The laboratory was founded in 1968 by Professor Voldemars Fricbergs (Fritsberg) (1926-1982). In 1975, the laboratory was among the entities which established ISSP. For a long term, laboratory performed a comprehensive research of ferroelectric solid solutions of perovskite structure, developed technology of transparent PLZT ceramics and its application in electronic and photonic devices. A skilled team of chemists has permanently been a part of the laboratory staff, allowing production and development of ferroelectric materials on the spot. Presently, the laboratory is focused on R&D of lead-free ferroelectric ceramics. NBT-based solid solutions are prepared and studied in respect of structure, dielectric, electromechanical, electrocaloric and other properties. The aim of the research is to get a deeper insight in the complicated nature of the polar state in this family of materials and to develop compositions with properties prospective for applications.
|Scientific degree||Name Surname||Position||Phone number|
|Dr.phys.||Eriks Birks||Head of laboratory||67187522||Eriks.Birks@cfi.lu.lv|
|Dr.phys.||Karlis Bormanis||Senior researcher||Karlis.Bormanis@cfi.lu.lv|
|Dr.habil.phys.||Vilnis Dimza||Senior researcher||Vilnis.Dimza@cfi.lu.lv|
|Dr.phys.||Marija Dunce||Senior researcher||Marija.Dunce@cfi.lu.lv|
|Dr.habil.phys.||Andris Sternbergs||Senior researcher||67187810||Andris.Sternbergs@cfi.lu.lv|
|MSc.||Lelde Lace||Research assistant||Lelde.Lace@cfi.lu.lv|
|Ojars Martins Eberlins||Engineer||Ojars-Martins.Eberlins@cfi.lu.lv|
|Miks Krisjanis Jurjans||Engineer||Miks.Jurjans@cfi.lu.lv|
Interpretation of phase transitions in NBT and NBT-based compositions.
This research direction is challenging due to the diffused nature of phase transitions in these materials and apparently weak correlation with behaviour of physical properties.
The aim of the research is to get deeper insight in this problem, comparing NBT with NBT-based compositions, where particular changes of properties are better expressed. In order to characterise the nature of polarisation, special attention is paid to dielectric properties. Unpoled and poled states, where interpretation of crystalline structure and properties is better-grounded, is being compared.
New lead-free compositions with advanced electromechanical properties.
This is one of the main research directions in respect of NBT-based compositions. The large electric field-induced strains are found at the morphotropic phase boundary (MPB) of NBT-based solid solutions.
The aim of the research is to study strains in NBT-based compositions in electric field-induced phase transition between nonpolar and ferroelectric states outside the traditionally considered MPB. Laser interferometer and LVDT are used for mesurement of strain dependence on electric field. Piezoelectric properties are characterised by d33 and d31, measured by d33-meter and resonance-antiresonance method.
Electrocaloric effect (ECE) in ferroelectrics.
This research direction is a hot topic in the recent decade. The reason for such an interest is long term ideas about a new generation of cooling devices based on ECE. Here, the main obstacle until now is that the observed values of ECE are too low for such applications. A huge number of recently published results is obtained by the indirect method of determination of ECE and reveals possibilities to achieve large values of ECE upon increasing of the operating electric field.
The aim of the research is to extend the field range of direct measurements of ECE. The relation between ECE and behaviour of polarisation is being interpreted.
Photoluminescence in lanthanide-doped ABO3 perovskites, including NBT.
Photoluminescence in these materials is studied repeatedly. In literature, studies at room temperature and above it prevail, describing the temperature dependence of luminescence intensity and the role of phase transition in it.
The aim of the research is to extend the temperature range of studies in the direction of low temperatures, approaching liquid helium temperature, what allows extracting the number of different environments where lanthanide ions reside. Possibility to modify luminescence intensity by electric field is also studied.
Characterisation of ceramics and process of its producing.
While research of modification of properties of NBT-based compositions is very intense, characterisation of ceramic and process of its producing is left without due attention. Partly it explains some discrepancies regarding the results of published studies, devoted to the same compositions, as well as reduces quality of interpretation.
The aim of the research is to study grain growth mechanisms of NBT-based ferroelectric ceramics. The attention is paid to content and homogeneity of a real composition. Compensation mechanisms of deficiencies of elements, created with and without intention, are being extracted.
Critical analysis of interpretation of electrocaloric effect (ECE) in Na0.5Bi0.5TiO3 (NBT) is done. It is found that the indirect method of evaluation of ECE, used in a large number of publications on this topic, is inappropriate. ECE values are determined by the direct method and compared with the values obtained by the indirect approach. The possible reasons for the discovered differences and discrepancies are discussed.
Structure of NBT-based solid solutions is deeply studied. A real structure with octahedral tilt system, which was earlier known only from the group theoretical considerations, is discovered experimentally (Fig.1).
