles and good structural integrity were still maintained after calcination. The TGA analysis indicated the improved thermal stability properties of the composite nanofibers. The Brunauer-Emmett-Teller (BET) analysis indicated that C/Co composites nanofibers with meso-pores possessed larger specific surface area than that of carbon nanofibers.

scholarly journals Structure and Thermal Stability of wtRop and RM6 Proteins through All-Atom Molecular Dynamics Simulations and Experiments

2021 ◽  
Vol 22 (11) ◽  
pp. 5931
Author(s):  
Maria Arnittali ◽  
Anastassia N. Rissanou ◽  
Maria Amprazi ◽  
Michael Kokkinidis ◽  
Vagelis Harmandaris
Keyword(s):  
Molecular Dynamics ◽  
Thermal Stability ◽  
Structural Integrity ◽  
Md Simulations ◽  
Effect Of Temperature ◽  
Key Factors ◽  
Loop Region ◽  
Dynamics Simulations ◽  
Experimental Findings ◽  
Thermal Stability Of

In the current work we study, via molecular simulations and experiments, the folding and stability of proteins from the tertiary motif of 4-α-helical bundles, a recurrent motif consisting of four amphipathic α-helices packed in a parallel or antiparallel fashion. The focus is on the role of the loop region in the structure and the properties of the wild-type Rop (wtRop) and RM6 proteins, exploring the key factors which can affect them, through all-atom molecular dynamics (MD) simulations and supporting by experimental findings. A detailed investigation of structural and conformational properties of wtRop and its RM6 loopless mutation is presented, which display different physical characteristics even in their native states. Then, the thermal stability of both proteins is explored showing RM6 as more thermostable than wtRop through all studied measures. Deviations from native structures are detected mostly in tails and loop regions and most flexible residues are indicated. Decrease of hydrogen bonds with the increase of temperature is observed, as well as reduction of hydrophobic contacts in both proteins. Experimental data from circular dichroism spectroscopy (CD), are also presented, highlighting the effect of temperature on the structural integrity of wtRop and RM6. The central goal of this study is to explore on the atomic level how a protein mutation can cause major changes in its physical properties, like its structural stability.

Improved upconversion efficiency and thermal stability of NaYF4@SiO2 photonic crystal film

2018 ◽  
Vol 741 ◽  
pp. 337-347 ◽  
Author(s):  
Cheng Zhu ◽  
Wenying Zhou ◽  
Jiaojiao Fang ◽  
Yaru Ni ◽  
Liang Fang ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Photonic Crystal ◽  
Crystal Film ◽  
Thermal Stability Of

Thermal and Fade Aspects of a Non Asbestos Semi Metallic Disc Brake Pad Formulation with Two Different Resins

2012 ◽  
Vol 622-623 ◽  
pp. 1559-1563
Author(s):  
M.A. Sai Balaji ◽  
K. Kalaichelvan
Keyword(s):  
Thermal Stability ◽  
Friction And Wear ◽  
Phenolic Resin ◽  
Structural Integrity ◽  
Friction Material ◽  
Performance Criteria ◽  
Brake Pad ◽  
Friction Materials ◽  
Brake Pads ◽  
Thermal Stability Of

The formulation of a brake pad requires the optimization of multiple performance criteria. To achieve a stable and adequate friction (µ), the brake pad materials should have low fade and higher recovery characteristics coupled with less wear and noise. Among the properties mentioned, resistance to fade is very difficult to achieve. The type and amount of resin in the friction material is very critical for structural integrity of the composites. The binder should not deteriorate under any diverse conditions. The thermal stability of friction materials and its capacity to bind its ingredients collectively under diverse conditions depend upon the quality and proportion of resin. The current work evaluates the fade and recovery behaviour of developed friction composites from two different resins which are traditional straight phenolic resin and the alkyl benzene modified phenolic resin. Two brake pads with these different resins were fabricated as per Industrial Standard. TGA is carried between 150 – 4000 C as this zone of temperature is very critical which accounts for the weight loss (Thermal degradation). Friction and wear studies were carried out on a friction coefficient test rig as per SAE J661a standard. The results showed that the fade and wear of the friction materials were closely related to the thermal decomposition of the binder resin and durability of the contact plateaus, which were produced by the compaction of wear debris around hard ingredients on the rubbing surface. It was clearly observed that the friction materials with modified resin showed significant reduction in fade %. Friction materials made with higher thermal stability showed resistance to fade. However wear didn’t show much noticeable changes.

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