Top PDF Structural, Optical, and Dielectric Properties of A[(Mg0.32Co0.02) Nb0.66]O3 Semiconductor, Where (a = Ba, Sr or Ca)

Structural, Optical, and Dielectric Properties of A[(Mg0.32Co0.02) Nb0.66]O3 Semiconductor, Where (a = Ba, Sr or Ca)

Structural, Optical, and Dielectric Properties of A[(Mg0.32Co0.02) Nb0.66]O3 Semiconductor, Where (a = Ba, Sr or Ca)

is shown in Fig. 10. It exhibits a transition from gradually enhancing nature of s to decreasing type at around 370 K. Such a thermally activated behavior of s according to small polaron tunneling model (SPT) indicates that the conductivity is due to polarons, independent of the inter-site separation [13]. On the other hand, for temperatures beyond 370 K, the decreasing nature of s is inferred from the correlated barrier-hopping model (CBH) [14]; here, the conduction is due to electron transfer over the barrier between two sites having their own columbic potential wells. The CBH model is of particular interest as it explains the conductivity mechanism in systems investigated here, in which the dc conductivity is not negligible. We also note the significance of transition from SPT type conduction behavior to CBH type conduction at ~ 370 K in the form of observed “Switching behavior” in the thin films of SMCN at the same temperature [10].
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Structural, optical and electrical properties of Ni-doped Co3O4 prepared via Sol-Gel technique

Structural, optical and electrical properties of Ni-doped Co3O4 prepared via Sol-Gel technique

order to investigate their optical, structural and electrical properties. X-ray diffraction patterns revealed that Ni-doped Co 3 O 4 samples were crystallized in cubic spinel structure knowing that the crystallite size was found to be from 214 to 279 Å. The as synthesis films, exhibit a high transmission ~ 60-85% in the visible region. Optical studies concluded that Co 3 O 4 has multiple band gap energies with direct transitions 2.20 eV (O 2- →Co 2+ ) and 1.50 eV (O 2- →Co 3+ ). The band gap

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Structural properties of nanoscopic ring systems and their optical response

Structural properties of nanoscopic ring systems and their optical response

We have studied asymmetry effects in QRs motivated by experimental results of deformed QRs obtained during the growth process whose main consequence is the circularly symmetry breakdown. The asymmetric diffusion of atoms leads to some degree of anisotropy along the [110] and [1¯10] directions and subsequently to elongated QRs. The characterization of the lo- cal in-plane strain field shows that the most strained region of QDs is located at intermediary distances from the center, whereas for QRs the strain regions coincide with the highest In- concentration regions. The presence of strain fields affects the electronic structure and this may tune the state hybridization of the valence band ground state, as found in our multiband calcula- tion. Non-zero values of the effective angular momentum may appear for certain combinations of strain fields and QR sizes. Thus, a fine control of the structural parameters and deformation during the QR synthesis and capping processes may become a powerful tool for the modulation of their optical properties and, certainly, their potential magnetic response.
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Structural and Optical Properties of Electro Sprayed Tin Oxide Thin Films

Structural and Optical Properties of Electro Sprayed Tin Oxide Thin Films

processed electro spraying technique. The structural and optical properties of the films were studied using X-ray diffractometer, UV-Vis spectrophotometer and Photoluminescence spectroscopy respectively. The polycrystalline nature of the films with tetragonal structure was observed from XRD pattern with the mean grain size of 17 nm. The Optical band gap of the films was calculated from the absorption curve and the interference pattern was observed on transmittance spectra. The calculated band gap of 3.5 eV is larger than the bulk band gap of Tin oxide. The blue emission band at 388 nm was observed from room temperature photoluminescence analysis and the effect of excitation wavelength of the films were studied and discussed.
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Structural, optical, and magnetic properties of NiMoO4 nanorods prepared by microwave sintering

Structural, optical, and magnetic properties of NiMoO4 nanorods prepared by microwave sintering

We report on the structural, optical, and magnetic properties of �,�-NiMoO 4 nanorods synthesized by annealing the NiMoO 4 :nH 2 O precursor at 600 ∘ C for 10 minutes in a domestic microwave. he crystalline structure properties of �,�-NiMoO 4 were investigated using X-ray difraction (XRD), Fourier transform infrared (FTIR), and Raman (FT-Raman) spectroscopies. he particle morphologies and size distributions were identiied by ield emission microscopy (FE-SEM). Experimental data were obtained by magnetization measurements for diferent applied magnetic ields. Optical properties were analyzed by ultraviolet- visible (UV-vis) and photoluminescence (PL) measurements. Our results revealed that the oxygen atoms occupy diferent positions and are very disturbed in the lattice and exhibit a particular characteristic related to diferences in the length of the chemical bonds (Ni-O and Mo-O) of the cluster structure or defect densities in the crystalline �,�-NiMoO 4 nanorods, which are the key to a deeper understanding of the exploitable physical and chemical properties in this study.
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Effect of Annealing on Structural and Optical Properties of Cu Doped In2O3 Thin Films

