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The present paper widely describes the details of technology of (Ba0.6Pb0.4)TiO3 ceramics modified with PbO-B2O3-Al2O3-WO3 special glass, as well as the influence of admixture on the microstructure and crystal structure of basic material. The microstructure investigations reveal the significant increase of grain size and a decrease of pores participation in volume of modified samples, whereas the X-Ray Diffraction (XRD) measurements show a decrease of the volume of unit cell. The obtained results are discussed due to processes occurring during the sintering process at high temperature.

In order to improve a corrosion resistance and biocompatibility of NiTi shape memory alloys, the surface of the NiTi alloy was covered by protective layers. The paper presents results of the layers composed of titanium nitride and hydroxyapatite (HAp). The TiN layers were deposited using the glow discharge technique and then the bioactive hydroxyapatite layer was formed from simulated body fluids solution. The results of the structure studies and microscopic observations confirmed that on the surface of the NiTi alloy a thin titanium nitride layer 35-50 nm thick (depending on the glow discharge technique parameters) was obtained. The structure of the deposited layers was studied by means of the X-ray diffraction technique. Also, mechanical parameters of obtained layers were characterized using nanoindentation. On the top of the titanium nitride, a layer consisted of hydroxyapatite and NaCl was formed. Applied parameters of deposition process did not lead to decomposition of the NiTi parent phase (B2) to the equilibrium ones.

The NiTi shape memory alloys have been known from their application in medicine for implants as well as parts of medical devices. However, nickel belongs to the family of elements, which are toxic. Apart from the fact that nickel ions are bonded with titanium into intermetallic phase, their presence may cause allergy. In order to protect human body against release of nickel ions a surface of NiTi alloy can be modified with use of titanium nitrides, oxides or diamond-like layers. On the one hand the layers can play protective role but on the other hand they may influence shape memory behavior. Too stiff or too brittle layer can lead to limiting or completely blocking of the shape recovery. It was the reason to find more elastic covers for NiTi surface protection. This feature is characteristic for polymers, especially, biocompatible ones, which originate in nature. In the reported paper, the chitosan was applied as a deposited layer on surface of the NiTi shape memory alloy. Due to the fact that nature of shape memory effect is sensitive to thermo and/or mechanical treatments, the chitosan layer was deposited with use of electrophoresis carried out at room temperature. Various deposition parameters were checked and optimized. In result of that thin chitosan layer (0.45µm) was received on the NiTi alloy surface. The obtained layers were characterized by means of chemical and phase composition, as well as surface quality. It was found that smooth, elastic surface without cracks and/or inclusions can be produced applying 10V and relatively short deposition time - 30 seconds.

A 20 gram batch weight of NiTi alloy, with a nominal equiatomic composition, was produced by mechanical alloying with milling times of 100, 120, and 140 hours. The differential scanning calorimetry was used to analyze the progress of the crystallization process. The X-ray diffraction examined the crystal structure of the alloy at individual crystallization stages. The observation of the powders microstructure and the chemical composition measurement were carried out using a scanning electron microscope equipped with an energy-dispersive detector. After the milling process, the alloy revealed an amorphous-nanocrystalline state. The course of the crystallization process was multi-stage and proceeded at a lower temperature than the pure amorphous state. The applied production parameters and the stage heat treatment allowed to obtain the alloy showing the reversible martensitic transformation with an enthalpy of almost 5 J/g. [ABSTRACT FROM AUTHOR]

The main objective of the work was to create a layer of carbon nanofibre on the surface of the NiTi shape memory alloy. The coating process was carried out in three stages. First, polyacrylonitrile was deposited by electrospinning. Then it was stabilized at temperatures up to 250°C. The last stage was the carbonization performed below 1000°C. The microstructure of the obtained coatings was observed using a scanning electron microscope. The X-ray diffraction techniques were applied to analyze the coating structure. After the polyacrylonitrile deposition, the fibers had an average diameter of about 280 nm, and the final fibers were almost twice as tiny. The applied steps also changed the phase and crystalline state of the fibers, finally leading to the formation of amorphous-nanocrystalline graphite. [ABSTRACT FROM AUTHOR]

La0,7Ca0,3MnO3 polycrystalline were synthesized from La2O3, CaO and MnO2 powder mixture using a solid state reaction technique. The compound powders were obtained through the free sintering method at different temperatures and sintering times in order to study the influence of technological conditions on Ca doped La manganites. The most important physical features as structure, microstructure and morphology were described after X-ray diffraction investigation. Photographs of the specimen fractures were taken with SEM (scanning electron microscope) and they revealed high porosity of the tested material and great tendency for its grains to create agglomerates. Influence of doping and technological conditions on lattice parameters were studied by means of Rietvield analysis. The XRD measurements reveal that La0,7Ca0,3MnO3 has orthorhombic symmetry with Pnma space group. [ABSTRACT FROM AUTHOR]

