Search Results

1 - 10 of 225 items :

  • "structural properties" x
Clear All
Structural properties of Sb- and Te-based binary compounds: Spin-orbit effect

Abstract

The band structure of AlSb, GaSb, ZnTe and CdTe is calculated using the empirical pseudopotential method (EPM) coupled with spin-orbit (SO) splitting. We applied our empirical model of bulk modulus with SO effect. It has been noticed that SO has a crucial effect on the band structure of these compounds but does not influence the structural phase transition. The calculated results are in good agreement with the experimental data.

Open access
Mechanical and structural properties of titanium dioxide deposited by innovative magnetron sputtering process

Abstract

Titanium dioxide thin films were prepared using two types of magnetron sputtering processes: conventional and with modulated plasma. The films were deposited on SiO2 and Si substrates. X-ray diffraction measurements of prepared coatings revealed that the films prepared using both methods were nanocrystalline. However, the coatings deposited using conventional magnetron sputtering had anatase structure, while application of sputtering with modulated plasma made possible to obtain films with rutile phase. Investigations performed with the aid of scanning electron microscope showed significant difference in the surface morphology as well as the microstructure at the thin film cross-sections. The mechanical properties of the obtained coatings were determined on the basis of nanoindentation and abrasion resistance tests. The hardness was much higher for the films with the rutile structure, while the scratch resistance was similar in both cases. Optical properties were evaluated on the basis of transmittance measurements and showed that both coatings were well transparent in a visible wavelength range. Refractive index and extinction coefficient were higher for TiO2 with rutile structure.

Open access
Experimental and theoretical approaches on thermal and structural properties of Zn doped BSCCO glass ceramics

have been analyzed. In the present work, variation in thermal and structural properties of the glass-ceramic Bi 1.8 Sr 2 Ca 2 Cu 3.2-x Zn x O 10+δ system (x = 0, 0.1 and 0.5) with various Zn doping levels have been studied. 2. Experimental One of common methods used for preparing ceramic materials is the glass-ceramic method. Therefore, in this study, the amount of copper in the BSCCO system was reduced by zinc doping using the glass-ceramic method. High purity Bi 2 O 3 , SrCO 3 , CaCO 3 , CuO and ZnO powders were used as starting materials in the

Open access
Influence of preparation method on structural, optical and magnetic properties of nickel ferrite nanoparticles

Abstract

Nanocrystalline NiFe2O4 particles were prepared by conventional sol-gel, citrate-nitrate sol-gel combustion and co-precipitation methods. The synthesized samples were annealed at 1000 °C for two hours and structural, chemical, morphological, optical and magnetic properties of nickel ferrite were investigated. The structural properties were investigated by X-ray diffraction (XRD) technique which confirmed the formation of single phase NiFe2O4 particles derived by the three methods. The chemical properties were analyzed by Fourier transform infrared (FT-IR) spectroscopy which confirmed the corresponding vibration modes in the samples. The optical properties were studied by UV-Vis spectroscopy. The morphological study of the as-synthesized samples was carried out by scanning electron microscopy (SEM). SEM images showed the agglomerated nanoparticles of NiFe2O4. The magnetic properties were investigated by vibrating sample magnetometer (VSM), which showed that the calcined samples exhibited typical magnetic behavior.

Open access
Structural Properties of Recursively Partitionable Graphs with Connectivity 2

Abstract

A connected graph G is said to be arbitrarily partitionable (AP for short) if for every partition (n 1, . . . , np) of |V (G)| there exists a partition (V 1, . . . , Vp) of V (G) such that each Vi induces a connected subgraph of G on ni vertices. Some stronger versions of this property were introduced, namely the ones of being online arbitrarily partitionable and recursively arbitrarily partitionable (OL-AP and R-AP for short, respectively), in which the subgraphs induced by a partition of G must not only be connected but also fulfil additional conditions. In this paper, we point out some structural properties of OL-AP and R-AP graphs with connectivity 2. In particular, we show that deleting a cut pair of these graphs results in a graph with a bounded number of components, some of whom have a small number of vertices. We obtain these results by studying a simple class of 2-connected graphs called balloons.

