Yuri V. Trushin

Antiferroelectric PbZrO3 thin films: structure, properties and irradiation effects

Abstract Irradiation effects on highly oriented antiferroelectric PbZrO 3 and ferroelectric Pb 0.92 La 0.08 (Zr 0.65 Ti 0.35 )O 3 thin films are investigated being exposed to neutron irradiation up to fluence 2*10 22 m −2 . The higher resistance of antiferroelectric PbZrO 3 thin films as compared to ferroelectric heterostructures to large fluences of neutron irradiation is recognized and discussed. Influence of two factors (structural and charge) was taken into account analysing irradiation effects on materials of different polarization states: ferroelectric PLZT (ceramics and thin films) and antiferroelectric PbZrO 3 films.

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 dielectric properties of the films were assessed before and after annealing in several steps up to 490 °C to remove the radiation induced defects.

Computer simulation of ferroelectric property changes in PLZT ceramics under neutron irradiation

The response of ferroelectric materials to high energy irradiation is of great interest because of their possible application in radiation environments such as thermonuclear reactors. In the present work a physical model for the defect evolution in PLZT ceramics under neutron irradiation and annealing is proposed. The influence of the defect system on the ferroelectric properties of these materials has been investigated. Satisfactory agreement between the theoretical estimated oxygen defect concentration after irradiation and annealing and the experimentally determined polarization has been obtained.

Nucleation of SiC on Si and their relationship to nano-dot formation: II. Theoretical investigation

The processes of SiC clusters growth on Si(111) surface has been investigated theoretically. The SiC cluster formation and growth on Si surface stimulated by deposition of elemental carbon onto Si(111) with molecular beams have been studied by applying the kinetic equations (co-called rate equations) method. The simulated cluster size distribution function obtained within this method appeared to be in reasonable agreement with the experimental data. Obtained cluster capture rates agree with KMC investigations.

Irradiation effects in lead zirconate thin films

Lead zirconate PbZrO3 (PZ) and PbZr0.53Ti0.47O3 (PZT) sol-gel films with a thickness of up to 1.5 μm were deposited on TiO2/Pt/TiO2/SiO2/Si substrates by spin coating technique and heterostructures of the same composition as well as on Pb0.92La0.08 (Zr0.65Ti0.35)O3 (PLZT-8) (with a thickness of 0.4 μm) were pulse laser deposited (PLD) on Pt/Ti/SiO2/Si. Observation of a typical antiferroelectric (AFE) double hysteresis loop in obtained PZ heterostructures at room temperature was attributed to the superior dielectric strength in case of thin film materials. The thermal behavior of dielectric permittivity ε of PZ film reveals a maximum near 225°C on heating and 219°C on cooling. The higher resistance of antiferroelectric PZ thin films as compared to ferroelectric (e.g., PZT, PLZT-8) heterostructures to neutron irradiation (up to fluence 2x1022m-2)* is recognized and discussed.

Dielectric Properties of Irradiated Ferroelectric and Antiferroelectric Thin Films

Irradiation effects on highly oriented antiferroelectric (AFE) PbZrO 3 (PZ) and on ferroelectric (FE) Pb 0.92 La 0.08 (Zr 0.65 Ti 0.35 ) O 3 (PLZT-8) films are investigated. The dielectric properties were measured in the frequency range from 20 Hz (hysteresis measurements) to 250 kHz, at temperatures from 400 C to room temperature, as well as before and after irradiation to fast neutron fluences of 1 2 10 22 m m 2 and 2 2 10 22 m m 2 . After each irradiation, the films were annealed in several steps up to ∼400 C to remove the radiation induced defects. The results are discussed in terms of radiation-induced structural defects and radiation-induced charges. We find that the AFE films show a significantly different behaviour from the FE films.

Influence of the growth temperature on SiC nanocluster nucleation on Si(111) surface during MBE process

Rate equations approach of computer simulation has been applied to investigate the SiC clusters nucleation and growth on Si surface during molecular beam epitaxy. Cluster surface densities have been obtained for a range of temperatures. The temperature influence on the consequent clusters density, including the surface phase transition (which occurs with simultaneous structure reconstruction), has been determined. The results obtained by the application of the suggested physical model have appeared to be in the reasonable agreement with experimental data.

Computational study of the influence of oxygen vacancies on the polarization in irradiated and annealed PLZT ceramics

A physical model for the oxygen defect evolution in PLZT ceramics under neutron irradiation and annealing is proposed. The influence of the defect system on the polarization of these materials has been investigated. The influence of the La content on the material structure and the oxygen defects has been taken into account. Satisfactory agreement between the theoretically estimated oxygen defect concentration after irradiation and annealing and the experimentally determined polarization has been obtained.

NEUTRON IRRADIATION EFFECTS IN PZ and PZT THIN FILMS

ABSTRACT Neutron irradiation effects on highly oriented antiferroelectric PbZrO3 (PZ) and ferroelectric PbZr0.53Ti0.47O3 (PZT) thin films are investigated in view of their possible application as a temperature sensitive element in a new bolometer system for fusion devices like ITER. All investigated thin films were prepared by a sol-gel technique and by pulsed laser deposition (PLD) respectively. The dielectric properties were investigated in a frequency range from 1 to 250 kHz and at temperatures up to 400°C, prior to and after irradiation to a neutron fluence of 3 * 1022 m−2 (E > 0.1 MeV). After irradiation, the films were anneald in several steps up to 400°C in order to remove the radiation-induced defects. The results are discussed in terms of two kinds of radiation-induced defects, i.e. structural defects, such as oxygen-vacancies, and radiation-induced charges. We find that the antiferroelectric PZ heterostructures are radiation harder than the PZT films and that the structural order of the film as well as the interfaces play an important role. †Originally presented at 10th European Meeting on Ferroelectricity, Cambridge, UK, August 3-8, 2003.

Changes in the temperature dependence of the dielectric constant in irradiated antiferroelectric thin films

A model describing the changes of the Curie-Weiss temperature in lead-zirconate thin films under neutron irradiation is proposed. The Curie-Weiss temperature in the irradiated material decreases which is connected to charges caused by neutron irradiation. The charges located near the surfaces due to Schottky effect and in the bulk of the film results in different rates of the Curie-Weiss temperature decreases with neutron fluence. However the influence of the Schottky layers seems to be more pronounced. Satisfactory agreement between the theoretical results and the experimental data is obtained for different neutron fluences.