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We have studied the magnetic properties of nanocrystals of ZnO :MnO prepared by traditional wet chemistry method. The detailed structural and morphological characterization was performed. The results of systematic measurements of AC magnetic susceptibility as a function of temperature and frequency as well as DC magnetization are reported. We observed two different types of magnetic behavior depending on the concentration doping. For samples with low nominal content (up to 30 wt% of MnO), superparamagnetic behavior was observed. We attribute the observed superparamagnetism to the presence of nanosized ZnMnO 3 phase. For nanocrystals doped above nominal 60 wt% of MnO ferrimagnetism was detected with TC at around 42 K. This magnetic behavior we assign to the presence of nanosized Mn3O4 phase.

Nanocrystalline samples of ZnO(Mn) were synthesized by hydrothermal method. The morphology of the samples was studied by HRTEM and SEM. X-ray diffraction was used to determine composition of the samples (ZnO and ZnMn2O4) and the mean crystalline size (from 16 to 99 nm). In this paper we report the experimental spectra of Raman scattering (from 100 to 1600 cm−1) with surface optical phonons (SOP) in range of 497–538 cm−1 as well as formation of new phases MnO, Mn3O4 and ZnMnO3. The phonon of registered phase's exhibit effects connected to phase concentration, while the SOP phonon mode exhibit significant confinement effect.

Nanocrystaline samples of ZnO(Fe) were synthesized by traditional wet chemical method followed by calcinations. Samples were characterized by X-ray diffraction to determine composition of the samples (ZnO, ZnFe 2 O 4 and Fe 2 O 3 ) and the mean crystalline size (from 8 to 51 nm). In this paper we report the experimental spectra of Raman scattering (from 200 to 1600 cm −1 ) with surface optical phonons (SOP) in range of 500–550 cm −1 . The phonon of registered phase’s exhibit effects connected to phase concentration, while the SOP phonon mode exhibit significant confinement effect.

The far-infrared reflectivity spectra of CdTe 0.97 Se 0.03 and CdTe 0.97 Se 0.03 (In) single crystals were measured at different temperatures. The analysis of the far-infrared spectra was carried out by a fitting procedure based on the dielectric function which includes spatial distribution of free carriers as well as their influence on the plasmon–phonon interaction. We found that the long wavelength optical phonon modes of CdTe 1 − x Se x mixed crystals exhibit a two-mode behavior. The local In mode at about 160 cm −1 is observed. In both sample, a surface layer with a low concentration of free carriers (depleted region) are formed.

Nanocrystalline samples of ZnO(Mn) were characterized by X-ray diffraction to determine composition of the samples (ZnO, Mn3O4, ZnMn2O4 and ZnMnO3) and the mean crystalline size (between 9 and 13 nm for ZnMnO3 phases, from 24 to 47 nm for Mn3O4 phases and above 100 nm for ZnO and ZnMn2O4 phases). In this paper we report the experimental spectra of Raman scattering (from 200 to 1600 cm−1) with surface optical phonons (SOP) in range of 520–575 cm−1. The phonon of registered phases exhibits effects connected to phase concentration, while the SOP phonon mode exhibits significant confinement effect.

Our work deals with the problem of producing a complex metal-ceramic composite using the processes of internal oxidation (IO) and severe plastic deformation. For this purpose, Cu-Al alloy with 0.4wt.% of Al was used. IO of sample serves in the first step of the processing as a means for attaining a fine dispersion of nanosized oxide particles in the metal matrix. Production technology continues with repeated application of severe plastic deformation (SPD) of the resulting metalmatrix composite to produce the bulk nanoscaled structural material. SPD was carried out with equal channel angular pressing (ECAP), which allowed that the material could be subjected to an intense plastic strain through simple shear. Microstructural characteristics of one phase and multiphase material was studied on internally oxidized Cu with 0.4wt.% of Al sample composed of one phase copper-aluminum solid solution in the core and fine dispersed oxide particles in the same matrix in the mantle region. In this manner AFM, X-ray diffraction and Raman spectroscopy were used. Local structures in plastically deformed samples reflect presence of Cu, CuO, Cu2O, Cu4O3 or Al2O3 structural characteristics, depending on type of sample. [Projekat Ministarstva nauke Republike Srbije, br. III45003]

