band gap structure
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Chemosensors ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 30
Author(s):  
Guochao Qian ◽  
Jin Hu ◽  
Shan Wang ◽  
Weiju Dai ◽  
Qu Zhou

Dissolved gas analysis (DGA) is recognized as one of the most reliable methods in transformer fault diagnosis technology. In this paper, three characteristic gases of transformer oil (CO, C2H4, and CH4) were used in conjunction with a Cr-decorated InN monolayer according to first principle calculations. The adsorption performance of Cr–InN for these three gases were studied from several perspectives such as adsorption structures, adsorption energy, electron density, density of state, and band gap structure. The results revealed that the Cr–InN monolayer had good adsorption performance with CO and C2H4, while the band gap of the monolayer slightly changed after the adsorption of CO and C2H4. Additionally, the adsorption property of the Cr–InN monolayer on CH4 was acceptable and a significant response was simultaneously generated. This paper provides the first insights regarding the possibility of Cr-doped InN monolayers for the detection of gases dissolved in oil.


Author(s):  
Sergei A. Nazarov ◽  
Jari Taskinen

AbstractWe consider the linear water-wave problem in a periodic channel $$\Pi ^h \subset {{\mathbb {R}}}^3$$ Π h ⊂ R 3 , which is shallow except for a periodic array of deep potholes in it. Motivated by applications to surface wave propagation phenomena, we study the band-gap structure of the essential spectrum in the linear water-wave system, which includes the spectral Steklov boundary condition posed on the free water surface. We apply methods of asymptotic analysis, where the most involved step is the construction and analysis of an appropriate boundary layer in a neighborhood of the joint of the potholes with the thin part of the channel. Consequently, the existence of a spectral gap for small enough h is proven.


Author(s):  
Xiaoping Ren ◽  
Fang Deng

We address the propagation dynamics of two-dimensional multi-peak solitons in the optical lattices based on the fractional Schrödinger equation. The effect of Lévy index and lattice depth on the band-gap structure of optical lattices are presented. Two-, three-, four-, six- and eight-peak solitons all can exist in the first gap and be stable in a wide region of their existence domain. The effective width, maximal peak value and the power of soliton are also studied. It indicates that the Lévy index plays a significant role on the properties of solitons.


2021 ◽  
Author(s):  
Fida Rehman ◽  
A. Dahshan ◽  
Muhammad Shariq ◽  
Pervaiz Ahmed ◽  
Y. Saeed

Abstract In order to probe the band gap engineering to tune optical properties in YAuPb1-xSix (x = 0, 0.25, 0.50, 0.75 and 1) alloys, we used all electron full-potential linearized augmented plane wave (FP-LAPW+lo) method within the frame work of the density functional theory. The optimized structural parameters were in good agreement with other theoretical and experimental results. The calculated results of elastic constant satisfy the condition for mechanical stability at each composition for cubic symmetry. In addition, the study of elastic parameters are summarized for the calculation bulk modulus, Young’s modulus, shear modulus, Kleinman parameters, Poisson’s ratio and Lame’s co-efficient. To predict the brittle (ductile) nature of this composition, the Cauchy pressure, Poisson’s ratio and B/G ratio were also calculated. Using modified Becke and Johnson GGA, the band gap values of each composition were computed precisely. Further, it was observed that for 0.25 < x < 0.75, band gap structure revealed a direct band gap configuration. In order to analyze the electronic structure of each composition, the total and partial densities of states have been investigated in detail. Furthermore, the investigation of optical parameters in terms of dielectric functions revealed the potential of these alloys for optoelectronic devices.


Crystals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1175
Author(s):  
Chan-Shan Yang ◽  
Yi-Sheng Cheng ◽  
Young-Chou Hsu ◽  
Yi-Cheng Chung ◽  
Jing-Ting Hung ◽  
...  

In this study, we propose a biochemical sensor that features a photonic cavity integrated with graphene. The tunable hybrid plasmonic-photonic sensor can detect the molecular fingerprints of biochemicals with a small sample volume. The stacking sequence of the device is “ITO grating/graphene/TiO2/Au/Si substrate”, which composes a photonic band gap structure. A defect is created within the ITO gratings to form a resonant cavity. The plasmonic-photonic energy can be confined in the cavity to enhance the interaction between light and the analyte deposited in the cavity. The finite element simulation results indicated that the current sensor exhibits very high values in resonance shift and sensitivity. Moreover, the resonance spectrum with a broad resonance linewidth can identify the molecular vibration bands, which was exemplified by the fingerprint detections of protein and the chemical compound CBP. The sensor possesses an electrical tunability by including a graphene layer, which allowed us to tune the effective refractive index of the cavity to increase the sensor’s sensing performance. In addition, our device admits a phononic bandgap as well, which was exploited to sense the mechanical properties of two particular dried proteins based on the simplified elastic material model instead of using the more realistic viscoelastic model. The dual examinations of the optical and mechanical properties of analytes from a phoxonic sensor can improve the selectivity in analyte detections.


Author(s):  
Shilpee Patil ◽  
Alka Verma ◽  
Anil Kumar Singh ◽  
Binod Kumar Kanaujia ◽  
Suresh Kumar

Abstract This study investigates a low-profile circularly polarized (CP) antenna using coplanar waveguide feeding. Rectangular-shaped slots and an inverted L-shaped slit are entrenched into the ground plane to enhance the impedance bandwidth of the antenna. Furthermore, the antenna is implemented with six elliptical electromagnetic band gap structures on its substrate to enhance the −10 dB return loss bandwidth and also to generate CP waves. The experimental and theoretical results closely match each other and indicate that a simple and compact design antenna with dimensions of 0.317λ0 × 0.317λ0 × 0.023λ0(λ0 is the operating wavelength at 4.74 GHz in free space) achieves 36.9% (3.91–5.68 GHz) of the −10 dB return loss bandwidth and 9.98% (4.09–4.52 GHz) of the 3-dB axial ratio bandwidth, thus making it a favorable entrant for radio altimeter and wireless avionics infra-communication systems.


2021 ◽  
Vol 60 (07) ◽  
Author(s):  
Mayur K. Chhipa ◽  
Boddapati T. P. Madhav ◽  
Savarimuthu Robinson ◽  
Vijay Janyani ◽  
Bhuvneshwer Suthar

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