Relaxor Pb(Mg1/3Nb2/3)O-3 thin films and their electromechanical properties

Pb(Mg1/3Nb2/3)O-3 thin films were prepared from modified alkoxide solution precursors and their dielectric and electromechanical characteristics were investigated. Preparation of the films is very sensitive to processing parameters. The influence of different seeding layers on the microstructures is discussed. Films show relaxer-like behavior, but with dielectric permittivity which is low (4500 at peak) compared to bulk ceramics and single crystals. Large electric de bias fields (up to 120 kV/cm) can be applied to the films. This de field reduces the permittivity, suppresses the frequency dispersion and flattens the permittivity-peak. No anomaly in temperature dependence of the permittivity associated with the held induced transition into, a ferroelectric phase was observed. The maximum field induced piezoelectric d(33) coefficient is around 85 pm/V and electrostrictive strains up to 1.6 10(-3) were measured with an electric field of 30 kV/cm.

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Dragan Damjanovic, Stéphane Hiboux, Zian Kighelman, Andreas Seifert, Nava Setter
1999
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https://infoscience.epfl.ch/record/88944?ln=fr

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Diélectrique

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Ferroélectricité

On appelle ferroélectricité la propriété selon laquelle un matériau possède une polarisation électrique à l'état spontané, polarisation qui peut être renversée par l'application d'un champ électrique

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Une couche mince () est un revêtement dont l’épaisseur peut varier de quelques couches atomiques à une dizaine de micromètres. Ces revêtements modifient les propriétés du substrat sur lesquels ils son

Electromechanical properties and self-polarization in relaxor Pb(Mg1/3Nb2/3)O-3 thin films

Dragan Damjanovic, Zian Kighelman, Nava Setter

Pyrochlore free Pb(Mg1/3Nb2/3)O-3 (PMN) thin films were prepared from alkoxide-based solution precursors. The influence of different seeding layers and chemical solution on the microstructures is shown. Dielectric, electrostrictive, and piezoelectric properties of the films were characterized in detail. Films show relaxor-like behavior, but with dielectric permittivity which is low (around 4000 at peak) compared to bulk ceramics and single crystals. Several parameters which might be responsible for this lower permittivity are suggested. Electrostrictive coefficients, M and Q, were determined by measuring strain S and polarization P as a function of the electric field (E-ac). At large fields (>2.6x10(6) V/m), S vs P-2 appears to deviate from linear behavior possibly suggesting that the electrostrictive coefficient Q becomes nonlinear in this field range. Investigated as-prepared PMN films exhibit piezoelectric response in the absence of a dc electric field (d(33)=8-20 pm/V). The value of the associated self-polarization in the films is estimated and its presence confirmed by zero-field pyroelectric measurements. The self-polarization and the piezoelectric coefficient are strong functions of the ac field amplitude. Asymmetry of S vs E-ac and d(33) vs E-dc loops are related to the self-polarization. An ac field induces shift in P vs E loops along the field axis. This increase in the coercive field is associated, through a simple model, with the presence of the self-polarization. (C) 2001 American Institute of Physics.

2001

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Dielectric and electromechanical properties of ferroelectric-relaxor 0.9 Pb(Mg1/3Nb2/3)O-3-0.1PbTiO(3) thin films

Dragan Damjanovic, Zian Kighelman, Nava Setter

Pyrochlore free 0.9Pb(Mg1/3Nb2/3)O-3-0.1PbTiO(3) thin films were prepared from alkoxide-based solution precursors. Preferential (111) crystallographic orientation was obtained on TiO2/Pt/TiO2/SiO2/Si substrates by spin coating. Dielectric, electrostrictive, and piezoelectric properties of the films were characterized in detail. Films show relaxor-like behavior, but with dielectric permittivity which is low (around 4300 at peak and at 340 Hz with E-ac=1.6x10(6) V/m) compared to bulk ceramics and single crystals. Several parameters which might be responsible for this lower permittivity are suggested. The ac and dc field dependences of the dielectric response have been investigated. Electrostrictive coefficients, M-11(7.76x10(-18) m(2)/V-2) and Q(11)(1.9x10(-2) m(4) C-2), were determined by measuring strain and polarization as a function of the electric field (E-ac). The maximum field induced piezoelectric d(33) coefficient is 100 pm/V and electrostrictive strains up to 1.2x10(-3) (with an ac electric field of 140 kV/cm) were measured. (C) 2001 American Institute of Physics.

2001

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Pb(Mg1/3Nb2/3)O-3 and (1-x)Pb(Mg1/3Nb2/3)O-3-xPbTiO(3) relaxor ferroelectric thick films: Processing and electrical characterization

Dragan Damjanovic, Nava Setter

The lead magnesium niobate [Pb(Mg1/3Nb2/3)O-3 or PMN], and its solid solutions with lead titanate (PbTiO3 or PT), are of great interest because of their high electromechanical properties. At large PMN content, these materials exhibit relaxor characteristics with large electrostrictive strains and a large permittivity, while compositions near the morphotropic phase boundary present very interesting piezoelectric properties. So far, properties of these materials in ceramic, thin film and single-crystal form have been investigated. In this paper, we report on preparation and properties of pyrochlore free PMN and 0.65PMN-0.35PT thick films ( thickness = 10 to 20 mum). The films were prepared from ethyl cellulose ink by screen printing on alumina substrate. The influence of various parameters, such as powder characteristics, inks formulation and films sintering conditions, on films densification are discussed. The dielectric and electromechanical properties of the films were examined. Relaxor-like behaviour was clearly demonstrated in PMN films. The maximum relative permittivity for PMN film was 10000 (at 0.1 kHz), which is lower than in bulk ceramics ( 17800 at 0.1 kHz) prepared under the same conditions. For 0.65PMN-0.35PT, the maximum relative permittivity was around 15500 against 24000 in the bulk. Several parameters, which might be responsible for the lower permittivity, are discussed. Poled 0.65PMN-0.35PT thick films exhibit relatively large piezoelectric response (d(33) up to 200 pm/V) and unipolar strains approaching 0.1%, making these films of interest for various actuator and transducer applications.

2004

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