Effect of Annealing on Structural and Optical Properties of Cu Doped In2O3 Thin Films

applications. In addition to this its cubic structure will allow to use low cost substrates such as MgO, which has interesting applications. In order to enhance the band gap, various doping elements such as Li, Cr, Ni [12-14] were doped into the host material and their physical properties were extensively studied. Hence here the attempt is made to dope the impurity copper (Cu) to study the change in structural, optical proper- ties of In 2 O 3 by doping using the flash evaporation

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Growth Structural and Optical Properties of the Thermally Evaporated Tin Diselenide (SnSe2) Thin Films

Growth Structural and Optical Properties of the Thermally Evaporated Tin Diselenide (SnSe2) Thin Films

The sharp peaks present in X-ray diffraction pattern indicate that the prepared SnSe 2 has hexagonal structure and polycrystalline in nature [10]. EDAX analysis of the compound was done to confirm the stoichiometric. The EDAX pattern of the powder is also shown in Fig. 1 b. Table 1 presents EDAX data which indicates the stoichiometry of elements which verifies formation of SnSe 2 phase in synthesized powder.

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MAYRA ALEXANDRA PADRÓN GÓMEZ STRUCTURAL AND OPTICAL PROPERTIES OF LOW DIMENSIONAL LEAD HALIDE PEROVSKITES

MAYRA ALEXANDRA PADRÓN GÓMEZ STRUCTURAL AND OPTICAL PROPERTIES OF LOW DIMENSIONAL LEAD HALIDE PEROVSKITES

increase. The two very intense peaks located around 522 nm in all PL spectra are related to Raman active modes of the diamonds of the high pressure cell. The PL intensity showed a gradual increase upon pressure until reaches a maximum value at 1.33GPa, from this point the intensity decrease until the pressure of 2.71 GPa where the PL emission vanish (Figure 12 (b)). This changing on intensity around 1.33 GPa can be related to changes on structure or a starting point of phase transitions. Besides the changes on PL emission intensity, the maximum position also showed a gradual and linear red shift up to 1.76 GPa (Figure 12 (c)). At this point, the PL undergoes a jump from 526 to 528 nm at 1.93 GPa from which a sudden blue shift follows up to the pressure reaches 2.71 GPa, where the PL peak disappear. The abrupt change in the PL peak pressure behavior has been understood as the crystalline structure undergoing a phase transition, as observed in several halide perovskite pressure dependent studies (JAFFE et al., 2016; SZAFRAŃSKI; KATRUSIAK, 2016; ZHANG et al., 2018c; ZHANG; ZENG; WANG, 2017b). Thus, these results are indicative that the CsPb 2 (Br 0.85 I 0.15 ) 5 undergoes a phase transition at 1.76 GPa reinforcing first phase transition
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Structural and Optical Properties of Cu2ZnSnS4 Nanoparticles for Solar Cell Applications

Structural and Optical Properties of Cu2ZnSnS4 Nanoparticles for Solar Cell Applications

X-ray diffraction patterns of the CZTS nanoparti- cles at various synthesis temperatures are shown in Fig. 1. The diffraction peaks at 2θ values 28.59 , 33.09 and 47.44 are indexed as (112), (200) and (220) corre- sponding to that of Kesterite structure of CZTS (JCPDS 26-0575). The lattice constants were calculated and were found to be a 5.427 Å and c 10.848 Å, which are good agreement with the previous reported data of stoichiometric CZTS with tetragonal phase [16- 18]. The intensity of peaks increased with increasing the synthesis temperature up to 150 C indicating im- provement in crystallinity. Further increasing the stir- ring temperature, the intensity of the peaks decreased and an impurity peak was observed at 2θ 43.12 cor- responding to copper (JCPDS 85-1326). From the XRD studies we confirmed that, stoichiometric CZTS na- nopowder was observed at a synthesis temperature of 150 C.
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Braz. J. Phys.  vol.29 número4