The aim of the present work is to study the magnetic properties of nanocrystals of ZnO(Co) prepared by two methods of synthesis. We used the microwave assisted hydrothermal synthesis and traditional wet chemistry method followed by calcination. The detailed structural characterization was performed by means of X-ray diffraction and micro-Raman spectroscopy measurements. The magnetic properties were studied by means of AC susceptibility χ. All samples demonstrated Curie–Weiss behavior at higher temperatures. For calcination process, the negative values of the Curie–Weiss θ temperature were observed indicating the predominance of antiferromagnetic interactions. For samples prepared by hydrothermal synthesis, we observed the breakdown of predominance of antiferromagnetic interactions.

This paper describes the structural and optical properties of Cu-Se-CuSe2 thin films. The surface morphology of thin films was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Formation of thin films is concluded to proceed unevenly, in the form of islands which later grew into agglomerates. The structural characterization of Cu-Se-CuSe2 thin film was investigated using X-ray diffraction pattern (XRD). The presence of two-phase system is observed. One is the solid solution of Cu in Se and the other is low-pressure modification of CuSe2. The Raman spectroscopy was used to identify and quantify the individual phases present in the films. Red shift and asymmetry of Raman mode characteristic for CuSe2 enable us to estimate nanocrystal dimension. In the analysis of the far-infrared reflection spectra, numerical model for calculating the reflectivity coefficient of layered system, which includes film with nanocrystallite inclusions (modeled by Maxwell–Garnet approximation) and substrate, has been applied. UV–VIS spectroscopy and photoluminescence spectroscopy are employed to estimate direct and indirect band gap of CuSe2.

The aim of the present work is to study influence of preparation method on samples characteristics, creation and behavior of surface optical phonons (SOP) modes with change of concentration of doping elements by micro Raman spectroscopy. Nanocrystalline samples of ZnO(Co) were prepared by use of traditional wet chemistry method followed by calcinations and the microwave assisted hydrothermal synthesis. The phase composition of the samples (ZnO, Co3O4, ZnCo2O4) and the mean crystalline size (14–300 nm) were determined using X-ray diffraction measurements. In this paper we report the experimental spectra of Raman scattering (from 100 to 1600 cm−1) for both type of samples. Main characteristic of experimental Raman spectrum are: sharp peak at 436 cm−1 and broad multi phonon structure at ~1150 cm−1, typical for ZnO; sharp peaks at 194, 482, 521, 618 and 691 cm−1 typical for Co3O4 and sharp peaks at 185, 475, 520, 610 and 690 cm−1 typical for ZnCo2O4 nanoparticles. The phonon of registered phase’s exhibit effects connected to phase concentration, while the SOP phonon mode exhibit significant confinement effect.

The effects induced by α-particles and laser beam irradiation in air atmosphere in uncured and cured bisbenzocyclobutene (BCB) 2 μm thick films, spin-coated on glass/ITO surface have been investigated. α-Particle irradiation was done by means of a thin film 241 Am source ( E α = 5.486 MeV), up to the total fluence of about 5 × 10 10 particles/cm 2 . Laser irradiation was performed by a Nd 3+ :YAG ( λ = 1.06 μm) laser in the free generation and the Q-switch regime, using both focused and unfocused beams. Irradiation induced changes were investigated using Light and Atomic Force Microscopy (AFM), infrared (IR), Ultraviolet/visible (UV/vis) and Raman spectroscopy by inspecting several uncured and cured BCB films before and after irradiation. It has been found that both types of irradiation under investigated conditions have produced a novel phase in the material, which is not present either in the uncured or the cured BCB films. Possible implications of the observed effects on curing and degradation of BCB films have been discussed.

