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1

Structural optical and magnetic properties of transition metal doped ZnO magnetic nanoparticles synthesized by sol-gel auto-combustion method

Sarfraz Madiha, Ahmed Nasar, Khizar-ul-Haq, Shahida Shabnam, Khan M. A.

Materials Science Poland

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2019

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Vol. 37, No. 2

280--288

EN

Transition metals, such as chromium (Cr) and manganese (Mn) doped zinc oxide (ZnO) magnetic nanoparticles, were synthesized via sole gel auto-combustion method. The prepared magnetic (Zn1−(x+y)MnxCryO, where x, y = 0, 0.02, 0.075) nanoparticles were calcined in an oven at 6000 °C for 2 hours. The morphologies of the nanoparticles were investigated using different techniques. X-ray diffraction (XRD) analysis revealed that the hexagonal wurtzite structure of the synthesized nanoparticles was unaffected by doping concentration. The crystallite size measured by Scherrer formula was in the range of 32 nm to 38 nm at different doping concentrations. Nanosized particles with well-defined boundaries were observed using a field emission scanning electron microscopy (FE-SEM). Fourier transform infrared (FT-IR) spectra showed a wide absorption band around 1589 cm−1 in all the samples, corresponding to the stretching vibration of zinc and oxygen Zn–O bond. A blue shift in optical band gaps from 3.20 eV for ZnO to 3.08 eV for Zn0.85Mn0.75Cr0.75 O nanoparticles was observed in diffuse reflectance spectra, which was attributed to the sp-d exchange interactions. The field-dependent magnetization M-H loops were measured using vibrating sample magnetometer (VSM). The VSM results revealed diamagnetic behavior of the ZnO nanoparticles which changed into ferromagnetic, depending on the doping concentration and particle size. The compositions of Zn, Cr, Mn and O in the prepared samples were confirmed by using the energy dispersive X-ray spectroscopy (EDX). Our results provided an interesting route to improve magnetic properties of ZnO nanoparticles, which may get significant attention for the fabrication of magnetic semiconductors.

2

Optical and thermal properties of TeO2–B2O3–Gd2O3 glass systems

Eevon C., Halimah M. K., Azlan M. N., El-Mallawany R., Hii S. L.

Materials Science Poland

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2019

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Vol. 37, No. 4

517--525

EN

New glass samples with composition (1 – x)[(TeO₂)₇₀(B₂O₃)₃₀] – x(Gd₂O₃) with x = 0.2, 0.4, 0.6, 0.8 and 1.0 in mol% have been synthesized by conventional melt-quenching techniques. X-ray diffraction (XRD) studies were performed in order to confirm the amorphous nature of the samples. The density of the samples has been found to vary with the Gd₂O₃ content, whereas an opposite trend has been observed in the molar volume. The analysis of Fourier Transform Infrared (FT-IR) spectroscopy of the samples showed that the glass network is mainly built of TeO, TeO₄, BO₃ and BO₄ units. The addition of Gd₂O₃ changed the refractive index, optical band gap and Urbach energy of the glass samples. The thermal properties of the studied glasses were investigated by measuring the thermal diffusivity of the samples by using photoflash method at room temperature.

3

Effect of thermal annealing on structural and optical properties of In doped Ge-Se-Te chalcogenide thin films

Singh Pravin Kumar, Tripathi S. K., Dwivedi D. K.

Materials Science Poland

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2019

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Vol. 37, No. 4

554--562

EN

Thin films of Ge10–xSe60Te30Inx (x = 0, 2, 4 and 6) were developed by thermal evaporation technique. The annealing effect on the structural properties of Ge10–xSe60Te30Inx (x = 0, 2, 4 and 6) films has been studied by X-ray diffraction (XRD). The XRD results indicate amorphous nature of the as-prepared films whereas crystalline phases in annealed films were identified. Structural parameters such as average crystallite size, strain, and dislocation were determined for different annealing temperatures. Effect of annealing on optical constants of prepared films has been explored using UV-Vis spectrophotometer in the wavelength range of 400 nm to 1000 nm. Various optical constants were determined depending on annealing temperature. It has been noticed that the film transparency and optical bandgap Eg have been reduced whereas the absorption coefficient α and extinction coefficient k increased with increasing annealing temperature. It was found that the prepared samples obey the allowed direct transition. The reduction in optical bandgap with annealing temperature has been described by Mott and Davis model. Due to annealing dependence of the optical parameters, the investigated material could be utilized for phase change memory devices.

