Role of manufacturing process on structure and properties of NBT-based solid solutions (2020.-2022.)

Project leader Marija Dunce

Agreement No 1.1.1.2/16/I/001

Research application No 1.1.1.2/VIAA/3/19/558

The aim of the project is to study influence of the producing process on structure and properties in pure Na0.5Bi0.5TiO3 (NBT) and in NBT-based solid solutions, as a result optimizing producing process and improving properties of these materials, using innovative producing technologies. In its framework, it is planned to study influence of producing parameter on pure NBT considering stoichiometric and non-stoichiometric NBT, doped NBT and NBT-BT solid solutions, as well as evaluate the possibility to obtain pure and modified NBT with reduced porosity. The studied materials will be prepared, using different technologies, including innovative solutions. The research will  include studies of structure, microstructure, chemical composition and homogeneity, domain structure, dielectric and other properties of these materials, using such modern material characterization methods as SEM, EDX, XRD, PFM, dielectric spectroscopy and other. The obtained results will show, how to optimize physical properties for potential applications, by varying the producing process and composition of the material, and will allow improvement of industrial manufacturing technologies.

Total duration of the project is 36 months, the total costs are 133,805.88 EUR.

 

Project Progress

30.06.2020

There is supplemented the family of pure NBT solid solutions, which are obtained using the traditional ceramics synthesis method, varying the sintering temperature in the range from 1020oC to 1240oC.

For most samples from the composition family, there are done x-ray diffraction measurements, structure of the studied materials and corresponding unit cell parameters are determined. At the moment, the obtained results indicate that all compositions have cubic structure, the unit cell parameter of which increases upon increasing of the sintering temperature.

For most of the samples, SEM micrographs are obtained. The micrographs are mutually compared both qualitatively and quantitatively, analyzing and comparing grain sizes, concentration of inclusions and porosity. This work is in progress. However, the already obtained results indicate, for example, that the average grain size increases upon increasing of the sintering temperature and the grain size distribution becomes wider, whereas the porosity reaches minimal values at the sintering temperature around 1160oC.

Using EDX, concentrations of constituents of the basic substance and inclusions are locally analyzed for the obtained pure NBT samples and compared for different compositions in the family (the work is in progress). The already obtained results indicate that concentrations of Bi and other chemical elements do not significantly change due to changes of the sintering temperature, which could be an important conclusion about the valence compensation mechanisms for the case of nonstoichiometric compositions.

For most of the studied pure NBT samples there are done measurements of polarization hysteresis loops and dielectric permittivity. For examples, there is shown that remnant polarization decreases upon increasing of sinterinf temperature of the samples.


26.03.2020

In the framework of the project, there is started work on studies of manufacturing technology of pure NBT. Review of literature was done. Compositions of pure NBT were synthesized using conventional ceramics synthesis from oxides and carbonates at different sintering temperatures: 1100oC, 1130oC, 1160oC, 1180oC, 1200oC and 1220oC. For the obtained compositions, microstructure studies, using scanning electron microscopy, structural studies, using x-ray diffractometry, as well as measurements of dielectric spectroscopy and polarization hysteresis loops are started.

 

Before beginning the experimental work, the leader of the project went through training and obtained knowledge for work with x-ray diffractometer Rigaku, scanning electron microscope Phenom Pro and scanning electron microscope Tescan Lyra, as well as obtained license for work in the clean-room, after undergoing the appropriate training. The work is done in close cooperation with the Team of Chemical Synthesis of the Laboratory of Ferroelectrics.

 

On February 6, the project author participated in Latvian Radio 1 radio popular science broadcast “The known in the unknown” with a conversation of her work area in science, background and topicality of the project, as well as its aims and tasks: https://lr1.lsm.lv/lv/raksts/zinamais-nezinamaja/jauni-materiali-svina-aizstasanai.-latvijas-zinatnieku-petijumi.a126217/