Braz. J. Phys. vol.29 número4

structure and this can be exploited to enhance the per- formance of optoelectronic devices. However, a strain relaxation process may occur if the layer thickness ex- ceeds a critical value and mis t dislocations are cre- ated [1]. It is possible to compensate the total strain of a multi- quantum well (MQW) structure through the use of tensile strained barriers and compressive strained wells. Such structures are referred as zero-net-strained (ZNS). Nevertheless, the strain relaxation can occur prior to the mis t generation through elastic mecha- nisms. Also, the quaternary InGaAsP alloy may be a ected by the miscibility gap [2,3], where a range of compositions and temperatures exist and the solid so- lution is energetically unstable. These mechanisms pro- duce undulation at the interfaces, composition uctu- ations, wavy morphologies and contribute to degrade the optical and structural properties of the grown lay-
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Effect of Annealing on the Properties of Nanocrystalline CdS Thin Films Prepared by CBD Method

Effect of Annealing on the Properties of Nanocrystalline CdS Thin Films Prepared by CBD Method

The CdS thin films were deposited on glass substrate by chemical bath deposition (CBD). The effect of annealing temperature on the morphological, structural, optical and electrical properties of the crystalline CdS films were investigated for different annealing temperature (as deposited, 300, 400 and 500 °C).The annealing time is 1 h. The materials have been prepared using simple aqueous solutions containing cad- mium sulfate, as source of cadmium, and thiourea as source of sulfur and ammonium hydroxide as the complexing agent. The temperature of the bath was maintained at low temperature of 80 °C. The surface morphological properties studied by SEM and AFM respectively. The structural properties of CdS thin film was studied by X-ray diffraction. The optical parameter such as transmittance and energy band gap of the films with thermal annealing temperature was investigated by UV-Visible spectrophotometer. The varia- tion of band gap values of CdS thin film samples were found to be in the range of 2.37 to 2.5 eV. Electrical resistivity measurements were carried out in four-probe Van Der Pauw geometry at room temperature by the Hall measurement. SEM image confirmed that film of smooth surface morphology.
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Mat. Res.  vol.15 número4

Mat. Res. vol.15 número4

In this work, mechanical and structural parameters related to the optical properties of polyethylene terephthalate (PET) fibers drawn at hot multistage have been investigated. The changes in optical parameters upon changing draw ratio are used to obtain the mechanical orientation factors <P 2 (cos θ)> and <P 4 (cos θ)>, various orientation functions f 2 (θ), f 4 (θ) and f 6 (θ), and amorphous and crystalline orientation functions (f a and f c ). Also, the numbers of random links between the network junction points (N 1 ), the average optical orientation (F av ), and the distribution function of segment ω(cos θ) were calculated. In addition, an empirical formula was suggested to correlate changes in the birefringence with the draw ratio and its constants were determined. The study demonstrated change on the molecular orientation functions and structural parameters upon hot multistage drawing. Significant variations in the characteristic properties of the drawn PET fibers were due to reorientation of the molecules caused by applied heat and external tension.
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Mat. Res.  vol.19 número4

Mat. Res. vol.19 número4

glasses are proved to be efective. In the present work, we report the structural properties of the Pr 2 O 5 doped borate glasses that were determined by X-ray difraction (XRD) analysis and FTIR and FT-Raman analysis. It was conirmed that the prepared glasses were amorphous. The bonding parameters of the glasses were analyzed by using FTIR and FT Raman analysis and were conirmed to be ionic in nature. The optical properties were characterized by using the photoluminescence studies. The electrical properties of Pr 2 O 5 doped borate glasses were studied. Since being a member of Lanthanide, Prasuedomium shows eicient luminescence in triplet state. Hence, the prepared borate glass can be used for some applications like optical data reading, colour display etc.
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EFFECTS OF NEODYMIUM DOPING ON DIELECTRIC AND OPTICAL PROPERTIES OF Ba(1-x)NdxTi1.005O3 CERAMICS

EFFECTS OF NEODYMIUM DOPING ON DIELECTRIC AND OPTICAL PROPERTIES OF Ba(1-x)NdxTi1.005O3 CERAMICS

properties and optical properties of the ceramics were studied. The structural analysis performed on the X-ray diffractometer shows that the phase compositions of all ceramics are tetragonal phase structure. The red shift of the absorption edge indicates the presence of defect energy levels which was proved by the UV-Vis-NIR diffuse reflection spectra. Dielectric property measurements show that Nd-doped BaTiO 3 ceramics possess improved dielectric properties at low Nd 3+ contents