4

Substitutional effect of copper on the cation distribution in cobalt chromium ferrites and their structural and magnetic properties

Zeeshan T., Anjum S., Iqbal H., Zia R.

Materials Science Poland

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2018

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Vol. 36, No. 2

255-263

EN

A series of copper substituted cobalt chromium ferrites, CuxCo1 - xCr0.5Fe1.5O4 (x = 0, 0.2, 0.4, 0.6, 0.8, 1.0) has been synthesized, by employing powder metallurgy method. Calcination of the samples has been carried out for 24 hours at 1100 °C. The resultant materials have been investigated by using a variety of techniques, including X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM)), scanning electron microscopy (SEM), and ultraviolet visible spectroscopy (UV-Vis). The XRD patterns confirmed that all compositions had a cubic spinel structure with a single phase and the lattice parameter was found to increase with increasing copper concentration. FT-IR spectroscopy has been used for studying the chemical bonds in the spinel ferrite. Shifting of the bands ν1 and ν2 has been observed. It has been revealed from VSM analysis that saturation magnetization and coercivity decrease with rising the Cu+2 doping. Magnetic properties have been explained on the basis of cation distribution. Scanning electron microscopy (SEM) has been used to study the surface morphology of prepared samples. UV-Vis analysis revealed the optical absorption of the samples. An increase in band gaps has been observed with increasing copper concentration in the sample.

5

Temperature Effect on the Growth Rate and Physical Characteristics of SnO2 Thin Films Grown by Atomic Layer Deposition

Kim D., Kim D. H., Riu D.-H., Choi B. J.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 2

1061--1064

EN

Among the various thin film coating techniques, atomic layer deposition (ALD) has features of good controllability of the thickness, excellent step-coverage in 3-dimensional object even in the sub-nm thickness range at the relatively low deposition temperature. In this study, SnO2 thin films were grown by ALD in the variation of substrate temperatures from 150 to 250°C. Even such a low temperature may influence on the growth kinetics of the ALD reaction and thus the physical characteristics of thin films, such as crystallinity, film density and optical band gap, etc. We observed the decrease of the growth rate with increasing substrate temperature, at the same time, the density of the film was decreased with increasing temperature. Steric hindrance effect of the precursor molecule was attributed to the inverse relationship of the growth temperature and growth rate as well as the film density. Optical indirect band gap energy (~3.6 eV) of the ALD-grown amorphous SnO2 films grown at 150°C was similar with that of the literature value, while slightly lower band gap energy (~3.4 eV) was acquired at the films grown at higher temperature.

6

Effect of deposition temperature on structural, optical and electrical properties of copper bismuth sulphide (CuBiS2) thin films deposited by chemical bath deposition

Balasubramanian V., Kumar P. N., Sengottaiyan D.

Materials Science Poland

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2017

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Vol. 35, No. 2

329--334

EN

The effect of deposition temperature on the structural, optical and electrical properties of copper bismuth sulphide (CuBiS2) thin films deposited by chemical bath deposition onto glass substrates at different deposition temperatures (40 °C, 50 °C, 60 °C and 70 °C) for 5 hours deposition time period was investigated. The obtained films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX) and optical absorption spectra. All deposited films were polycrystalline and had an orthorhombic structure. Their grain size had changed with deposition temperature and their compositions were nearly stoichiometric. The optical band gap value was decreased from 2.44 eV to 2.33 eV with increasing the film thickness. Electrical parameters such as mobility and type of electrical conduction were determined from the Hall effect measurements. They showed that the obtained films have n-type conductivity and mobility values of the copper bismuth sulphide (CuBiS2) films have changed with deposition temperature.