Open access
Electronic and structural properties of rare earth pnictides

p-f mixing on the structural properties of these compounds. The rare-earths have different occupation numbers for the shallow inner 4f shell. Due to the unfilled 4f shells of rare-earth atoms, it is a challenging problem to obtain an accurate theoretical description of the electronic structure of the rare-earth compounds. Because of the highly localized nature of the 4f electrons, direct f-f interactions between neighboring rare-earth atoms are generally considered to be nearly negligible [9] . The present pnictides (XBi; X = Am, Cf) exhibit six-fold coordinated

Open access
Structural properties of hypothetical CeBa2Cu3O7 compound from LSDA+DMFT calculations

susceptibility suggesting the existence of local magnetic moments while the α phase shows a Pauli-like temperature independent paramagnetism [ 17 , 18 ]. It was noted that in the γ phase 4f electrons are localized whereas upon pressure they are more and more delocalized [ 19 ]. According to our best knowledge, it is not known whether similar situation could also take place in case of cerium in the Ce123 system. In the present paper we extend the latter approach [ 6 ] to the structural properties of the hypothetical stoichiometric CeBa 2 Cu 3 O 7 system and present the

Open access
Synthesis and characterization of Ag-chalcogenide nanoparticles for possible applications in photovoltaics

Abstract

Bottom-up technique has been used to synthesize Ag-chalcogenide nanoparticles. This work reports on the synthesis of Ag2Se by varying the molar ratio of capping agent and pH of the solution. The synthesized nanoparticles have been characterized in terms of structural parameters using X-ray diffraction. By this technique, various parameters such as crystallite size, dislocation density and strain of the nanoparticles were calculated. The crystallite size decreased with the increase in pH of the solution. The optical characterization was carried out by UV-Vis-NIR spectrophotometer. With the decrease in the crystallite size, a blue shift in the absorption peak of the nanoparticles was observed. These properties are suitable for energy harvesting with the help of photovoltaics.

Open access
Investigations of structural, elastic, electronic and thermodynamic properties of lutetium filled skutterudite LuFe4P12 under pressure effect: FP-LMTO method

Abstract

Structural, elastic, electronic and thermodynamic properties of ternary cubic filled skutterudite compound were calculated. We have computed the elastic modulus and its pressure dependence. From the elastic parameter behavior, it is inferred that this compound is elastically stable and ductile in nature. Through the quasi-harmonic Debye model, in which phononic effects are considered, the effect of pressure P (0 to 50 GPa) and temperature T (0 to 3000 °C) on the lattice constant, elastic parameters, bulk modulus B, heat capacity, thermal expansion coefficient α, internal energy U, entropy S, Debye temperature θD, Helmholtz free energy A, and Gibbs free energy G are investigated.

Open access
Structural and electrical properties of barium titanate (BaTiO3) thin films obtained by spray pyrolysis method

Abstract

Barium titanate (BaTiO3) thin films have been prepared using the spray pyrolysis method. The films were deposited onto a glass substrate at varying substrate temperature ranging from 250 to 350 °C with the interval of 50 °C. The structural, morphological, electrical and dielectric properties of the deposited films have been studied. The X-ray diffraction pattern confirmed the polycrystalline nature of the films with a cubic crystal structure. X-ray photoelectron spectroscopy (XPS) showed a good agreement of the thin films stoichiometry with BaTiO3. A presence of Ba, Ti and O in the BaTiO3 thin films was observed by energy dispersive X-ray analysis. The scanning electron microscopy (SEM) showed the heterogeneous distribution of cubical grains all over the substrate. The grain size decreased with an increase in substrate temperature. The dielectric constant and dielectric loss showed the dispersion behaviour as a function of frequency, measured in the frequency range of 20 Hz to 1 MHz. The AC conductivity (σac) measurement showed the linear nature of obtained films, which confirms conduction mechanism due to small polarons. Impedance spectroscopy has been used to study the electrical behaviour of BaTiO3 ferroelectric thin films. The ferroelectric hysteresis loop has been recorded at room temperature.

Open access