0000000000181475
AUTHOR
M. Tyunina
Influence of Structure Ordering, Defects and External Conditions on Properties of Ferroelectric Perovskites
Results of comprehensive studies of the (A’A“)(B’B”)O3-ferroelectric perovskites are reported. Examined compositions include Pb1-xLax(Zr0.65Ti0.35)1-x/4O3(PLZT), PbSc0.5Nb0.5O3(PSN), PbSc0.5Ta0.5O3(PST), and PMNT, PSNT and PLuNT pseudo-binary systems exhibiting pronounced dielectric, electrooptical, and electromechanical properties. Degree of ordering in the materials has been varied by chemical composition (modification, isomorphic ion substitution), by variation of technology (hot-pressing, specific thermal treatment, thin films), and by irradiation of different kind and intensity (γ-rays, electrons, neutrons).
Effects of structure ordering, structure defects and external conditions on properties of complex ferroelectric perovskites
Abstract Structural rearrangements in lead-containing (A‘A’) (B’B“)O3 type perovskite compounds are caused by technological treatment, high-energy radiation and ambient conditions. Variation of structure ordering along with modification (substituted or defected solid solutions) may provide promising compositions for applications, e.g., cascade microcryogenic devices (PST solid solutions); efficient piezoelectric materials – here the new (1 – x)Pb(Lu1/2Nb1/2)O3 – xPbTiO3 system in the morphotropic region. The maximum values of the electromechanical coupling coefficients kp = 0·663, kt = 0·481, k 31 = 0·355 were attained in compositions PLuNT 59/41 (Tm = 353°C) near the morphotropic phase bou…
<title>Glass to ferroelectric phase transition induced by ac electric field in PbMg<formula><inf><roman>1/3</roman></inf></formula>Nb<formula><inf><roman>2/3</roman></inf></formula>O<formula><inf><roman>3</roman></inf></formula> thin films</title>
The nonlinear dielectric response of epitaxial heterostructures of relaxor ferroelectric PbMg1/3Nb2/3O3 thin films was experimentally studied using digital Fourier analysis. The amplitudes and the phase angles of the dielectric harmonics were determined as a function of temperature and the amplitude of the sinusoidal ac field. The response of the films was reconstructed assuming a linear contribution of the film-electrode interface capacitance. In the films at low amplitudes of ac field, a glass-like behavior was identified by a maximum in the third-order nonlinear dielectric permittivity around the freezing temperature, accompanied by a square field dependence of the amplitudes of the odd …
Interface Effects in Ferroelectric Thin Films
Dielectric, ferroelectric and piezoelectric characteristics in sol-gel derived and pulsed laser deposited (PLD) lead zirconate titanate (PZT), La modified lead titanate (PLT) and zirconate titanate (PLZT) ferroelectric thin films are investigated focusing on maintenance of thin film ferroelectric (FE) properties in a variety of thin film-electrodesubstrate interfaces. Interferometric studies of piezoelectric response of the heterostructures were performed with respect to a DC electrical bias and AC measurement frequency. The asymmetry of piezoelectric coefficient (d33) hysteresis, diminished values of d33, frequency-displacement and spot size — deformation behaviour in the ferroelectric het…
Dielectric properties of reactor irradiated ferroelectric thin films
Abstract Radiation effects in highly oriented Pb1Zr0.53Ti0.47O3 (PZT), Pb0.94La0.06Zr0.65Ti0.35O3 (PLZT-6), and PbiZriO3 (PZ) ferroelectric (FE) and antiferroelectric (AF) thin films are investigated in view of their possible application as a temperature sensitive element in a new bolometer system for ITER (International Thermonuclear Experimental Reactor). The dielectric properties (i.e. hysteresis loops, dielectric constants) of the films were investigated in a frequency range from 20 to 105 Hz and at temperatures up to 450 °C, before and after neutron irradiation to a neutron fluence of 5×1021 m−2 (E<0.1 MeV). The dielectric constant was measured during cooling with 1.7 °Cmin−1. The diel…
The electronic properties of SrTiO3-δ with oxygen vacancies or substitutions
The authors would like to thank R. Dittmann for useful discussions, T. Kocourek, O. Pacherova, S. Cichon, V. Vetokhina, and P. Babor for their contributions to sample preparation and characterization. The authors (M.T., A.D.) acknowledge support from the Czech Science Foundation (Grant No. 19-09671S), the European Structural and Investment Funds and the Ministry of Education, Youth and Sports of the Czech Republic through Programme “Research, Development and Education” (Project No. SOLID21 CZ.02.1.01/0.0/0.0/16-019/0000760). This study was partly supported by FLAG-ERA JTC project To2Dox (L.R. and E.K.). Calculations have been performed on the LASC Cluster in the Institute of Solid State Phy…
Compositional Evolution of Properties in Epitaxial Films of Relaxor PbMg1/3Nb2/3O3-PbTiO3
Epitaxial heterostructures of relaxor (1− x) PbMg1/3Nb2/3O3−(x) PbTiO3 thin films with La0.5Sr0.5CoO3 bottom electrodes were grown by pulsed laser ablation on MgO substrates. Perovskite films with x = 0–0.32 were deposited using sub-monolayer mixing from two targets. Both the room-temperature studies of microstructure and studies of dielectric response as a function of frequency and temperature were performed. For all x, a relaxor-like behavior was observed. The compositional evolution of lattice parameter, permittivity, and temperature of dielectric maxima T m was in a qualitative agreement with that in bulk. The relatively low temperatures T m in the presence of an in-plane compression we…
Ferroelectric Behavior in Epitaxial Films of Relaxor PbMg1/3Nb2/3O3
The nonlinear dielectric response of epitaxial thin films of relaxor ferroelectric PbMg1/3Nb2/3O3 was experimentally studied using digital Fourier analysis. Change from glass-like to ferroelectric behavior was detected in a broad temperature range, at relatively low ac and/or dc electric fields, and at a time scale of seconds. The presence of interfaces and peculiar microstructure of thin films are suggested to determine such a specific behavior.