7

Optimization of S:Sn precursor molar concentration on the physical properties of spray deposited single phase Sn2S3 thin films

Srivind J., Nagarethinam V. S., Balu A. R.

Materials Science Poland

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2016

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Vol. 34, No. 2

393--398

EN

Nanoneedle structured Sn2S3 thin films were prepared by spray pyrolysis technique from aqueous solutions of tin (II) chloride and thiourea, keeping the molar concentrations of S:Sn = 0.01:0.01, 0.02:0.02, 0.03:0.03 and 0.04:0.04 in the starting solutions. XRD studies reveal that all the films exhibit orthorhombic crystal structure with a preferential orientation along the [2 1 1] direction. The peak intensity of the (2 1 1) plane is found to be maximum for the film coated with 0.02:0.02 S:Sn molar concentration which confirms the improved crystalline nature of this film. SEM images depict that the film coated with S:Sn molar concentration 0.02:0.02 exhibit needle shaped grains. The optical band gap exhibits red shift from 2.12 eV to 2.02 eV with an increase in S:Sn precursor molar concentration. Electrical studies show that the films having S:Sn molar concentrations 0.01:0.01 and 0.02:0.02 exhibit minimum resistivity values of 0.238 and 0.359Ω ·cm, respectively.

8

Optical spectroscopic analysis of annealed Cd1−xZnxSe thin films deposited by close space sublimation technique

Ali I., Iqbal A., Mahmood A., Shah A., Zakria M., Ali A.

Materials Science Poland

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2016

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Vol. 34, No. 4

828--833

EN

Cd1−xZnxSe (x = 0, 0.40 and 1) thin films were deposited on a glass substrate at room temperature by closed space sublimation method. Optical investigation has been performed using spectrophotometry and ellipsometry. It has been found that for as deposited films the optical band gap increased and the optical constants decreased with increasing Zn content. To improve the optical properties of Cd1−xZnxSe thin films annealing effect at 400 °C was taken into consideration for various Zn contents. It was observed that the optical transmittance and band gap decreased while optical constants increased with increasing Zn content after annealing. The effects of composition and annealing on the optical dispersion parameters Eo and Ed were investigated using a single effective oscillator model. The calculated value of the average excitation energy Eo obeys the empirical relation (Eo = Eg/2) obtained from the single oscillator model.

9

Modification in surface properties of poly-allyl-diglycol-carbonate (CR-39) implanted by Au+ ions at different fluences

Sagheer R., Rafique M. S., Saleemi F., Arif S., Naab F., Toader O., Mahmood A., Rashid R., Hussain I.

Materials Science Poland

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2016

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Vol. 34, No. 2

468--478

EN

Ion implantation has a potential to modify the surface properties and to produce thin conductive layers in insulating polymers. For this purpose, poly-allyl-diglycol-carbonate (CR-39) was implanted by 400 keV Au+ ions with ion fluences ranging from 5 × 1013 ions/cm2 to 5 × 1015 ions/cm2. The chemical, morphological and optical properties of implanted CR-39 were analyzed using Raman, Fourier transform infrared (FT-IR) spectroscopy, atomic force microscopy (AFM) and UV-Vis spectroscopy. The electrical conductivity of implanted samples was determined through four-point probe technique. Raman spectroscopy revealed the formation of carbonaceous structures in the implanted layer of CR-39. From FT-IR spectroscopy analysis, changes in functional groups of CR-39 after ion implantation were observed. AFM studies revealed that morphology and surface roughness of implanted samples depend on the fluence of Au ions. The optical band gap of implanted samples decreased from 3.15 eV (for pristine) to 1.05 eV (for sample implanted at 5 × 1015 ions/cm2). The electrical conductivity was observed to increase with the ion fluence. It is suggested that due to an increase in ion fluence, the carbonaceous structures formed in the implanted region are responsible for the increase in electrical conductivity.