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art aflalmeida optical and electrical

art aflalmeida optical and electrical

In this paper we will study the effect of the presence of hydroxyapatite (HA—Ca 10 (PO 4 ) 6 (OH) 2 ) on the dielectric permittivity and losses of the barium titanate (BTO—BaTiO 3 ) thick films. These films were prepared in two layers geometry using the screen printing technique on Al 2 O 3 substrates. Mechanical alloying has been used successfully to produce nanocrystalline powders of hydroxyapatite (HA) used in the films. We also look for the effect of the grain size of the BTO and HA on the final properties of the film. The samples were studied using X-ray diffraction, scanning electron microscopy (SEM), Raman and infrared spectroscopies, dielectric permittivity and losses measurements. The study of the dielectric permittivity and losses was done in the radio-frequency range (100 Hz–10 MHz). The role played by the firing process in the film preparation and the crystallite size of HA and BTO on the dielectric constant and structural properties of the films are discussed.
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Mat. Res.  vol.18 número1

Mat. Res. vol.18 número1

The objective of the present investigation is to study the effect of beryllium doping on the structural, optical, and electrical properties of CdO, focusing on the improvement of carrier mobility (μ) that accompanied with high electrical conductivity and good optical transparency in the near-infrared region. Thus, nanocrystallite Be-doped CdO ilms were prepared by vacuum evaporation method. The characterisation of the samples was done by using X-ray diffraction (XRD), scanning electron microscope (SEM), absorption spectroscopy, and Hall measurements. The characteristic XRD patterns indicated that the prepared Be-doped CdO ilms were single phase of cubic CdO structure of highly [111] orientation. Scanning electron microscope analysis revealed that the studied CdO ilms were characterized with high-density threads (wooly structure) and the incorporation of beryllium ions modiied that structure forming almost round grains. It was observed that the room temperature conductivity (σ) and mobility (μ) could be controlled through the level of beryllium doping. The utmost carrier mobility was found to be ~130 cm 2 /Vs in ~ 0.10% Be ilms maintaining a low electrical
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J. Braz. Chem. Soc.  vol.26 número11

J. Braz. Chem. Soc. vol.26 número11

In this work, we used CT, one of the perovskite oxides, to prepare nanosized undoped and Thulium (Tm) and/or Ytterbium (Yb)-doped CT. The HTMW approach was selected to obtain powders under favorable conditions, i.e., low temperatures and a short reaction time (480 seconds). Detailed optical properties were evaluated using UV-Vis spectroscopy, and photoluminescence (PL) emission spectra of doped and undoped CT were employed to examine the structural order-disorder of the synthesized materials and the possible correlation between their structure and photoluminescence.
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Synthesis and Characterisation Of CdxZn1–xS Nanocomposites

Synthesis and Characterisation Of CdxZn1–xS Nanocomposites

A facile, easy controlled and economical method was described in this article. We used simple inorganic raw materials to synthesize a series of nano- sized Cd x Zn 1 – x S samples involved in hydrothermal process. The central objective of the present study is to understand the growth behavior of ZnS-CdS nanoparticles, the optical and structural properties have been studied, and the results indicate that the absorption edges of those nanoparticles can be varied from blue to UV, while the emission peak can be adjusted from 470 to 690 nm which shows it has potential applications as wide band gap window materials.
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Mat. Res.  vol.19 número2

Mat. Res. vol.19 número2

estimated to be 3.735 and 0.0425 respectively. The lower and positive value of dielectric constant of the material enables the occurrence of the induced polarization due to intense incident light radiation. Titanium dioxide (TiO 2 ) has attracted signiicant attention from researchers because of its many interesting physical and chemical properties that make it suitable for a variety of applications. For instance, TiO 2 has high corrosion resistance and chemical stability and an excellent optical transparency in the visible and near infrared regions. It also has high refractive index that makes it suitable for anti-relection coatings in optical devices. It has been used mostly as a pigment in paints, sunscreens, ointments, toothpaste etc.
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Production of Sr-deficient bismuth tantalates from microwave–hydrothermal derived precursors: Structural and dielectric properties

Production of Sr-deficient bismuth tantalates from microwave–hydrothermal derived precursors: Structural and dielectric properties

Besides, to detect the presence of sodium in the powders after microwave–hydrothermal synthesis, different charac- terization methods like energy dispersive X-ray (EDX) spectroscopy and atomic absorption spectrometry (AAS) were used. In all cases, sodium ions were not detected, indicating that the amount of sodium ions, if present, is below the maximum detection limits of the used techni- ques. Chemical analysis (AAS-Perkin Elmer 5000) indi- cated that a Sr-deficient precursor was obtained with final composition Sr 0:85 Bi 2:1 Ta 2 O 9 . Heat treatments occurred in
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