Expanded Thermochromic Color Changes in VO2 Thin Film Devices Using Structured Plasmonic Metal Layers

2013 ◽  
Vol 1494 ◽  
pp. 171-177
Author(s):  
Yan Wang ◽  
John F. Muth
Keyword(s):  
Thin Films ◽  
Near Infrared ◽  
Color Change ◽  
Large Change ◽  
Metallic Phase ◽  
Metallic Thin Films ◽  
Color Changes ◽  
Surface Plasmas ◽  
Metal Layers

ABSTRACTWe investigate metallic thin films on VO2 and show that the magnitude of the reflected color change in that visible portion of the spectrum as VO2 undergoes the insulating to metallic phase transition can be controlled by changing the type of metal, the thickness of the metal and by patterning the metal at the nano scale. We consider the role of surface plasmas in the metal film and show that in the near infrared, the magnitude of the reflectivity increase for metal coated VO2 films, but decrease for uncoated VO2 thin films. This is explained in the context of Fresnel equations and considering the large change in the imaginary part of the dielectric constant as the VO2 changes state from the insulating to metallic phase.

scholarly journals Changes of quality of rennets during storing

2012 ◽  
Vol 60 (6) ◽  
pp. 189-196
Author(s):  
Monika Kozelková ◽  
Miroslav Jůzl ◽  
Táňa Lužová ◽  
Květoslava Šustová ◽  
Aneta Bubeníčková
Keyword(s):  
Near Infrared ◽  
Color Change ◽  
Coagulation Time ◽  
Time Activity ◽  
Spectrophotometric Methods ◽  
Color Changes ◽  
Rennet Coagulation ◽  
Total Color Change ◽  
Instrumental Methods

This work deals about evaluation of qualitative parameters of rennets. During the six months storing of rennets were determined following qualitative parameters: pH, rennet coagulation time, activity (strange) of rennet and dose of rennet, and finally were used instrumental methods: Near infrared spectroscopy (NIR) for recognizing age of rennets and spectrophotometric methods of determining the color of rennets. The theory found in the references suggests, that the activity of rennet should decrease by an average of 1–2 % per month, but the results are showing, that are changing quality of rennets namely mostly activity (strange) of rennet, which was decreased by 33% per half year. In analysis of color of rennets weren’t observed major changes by the whole group. Some statistical differences were detected in the partial values L*a*b*, most advantageous were evaluation by rennet total color change during storage, which were higher than noticeable change in four samples. The least color changes (P > 0.05) were observed in microbial rennets, with no values observed (ΔEab < 2) that can be recognized even by the human eye when subjected to parallel comparison. It was found that the NIR analysis can be used to recognizing of rennets, which are different ages.

New insights into sensors based on radical bisphthalocyanines

2009 ◽  
Vol 13 (11) ◽  
pp. 1159-1167 ◽  
Author(s):  
María Luz Rodriguez-Méndez ◽  
Mónica Gay ◽  
J. Antonio de Saja
Keyword(s):  
Thin Films ◽  
Optical Sensors ◽  
Near Infrared ◽  
Electrochemical Sensors ◽  
Color Change ◽  
Charge Transfer Band ◽  
Infrared Region ◽  
Electrical Measurements ◽  
Sensing Applications ◽  
The Rich