10

Characteristics of TlBr single crystals grown using the vertical Bridgman-Stockbarger method for semiconductor-based radiation detector applications

Kim D. J., Oh J.-H, Kim H. S., Kim Y. S., Jeong M., Kang C. G., Jo W. J., Choi H., Kim J. G., Lee S. H., Ha J. H

Materials Science Poland

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2016

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Vol. 34, No. 2

297--301

EN

TlBr single crystals grown using the vertical Bridgman-Stockbarger method were characterized for semiconductor based radiation detector applications. It has been shown that the vertical Bridgman-Stockbarger method is effective to grow high-quality single crystalline ingots of TlBr. The TlBr single crystalline sample, which was located 6 cm from the tip of the ingot, exhibited lower impurity concentration, higher crystalline quality, high enough bandgap (>2.7 eV), and higher resistivity (2.5 × 1011 Ω·cm) which enables using the fabricated samples from the middle part of the TlBr ingot for fabricating high performance semiconductor radiation detectors.

11

Structural and optical properties of pure and Ag doped ZnO thin films obtained by sol gel spin coating technique

Ali S. M., Farooq W. A., Baig M. R., Shar M. A., Atif M., Alghamdi S. S., Algarawi M. S., Naeem U. R., Aziz M. H.

Materials Science Poland

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2015

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Vol. 33, No. 3

601--605

EN

We have investigated the influence of Ag doping on zinc oxide thin films. Pure and Ag doped, preferentially oriented transparent zinc oxide thin films were prepared by sol gel technique on a glass substrate using diethyl amine as a stabilizer. The X-ray diffraction analysis revealed that the films with hexagonal wurtzite type structure were polycrystalline in nature with a preferred grain orientation in the 101 direction. The crystallite sizes decreased from 34 nm to 27 nm after silver doping. Both photoluminescence and optical transmission measurements showed that the band gap increased after the Ag doping. The structure and optical characterization studies clearly indicated the incorporation of Ag in ZnO. Hence, the observed increase in the optical band gap and decrease in crystallite size can be directly attributed to the effect of Ag ion incorporation into the ZnO lattice.

12

Optical and surface morphological studies on CuPcOC8 thin films prepared by physical vapour deposition

Vadakel V. T., Menon C. S.

Materials Science Poland

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2013

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Vol. 31, No. 3

391--396

EN

2,3,9,10,16,17,23,24-copper octakis (octyloxy) phthalocyanine (CuPcOC8) thin films deposited at room temperature have exhibited a change in their surface morphology with the post deposition annealing temperature under normal atmosphere.These films have been characterised by optical absorption also. SEM images have shown densely packed nano particles and nano-rod like structures on the substrates annealed at different temperatures. The optical transition was found to be direct allowed and the direct energy gap changed with the annealing temperature. The results of optical and surface morphological studies on CuPcOC8 have been discussed.

13

Determination of optical constants and thickness of amorphous GaP thin film

Pimpabute N., Burinprakhon T., Somkhunthot W.

Optica Applicata

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2011

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Vol. 41, nr 1

257--268

EN

Gallium phosphide (GaP) thin film was prepared by an asymmetric bipolar pulsed-dc magnetron sputtering technique onto glass substrate at room temperature in an Ar atmosphere. A compacted GaP powder was used as a target. The X-ray diffraction patterns show that the film is amorphous. The transmittance of the film was measured in the incident photon wavelength range of 300–2000 nm. The film’s refractive index, thickness and absorption coefficient as a function of wavelength were determined by using Swanepoel’s method. The deduced absorption data indicate that the optical transition in the film is dominated by the indirect type. The corresponding energy of 1.51 eV was obtained for the 563š16 nm thin film.

14

Effect of Sn dopants on the optical and electrical properties of ZnO films

Aksoy S., Caglar Y., Ilican S., Caglar M.

Optica Applicata

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2010

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Vol. 40, nr 1

7--14

EN

The undoped and tin (Sn) doped ZnO films were deposited by a spray pyrolysis method onto the glass substrates. 0.2 M solution of zinc acetate in a mixture of ethanol and deionised water, in a volume proportion of 3 : 1, was employed. Dopant source was tin chloride. The atomic percentage of dopant in solution were Sn/Zn = 1%, 3% and 5%. The effect of tin doping on the optical and electrical properties of ZnO films was studied. The optical transmittance was about 76% in a visible range for Sn-doped ZnO films. The optical band gaps of the films were calculated. This suggests that the absorption edge shifts to the lower wavelengths with Sn dopant. Optical constants of the films were determined. These parameters changed with Sn dopant.

