Projects / Programmes
Complex metallic alloys - novel materials for the future
| Code |
Science |
Field |
Subfield |
| 1.02.01 |
Natural sciences and mathematics |
Physics |
Physics of condesed matter |
| Code |
Science |
Field |
| P260 |
Natural sciences and mathematics |
Condensed matter: electronic structure, electrical, magnetic and optical properties, supraconductors, magnetic resonance, relaxation, spectroscopy |
novel materials, metallic alloys, electrical resistivity, nuclear magnetic resonance, computer simulations, X-ray diffraction
Researchers (1)
| no. |
Code |
Name and surname |
Research area |
Role |
Period |
No. of publicationsNo. of publications |
| 1. |
21545 |
PhD Peter Jeglič |
Physics |
Head |
2007 - 2008 |
219 |
Organisations (1)
| no. |
Code |
Research organisation |
City |
Registration number |
No. of publicationsNo. of publications |
| 1. |
0106 |
Jožef Stefan Institute |
Ljubljana |
5051606000 |
90,724 |
Abstract
Subject and targets of the research
Complex metallic alloys are materials for the future. Compared to metallic alloys that are nowadays used in the industry, new materials will surpass them in every respect. By studying physical nature of these materials we are able to give guidelines for searching new materials with wanted properties. One of the main targets of the proposed postdoc research project is to understand why the complex metallic alloys possess properties like mechanical resistance, ductility, strength, they are not brittle, they can be simultaneously good electrical conductors but poor thermal conductors and are, e.g., corrosion resistant. It seems that the answer lies in their twofold structural nature with coexisting periodic long-range order and quasiperiodic short-range order. This is a point where we can learn a lot with nuclear magnetic resonance, which gives us information about the structure, chemical and structural disorder, diffusion and magnetism. In combination with transport measurements and other magnetic measurements we can significantly contribute to the search for potentially useful metallic alloys.
Research project phases
In the first phase of the project we will thoroughly investigate a '-AlPdMn sample with 258 atoms in the unit cell. Preliminary studies have demonstrated temperature-independent electrical resistivity. In the second phase we will compare the results with binary -Al3Mg2 alloy, comprising 1168 atoms in the unit cell. We should mention that we are dealing with high-quality monocrystals as it was already confirmed by various crystallographic and characterization techniques. On the basis of NMR, SQUID magnetometer and transport measurements we expect to obtain important conclusions, which will serve as guidelines for new candidates of complex metallic alloys with useful properties. Being members of EU »Complex Metallic Alloys« network of excellence will enable us in the third phase of the project to concentrate on newly synthesized materials. NMR is very flexible method; therefore, we will adjust our study to current searching of potentially applicable properties and their understanding. In the fourth phase we will offer our knowledge to the industrial partners.
Significance for science
Complex metallic alloys have earned a special place within the materials science. To gain this position our postdoc research project played an important role. From a structural point of view the complex metallic alloys share elements of periodicity and quasiperiodicity. These have strong influence on their mechanical, transport, magnetic and optic properties, with a combination of characteristics that are usually incompatible in classical metallic alloys.
Within the framework of our postdoc research project we contributed to the understanding of complex metallic alloys. We find out that valuable information about a structural disorder can be obtained by nuclear magnetic resonance, which are complementary to X-ray diffraction data. “Only” an averaged unit cell is determined from the X-ray analysis, whereas from the nuclear magnetic resonance a distribution of local environments is obtained, which is observed in the distribution of resonance frequencies. Furthermore, we developed a theoretical description of electrical, thermal and magnetic transport properties of complex metallic alloys based on the Boltzmann semiclasical theory. We showed that the anisotropy observed in transport properties of the complex metallic alloys mainly originates from the anisotropy of electronic Fermi surface.
Finally, using nuclear magnetic resonance we proved the existence of linear molecular groups Co-Al-Co, which are trapped in the cages formed by the rest of Co4Al13 atoms. This places the above complex metallic alloy in the class of clathrate structures, where guest ions are trapped in the framework of host ions. It is known that this structures exhibit high electrical conductivity accompanied with low thermal conductivity. Similar structural feature was observed in related complex metallic alloys such as Fe4Al13, (Fe,Ni)4Al13 and Ru4Al13. Therefore, we suspect that this structural feature might be responsible for the observed unusual transport properties of many complex metallic alloys. This work initiated additional research of clathrate structures. For example, we were able to confirm incorporation of boron into the framework of clathrate Ba8Al14Si31 structure. Last work is an important step towards efficient thermoelectric material for a conversion of thermal energy into electric energy.
Significance for the country
In order that European (and also Slovenian) metal-based industry remains successful, it should stand up against their world competitors producing metals, polymers and ceramics. Of the two possible strategies to respond to these challenges, i.e. improvement of known materials or a development of completely new metallic material with properties offering superior solutions with respect to the market demand for outstanding properties at competitive cost combined with environmental harmlessness and low energy consumption during production, service and recycling.
Complex metallic alloys show a combination of mechanical resistance, strength, ductility, electrical conductivity, low thermal conductivity, low friction coefficient, corrosion and oxidation resistance and other outstanding properties. Their properties could offer completely new technological approaches for the large variety of metal-based products. On the horizon are temperature insensitive resistors, hydrogen storage devices, efficient solar absorbers, resistant metallic coatings and economically competitive novel complex metallic alloys, which could accelerate the introduction of new technologies in Slovenian economy and industry.
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