FĀŽU PĀREJAS UN FIZIKĀLĀS ĪPAŠĪBAS CIETAJOS ŠĶĪDUMOS UZ Na1/2Bi1/2TiO3 BĀZES
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Latvijas Universitāte
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Abstract
Promocijas darba mērķis ir jaunu, uz Na1/2Bi1/2TiO3 (NBT) bāzētu savienojumu sintēze un izpēte,
kas ļautu paplašināt priekšstatus par to pielietošanas iespējām, kā arī fāžu pāreju un relaksoru
stāvokļa dabu, kas darba iestrādē konstatēts NBT-SrTiO3-PbTiO3. Ir aplūkotas dielektriskās,
elektromehāniskās un polarizācijas īpašības, termiskā izplešanās, elektrokaloriskais efekts, pētīta
struktūra. Piedāvāta jauna pieeja dielektriskās dispersijas aprakstam segnetoelektriskajos relaksoros.
Izpētīta dažādas aizvietošanas perovskita A- un B-apakšrežģī ietekme uz NBT-SrTiO3-PbTiO3
cietajiem šķīdumiem. Precizētas fāžu diagrammas un fizikālā stāvokļa raksturs NBT-BaTiO3 un
NBT-CdTiO3 cietajos šķīdumos. Iegūtie rezultāti palīdz arī izdarīt vērtīgus secinājumus par fāžu
pārejām tīrā NBT, kas pasaulē ir plašu diskusiju objekts.
Atslēgvārdi: Na1/2Bi1/2TiO3, segnetoelektriskie relaksori, cietie šķīdumi, fāžu pārejas.
The aim of the doctoral thesis is synthesis and study of Na1/2Bi1/2TiO3 (NBT) -based compounds, which would widen the concept of possible applications, as well as nature of phase transitions and relaxor state, found in NBT-SrTiO3-PbTiO3 in the groundwork. The attention is paid to structure, dielectric, electromechanical and polarization properties, thermal expansion and electrocaloric effect. There is proposed a new approach for description of dielectric dispersion in relaxor ferroelectrics. Influence of different substitution in perovskite A- and B-site on NBT-SrTiO3- PbTiO3 solid solutions is studied. Phase diagrams and character of the physical state in NBTBaTiO3 and NBT-CdTiO3 are specified. The obtained results help to make important conclusions about phase transitions in pure NBT, which is an object of wide discussions in the world. Keywords: Na1/2Bi1/2TiO3, relaxor ferroelectrics, solid solutions, phase transitions.
The aim of the doctoral thesis is synthesis and study of Na1/2Bi1/2TiO3 (NBT) -based compounds, which would widen the concept of possible applications, as well as nature of phase transitions and relaxor state, found in NBT-SrTiO3-PbTiO3 in the groundwork. The attention is paid to structure, dielectric, electromechanical and polarization properties, thermal expansion and electrocaloric effect. There is proposed a new approach for description of dielectric dispersion in relaxor ferroelectrics. Influence of different substitution in perovskite A- and B-site on NBT-SrTiO3- PbTiO3 solid solutions is studied. Phase diagrams and character of the physical state in NBTBaTiO3 and NBT-CdTiO3 are specified. The obtained results help to make important conclusions about phase transitions in pure NBT, which is an object of wide discussions in the world. Keywords: Na1/2Bi1/2TiO3, relaxor ferroelectrics, solid solutions, phase transitions.