15

Optical properties of ternary tellurite glasses

Halimah M. K., Daud W. M., Sidek H. A. A., Zaidan A. W., Zainal A. S.

Materials Science Poland

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2010

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Vol. 28, No. 1

173--180

EN

Test samples of ternary glass tellurite [(TeO2)65(B2O3)35]y[Ag2O]y with y = 10, 15, 20, 25, 30 mol % have been fabricated and their physical and optical properties were investigated. The optical absorption was recorded at room temperature in the wavelength range from 200 to 800 nm. From the absorption edge data, the value of the optical band gap Eopt and the Urbach energy ?E were evaluated. The value of Eopt lies between 2.15 eV and 1.85 eV for the indirect transition and for direct transition the values vary from 2.77 eV to 2.35 eV. From the experimental results, values of the optical band gap and Urbach energy were calculated. They were found to be dependent on the glass composition.

16

Effect of annealing and Gamma irradiation on tin phthalocyanine thin films

Regimol C. C., Menon C. S.

Materials Science Poland

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2007

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Vol. 25, No. 3

649--655

EN

Metal phthalocyanines are important among organic dyes because of their chemical and thermal stability. Thin film samples of tin phthalocyanine (SnPc) have been prepared for examination by thermal evaporation technique. Some optical and electrical properties of the samples were studied as a function of annealing temperature and Gamma radiation doses. Optical transition is found to be of direct type and optical band gaps are determined by analyzing the absorption spectrum. The activation energy of the dark conductivity is found to be highly dependent on both annealing and Gamma radiation doses.

17

Refractive index dispersion and analysis of the optical constants of an ionomer thin film

Yakuphanoglu F., Erten H.

Optica Applicata

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2005

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Vol. 35, nr 4

969-976

EN

The basic optical properties and optical constants of the ionomer thin film have been investigated by means of transmittance and reflectance spectra. The real (n) and imaginary (k) parts of the complex refractive index and dielectric constant of the thin film were determined. The oscillator energy Eo, dispersion energy Ed and other parameters have been determined by the Wemple-DiDomenico method. The optical band gap Eg was determined and the optical absorption spectra show that the absorption mechanism is a direct transition. The most significant result of the present study is to determine optical constants and optical band gap of the thin film.

18

Optical characterization of an amorphous organic thin film

Yakuphanoglu F., Sekerci M.

Optica Applicata

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2005

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Vol. 35, nr 2

209-214

EN

The optical characteristics of Co(II) complex having 5,6-O-cyclohexylidene-1-amino-3-azahexane thin film were investigated by spectrometric measurements. The optical parameters, optical band gap Eg and width of localized states Ea of the film were determined using the transmittance T and the reflectance R at normal incidence in the spectral range 540-660 nm. The absorption edge of the film exhibits the exponential behavior which is attributed to the electronic transition in the localized states tailed off in the indirect energy band gap of the film. The refractive index spectra of the film show normal dispersion up to about 2 e V and afterwards, the refractive index increases with increasing photon energy.

19

Electrical and optical studies on thin films of indium phthalocyanine chloride

Mammen S., Menon C. S., Unnikrishnan N. V.

Materials Science Poland

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2005

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Vol. 23, No. 3

707--713

EN

Vacuum evaporated thin films of indium phthalocyanine chloride are prepared at room temperature. Post evaporation annealing is done at temperatures of 353 K, 403 K, 453 K and 503 K. The electrical conductivity and optical absorption spectra of these films are studied. From the optical absorption spectra, over a wavelength range of 200-900nm, the optical energy band gap Eg is calculated. A decrease in Eg is observed with an increase of annealing temperature. The thermal activation energy, Ea, is not notably affected by annealing. It is found that Ea is varied with a change in thickness of the film