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A new study investigates the piezoelectric and dielectric properties of PMN-PZT thin films prepared using the sol-gel method.

We calculate the electronic structures of FePt and Fe0.5Mn0.5Pt using first-principles calculations based on density functional theory within the local-spin-density approximation. The Curie temperature (Tc) was calculated by mean field approximation. Composition dependence of the Cure temperature (Tc(x)) of Fe1-xMnxPt was used to identify a composition to meet the desired Tc in the range of 600-650K. The identified composition (0.0294≤x≤0.0713) gives saturation magnetization (Ms) in the range of 1041-919 emu/cm3 and magnetocrystalline anisotropy constant (K) in the range of 9.96-8.36 × 106 J/m3 at 0 K. Temperature dependent M(T) and K(T) of Fe1-xMnxPt (0.0294≤ x ≤ 0.0713) were calculated using the Brillouin function and Callen-Callen experimental relation, respectively. Fe1-xMnxPt (0.0294≤ x ≤0.0713) shows 930-800 emu/cm3 of Ms and 7.18-5.61 × 106 J/m3 of K at 300K, thereby satisfying desired magnetic properties for heat-assisted magnetic recording media to achieve 4 Tb/in.2 areal density. [ABSTRACT FROM AUTHOR]

Ferroelectric Pb[sub 0.99][(Zr[sub 0.6]Sn[sub 0.4])[sub 0.85]Ti[sub 0.15]][sub 0.98]Nb[sub 0.02]O[sub 3] (PZSTN) thin films with different preferred orientations were fabricated by modifying with 20 mol% excess lead that contained a Pb(Zr[sub x]Ti[sub x-1])O[sub 3] seed layer (x = 0,0.3,0.52,0.65). Ferroelectric properties were investigated in terms of the texturing character of the PZSTN thin film. With an increase in Zr content in the seed layer, the (100) texturing of the PZSTN film was enhanced. The highly (100) texture (∼97%) was developed by inserting a seed layer with x = 1 between the Pt-coated substrate and the PZSTN thin film, whereas in the case of annealing in a reduced condition, the orientation of the film became nearly (111). The (111)-oriented PZSTN film showed relatively higher remanent polarization compared to that of the (100)-oriented film, while the (100)-oriented PZSTN film showed more fatigue behavior than the (111)-oriented film after 10[sup 9] switching cycles. The (111)-oriented PZSTN film with rhombohedral structure is believed to be suspected to significant stress along applied field direction, resulting in the production of many defects, causing degradation of the polarization during switching cycles. [ABSTRACT FROM AUTHOR]

To investigate the structural effect on the ferroelectric electron emission, the electric field distribution in a two-dimensional structure was calculated as a function of thickness and upper electrode diameter, and the switching charge density and emission charge were measured simultaneously. The simulation results of the electric field distribution showed that an asymmetric electrode structure caused a stray field on the bare surface of the ferroelectric cathode near the edge of upper electrode. The distance of the stray field from the electrode edge increased with increasing ferroelectric thickness, but it did not depend on the upper electrode diameter. The switching charge density increased more on the cathode with thicker ferroelectric and smaller upper electrode diameter. This was attributed to the difference of field distribution on the bare ferroelectric surface near the electrode edge. The expanded stray field for the thicker ferroelectric cathode enhanced polarization switching near the electrode edge. As a result, with increasing ferroelectric thickness, the emission charge increased and the threshold field decreased. However, there was no apparent difference between the emission charges from the different upper electrode diameters. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The dielectric and piezoelectric properties of sol-gel derived (x)Pb(Mg1/3Nb2/3)O3-(1 -x)Pb(Zr1/2Ti1/2)O3[(x)PMN-(1-x)PZT] thin films were investigated as a function of PMN content (x=0-1). For all compositions in the (x)PMN-(1-x)PZT thin films, a well-developed perovskite phase with (111) preferred orientation was obtained at the annealing temperature range of 700-800 degreesC. With increasing PMN content, the dielectric constant increased, while the remnant polarization and coercive field decreased. The enhanced dielectric properties were shown in the region of x= 0.2. At this composition, the dielectric constant and remnant polarization were 1750 and 12.75 C/cm2, respectively, which indicate that the morphotropic phase boundary (MPB) exists near the composition of x= 0.2. The transverse piezoelectric coefficient (d31) showed a maximum value of -84 pC/N at x = 0.2. These results confirmed that enhancement of the dielectric constant and remnant polarization improved the piezoelectric properties at the MPB. c 2001 American Institute of Physics. [DOI: 10.1063/1.1388572]
the main purpose of this investigation is to study the dielectric and piezoelectric properties of PMN-PZT thin films with various compositions and to develop a high-performance composition of the PMN-PZT thin film suitable for actuator applications. [ABSTRACT FROM AUTHOR]

The effect of field distribution on polarization switching and electron emission of the Pb(Zr(sub 0.8)Ti(sub 0.2))O3 (PZT) ferroelectric cathode is investigated as a function of the ferroelectric thickness and upper electrode diameter. It was seen that with increasing ferroelectric thickness, the emission charge increased and the threshold field decreased but there was no apparent difference between the emission charges from the different upper electrode diameters.

Magnetic properties and ferromagnetic resonance (FMR) frequency of Ni0.7Mn0.3-xCoxFe2O4 ferrites (NiMnCo: x = 0.00, 0.04, 0.06, and 0.10) were controllable with the concentration of cobalt (Co). The measured saturation magnetization remains almost constant at 57 emu/g in the studied range of the Co content. However, the coercivity increased to 72 Oe (x = 0.10) from 12 Oe (x = 0.00). Ferromagnetic resonance frequency increased from 129 MHz to the GHz frequency with increasing the Co content from x = 0.00 to x = 0.10, but the real part of permeability decreased to 1.6 from 16.7. This is because FMR frequency increases with the magnetocrystalline anisotropy (Hk) of the Co according to fr = (γ/2π)Hk. The permeability decreased with the Co content by µ = 1 + (4πMs/Hk). Temperature coefficient, in the range of 20-100 °C, was 0.002 for Ni0.7Mn0.3Fe2O4 (x = 0.00) and 0.008 for Ni0.7Mn0.2Co0.1Fe2O4 (x = 0.10). The results suggest that Ni0.7Mn0.3-xCoxFe2O4 ferrites have excellent temperature stability, and also are applicable to very high frequency: 30-300 MHz) and ultra high frequency: 300 MHz-3 GHz) devices. [ABSTRACT FROM AUTHOR]