The work three ceramic compositions based on PbZr0.49Ti0.51O3 doped with manganese (Mn), antimony (Sb), lanthanum (La) and tungsten (W) were obtained. The introduction of a set of admixtures was aimed at improving the sinterability of ceramic materials and optimizing its electrophysical parameters. Multi-component materials of the PZT-type with a general formula: Pb(Zr0.49Ti0.51)0.94Mn0.021Sb0.016LayWzO3 (where y from 0.008 to 0.012 and z from 0.012 to 0.014) were prepared by the conventional mixed oxide method. After mixing and drying the powder mixtures were calcined in air at 850°C for 4 h, while densification of the powders was carried out by the free sintering method at 1150°C for 2 h. The final steps of technology were grinding, polishing, annealing and putting silver paste electrodes onto both surfaces of the samples for electrical testing. XRD, SEM, EDS, dielectric, ferroelectric, piezoelectric properties and DC electrical conductivity of the obtained ceramic compositions were carried out. X-ray tests of the crystal structure conducted at room temperature have shown that all obtained the PZT-type materials were a single phase (perovskite type) without the presence of a foreign phase. Symmetry of the crystal lattice was identified as space group P4mm. Temperature dielectric studies have shown high values of dielectric permittivity and low dielectric loss. The presented physical properties of ceramic samples based on PZT confirm their predisposition for application in modern microelectronic and micromechatronic applications. [ABSTRACT FROM AUTHOR]

The paper reports the consequences of lanthanum modifications of barium bismuth niobiate (BaBi2Nb2O9) ceramics. The discussed materials were prepared by solid state synthesis and a one-step sintering process. The investigations are focused on dielectric aspects of the modification. The presented results reveal that the trivalent lanthanum ions incorporate twovalent barium ions, which is connected with the creation of A-site cationic vacancies as well as oxygen vacancies. Such a scenario results in significant decreasing in grain boundaries resistivity. The activation energy of grain boundaries conductivity is significantly reduced in the case of lanthanum admixture. [ABSTRACT FROM AUTHOR]

Mixture of nickel and titanium powders were milled in planetary mill under argon atmosphere for 100 hours at room temperature. Every 10 hours the structure, morphology and chemical composition was studied by X-ray diffraction method (XRD), scanning electron microscope (SEM) as well as electron transmission microscope (TEM). Analysis revealed that elongation of milling time caused alloying of the elements. After 100 hours of milling the powders was in nanocrystalline and an amorphous state. Also extending of milling time affected the crystal size and microstrains of the alloying elements as well as the newly formed alloy. Crystallization of amorphous alloys proceeds above 600°C. In consequence, the alloy (at room temperature) consisted of mixture of the B2 parent phase and a small amount of the B19' martensite. Dependently on the milling time and followed crystallization the NiTi alloy can be received in a form of the powder with average crystallite size from 1,5 up to 4 nm. [ABSTRACT FROM AUTHOR]

In this work, the fabrication of glass-ceramic materials containing MF3:Eu3+ (M = La, Gd) nanocrystals dispersed in silica sol-gel hosts has been presented. The transformation from liquid sols towards bulk samples was also examined based on IR measurements. The crystallization temperatures and formation of MF3 phases were verified based on TG/DSC analysis and XRD measurements. The optical properties of prepared Eu3+-doped samples were evaluated based on PLE and PL as well as luminescence decay analysis of the 5D0 excited state. Obtained samples exhibit a series of the 5D0 7FJ (J = 1-4) emission bands, which were recorded within the reddish-orange spectral area under near-UV illumination (λexc = 393 nm). Recorded luminescence spectra and double-exponential character of decay curves for prepared glass-ceramic samples indicated the successful migration of Eu3+ dopant ions from amorphous silica framework to low-phonon energy MF3 nanocrystal phases. [ABSTRACT FROM AUTHOR]

The discovery of (BaxCa1-x)(ZryTi1-x)O3 lead-free ceramics drawn a lot of attention to those novel materials because of their excellent piezoelectric properties. However, quite a little attention has been paid to other features of the material. This article reports a wide range of research, including composition, structure and microstructure, dielectric response and impedance spectroscopy in order to systematize and expand knowledge about this peculiar ceramics and strontium doping effect on its properties. In order to test that influence a series of samples with various strontium concentration, precisely the admixtures of 0.02, 0.04 and 0.06 mol% were prepared, as well as basic ceramics to compare obtained results. [ABSTRACT FROM AUTHOR]

In the work five ceramic compounds based on the (K0.44Na0.52Li0.04)NbO3 (KNLN) material modified with oxides: Cr2O3, ZnO, Sb2O3 or Fe2O3 (in an amount of 0.5 mol.%) were obtained. The KNLN-type composition powder was prepared by solid phase synthesis from a mixture of simple oxides and carbonates, while compacted of the ceramic samples was conducted by free sintering methods. In the work the effect of the used admixture on the electrophysical properties of the KNLN ceramics was presented. The XRD, EDS tests, the SEM measurements of the morphology ceramic samples, dielectric properties and DC electric conductivity were conducted. The research showed that the used admixtures introduced into the base of KNLN-type composition improve the microstructure of the ceramic samples and improve their sinterability. In the case of the dielectric measurements, it was observed a decrease in the maximum dielectric permittivity at the TC for dopred KNLN-type samples. The addition of an admixture of chromium, zinc, antimony or iron in an amount of 0.5 mol.% to the base composition (K0.44Na0.52Li0.04)NbO3 practically does not change the phase transition temperature. The diminution in the density value of doped KNLN ceramics was attributed to the alkali elements volatilization. [ABSTRACT FROM AUTHOR]