scholarly journals Thermochromic and opacity behaviors in vanadium dioxide nanofilms: a theoretical study

Author(s):  
Ikhlas Hameem Shallal ◽  
Nidhal Moosa Abdul-Ameer ◽  
Shaimaa Qassim Abdul-Hasan ◽  
Moafak cadhem Abdulrida

Abstract Vanadium dioxide nanofilms are one of the most essential materials in electronic applications like smart windows. Therefore, studying and understanding the optical properties of such films is crucial to modifying the parameters that control these properties. To this end, this work focuses on investigating the opacity as a function of the energy directed at the nanofilms with different thicknesses (1 – 100) nm. Effective mediator theories (EMTs), which are considered as the application of Bruggeman's formalism and the Looyenga mixing rule, have been used to estimate the dielectric constant of VO2 nanofilms. The results show different opacity behaviors at different wavelength ranges (ultraviolet, visible, and infrared). The results depict that the highest opacity of the insulating phase is achieved at the ultraviolet region and it reduces for the metal phase. Besides, the results demonstrate that the opacity possesses a redshift during the changes at the three phases. Regarding the infrared region, the lowest opacity value is achieved at the insulator phase and it increases to the highest value at the metal phase. In the visible region, the opacity behavior remains similar in the three phases. It is worth noting that the lowest opacity is found for thinner nanofilm. Since both the refractive index and the extinction index are among the most essential optical constants, hence, both of them were compared with the experiment results, and an excellent agreement is achieved between them.

2018 ◽  
Vol 6 (8) ◽  
pp. 1903-1919 ◽  
Author(s):  
Fang Xu ◽  
Xun Cao ◽  
Hongjie Luo ◽  
Ping Jin

Vanadium dioxide (VO2) is a well-known thermochromic material since it exhibits a notable optical variation in the near-infrared region from transmitting to reflecting upon the semiconductor-to-metal phase transition (SMT).


2003 ◽  
Vol 785 ◽  
Author(s):  
Masato Tazawa ◽  
Hideo Asada ◽  
Gang Xu ◽  
Ping Jin ◽  
Kazuki Yoshimura

ABSTRACTWe determined the optical constants of a vanadium dioxide (VO2) thermochromic film deposited on glass substrate by ellipsometry in wavelength range from 380 nm to 1700 nm. The optical constants were employed to design the optimal stacked thin film structure for smart windows which control the solar radiation and heat transmission from the viewpoint of high luminous transmission.


Author(s):  
Farah Kadhum ◽  
Shaymaa Kafi ◽  
Asrar Saeed ◽  
Ali Al-Zuky ◽  
Anwar Al-Saleh

Surface plasmon resonance (SPR) is a highly sensitive method for monitoring changes in the optical characteristics that are near the sensor surface. It can be stimulated by an evanescent field that comes from the total internal reflection of the backside of the sensor surface in the Otto setup. In this setup, SPR can be used to build a simulation model at different thicknesses of titanium oxide (TiO2) (dTiO2 = 50 nm) and silver (Ag) (dAg = 10–80 nm) layers, which are deposited on the semicircular glass prism D-ZLAF50 by using water as a sensing medium. The surface plasmon resonance angle (θSPR) properties were calculated; SPR was not observed in the ultraviolet region (300 nm) or in the infrared region at 800 nm, but appeared strongly in the visible region at 600 and 700 nm and in the infrared region (900 and 1000 nm). The best sensitivity (S = 140) can be observed in the visible region, where the values of SPR dip length (Ld) and full-width half maximum (FWHM) are very good at silver layer thicknesses 40–60 nm; therefore, the proposed sensor can be used in the visible and infrared regions at the wavelengths 600, 700, 900, and 1000 nm.


Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 358
Author(s):  
Sisi Wu ◽  
Lingyu Wan ◽  
Liangmin Wei ◽  
Devki N. Talwar ◽  
Kaiyan He ◽  
...  

Systematic investigations are performed to understand the temperature-dependent optical properties of graphene on Si and SiO2/Si substrates by using a variable angle spectroscopic ellipsometry. The optical constants of graphene have revealed changes with the substrate and temperature. While the optical refractive index (n) of monolayer graphene on Si exhibited clear anomalous dispersions in the visible and near-infrared region (400–1200 nm), the modification is moderate for graphene on SiO2/Si substrate. Two graphene sheets have shown a pronounced absorption in the ultraviolet region with peak position related to the Van Hove singularity in the density of states. By increasing the temperature from 300 K to 500 K, for monolayer graphene on Si, the n value is gradually increased while k decreased. However, the optical constants [n, k] of monolayer graphene on SiO2/Si exhibited unpredictable wave variations. In the wavelength range of 400–1200 nm, an experiential formula of a like-Sellmeier equation is found well suited for describing the dispersions of graphene on Si and SiO2/Si substrates.


2021 ◽  
Vol 886 ◽  
pp. 108-116
Author(s):  
Nidhal M. Abdul-Ameer ◽  
Imad H. Khaleel ◽  
Shaymaa Qasim Abdul Hasan ◽  
Moafak C. Abdulrid

A significant influence of temperature width found on the vanadium oxide properties, it plays a major role in highlighting the thermal limits of the three phases (metallic, semiconductor, and dielectric). Two values of the temperature width , and , had taken and studied their effect on both the dielectric constant and its two parts; refractive index, and extinction coefficient, and. It found that: as the temperature width is greater, the more the properties of the three phases for . In addition to increasing the thermal range for phases which can be reached to when , while it's at . Our results have achieved great compatibility with the published results globally. In addition to the effect of both ultraviolet, visible, and infrared radiation on vanadium oxide, according to the different phases of the metal, semiconductor, and dielectric, where the behavior of any of them differs according to the effect of the radiation affecting it. It is noted that the behavior is almost identical to both the extinction coefficient, and refractive at the visible region, on the contrary other two regions where the behavior of the three phases is evident in it.


Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 338
Author(s):  
Yanqing Zhang ◽  
Weiming Xiong ◽  
Weijin Chen ◽  
Yue Zheng

Vanadium dioxide (VO2) is a typical metal-insulator transition (MIT) material, which changes from room-temperature monoclinic insulating phase to high-temperature rutile metallic phase. The phase transition of VO2 is accompanied by sudden changes in conductance and optical transmittance. Due to the excellent phase transition characteristics of VO2, it has been widely studied in the applications of electric and optical devices, smart windows, sensors, actuators, etc. In this review, we provide a summary about several phases of VO2 and their corresponding structural features, the typical fabrication methods of VO2 nanostructures (e.g., thin film and low-dimensional structures (LDSs)) and the properties and related applications of VO2. In addition, the challenges and opportunities for VO2 in future studies and applications are also discussed.


2021 ◽  
pp. 100827
Author(s):  
Nan Shen ◽  
Shi Chen ◽  
Runqing Huang ◽  
Jiaqi Huang ◽  
Jingyi Li ◽  
...  

2000 ◽  
Vol 62 (15) ◽  
pp. 10173-10184 ◽  
Author(s):  
D. Comoretto ◽  
G. Dellepiane ◽  
F. Marabelli ◽  
J. Cornil ◽  
D. A. dos Santos ◽  
...  

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