Marcin Perzanowski

Crystalline hydroxyapatite coatings synthesized under hydrothermal conditions on modified titanium substrates

Hydroxyapatite coatings were successfully produced on modified titanium substrates via hydrothermal synthesis in a Ca(EDTA)(2-) and (NH4)2HPO4 solution. The morphology of modified titanium substrates as well as hydroxyapatite coatings was studied using scanning electron microcopy and phase identification by X-ray diffraction, and Raman and FTIR spectroscopy. The results show that the nucleation and growth of hydroxyapatite needle-like crystals with hexagonal symmetry occurred only on titanium substrates both chemically and thermally treated. No hydroxyapatite phase was detected on only acid etched Ti metal. This finding demonstrates that only a particular titanium surface treatment can effectively induce the apatite nucleation under hydrothermal conditions.

Chemical order and crystallographic texture of FePd:Cu thin alloy films

FePd thin films have been recently considered as promising materials for high-density magnetic storage devices. However, it is necessary to find a proper method of fabrication for the (001)-textured and chemically well-ordered alloy. In this paper, we present the detailed investigations of lattice parameters, chemical order degree, grain sizes, and crystallographic texture carried out on FePd alloys with 10 at.% of Cu addition. The initial [Cu(0.2 nm)/Fe(0.9 nm)/Pd(1.1 nm)]5 multilayers were thermally evaporated in an ultrahigh vacuum on MgO(100), Si(100), Si(111), and Si(100) covered by a 100-nm-thick layer of amorphous SiO2. In order to obtain a homogeneous FePd:Cu alloy, the multilayers were annealed in two different ways. First, the samples were rapidly annealed in nitrogen atmosphere at 600 °C for 90 seconds. Next, the long annealing in a high vacuum for 1 h at 700 °C was done. This paper focuses on quantitative investigations of the chemical order degree and crystallographic texture of ternary FePd:...

X-ray absorption fine structure and x-ray diffraction studies of crystallographic grains in nanocrystalline FePd:Cu thin films

FePd alloys have recently attracted considerable attention as candidates for ultrahigh density magnetic storage media. In this paper we investigate FePd thin alloy film with a copper admixture composed of nanometer-sized grains. [Fe(0.9 nm)/Pd(1.1 nm)/Cu(d nm)]×5 multilayers were prepared by thermal deposition at room temperature in UHV conditions on Si(100) substrates covered by 100 nm SiO2. The thickness of the copper layer has been changed from 0 to 0.4 nm. After deposition, the multilayers were rapidly annealed at 600 °C in a nitrogen atmosphere, which resulted in the creation of the FePd:Cu alloy. The structure of alloy films obtained this way was determined by x-ray diffraction (XRD), glancing angle x-ray diffraction, and x-ray absorption fine structure (EXAFS). The measurements clearly showed that the L10 FePd:Cu nanocrystalline phase has been formed during the annealing process for all investigated copper compositions. This paper concentrates on the crystallographic grain features of FePd:Cu alloy...

Influence of Superparamagnetism on Exchange Anisotropy at CoO/[Co/Pd] Interfaces

Magnetic systems exhibiting an exchange bias effect are being considered as materials for applications in data storage devices, sensors, and biomedicine. Because the size of new magnetic devices is being continuously reduced, the influence of thermally induced instabilities in magnetic order has to be taken into account during their fabrication process. In this study, we show the influence of superparamagnetism on the magnetic properties of an exchange-biased [CoO/Co/Pd]10 multilayer. We find that the process of progressive thermal blocking of the superparamagnetic clusters causes an unusually fast rise of the exchange anisotropy field and coercivity and promotes easy-axis switching to the out-of-plane direction.

Biological effect of hydrothermally synthesized silica nanoparticles within crystalline hydroxyapatite coatings for titanium implants

Development of functional coatings for artificial bone implants that strengthen the osseointegration and accelerate bone healing processes is urgently needed in the biomedical field. In this study we present biological effect of novel composite coatings with different concentration of silica nanoparticles within crystalline hydroxyapatite matrix (HAp-SiO2) synthesized on titanium under hydrothermal conditions. Samples were analyzed for their elemental composition, structure, bioactivity and in vitro cytotoxicity. The results indicate the formation and homogeneous distribution of silica nanoparticles on the surface of hexagonal hydroxyapatite (HAp) crystals. The coatings show improved bioactivity in comparison with pure HAp after 4 days of immersion in simulated body fluid (SBF). The responses of human osteoblast-like cells (MG-63) cultured onto the synthesized materials provide evidence that HAp-SiO2 composites exhibit good biocompatibility. We propose that this is because HAp-SiO2 composites favor biomineralization process with cell proliferation remaining unaffected, regardless of the amount of silica. Furthermore, SEM and fluorescence measurements demonstrate that HAp-SiO2 had positive effect on cell morphology, favoring cell adhesion.

From monetite plate to hydroxyapatite nanofibers by monoethanolamine assisted hydrothermal approach

Calcium phosphates offer outstanding biological adaptability. Thanks to their specific physico-chemical properties they are one of the most widely used materials in bone tissue engineering applications. The search for an innovative and economic strategy of synthesizing their different forms has been drawing considerable attention in the field. Herein, we report on a facile hydrothermal process in the presence of ethylenediamine tetraacetic acid and monoethanolamine to obtain various forms of calcium phosphates. The monoethanolamine served as an alkaline source and crystal growth modifier, while ethylenediamine tetraacetic acid was used to control the Ca2+ supersaturation level under high temperature and high pressure conditions. The obtained inorganic compounds were examined for their elemental composition, morphology, and structure using scanning electron microscopy, Raman spectroscopy, and powder x-ray diffraction. We were able to selectively synthesize monetite plate-like microcrystals as well as hydroxyapatite plates and nanofibers by simply varying the concentration of monoethanolamine.

Tailoring of Magnetic Properties of NiO/Ni Composite Particles Fabricated by Pulsed Laser Irradiation

We present NiO/Ni composite particles with face-centered cubic (fcc) structure prepared by a pulsed laser irradiation of NiO nanoparticles dispersed in liquid. The sizes of particles and the Ni content in NiO/Ni composites were controlled by tuning the laser parameters, such as laser fluence and irradiation time. We found that the weight fraction of Ni has a significant impact on magnetic properties of composite particles. Large exchange bias (HEB) and coercivity field (HC) were observed at 5 K due to the creation of heterojunctions at interfaces of ferromagnetic Ni and antiferromagnetic NiO. For the NiO/Ni composites with 80% of NiO we have observed the largest values of exchange bias (175 Oe) and coercive field (950 Oe), but the increase of Ni weight fraction resulted in the decrease of both HC and HEB values.

Exchange Bias in the [CoO/Co/Pd]10 Antidot Large Area Arrays

Magnetic nanostructures revealing exchange bias effect have gained a lot of interest in recent years due to their possible applications in modern devices with various functionalities. In this paper, we present our studies on patterned [CoO/Co/Pd]10 multilayer where ferromagnetic material is in a form of clusters, instead of being a continuous layer. The system was patterned using nanosphere lithography technique which resulted in creation of an assembly of well-ordered antidots or islands over a large substrate area. We found that the overall hysteresis loop of the films consists of hard and soft components. The hard component hysteresis loop exhibits a large exchange bias field up to -11 kOe. The patterning process causes a slight increase of the exchange field as the antidot radius rises. We also found that the material on edges of the structures gives rise to a soft unbiased magnetization component.