Petra Jenus

Jožef Stefan Institute | IJS · Department of Nanostructured Materials

In this review article, we focus on the relationship between permanent magnets and the electric motor, as this relationship has not been covered in a review paper before. With the increasing focus on battery research, other parts of the electric system have been neglected. To make electrification a smooth transition, as has been promised by governi...

Development of refractory metals for application as plasma-facing armour material remains among priorities of fusion research programmes in Europe, China and Japan. Improving the resistance to high temperature recrystallization, enhancing material strength to sustain thermal fatigue cracking and tolerance to neutron irradiation are the key indicato...

Tungsten-tungsten carbide (W/W2C) composites are considered as possible structural materials for future nuclear fusion reactors. Here, we report on the effect of helium (He) implantation on microstructure evolution of polycrystalline W/W2C composite consolidated by field-assisted sintering technique (FAST), homogenously implanted at room temperatur...

A plethora of modern technologies rely on permanent magnets for their operation, including many related to the transition towards a sustainable future, such as wind turbines or electric vehicles. Despite the overwhelming superiority of magnets based on rare-earth elements in terms of the magnetic performance, the harmful environmental impact of the...

In the last few years, significant effort has again been devoted to ferrite-based permanent magnet research due to the so-called rare-earth crisis. In particular, a quest to enhance ferrites maximum energy product, BH max , is underway. Here, the influence of composition and sintering conditions on the microstructure and consequently magnetic prope...

The generated process losses such as broken ware from shaping, if not recycled internally, are considered as waste. Furthermore, the collected process losses are provided to external recycling companies or waste disposal facilities. This study investigated the recycling potential of waste alumina powder, which was accumulated during industrial mach...

Composites of magnetically hard and soft phases are present in multiple and diverse applications, ranging from bulk permanent magnets in motors and generators to state-of-the-art recording media devices. The nature of the magnetic coupling between the hard and soft phases is of great technological relevance, as the macroscopic properties of the fun...

The particle reinforcement of fusion-relevant tungsten through the incorporation of tungsten sub-carbide W2C particles at the grain boundaries is demonstrated as an effective way of eliminating the harmful W oxide, enhancing densification and stabilising the composite's microstructure and flexural strength at room and high temperatures. The W2C par...

Platelets of strontium hexaferrite (SrFe12O19, SFO), up to several micrometers in width, and tens of nanometers thick have been synthesized by a hydrothermal method. They have been studied by a combination of structural and magnetic techniques, with emphasis on Mössbauer spectroscopy and X-ray absorption based-measurements including spectroscopy an...

Tungsten (W) and various composites are being considered as the primary plasma-facing materials for fusion reactors. Like all engineering materials, they contain certain levels of impurities, which can have an important impact on the mechanical properties. In the present work, oxygen was identified as a major impurity in our starting tungsten powde...

Tungsten is considered to be the primary candidate material for high-heat-loaded structural parts in the DEMO demonstration fusion power plant. Its recrystallisation at high temperatures, which results in a loss of strength, can be suppressed by the incorporation of ceramic particles in the form of oxides or carbides. Here we propose the reinforcem...

Tungsten is a candidate material for the demonstration fusion power plant DEMO. To ensure high density and structural stability, Field-Assisted Sintering Technique (FAST) is proposed as a consolidation method. This study discusses the formation of phases during sintering of tungsten by the FAST. Scanning electron microscopy, X-ray diffraction and t...

Thermoelectric application of half-Heusler compounds suffers from their fairly high thermal conductivities. Insight into how effective various scattering mechanisms are in bringing down the thermal conductivity of fabricated XNiSn compounds (X = Hf, Zr, Ti, and mixtures thereof) is therefore crucial. Here, we show how such insight can be obtained t...

The impact of ultra-short milling at liquid nitrogen temperatures on structural and magnetic properties of cobalt ferrite (CoFe2O4) powders has been explored for the first time. Cryomilling for only up to 9 min increases the coercivity of the isotropic powder from 139 to 306 kA/m (1.74–3.85 kOe) and results in its modifications comparable with mill...

Ferrite‐based, hard‐soft magnetic nanocomposites with the composition (100%−x)SrFe12O19–xCoFe2O4, where x = 5, 10, and 15 wt%, were prepared by mixing the constituent powders, followed by spark plasma sintering. In order to control the particle size of the constituent materials, the SrFe12O19 and CoFe2O4 powders were synthesized using the hydrother...

The fabrication of patterned arrays consisting of magnetic nanoparticles is gaining more and more research activities due to the possibility of enhancing a material's properties for the use in various fields (i.e. magneto-electrics). Here we present the influence of the particle size, the magnetic interactions between the particles and the strength...

The effect of the morphology of ferrite nanoparticles on their assembly in a magnetic field was studied. Thin BaFe12O19 nanoplatelets were compared with isotropic, spherical or octahedral, CoFe2O4 nanoparticles, all of which were synthesized hydrothermally. The nanoplatelets and nanoparticles assembled into a variety of hierarchical structures from...

The presented work is a study of magnetic field directed assembly of magnetic nanoparticles into hierarchically ordered structures and their potential use for the preparation of magneto-electric composites. The work is thematically divided into three parts. The first part comprises the effect of the particle size, the magnetic interactions between...

The presented work is a study of magnetic field directed assembly of magnetic nanoparticles into hierarchically ordered structures and their potential use for the preparation of magneto-electric composites. The work is thematically divided into three parts. The first part comprises the effect of the particle size, the magnetic interactions between...

Magneto-electric (ME) ceramic composites of cobalt ferrite (CoF) and lead zirconate titanate (PZT) were prepared by mechanical mixing of the constituent powders followed by cosintering. The cosintering conditions for nano-sized CoF and submicrometer-sized PZT powders were studied in detail. It was found that the CoF powder needs to be presintered a...

The focus of nanoscience and nanotechnology is increasingly shifting from the synthesis of individual components to their assembly into larger systems. Hereby, the use of external fields (electric, magnetic) has an enormous potential in the preparation of nanoparticles assemblies. We report a study on magnetically directed assembly of cobalt ferrit...

We have studied the assembly of cobalt ferrite nanoparticles in a magnetic field. Nanoparticles of different sizes, i.e., 5-40 nm, were synthesized with coprecipitation or under hydrothermal conditions. Their saturation magnetization values ranged between 31 and 68 Am2 /kg, respectively, resulting in a strong magnetic attraction and agglomeration b...

The assembly of nanoparticles into organized structures has in the last years attracted great attention of scientists due to their interesting properties and new technological applications. Much effort has been focused on patterning of magnetic nanoparticles. Many different ways of preparation of assemblies of magnetic nanoparticles were used, such...

In multiferroic composites the ferro(piezo)electric and magnetostrictive phases can be electromagnetically coupled via stress mediation (1). In our work we focused on the cosintering of cobalt ferrite (CF) - barium titanate (BT) and cobalt ferrite (CF) - lead zirconate titanate (PZT) composites. The CF nanoparticles were prepared by hydrothermal s...

Cobalt ferrite nanoparticles were synthesized with coprecipitation or with the hydrothermal method. Stable water suspensions were prepared from the as-synthesized nanoparticles, with the addition of citric acid as a surfactant, and then used for the preparation of deposits under an applied magnetic field. The morphology of the cobalt ferrite nanopa...