Surface optical phonons (SOP) were observed in the range of 496–572 cm−1 on Raman scattering spectra of nanocrystalline samples of ZnO(Co) prepared by use of the microwave assisted hydrothermal synthesis and traditional wet chemistry method followed by calcinations. The phase composition of the samples (ZnO, Co3O4, ZnCo2O4) and the mean crystalline size (14–300 nm) were determined using X-ray diffraction measurements. The SOP phonon mode exhibit significant size confinement effect, while the phonons of registered phases exhibit effects connected to phase concentration.

Nanocrystalline samples of ZnO(Fe) were synthesized by wet chemical method. Samples were characterized by X-ray diffraction to determine composition of the samples (ZnO, Fe2O3, ZnFe2O4) and the mean crystalline size (8–52 nm). In this paper we report the experimental spectra of the Raman scattering (from 200 to 1600 cm−1). Main characteristics of experimental Raman spectrum in 200 to 1600 cm−1 spectral region are: sharp peak at 436 cm−1 and broad two-phonon structure at ≈ 1150 cm−1, typical of ZnO; broad structure below 700 cm−1 that has different position and shape in case of ZnFe2O4 or Fe2O3 nanoparticles. PACS numbers: 63.20.−e, 78.30.Fs, 78.67.−n

Nanocrystalline samples of ZnO doped with CoO, MnO and Fe2O3 were synthesized by traditional wet chemical method followed by calcinations. Samples where characterized by X-ray diffraction to determine composition of the samples (ZnO, Co3O4, Mn3O4, ZnMn2O4, ZnMnO3, ZnFe2O4 and Fe2O3) and the mean crystalline size (from 8 to 156 nm, depending on the sample). In this paper we report the experimental Raman scattering spectra (from 100 to 1600 cm−1 and from 200 to 1600 cm−1) with surface optical phonons (SOP) in range of 496−575 cm−1. This shows the change of position of SOP modes with crystalline size and change of intensity of SOP modes with change of concentration of doping elements. The phonon of registered phase’s exhibits effects connected to phase concentration, while the SOP phonon mode exhibit significant confinement effect.

The far-infrared reflectivity spectra of CdTe0.97Se0.03 and CdTe0.97Se0.03(In) single crystals were measured at different temperatures. The analysis of the far-infrared spectra was carried out by a fitting procedure based on the dielectric function which includes spacious distribution of free carrier as well as their influence on the plasmon–phonon interaction. We found that the long wavelength optical phonon modes of CdTe1-xSex mixed crystals exhibit a two-mode behavior. The local In mode at about 160 cm−1 is observed. In both samples, a surface layer with a low concentration of free carriers is formed.

In this paper, we used Raman spectroscopy and spectroscopic ellipsometry to investigate optical properties of plastically deformed copper. Chemically pure copper prepared in a sample of square cross section (10 × 10 mm2) and about 50 mm long was extremely plastically deformed with the repeated application of Equal Channel Angular Pressing. Information about microstructure with ultrafine grains is obtained by atomic force microscopy. The structure of the sample surface—the copper oxide and surface roughness over-layer—was registered by spectroscopic ellipsometry. By Raman spectroscopy, two types of lines are registered: narrow, with the width ∼7 cm−1; and wide, ∼40 cm−1, which implies that nano-sized crystal structures related to three-dimensional amorphous boundary spaces exist in the specimen.

Pure copper (99.99), prepared in the sample of square cross-section (10 x 10 mm2) and length about 50 mm, was extremely plastically deformed with the repeated application of Equal Channel Angular Pressing (ECAP). ECAP was applied as an effective technique for producing bulk nano-scaled structures. Optical properties of the sample were investigated using Raman spectroscopy. Two types of lines: narrow (with width of 7 cmi1) and wide ( 40 cmi1) are registered. Existence of two types of lines indicates that in the specimen exists nano-sized crystal structures of both Cu and CuO related with three dimensional amorphous boundary spaces, which indicates that plastic deformation of the sample did not lead to total amorphisation of the specimen.

Chemically pure copper (99.99) prepared in the sample of square cross-section (10 x 10 mm2) and length about 50 mm was extremely plastically deformed with the repeated application of equal channel angular pressing. Equal channel angular pressing was applied as an effective technique for producing bulk nanoscaled structures. It is well known that severe plastic deformation of metallic materials often leads to microstructure with ultrafine grains and cross-sections which remain about equal before and after deformation. Optical properties of the sample were studied using spectroscopic ellipsometry in UV-VIS range. The parameters of the sample like copper oxide and surface roughness overlayer were calculated using two-film model together with the Bruggeman effective medium approximation.