Epitaxial Films of Relaxor Ferroelectric PbMg1/3Nb2/3O3in Strong Electric Fields
Epitaxial thin films of perovskite relaxor ferroelectric PbMg 1/3 Nb 2/3 O 3 were grown on MgO (001) substrates by pulsed laser deposition using La 0.5 Sr 0.5 CoO 3 bottom electrode layers. Dielectric response of the films was experimentally studied as a function of temperature and frequency in a broad range of amplitudes of ac electric field (to 10 MV/m) and magnitudes of dc electric field (to 50 MV/m). At small fields, a glass-like behavior was observed. With increasing magnitude of the dc field, an onset of a polar state was detected. The orientation of the polar clusters along the direction of the field and fluctuations of the direction of their dipole moments were suggested to determin…
Structural characterization of relaxor ferroelectric PbMg 1/3 Nb 2/3 O 3 -PbTiO 3 thin film heterostructures deposited by pulsed laser ablation
Highly oriented and epitaxial films of relaxor ferroelectric PbMg1/3Nb2/3O3-PbTiO3 (PMN-PT) with a composition (68/32) near the morphotropic phase boundary were deposited by pulsed laser ablation on La0.5Sr0.5CoO3 bottom electrodes, deposited on MgO (100) and LaAlO3 (100). The formation of crystalline phases, epitaxy, film–electrode–substrate orientation relationships and crystal perfection were studied by X-ray diffraction and scanning electron microscopy. The structural properties were found to depend on the deposition conditions and substrate. Correlation of both the dielectric and relaxor properties in the heterostructures and the structural properties of the PMN-PT films was observed.
Pulsed laser deposition of relaxor ferroelectric films
Heterostructures of perovskite relaxor ferroelectric (RFE) thin films onto La 0.5 Sr 0.5 CoO bottom electrode layers were grown by pulsed laser deposition on MgO(100) crystal substrates. The films were highly oriented, with (h00) planes parallel to the substrate surface, and demonstrated good dielectric and ferroelectric quality at room temperature. The studies of the dielectric properties of the films over the frequency range of 20 Hz....100 kHz and over the temperature range of 0...350°C revealed relaxor type behavior in the films. A diffuse ferroelectric phase transition and a shift of the maximum dielectric permittivity towards higher temperatures with increasing frequency were observed…
Epitaxial growth of perovskite oxide films facilitated by oxygen vacancies
The authors would like to thank P. Yudin for valuable discussions, N. Nepomniashchaia for VASE studies, and S. Cichon for XPS analysis. The authors acknowledge support from the Czech Science Foundation (Grant No. 19-09671S), the European Structural and Investment Funds and the Ministry of Education, Youth and Sports of the Czech Republic through Programme ‘‘Research, Development and Education’’ (Project No. SOLID21 CZ.02.1.01/0.0/0.0/16-019/0000760), and ERA NET project Sun2Chem (E. K. and L. R.). Calculations have been done on the LASC Cluster in the ISSP UL.
Phase transitions and properties of perovskite ferroelectric ceramics and films for certain applications
Abstract The structure-properties relationships and phase transitions in perovskite ceramics, and films of PLZT, PLZST, PST, PSN, PMNT compounds are discussed with regard to ordering, relaxor behaviour, pronounced ferroelectric, electromechanical and electrocaloric properties. The theoretical approach is extended to the time dependent Ginsburg-Landau model. The evolution of dielectric properties in relaxors after the change of temperature and electric field creating an increase of dielectric permittivity is found to follow a logarithmic law of decay. A strong electromechanical response is observed in a number of thin films of different compositions.