Interpretation of phase transitions in NBT is done, basing on comparison with NBT-CaTiO3 solid solutions. The origin for the characteristic temperature dependence of dielectric permittivity, widely-discussed in literature, is proposed.
Luminescence in lanthanide-doped NBT is studied, establishing the role of disorder on luminescence spectra in this composition (Fig.2).
- A new family of relaxor ferroelectrics NBT-SrTiO3-PbTiO3 solid solutions is discovered (Fig.3). This system of solid solutions passes different stages of relaxor properties depending on PbTiO3 concentration.
- University of Oulu (Dr. M. Tyunina, Dr. J. Hagberg).
- Institute for Problem of Materials Science NASc of Ukraine (Dr. I. Bykov)
- University of Vienna, Faculty of Physics, Functional Materials (Prof. A. Fuith).
- Vienna University of Technology, Institute of Atomic and Subatomic Physics (Prof. H.W. Weber).
- Vilnius University, Vilnius (Prof. J. Banys, Dr. R. Grigalaitis).
- Institute of Physics, Krakow Pedagogical University, Krakow (Prof. Cz. Kus, Dr. B. Garbarz – Glos, Prof. J. Suchanich, Dr.phys. R. Bujakiewicz-Koronska, Dr. W. Šmiga, , Dr. D. Sitko).
- University of Aveiro, Department of Ceramic and Glass Engineering Research Unit on Ceramic Materials, Aveiro (Prof. A. Kholkine).
- I.V. Kirensky Institute of Physics of Russian Academy of Science, Krasnoyarsk (I. Flerov).
- Ural Federal University, Institute of Natural Sciences, Ferroelectric laboratory, Ekaterinburg (V. Shur).
- Southern Federal University, Research Institute of Physics and Physics Department, Rostov on Don, (I.P. Raevski, L. Reznichenko, I.A. Parinov).
- I.V. Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials of Kola Science Centre of RAS, Apatity (M.N. Palatnikov, N.V. Sidorov).
- Volgograd State Architectural and Engineering University, Volgograd (A.I. Burkhanov).
Š.Svirskas, M.Dunce, E.Birks E., A.Sternbergs, J.Banys. Electromechanical properties of Na0.5Bi0.5TiO3-SrTiO3-PbTiO3 solid solutions. J.Phys.Chem.Sol., 114, 94 (2018)
M.Dunce, G.Krieke, E.Birks, M.Antonova, L.Eglite, J.Grube, A.Sarakovskis. The role of disorder on Er3+ luminescence in Na1/2Bi1/2TiO3. J.Alloys Compd., 762, 326 (2018)
E.Birks, M.Dunce, J.Peräntie, J.Hagberg, A.Sternberg. Direct and indirect determination of electrocaloric effect in Na0.5Bi0.5TiO3. J.Appl.Phys.121, 224102 (2017)
R.Ignatans, M.Dunce, E.Birks, A.Sternberg. Novel octahedral tilt system a+b+c+ in (1-x)Na0.5Bi0.5TiO3-xCdTiO3 solid solutions. J.Mater.Sci. 52, 7149-715 (2017)
M. Dunce, E. Birks, A. Kuzmin, R. Ignatans, A. Plaude, M. Antonova, A. Sternberg. X-ray Diffraction and Raman Spectroscopy Studies in Na1/2Bi1/2TiO3-SrTiO3-PbTiO3 Solid Solutions. Ferroelectrics, 503, p.52-59 (2016)
E. Birks, M. Dunce, R. Ignatans, A. Kuzmin, A. Plaude, M. Antonova, K. Kundzins, and A. Sternberg. Structure and dielectric properties of Na1/2Bi1/2TiO3-CaTiO3 solid solutions. J.Appl.Phys.119, 074102 (2016)
H.Kabelka, A.Fuith, E.Birks, A.Sternberg. Phase transitions of Pb0.99Nb0.02(Zr0.75Sn0.20Ti0.05)O3 ceramics. Ferroelectrics, 258, 61 (2001)
E.Birks, M.Kundzinsh, A.Sternberg, H.Schmitt. Evolution of dielectric properties in transparent PLZT 8.3/70/30 ceramics at the diffused phase transition. Ferroelectrics, 234, 263 (1999)
A.Sternberg, L.Shebanovs, E.Birks, V.Dimza, H.W.Weber, F.M.Sauerzopf, H.Klima, U.Ulmanis. Radiation effects on lead-containing perovskite ceramics. Ferroelectrics, 183, 301 (1996)
L.Shebanov, K.Borman. On lead-scandium tantalate solid solutions with high electrocaloric effect. Ferroelectrics, 127, 143 (1992)