Projects / Programmes
| Code |
Science |
Field |
Subfield |
| 2.21.00 |
Engineering sciences and technologies |
Technology driven physics |
|
| Code |
Science |
Field |
| T153 |
Technological sciences |
Ceramic materials and powders |
| Code |
Science |
Field |
| 1.03 |
Natural Sciences |
Physical sciences |
environment, cooling, enviromental-friendly cooling systems, HFC-free, caloric materials
Researchers (14)
Organisations (2)
Abstract
We have an old and inefficient cooling technology based on the vapour compression, which simply cannot cope with enormous demands now being placed in the world on cooling. Majority of domestic refrigerators operate around 20-40% of Carnot cycle efficiency (CCE). Another problem with vapour compression is the use of chlorofluorocarbon (HCFC) refrigerants, which are proven to be detrimental to climate conditions. Due to these drawbacks the interest is growing for new cooling devices based on caloric effects – electrocaloric (EC), magnetocaloric (MC) or mechanocaloric (mC) – where the material’s entropy changes under the application of an external field – electric, magnetic or mechanical. The objective of the project is to develop a new generation of materials that combine the magneto- and electro- caloric effects in the same material.
In 2016 our group made a breakthrough when we published the first report of a relaxor material 0.8Pb(Fe0.5Nb0.5)O3–0.2Pb(Mg0.5W0.5)O3, (short PFN-20PMW) that exhibits both magneto- and electro- caloric effects. Individually, these effects have been known for 100 years, but until 2016 they had never been measured together in one relaxor multiferroic material. Although PFN-20PMW appears promising, it possesses very small EC and MC temperature changes (~0.25 K). Further, the largest caloric effects in this material are observed at low temperatures of 220 K (EC) and 5 K (MC), which is far too low for practical applications. The second problem is also relatively high electrical conductivity of this material, which results in Joule heating and therefore in decrease of EC properties.
In this project we propose to study the feasibility of preparing new multicaloric materials exhibiting the highest multicaloric effect close to room temperature. Ideal candidates for multicaloric materials should not only exhibit multiferroic properties and low electric conductivity, but other important characteristics, including, the propensity for easy electric and magnetic dipole orientation by application of electric/magnetic fields. The project proposal involves a multidisciplinary team that will look at Pb(Fe0.5Nb0.5)O3 (PFN) and BiFeO3 (BFO) based multiferroics and will try to design materials with better properties for specific application in comparison to the previously published PFN-20PMW. The objectives of the project are based on chemical modification of PFN in order to: i) decrease the electric conductivity and consequently to increase the EC temperature change, ii) decrease the temperature of dielectric permittivity peak in order to move the temperature of the highest EC effect closer to room temperature and iii) to increase the temperature of the magnetic susceptibility anomalies and consequently to move the temperature of the highest MC effect closer to room temperature and increase its MC value.
The project is divided into three scientific work packages. The first work package WP1 is about preparation of multicaloric materials, while the topic of WP2 and WP3 is oriented towards characterization of prepared multicalorics. We will study PFN-based and also lead-free BFO-based materials. Ceramic powders will be prepared from initial oxides. In order to obtain optimized samples the synthesis conditions will be studied. In terms of measuring the EC properties, the JSI has the facilities available to measure this effect directly, using a very-high-resolution calorimeter. These measurements are much more challenging to conduct than indirect measurements of the material’s polarisation, but they are more reliable and more relevant. The MC temperature changes will be calculated from the magnetic measurements performed by superconducting quantum interference device magnetometer and/or physical properties measuring system. Furthermore, measurement set-ups for measuring direct MC temperature changes are placed at partner institution Faculty of Mechanical Engineering.
Significance for science
There is an urgent need with strong competition between research institutions worldwide to find and develop materials with large caloric effects, reliable operation under elevated fields (electric and magnetic) and broad temperature interval where future cooling devices can operate. In the frame of this project we will go one step further; we will study the materials, where EC and MC effects are acting together in a single multi-caloric material. We will try to design the multi-caloric materials with both caloric effects close or above room temperature. The research field of such multicalorics is very young (theoretical beginning in 2012, the experimental start in 2014) and in a view of the current climate change it is extremely important for future. So we can say with certainty that the results obtained within the project will be new, original contribution to the science and very useful for future society. We shouldn’t forget that the project group has many years of experience in research of caloric materials, electrocaloric as well as magnetocaloric (even proof of concept in multicalorics). Therefore they are appropriate candidates to develop more efficient multicalorics and with that to initiate faster development of this young research field in the next years.
The results of the research will be presented at international conferences and will be published in papers in high impact journals. PhD students will also be included in the project. The project applicant has already a PhD student Uroš Prah who already started to work on the topic related to the project.
Significance for the country
There is an urgent need with strong competition between research institutions worldwide to find and develop materials with large caloric effects, reliable operation under elevated fields (electric and magnetic) and broad temperature interval where future cooling devices can operate. In the frame of this project we will go one step further; we will study the materials, where EC and MC effects are acting together in a single multi-caloric material. We will try to design the multi-caloric materials with both caloric effects close or above room temperature. The research field of such multicalorics is very young (theoretical beginning in 2012, the experimental start in 2014) and in a view of the current climate change it is extremely important for future. So we can say with certainty that the results obtained within the project will be new, original contribution to the science and very useful for future society. We shouldn’t forget that the project group has many years of experience in research of caloric materials, electrocaloric as well as magnetocaloric (even proof of concept in multicalorics). Therefore they are appropriate candidates to develop more efficient multicalorics and with that to initiate faster development of this young research field in the next years.
The results of the research will be presented at international conferences and will be published in papers in high impact journals. PhD students will also be included in the project. The project applicant has already a PhD student Uroš Prah who already started to work on the topic related to the project.
Most important scientific results
Interim report
Most important socioeconomically and culturally relevant results
Interim report
