97 research outputs found
Leakage current conduction of pulsed excimer laser ablated BaBi<SUB>2</SUB>Nb<SUB>2</SUB>O<SUB>9</SUB> thin films
No full textThe leakage current behavior of the BaBi2Nb2O9 (BBN) thin films was investigated over a wide range of temperatures. The current density, calculated from current-voltage (I-V) characteristics at room temperature, was 4.02× 10-9A/cm2 at an electric field of 3× 105V/m. The I-V characteristics of the films showed ohmic behavior for electric field strength lower than 1 MV/m. Nonlinearity in the current density-voltage (J-V) behavior was observed at an electric field above 1 MV/m. Different conduction mechanisms were brought into picture to explain the I-V characteristics of BBN thin films. The J-V behavior of BBN thin films was found to follow the Lampert's theory of space charge limited conduction in an insulator with traps. Three different regions, i.e., ohmic, trap filled limited, Child's law were explicitly observed in J-V characteristics. The activation energies in the ohmic region calculated from the Arrhenius plot were 0.46, 0.48, and 0.51 eV, respectively. These energies were attributed to the shallow traps, distributed near the conduction band edge in the forbidden gap of the materials
Compositionally and structurally modulated Pb(Mg<SUB>1/3</SUB>Nb<SUB>2/3</SUB>)O<SUB>3</SUB>-PbTiO<SUB>3</SUB> relaxor thin films for microactuator
No full textThin films of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3(x = 0.1 to 0.3) (PMN-PT) were successfully grown on the platinum coated silicon substrate by pulsed excimer laser ablation technique. A thin template layer of LaSr0.5Co0.5O3 (LSCO) was deposited on platinum substrate prior to the deposition of PMN-PT thin films. The composition and the structure of the films were modulated via proper variation of the deposition parameter such as substrate temperature, laser fluence and thickness of the template layers. We observed the impact of the thickness of LSCO template layer on the orientation of the films. The crystallographic structure and compositional variation were confirmed with x-ray diffraction and energy diffraction x-ray (EDX) analysis. A room temperature dielectric constant varying from 2000 to 4500 was noted for different composition of the films. The dielectric properties of the films were studied over the frequency range of 100 Hz - 100 kHz over a wide range of temperatures. The films exhibited the relaxor-type behavior that was characterized by the frequency dispersion of the temperature of dielectric constant maxima (Tm) and also diffuse phase transition. This relaxor nature in PMN-PT thin films was attributed to freezing of the dipole moment, which takes place below a certain temperature. This phenomenon was found to be very similar to spin glass system, where spins are observed to freeze after certain temperature
Integrated piezoelectric thin films for microactuators
No full textThin films of (1-x)Pb(Mg1/3Nb2/3)O3 - xPbTiO3 (x = 0.1 to 0.3) (PMN-PT) were grown on the platinum coated silicon substrate by pulsed excimer laser ablation technique. The composition and the structure of the films were modulated via proper variation of the deposition parameters. A room temperature dielectric constant varying from 2000 to 4500 was noted for different composition of the films. The dielectric properties of the films were studied over the frequency range of 100 Hz - 100 kHz over a wide range of temperatures. The films exhibited the relaxor- type behavior that was characterized by the frequency dispersion of the temperature of dielectric constant maxima (Tm) and also diffuse phase transition. This relaxor nature in PMN-PT thin films was attributed to freezing of the dipole moment, which takes place below a certain temperature. This phenomenon was found to be very similar to spin glass systems, where spins are observed to freeze after certain temperature. Antiferroelectric lead zirconate (PZ) thin films were deposited by pulsed laser ablation technique on Pt coated Si substrates. The films that were deposited at a lower temperature of 300° C with subsequent post annealing at 650° C for 5 min. (ex-situ films) exhibited polycrystalline multi-grained microstructure, whereas the films that were deposited at a higher substrate temperature (in-situ films) of 550° C exhibited highly oriented (110) columnar microstructure. The antiferroelectric nature of the PZ films was confirmed by the double hysteresis behavior in polarization vs. applied electric field characteristics. These two films showed a difference in the dielectric and electrical properties and were attributed to the difference in their microstructure
Effect of electric field on dielectric response of PMN-PT thin films
No full textElectric field (ac and dc) induced complex dielectric properties of 0.7 Pb(Mg1/3Nb2/3)O3-0.3 PbTiO3 (PMN-PT) thin films were studied as a function of frequency at different temperatures. A non-linear behavior of dielectric susceptibility, with respect to the amplitude of the ac drive, was observed at lower temperatures. The magnitude of the dielectric constant measured at 1 kHz was increased from 2000 to 6000 with increasing ac signal amplitude from 0.5 to 10 kV/cm, while temperature of maximum dielectric constant (Tm) was observed to follow reverse trend at all frequencies. The relaxor nature of PMN-PT thin films was studied in terms of diffused phase transition along with frequency dispersion of temperature of dielectric maximum (Tm). Vogel-Fulcher relationship was used to analyze the frequency dependence of temperature of dielectric maximum (Tm). The dielectric constants (both real and imaginary) of PMN-PT thin films were observed to reduce with the application of external dc field. The external dc bias suppressed the frequency dispersion and increased the ferroelectric stability by increasing the transition temperature (Tm). The disappearance of relaxor nature in PMN-PT (70/30) films was attributed to manifestation of long-range order at higher bias voltage
Integrated piezoelectric thin films for microactuators
