Phonon Polariton Dispersion in Metal-Doped Nanocomposite Superlattice System

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
R. Krishnamurthy ◽  
V. Revathy ◽  
K. S. Joseph Wilson ◽  
Sofyan A. Taya ◽  
I. S. Amiri

AbstractCopper nanoparticles (Cu) anchored lithium niobate (LiNbO3) nanostructures were prepared by a simple hydrothermal technique. The fine and sparse Cu nanoparticles were homogeneously dispersed over the surface of LiNbO3. An effectual anchoring of Cu was evidenced from the acquired reflection planes in diffraction analysis, which clearly indicate the face-centered cubic structure of Cu. The UV-Visible spectrum of LiNbO3 and Cu/LiNbO3 nanocomposites were also studied. When the Cu nanoparticles were doped with LiNbO3/LiTaO3 superlattice system, the change in the dispersion relation was observed theoretically. The characteristics of the polariton dispersion variation with filling factor of Cu nanoparticles concentration were investigated systematically. The importance of the polariton modes in communication sector was analyzed and the occurrence of new modes on the polaritonic gap, where the propagation of the electromagnetic wave is forbidden, were obtained in the system due to the presence of copper nanoparticles.

Author(s):  
Ghassan Adnan NAEEM ◽  
Ahmed Saadoun JALOOT ◽  
Mustafa Nadhim OWAID ◽  
Rasim Farraj MUSLIM

The present research aims to produce gold nanoparticles (AuNPs) from the aqueous extract of locally isolated mushroom Coprinus comatus from Hit city, Iraq. Its properties were studied using the optical vision, UV-Vis, EDX, XRD, FTIR, AFM, and Zetasizer analyses. The exposure of the colloidal solution of AuNPs to UV radiation was investigated for 1, 2, and 3 h. The results showed the color change of the interaction mixture from light yellow to purple after 25 min. The lambda max of the absorbance reached 530 nm using UV-Visible spectrum as evident in the formation of AuNPs. FTIR spectra revealed the presence of functional groups related to peptides, proteins, flavonoids, monosaccharides, and phenolic compounds, which reduced gold ions. The EDX technique showed that the formed nanoparticles were AuNPs. XRD results showed that AuNPs have a face-centered cubic (fcc) crystal. The UV irradiation at different times led to an increase in the intensity of absorbance and sizes of AuNPs from 17.39 nm before the irradiation and switched to 58.16, 59.13, and 47.35 nm after 1, 2, and 3 h, respectively, but their sizes remained within the nanoscale range (less than 100 nm). In conclusion, the best result was observed after about an hour on the effects of UV irradiation on sizes of AuNPs, which reached smaller nanoparticles compared with times 2 and 3 h.


2018 ◽  
Vol 17 (2) ◽  
pp. 75-87
Author(s):  
Mustafa Nadhim OWAID ◽  
Ghassan Adnan NAEEM ◽  
Rasim Farraj MUSLIM ◽  
Raheel Saeed OLEIWI

The object of this study is to synthesize and characterize silver nanoparticles from Agaricus bisporus pileus extracts and their applications. Agaricus bisporus-mediated synthesis of AgNPs was characterized using changing the color solution, UV-Visible spectroscopy, SEM, AFM, SPM, FTIR spectrum, XRD, and EDS analyses. The change of the mixture color of 10-3 M AgNO3 with the watery extract of fresh A. bisporus caps from colorless to brown color is an indicator for the formation of silver nanoparticles (AgNPs). The UV-Visible spectrum exhibits the absorption peak at 418 nm. The FTIR spectra exhibited that the structures of amino acids, polysaccharides, and polyphenols in the crude extract of A. bisporus are not affected because of the joining and interaction of their functional groups with silver ions, and act as reducing and capping agents to the biosynthesized Ag nanoparticles. SEM and EDS refer to the formation of AgNPs with irregular or spherical shapes. The XRD pattern exhibits face-centered cubic (fcc) silver nanocrystals, with crystalline AgNPs size of 43.9 nm. The biosynthesized AgNPs play a suitable role against mouse cell line, which has receptors for polioviruses (L20B). After exposure of the colloid AgNPs to UV radiation (256 nm), the absorption band transferred from 418 nm to 435 nm, indicating that UV rays affect on physical properties of AgNPs. Roughness average of the biosynthesized AgNPs from A. bisporus caps is 15.4 nm, but the roughness is increased after UV irradiation for 1 h to average 33.6 nm. Histograms of particle size distribution of AgNPs show the average of AgNPs is 103.57 nm, while the size of nanoparticles reaches 69.47 nm after exposure to UV radiation of 256 nm. The use of UV radiation leads to enhanced characteristics of silver nanoparticles.


Author(s):  
F. Monchoux ◽  
A. Rocher ◽  
J.L. Martin

Interphase sliding is an important phenomenon of high temperature plasticity. In order to study the microstructural changes associated with it, as well as its influence on the strain rate dependence on stress and temperature, plane boundaries were obtained by welding together two polycrystals of Cu-Zn alloys having the face centered cubic and body centered cubic structures respectively following the procedure described in (1). These specimens were then deformed in shear along the interface on a creep machine (2) at the same temperature as that of the diffusion treatment so as to avoid any precipitation. The present paper reports observations by conventional and high voltage electron microscopy of the microstructure of both phases, in the vicinity of the phase boundary, after different creep tests corresponding to various deformation conditions.Foils were cut by spark machining out of the bulk samples, 0.2 mm thick. They were then electropolished down to 0.1 mm, after which a hole with thin edges was made in an area including the boundary


2009 ◽  
Vol 18 (08) ◽  
pp. 1159-1173 ◽  
Author(s):  
CASEY MANN ◽  
JENNIFER MCLOUD-MANN ◽  
RAMONA RANALLI ◽  
NATHAN SMITH ◽  
BENJAMIN MCCARTY

This article concerns the minimal knotting number for several types of lattices, including the face-centered cubic lattice (fcc), two variations of the body-centered cubic lattice (bcc-14 and bcc-8), and simple-hexagonal lattices (sh). We find, through the use of a computer algorithm, that the minimal knotting number in sh is 20, in fcc is 15, in bcc-14 is 13, and bcc-8 is 18.


1976 ◽  
Vol 31 (12) ◽  
pp. 1539-1542 ◽  
Author(s):  
H. M. Ledbetter

Abstract The Poisson ratio υ of a polycrystalline aggregate was calculated for both the face-centered cubic and the body-centered cubic cases. A general two-body central-force interatomatic potential was used. Deviations of υ from 0.25 were verified. A lower value of υ is predicted for the f.c.c. case than for the b.c.c. case. Observed values of υ for twenty-three cubic elements are discussed in terms of the predicted values. Effects of including volume-dependent electron-energy terms in the inter-atomic potential are discussed.


2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
M. Z. Kassaee ◽  
F. Buazar ◽  
E. Motamedi

Arc-fabricated copper nanoparticles (Cu Nps) size, morphology and the crystalline structure, as well as the yields of Nps appear sensitive to the applied currents (50–160 A) in distilled water. The results indicate that the sizes of Cu Nps are directly proportional to the currents employed. At 50 A, TEM, XRD, and SEM analyses show fabrication of relatively purest, the most dispersed, face-centered cubic (fcc) brown Cu Nps with rather smallest average size of 20 nm. At the same current, the TGA-DTA analysis reveals neither weight loss nor gain, indicating thermal stability of the fabricated Cu Nps.


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