R. Kostic, N. Romcevica,∗, M. Romcevic, B. Hadžic, R. Rudolf, I. Kuryliszyn-Kudelska, W. Dobrowolski, U. Narkiewicz and D. Sibera Institute of Physics, Pregrevica 118, 11080 Belgrade, Serbia Faculty of Mechanical Engineering, University of Maribor, Smetanova 17, 2000 Maribor, Slovenia Zlatarna Celje d.d., Kresnikova 19, 3000 Celje, Slovenia Institute of Physics, Polish Academy of Sciences, al. Lotnikow 32/46, 02-668 Warszawa, Poland Szczecin University of Technology, Institute of Chemical and Environment Engineering

The effect of Sn for Ti substitution on the crystal structure of a perovskite, barium titanate stannate (BTS), BaTi1−xSnxO3forx= 0, 0.025, 0.05, 0.07, 0.10, 0.12, 0.15 and 0.20, was investigated. The powders were prepared by the conventional solid-state reaction technique. The structural investigations of the BTS powders were done at room temperature by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), selected-area electron diffraction (SAED) and Raman spectroscopy analyses. Rietveld refinement of XRD data indicates that gradual replacement of titanium by tin in BaTiO3provokes a phase transition from tetragonal for 0 ≤x≤ 0.07 to cubic forx= 0.12, 0.15 and 0.20. The coexistence of tetragonal (P4mm) and cubic (Pm\overline 3m) crystal phases was established in powder with nominal composition BaTi0.9Sn0.1O3. The crystal phases determined by Rietveld refinement were confirmed by HRTEM and SAED analyses. The crystal structures of the BTS powders at short-range scale were studied by Raman spectroscopy, which shows tetragonal (P4mm) and a small fraction of orthorhombic (Pmm2) crystal phases for all the examined BTS powders, implying a lower local ordering when compared to the average symmetry.

The main challenge in the large-scale commercial applications of benzocyclobutene (BCB) dielectrics is to perform their curing rapidly and efficiently at low temperatures, and in the same time, to obtain large area, high quality, pinhole free dielectric thin films. For that purpose, we investigated numerous uncured and cured BCB films, approximately 2 mu m thick, spin-coated on glass/ITO surface, using optical and AFM microscopy, infrared (IR) and Raman spectroscopy, and complete these results with appropriate Linear Combination of Atomic Orbitals (LCAO) calculations. That way we relate microscopic characteristics of the involved molecules, and macroscopic properties of the cured and uncured polymers, which is important for their practical applications.

In this paper, we present room temperature unpolarized Raman scattering spectra of Ni doped PbTe single crystal sample. Crystal of PbTe(Ni) was grown by the Bridgman method. The Ni concentration in the sample used here was 1 × 10 at./cm. Well resolved peaks appear at about 126, 143, 181, 362 and 724 cm−1. The modes at 126 and 143 cm−1, which are also observed in other telluride compounds, originate from vibrations in TeO2. We assume that the mode at about 181 cm −1 is connected to excitations of a local phonon mode in the vicinity of an impurity atom (donor Ni state). Modes at about 362 cm−1 and 724 cm−1 are the second and fourth harmonic of a local phonon mode, registered here due to multiphonon emission.

We have studied the magnetic properties of ZnO nanocrystals doped with MnO and CoO in the wide range of magnetic dopant (from 5 to 95 wt. %), synthetized by wet chemical method. The samples were characterized by means of XRD and micro-Raman spectroscopy. The results of systematic measurements of magnetic susceptibility as a function of temperature and frequency as well as SQUID magnetization are presented. We observed different types of magnetic behavior. ZnO nanocrystals doped with CoO demonstrate Curie-Weiss behavior at higher temperatures. For samples doped with MnO, we observed the superparamagnetism above the blocking temperature.