No full textThin films of (x = 0.1 to 0.3) (PMN-PT) were grown on the platinum coated silicon substrate by pulsed excimer laser ablation technique. The composition and the structure of the films were modulated via proper variation of the deposition parameters. A room temperature dielectric constant varying from 2000 to 4500 was noted for different composition of the films. The dielectric properties of the films were studied over the frequency range of 100 Hz - 100 kHz over a wide range of temperatures. The films exhibited the relaxor- type behavior that was characterized by the frequency dispersion of the temperature of dielectric constant maxima and also diffuse phase transition. This relaxor nature in PMN-PT thin films was attributed to freezing of the dipole moment, which takes place below a certain temperature. This phenomenon was found to be very similar to spin glass systems, where spins are observed to freeze after certain temperature. Antiferroelectric lead zirconate (PZ) thin films were deposited by pulsed laser ablation technique on Pt coated Si substrates. The films that were deposited at a lower temperature of 300°C with subsequent post annealing at 650°C for 5 min. (ex-situ films) exhibited polycrystalline multi-grained microstructure, whereas the films that were deposited at a higher substrate temperature (in-situ films) of 550°C exhibited highly oriented (110) columnar microstructure. The antiferroelectric nature of the PZ films was confirmed by the double hysteresis behavior in polarization vs. applied electric field characteristics. These two films showed a difference in the dielectric and electrical properties and were attributed to the difference in their microstructure
Compositionally and structurally modulated Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 relaxor thin films for microactuator application
No full textCompositionally and structurally modulated Pb(Mg1/3Nb2/3)O3-PbTiO3 relaxor thin films for microactuator application
No full textThin films of (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3(x = 0.1 to 0.3) (PMN-PT) were successfully grown on the platinum coated silicon substrate by pulsed excimer laser ablation technique. A thin template layer of LaSr0.5Co0.5O3 (LSCO) was deposited on platinum substrate prior to the deposition of PMN-PT thin films. The composition and the structure of the films were modulated via proper variation of the deposition parameter such as substrate temperature, laser fluence and thickness of the template layers. We observed the impact of the thickness of LSCO template layer on the orientation of the films. The crystallographic structure and compositional variation were confirmed with x-ray diffraction and energy diffraction x-ray (EDX) analysis. A room temperature dielectric constant varying from 2000 to 4500 was noted for different composition of the films. The dielectric properties of the films were studied over the frequency range of 100 Hz - 100 kHz over a wide range of temperatures. The films exhibited the relaxor-type behavior that was characterized by the frequency dispersion of the temperature of dielectric constant maxima (Tm) and also diffuse phase transition. This relaxor nature in PMN-PT thin films was attributed to freezing of the dipole moment, which takes place below a certain temperature. This phenomenon was found to be very similar to spin glass system, where spins are observed to freeze after certain temperature
Compositionally and structurally modulated relaxor thin films for microactuator application
No full textThin films of (x = 0.1 to 0.3) (PMN-PT) were successfully grown on the platinum coated silicon substrate by pulsed excimer laser ablation technique. A thin template layer of (LSCO) was deposited on platinum substrate prior to the deposition of PMN-PT thin films. The composition and the structure of the films were modulated via proper variation of the deposition parameter such as substrate temperature, laser fluence and thickness of the template layers. We observed the impact of the thickness of LSCO template layer on the orientation of the films. The crystallographic structure and compositional variation were confirmed with x-ray diffraction and energy diffraction x-ray (EDX) analysis. A room temperature dielectric constant varying from 2000 to 4500 was noted for different composition of the films. The dielectric properties of the films were studied over the frequency range of 100 Hz - 100 kHz over a wide range of temperatures. The films exhibited the relaxor-type behavior that was characterized by the frequency dispersion of the temperature of dielectric constant maxima and also diffuse phase transition. This relaxor nature in PMN-PT thin films was attributed to freezing of the dipole moment, which takes place below a certain temperature. This phenomenon was found to be very similar to spin glass system, where spins are observed to freeze after certain temperature
Dielectric response and impedance spectroscopy of 0.7Pb(Mg<SUB>1/3</SUB>Nb<SUB>2/3</SUB>)O<SUB>3</SUB>-0.3PbTiO<SUB>3</SUB> thin films
No full textDielectric response of 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) thin films deposited by pulsed laser deposition has been studied as a function of frequency over a wide range of temperatures. The films exhibited maximum frequency dispersion in both real and imaginary part of dielectric susceptibility near and below the dielectric transition temperature. The relaxor behavior in the films was confirmed from the diffused phase transition (DP) together with frequency dependent of transition temperature (Tm). The frequency dependence of transition temperature Tm (temperature of the maximum of dielectric constant) was studied in terms of Vogel-Fulcher relation. The dielectric relaxation of PMN-PT thin films was studied at different temperatures using the complex impedance (Z∗) and electric modulus (M∗) formalism. The shape of complex impedance curve inferred that only one type of dielectric relaxation was involved in the present case. This was attributed to the contribution of bulk grain of the films while the other probable sources, such as grain boundaries, film electrode interfaces were negligible. The films exhibited Debye type dielectric relaxation at temperature sufficiently above the temperature of permittivity maximum (Tm), while a multi-Debye relaxation was observed at lower temperatures (<200 ° C), which was confirmed from the broad spectrum of dielectric relaxation. The average relaxation times estimated from Cole-Cole plots varied with temperature according to the V-F relation
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