| Title |
Processing, structural and broadband dielectric characterization of strontium titanate and related perovskite ceramics and thin films / |
| Translation of Title |
Stroncio titanato ir kitų jam giminingų perovskitų keramikų bei plonųjų sluoksnių gamyba, struktūrinis ir plačiajuostis dielektrinis charakterizavimas. |
| Authors |
Bagdzevičius, Šarūnas |
| Full Text |
|
| Pages |
31 |
| Keywords [eng] |
Strontium titanate ; strain engineering ; ferroic phase transitions ; disordered materials |
| Abstract [eng] |
One of the biggest functionally active material classes is ternary metal oxides with perovskite or distorted perovskite structures. Nonmagnetic perovskites can undergo ferroelectric and structural phase transitions, depending where soft mode condensates in Brillouin zone. Incipient ferroelectric SrTiO3 (STO) is a model system for investigation of ferroelectric and structural phase transition because both instabilities are competing in sufficiently close temperature ranges and both are rather sensitive to misfit and chemical strain. Misfit strain was introduced by PLD depositing epitaxial STO thin films on the lattice mismatched substrates. Misfit strain effects on STO phase diagram were experimentally investigated, induced strain enhances ferroelectric and antiferrodistortive phase transitions temperatures, making both transitions more accessible for characterization and more important for applications - ferroelectric phase transition enhanced above liquid nitrogen temperature and antiferrodistortive one above the room temperature. Chemical strain in SrTiO3 was induced by doping with Bi. Chemical strain in STO induces polar and antiferrodistortive nanoregion formation below Burns temperature and causes a complex dielectric relaxational dynamics below the phonon frequency range. To compare doped SrTiO3 ceramic dielectric properties two similar disordered solid state systems was chosen – (K0.5Na0.5)(Nb1-xSbx)O3 lead free ferroelectric material and 0.4Na0.5Bi0.5TiO3-(0.6-x)SrTiO3-xPtTiO3 disordered solid solution. The dielectric properties of before mentioned materials in dispersion regions were investigated using broadband dielectric spectroscopy in wide temperature (25 K – 1000 K) and frequency (10 mHz – 50 GHz) ranges. |
| Type |
Summaries of doctoral thesis |
| Language |
English |
| Publication date |
2014 |