The unique semiconducting, optical and electrochemical properties of radical lanthanide bisphthalocyanines make them ideal materials for sensing applications. A variety of chemical sensors have been developed using rare-earth bisphthalocyanine thin films. In this paper, the characteristics of sensors based on bisphthalocyanines are reviewed. The advantages of these sensors with respect to sensors developed using other metallophthalocyanines are discussed. Resistive sensors based on bisphthalocyanines change their conductivity when exposed to a variety of pollutant gases and volatile organic compounds. Because bisphthalocyanines are intrinsic semiconductors, the conductivity of their thin films is higher than the conductivity of metallophthalocyanine thin films. This facilitates the electrical measurements and enhances the sensitivity of the sensors. Optical sensors have also been developed based on the rich optical properties shown by bisphthalocyanines. Films characterized by a bright green color change to red or to blue upon oxidation or reduction. The changes also affect the charge-transfer band associated to the free radical that bisphthalocyanines show in the near infrared region. This band coincides with telecommunication wavelengths, making possible the fabrication of fiber optic sensors where a phthalocyanine film is deposited at one of the ends of the fiber. Electrochemical sensors have been developed taking advantage of the unique electrochemical behavior associated to the one-electron oxidation and one-electron reduction of the phthalocyanine ring. These reversible processes are extremely sensitive to the nature of the electrolytic solution. This has made possible the development of voltammetric sensors able to produce particular signals when immersed in different liquids. In the last part of the paper, the fundamentals and performance characteristics of electronic noses and electronic tongues based on bisphthalocyanines are described. Such devices have been successfully exploited in quality control, classification, freshness evaluation and authenticity assessment of a variety of food, mainly wines and olive oils.

A Confound in the Standard Control Condition of the Stroop Experiment

1981 ◽  
Vol 53 (3) ◽  
pp. 835-841 ◽  
Author(s):  
Michael J. Zajano ◽  
Elaine M. Hoyceanyls ◽  
Jeanne F. Ouellette
Keyword(s):  
Selective Attention ◽  
Color Word ◽  
Color Change ◽  
Response Competition ◽  
Naming Task ◽  
Color Naming ◽  
Experimental Conditions ◽  
Color Changes ◽  
General Source

Two experiments were performed to investigate the magnitude of the confound in the standard control condition of the Stroop experiment. The confound resides in the fact that only color changes from one item to the next in the control condition, whereas both color and configuration of the items that represent color change in the usual experimental conditions. The results of both experiments showed small but significant increases in color-naming time when both colors and non-verbal shapes changed from one item to the next. These findings are discussed in the context of the role of factors in selective attention in the color-naming task. While response competition appears to be the more substantial source of interference in Stroop color-word effects, a smaller but more general source of interference due to selective attention appears in whole-list tasks with more than one dimension of item-to-item change.

Thermal Boundary Conductance Between Thin Metal Films and Graphite Substrates

2011 ◽  
Author(s):  
Justin L. Smoyer ◽  
John C. Duda ◽  
Pamela M. Norris ◽  
Arthur W. Lichtenberger
Keyword(s):  
Thin Films ◽  
Adhesion Force ◽  
Thermal Conductance ◽  
Metallic Thin Films ◽  
Temperature Dependent ◽  
Carbon Structure ◽  
Thermal Boundary Conductance ◽  
Surrounding Structure ◽  
Intrinsic Thermal Conductivity

Due to the high intrinsic thermal conductivity of graphitic structures, much interest has developed in incorporating these materials into modern nano-devices for improved thermal abatement. In order to be integrated successfully, thermal energy must be able to transport efficiently through the graphitic materials and into the surrounding structure, most commonly a metal. However, thermal boundary conductance at metal-graphite interfaces is traditionally poor in comparison to non-graphitic substrates, due in large part to the weak van der Waals adhesion force between the metal and underlying carbon structure. To be applicable as thermal abatement materials, an enhanced understanding of the role of the metal-carbon interface is required. This paper reports the changes to phononic thermal transport across the interface between metallic thin films and highly oriented pyrolitic graphite (HOPG) substrates due to changes in interface structure and chemistry. The temperature dependent thermal boundary conductance is measured using transient thermoreflectance from 100 K to 400 K. It is found that the differences in metal-carbon bonding and structure at the interface have a significant impact on the thermal conductance between the metallic thin films and the HOPG substrates.

