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In this paper two methods of preparation of yttrium orthovanadate nanopowders were presented: Solid State Reaction (top – down approach) and Solution Combustion Synthesis (bottom – up approach). For starting structural characterization, X – Ray Powder Diffraction (XPRD) and Field Emission Scanning Electron Microscopy (FESEM) were used. We report the change in reflection spectra in europium doped YVO4 nanopowders with comparison to its bulk analog. In UV–Vis reflection spectra we consider the change in values of band gap in these structures, after resizing it from bulk to nanomaterial. In Far – Infrared (FIR) reflection spectra, we registered the existence of Surface Optical Phonon (SOP) and different multi – phonon processes which alter the reflection spectra of bulk YVO4. The influence of Eu ions is reflected through multi – phonon processes that occur and are connected with energy transfer from YVO4 lattice to Eu ions. All IR spectra were modeled using classical oscillator model with Drude part added which takes into account the free carrier contribution. Since our samples are distinctively inhomogeneous materials, we use Effective Medium theory in Maxwell Garnett approximation to model its effective dieletric function.

Sphene based glass-ceramics (CaTiSiO5), an excellent candidate for a host lattice of ceramic materials and for nuclear waste immobilization, has been prepared from a powder mixture of CaCO3, TiO2 and SiO2 using vibro-milling for homogenization. Starting powders were melted at 1400?C for 2 h, cooled to room temperature, grounded again, then crystallized by thermal treatment yielding a sphene glass-ceramic. The evolution of the phase composition during thermal treatment was investigated by X-ray powder diffraction (XRPD), FT-IR, Raman and thermal analyses (TG-DTA). Pure synthetic single phase sphene was formed at 800?C for 4 h, even it is very hard to obtain monophase powder at such low temperature. Powder morphology was analyzed by scanning electron microscopy (SEM).

Nanocomposite material containing NiO nanoparticles decorated on WO3 nanowires could be used for monitoring levels of H2S gas. The effectiveness of this material is mostly determined by NiO properties. The performed study presents the first stage in the preparation of modified NiO/WO3 nanocomposite material. In this article, NiO nanoparticles are prepared by a simple, low-cost method.The behavior of nano-sized NiO particles is probed by X-ray diffraction, Fourier transform Infrared Spectroscopy, Raman spectroscopy, and hysteretic measurement.

Processing and characterization of polymer nanocomposites based on poly (methyl methacrylate) (PMMA) matrix with embedded core-shell CdSe/ZnS quantum dots (QD's) were presented in this work. The aim is to preserve the optical activity of QD's in nanocomposite processing with improved mechanical properties. The modification of QD's CdSe/ZnS-PMMA interface was achieved with 3-mercaptopropyltrimethoxysilane (MPTMS). Nanocomposites were processed by solution casting. The samples of pure PMMA, and composites with unmodified and silane modified QD's CdSe/ZnS were processed. FTIR analysis revealed modification of QD's with silane and characteristic bonding with PMMA matrix. Raman spectrum confirms a presence of alloyed layer at the core-shell interface. Time-resolved laser induced fluorescence measurements confirmed slight blue shift in QD's CdSe/ZnS-PMMA composite without interface modification, while there was a slight red shift with modified particles. Oxidation effects in quantum dots were removed with the use of PMMA as a host, and the core remained active, which was confirmed with FTIR analysis and time-resolved laser induced fluorescence measurements.

Lithium iron phosphate (LiFePO4, LFP) is one of the widely used cathode materials for rechargeable lithium ion batteries. LFP batteries are widely used for electric vehicles and backup power due to their important advantages such as low cost, lifetime, efficiency, and reliability. There are still several technical challenges that need to be addressed: The increase of energy density or further reduction of their final cost. This paper concerned with the characterization of carbon coated LiFePO4 nanopowder cathode materials produced under different conditions by pulse combustion for providing energy to the reactor for the synthesis. The reactor was built according to the principles of the thermoacoustic burner on the basis of the Helmholtz resonator. The investigated nanopowders are synthesized by complete and incomplete combustion and calcined at 700 °C. The obtained samples were characterized by X-ray diffraction, Fourier transform infrared, Raman, and Mössbauer spectroscopy. Observed low-Temperature magnetic phase transitions definitively identified the crystal phases. The morphology of samples was controlled by scanning electron microscopy. The aim of this work is to show that it is possible to achieve a desired crystal phase by pulse combustion in a relatively cheap and fast way. The extremely rapid synthesis of almost pure phase material is possible due to the reduction in size of interacting particles and to an enormous number of collisions between them as a result of strong turbulent flow associated with explosive combustion. © 2019 Author(s).

In this paper, we describe synthesis and characterization of YVO 4 and Eu 3+ -doped YVO 4 nanopowders. Two methods of preparation were used—solution combustion synthesis (SCS) and classical ceramic method (CCM)—and compared. Morphology and structure of all samples were characterized with atomic-force microscopy (AFM), X-ray diffraction (XRD), and field-emission scanning electron microscopy (SEM). Raman spectroscopy was used to discuss the isotope-like effect. It is confirmed that doping with Eu ions results in a change of Raman spectra of doped samples—new modes arise, and intensity of existing ones change. Influence of different preparation methods on isotope-like effect is presented with detailed calculations of shifted modes. © 2019 John Wiley & Sons, Ltd.

Mesoporous TiO2 films with spherical architectures and promising performance in dye-sensitized solar cells (DSSCs) were prepared. The morphology of the films was investigated by scanning electron microscopy. Transmission electron microscopy analysis of the spheres disclosed the elongated shape of sub-20 nm primary particles, while BET analysis revealed their high surface area of 135m2/g. Anatase presence was observed in the films based on X-ray diffractometry, selected-area electron diffraction analysis and Raman spectroscopy analyses. Increased light scattering of the spheres in visible region was observed by UV-VIS-NIR spectroscopy. Photovoltaic performance of the operating N719-sensitized cells was tested using electrochemical impedance spectroscopy and current density-voltage (J-V) curves under simulated AM1.5 spectrum. The 0.25 cm2 cells exhibited photo-to-electric power efficiency of 4.9%, which is among noteworthy values for DSSCs with similar photoanodic structures

In this paper we describe the synthesis and characterization of the YVO4:Eu3+ nanopowder. The material was prepared using simple solution combustion synthesis. X-ray powder diffraction (XRD), scanning electron microscope (SEM), Raman and photoluminescence (PL) techniques were used to confirm and characterize the prepared material. The time resolved analysis of emission spectra was achieved by using the streak camera system. Beside luminescence lifetime of slow decayed transitions we also measured their rise time and lifetime of fast decayed transitions. We also determitied the excitation spectra of this nano material. Results of our analysis prove that YVO4:Eu3(+) nanopowder is appropriate material for various optoelectronic devices. (C) 2016 Elsevier Ltd. All rights reserved.

It must be noted that the main objective of this study was to obtain single crystals of calcium fluoride - CaF2, and after that the crystals were characterized with various spectroscopic methods. The crystals were grown using the Bridgman technique. By optimizing growth conditions, lt 111 gt oriented CaF2 crystals up to 20 mm in diameter were grown. Number of dislocations in CaF2 crystals was 5x10(4) - 2x10(5) per cm(2). Selected CaF2 single crystal is cut into several tiles with the diamond saw. The plates were polished, first with the silicon carbide, then the paraffin oil, and finally with a diamond paste. The obtained crystal w.s studied by Raman and infrared - IR spectroscopy. The crystal structure is confirmed by X-ray diffraction (XRD). One Raman and two IR optical modes predicted by group theory are observed. A low photoluminescence testifies that the concentration of oxygen defects within the host CaF2 is small. All performed investigations show that the obtained CaF2 single crystal has good optical quality, which was the goal of this work.

This paper describes the structural and optical properties of Cu-Se thin films. The surface morphology of thin films was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Formation of Cu-Se thin films is concluded to proceed unevenly, in the form of islands which later grew into agglomerates. The structural characterization of Cu-Se 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 Cu-Se 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 nanocrystalite inclusions (modeled by Maxwell -Garnett approximation) and substrate, has been applied. (C) 2016 Elsevier B.V. All rights reserved.

The objective of this study was characterization of anodic film obtained when Ag43Cu37Zn20 alloy was treated electrochemically in 3.5% wt. NaCI under potentiostatic conditions. At the potential of +0.25 V a complex multilayer film is formed. XRD shows that it consists of CuCI and zinc hydroxichlorides with a small amount of Cu2O, probably formed in the film pores. The anodic film is a mixture of Cu2O, CuCI, Zn-5(OH)(8)center dot H2O and beta-Zn(OH)Cl. Phases of the alloy, Ag and Cu rich, show different anodic behavior. It was assumed that all phonon lines in the obtained Raman spectra were of the Lorentzian type, which is one of the common type of lines for this kind of analysis. Phases of Ag, CuCI, fl-Zn(OH)CI, Cu2O and Zn-5(OH)(8)(Cl)(2)center dot H2O were all registered by XRD.

Dysprosium (Dy3+ ions) doped YAG nanopowders were prepared by the solution combustion synthesis (SCS) method and undoped yttrium aluminum garnet (YAG, Y3Al5O12) single crystal was grown by the Czochralski technique. The structure of the prepared materials has been confirmed and characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), Raman and photoluminescence (PL) spectroscopy. PL spectra were acquired using Optical Parametric Oscillator (OPO) excitation tuned at 350 nm. Several emission bands in Dy3+ emission spectrum were observed in the blue (470-500 nm), yellow (560-600 nm), red (660-685 nm) and infra-red (750-780 nm) regions, corresponding to F-4(9/2)-H-6(15/2), F-4(9/2)-H-6(13/2), F-4(9/2)-H-6(11/2), F-4(9/2)-(H-6(9/2) + H-6(11/2)) transitions in the 4f levels of Dy3+ ions, respectively. By using the Commission Internationale de lEclairage (CIE) chromaticity diagram of emission spectra it has been shown that this material can be used as a source of a white light. The result of lifetime analysis of the F-4(9/2) level in dysprosium ion has been reported, as well. (C) 2015 Elsevier B.V. All rights reserved.