Structure and Optical Properties of TiO2 Thin Films Prepared by a Sol-Gel Processing

2019 ◽  
Vol 74 (7) ◽  
pp. 635-642
Author(s):  
Zohra N. Kayani ◽  
Mehawish Saleem ◽  
Saira Riaz ◽  
Shahzad Naseem ◽  
Farhat Saleemi
Keyword(s):  
Thin Films ◽  
Near Infrared ◽  
Sol Gel ◽  
Dip Coating ◽  
Photovoltaic Devices ◽  
X Ray Diffraction ◽  
Tio2 Thin Films ◽  
Withdrawal Speed ◽  
Gel Processing

AbstractTitanium dioxide (TiO2) thin films were deposited on CR-39 by a sol-gel dip coating route with different withdrawal speeds ranging from 250 to 350 mm/s. The TiO2 thin films were characterised by x-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, ellipsometry, and ultraviolet (UV)-visible (VIS)-near infrared (NIR) spectro-photometry. The role of withdrawal speed on the thickness of thin films to tailor properties of TiO2 thin films was studied. The XRD results revealed that all the films are amorphous in nature. TiO2 thin films deposited at different withdrawal speeds exhibit a decrease in transmission with an increase in speed. The direct optical band gap of the films has been estimated to be in the range 3.48–3.00 eV by UV-VIS-NIR spectro-photometry and 3.52–3.38 eV by ellipsometry. TiO2 is a potential prospect in microelectronic applications and can serve as an absorber layer for photovoltaic devices. Surface morphology is granular with an increase in grain size and an increase in withdrawal speed.

The study of interfacial reactions of nickel thin films on GaAs

1983 ◽  
Vol 41 ◽  
pp. 156-157
Author(s):  
L.J. Chen ◽  
Y.F. Hsieh
Keyword(s):  
Thin Films ◽  
Integrated Circuits ◽  
Interfacial Reactions ◽  
Metal Contacts ◽  
Nickel Thin Films ◽  
Thin Foils ◽  
The Status ◽  
Si Doped ◽  
Electron Microscopes

One measure of the maturity of a device technology is the ease and reliability of applying contact metallurgy. Compared to metal contact of silicon, the status of GaAs metallization is still at its primitive stage. With the advent of GaAs MESFET and integrated circuits, very stringent requirements were placed on their metal contacts. During the past few years, extensive researches have been conducted in the area of Au-Ge-Ni in order to lower contact resistances and improve uniformity. In this paper, we report the results of TEM study of interfacial reactions between Ni and GaAs as part of the attempt to understand the role of nickel in Au-Ge-Ni contact of GaAs.N-type, Si-doped, (001) oriented GaAs wafers, 15 mil in thickness, were grown by gradient-freeze method. Nickel thin films, 300Å in thickness, were e-gun deposited on GaAs wafers. The samples were then annealed in dry N2 in a 3-zone diffusion furnace at temperatures 200°C - 600°C for 5-180 minutes. Thin foils for TEM examinations were prepared by chemical polishing from the GaA.s side. TEM investigations were performed with JE0L- 100B and JE0L-200CX electron microscopes.

Transmission Electron Microscopy studies of texture of Cr underlayer of magnetic recording hard disk

1991 ◽  
Vol 49 ◽  
pp. 580-581
Author(s):  
L. Tang ◽  
G. Thomas ◽  
M. R. Khan ◽  
S. L. Duan
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Transmission Electron Microscopy ◽  
Magnetic Recording ◽  
Magnetic Thin Films ◽  
Magnetic Films ◽  
Substrate Bias ◽  
Epitaxial Relationship ◽  
Transmission Electron

Cr thin films are often used as underlayers for Co alloy magnetic thin films, such as Co1, CoNi2, and CoNiCr3, for high density longitudinal magnetic recording. It is belived that the role of the Cr underlayer is to control the growth and texture of the Co alloy magnetic thin films, and, then, to increase the in plane coercivity of the films. Although many epitaxial relationship between the Cr underlayer and the magnetic films, such as ﹛1010﹜Co/ {110﹜Cr4, ﹛2110﹜Co/ ﹛001﹜Cr5, ﹛0002﹜Co/﹛110﹜Cr6, have been suggested and appear to be related to the Cr thickness, the texture of the Cr underlayer itself is still not understood very well. In this study, the texture of a 2000 Å thick Cr underlayer on Nip/Al substrate for thin films of (Co75Ni25)1-xTix dc-sputtered with - 200 V substrate bias is investigated by electron microscopy.

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