The aim of the present work is characterization of electrochemically treated Ag43-Cu37-Zn20 alloy in near neutral chloride solutions by the X-ray diffraction and Raman spectroscopy. At potential of +0.25 V, a complex multilayer film is formed. XRD shows that it consists of CuCl and zinc hydroxichlorides with small amount of Cu2O, probably formed in the film pores. It can be concluded that the Raman spectroscopy is observed almost all the modes that are registered with the XRD analysis.

U ovoj doktorskoj disertaciji detaljno su izuĉavane optiĉke osobine nanodimenzionih sistema formiranih u tri razliĉita materijala: plastiĉno deformisanom bakru, tankim filmovima CdS i heterostrukturama CdTe/ZnTe. Optiĉke osobine plastiĉno deformisanog bakra ispitivane su tehnikama spektroskopske elipsometrije i Ramanove spektroskopije, dok je površina uzorka ispitivana mikroskopijom atomske sile. Optiĉke osobine tankih filmova CdS razliĉite debljine ispitivane su metodama daleke infracrvene spektroskopije i Ramanove spektroskopije, a površina uzorka ispitivana je mikroskopijom atomske sile. Optiĉke osobine heterostruktura CdTe/ZnTe ispitivane su metodama fotoluminescencije, Ramanove spektroskopije i daleke infracrvene spektroskopije., In this PhD thesis the optical properties of nanoscaled systems developed in three different systems are thoroughly studied. The optical properties of plastically deformed copper are investigated by means of spectroscopic ellipsometry and Raman spectroscopy, and the samples surface was investigated by AFM measurements. Optical properties of CdS thin films of different thickness were investigated by means of Raman spectroscopy and far - infrared spectroscopy, and the surface of the samples was studied with AFM measurements. And finally, optical properties of CdTe/ZnTe heterostructures were investigated with photoluminescence, Raman spectroscopy and far - infrared spectroscopy.

In this paper, we used the Czochralski method to obtain good quality yttrium aluminium garnet (YAG, Y3Al5O12) and yttrium aluminium garnet doped with neodymium (Nd: YAG) crystals. The investigations were based on the growth mechanisms and the shape of the liquid/solid interface crystallization front on the crystal properties and incorporation of Nd3+ ions. The obtained single YAG and Nd: YAG crystals were studied by use of x-ray diffraction, Raman and IR spectroscopy. There are strong metal oxygen vibrations in the region of 650-800 cm(-1) which are characteristics of Al-O bond: peaks at 784/854, 719/763 and 691/707 cm(-1) correspond to asymmetric stretching vibrations in tetrahedral arrangement. Peaks at 566/582, 510/547 and 477/505 cm(-1) are asymmetric stretching vibrations and 453/483 cm(-1) is the symmetric vibration of the Al-O bond in octahedral arrangements of the garnet structure. Lower energy peaks correspond to translation and vibration of cations in different coordinations-tetrahedral, octahedral and dodecahedral in the case of the lowest modes.

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 metal-matrix 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.

In this work, single crystals of bismuth silicon oxide (BSO; Bi12SiO20) have been grown by the Czochralski method. The growth conditions were studied. The critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. The structure of the Bi12SiO20 has been investigated by x-ray diffraction (XRD), and Raman and Fourier transform infrared spectroscopy (FTIR) spectroscopy. The results obtained are discussed and compared with the published data. The pale yellow Bi12SiO20 single crystals prepared were without cores. Using spectroscopic measurements 19 Raman and 5 IR modes were observed.

We have synthesized CdS and Cd0.7Mn0.3S nanocrystals with diameters of about 4.5 nm. These materials have been studied using photoluminescence spectroscopy with various excitation energies in the temperature range from 1.8 to 300 K, in magnetic field up to 5T. We registered surface and defect states as well as two Mn2+ energy levels that correspond to Mn2+ ions in two different crystal environments. We proposed the scheme of energy levels and transitions that explain obtained experimental results. (C) 2012 Elsevier B. V. All rights reserved.

Bi12GeO20 single crystals were grown by the Czochralski technique. The critical diameter and the critical rate of rotation were calculated. Suitable polishing and etching solutions were determined. As a result of our experiments, the pale yellow and black single crystals were produced. The structure of the Bi12GeO20 has been investigated by X-ray diffraction, Raman and IR spectroscopy. The atomic ratio Bi/Ge was determined for the both crystals. The refractive indexes of both Bi12GeO20 crystals were determined by the spectroscopic ellipsometry method. Important properties of Bi12GeO20 for sensing applications, optical activity, Faraday rotation and absorption were measured and magneto optical quality was calculated and compared. (c) 2012 Elsevier B.V. All rights reserved.