• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.4
• /
• pp.577-584
• /
• 2003

A crack with growth in ferroelectric ceramics under purely electric loading is analyzed. The crack tip stress intensity factor for the growing crack under small-scale conditions is evaluated by employing the model of nonlinear domain switching. The crack tip stress intensity factor increases or decreases with crack growth, depending on the electrical nonlinear behavior and the direction of an applied electric field. It is shown that the ferroelectric material can be either toughened or weakened as the crack grows. The steady state crack growth in ferroelectric ceramics is also discussed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.14 no.9
• /
• pp.731-735
• /
• 2001

S $r_{0.89}$B $i_{2.4}$T $a_2$ $O_{9}$ (SBT) thin films are deposited on Pt-coated electrode(Pt/Ti $O_2$/ $SiO_2$/Si) using RF magnetron sputtering method. In the XRD pattern, the SBT thin films had (105) orientation. As annealing temperature was increased from $600^{\circ}C$ to 85$0^{\circ}C$, the intensities of peak were increased. In the SEM images, Bi-layered perovskite phase was crystallized above $650^{\circ}C$ and rod-like grains grew above 75$0^{\circ}C$. The maximum remanent polarization and the coercive electric field at annealing temperature of 75$0^{\circ}C$ are 11.60$\mu$C/$\textrm{cm}^2$ and 48kV/cm respectively. The dielectric constant and leakage current density at annealing temperature of 75$0^{\circ}C$ are 213 and 1.01x10$^{-8}$ A/$\textrm{cm}^2$, respectively. The fatigue characteristics of SBT thin filmsdid not change up to 10$^{10}$ switching cycles.s.s.

• Journal of the Korean Ceramic Society
• /
• v.26 no.6
• /
• pp.802-810
• /
• 1989

The temperature dependence of piezoelectric strain constant and the electric field induced strain are investigated as a function of PT in 0.5[xPT-(1-x)PZ]-0.5PNN ceramics. The piezoelectric strain constant d31 has the highest value(360$\times$10-12m/V) at PT=0.68. The temperature dependence of d31 is improved as Curie temperature of sample is increased, and the electric field dependence of induced strain is decreased with the coercive field increased. This ceramic system shows both piezoelectric effect and electrostrictive effect under the applied electric field. The piezoelectric of tetragonal phase is higher than that of rhombohedral phase, and the magnitude of electrostrictive constant is appeared in the order of morphotropic, rhombohedral and tetragonal phase. The piezoelectric strain constant with applied field must be considered theelectrostrictive effect due to 90$^{\circ}$domain wall displacements, and the displacement of bimorph type actuator agrees with the calulated value well.

• Proceedings of the KIEE Conference
• /
• 1999.07d
• /
• pp.1867-1869
• /
• 1999

Pulse electric field induced electron emission from ferroelectrics has been studied with Pb$(Zr_xTi_{1-x})O_3$ ceramics with varying Zr/Ti ratio from 35/65 to 65/35, Electron emission was proved to be concentrated on the electrode edge by emission profile test and emission capture photographs. The 65/35 composition showed largest emission charge in lowest field and lowest emission threshold field. The emission characteristics are closely dependent on their ferroelectric properties in hysteresis curve. Electron emission charge increases with the polarization charge and emission threshold voltage is dependent on coercive field regardless of their composition. But dielectric constant has little relation with emission property. Electron emission charge increases exponentially with pulse electric field irrespective of composition. On the assumption that the surface potential is linear with the pulse electric field, electron emission can be regarded as a field emission at the electrode edge using Fowler-Nordheim plot of ln$(Q_e/E_{fe})$ to $1/E_{fe}$.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.09a
• /
• pp.9-12
• /
• 2001

The $Sr_{0.8}Bi_{2.4}Ta_2O_9(SBT)$ thin films are deposited on Pt-coated electrode($Pt/TiO_2/SiO_2/Si$) using RF magnetron sputtering method. With increasing post-annealing temperature from $600[^{\circ}C]$ to $850[^{\circ}C]$, Bi-layered perovskite phase was crystallized above $650[^{\circ}C]$. The maximum remanent polarization and the coercive electric field is 11.60[${\mu}C/cm^{2}$] 48[kV/cm] respectively. The leakage current density of SBT capacitor at post-annealing temperature of $750[^{\circ}C]$ is $1.01{\times}10^{-8}A/cm^2$ at 100[kV/cm]

• The Transactions of the Korean Institute of Electrical Engineers C
• /
• v.52 no.12
• /
• pp.553-558
• /
• 2003

The A S $r_{0.7}$B $i_{2.6}$T $a_2$ $O_{9}$ (SBT)thin films are deposited on Pt-coated electrode(Pt/$TiO_2$/$SiO_2$/Si) using a RF magnetron sputtering method. The electrical properties of SBT capacitors with top electrodes were studied. In the XRD pattern, the SBT thin films in all annealing temperatures had (105) orientation. In the SEM images, Bi-layered perovskite phase was crystallized at 75$0^{\circ}C$ and grains largely grew in oxygen annealing atmosphere. The electrical properties of SBT capacitor with top electrodes represent a favorable properties in Pt electrode. The maximum remanent polarization and the coercive electric field with Pt electrode are 12.40C/$\textrm{cm}^2$ and 30kV/cm, respectively. The dielectric constant and leakage current density with Pt electrode is 340 and 6.8110$^{-10}$ A/$\textrm{cm}^2$, respectively.y.y.

• The Transactions of the Korean Institute of Electrical Engineers
• /
• v.34 no.10
• /
• pp.399-406
• /
• 1985

In this paper transparent PLZT ceramics for the composition of 9/65/35 (La/Zr/Ti ) are fabricated using hotpress and the possibility of application to optical shutter is examined by obtaining the On-Off characteristics of specimens. The ferroelectric E-P hysteresis loop exhibits slim loop suitable for the quadratic electrooptic effect. Measurements of the electrooptic effect show that specimens have the quadratic electrooptic effect but the light intensities as functions of electric field exhibit butterfly type hysteresis curves because of its slightly large saturation remanent polarization and coercive field. On-Off characteristics are obtained by electric fields of-6 kv/cm and +2kv/cm. As a result of experiments, 9/65/35 PLZT ceramics can be applied to optical shutter but construction with other composition which has more slim hysteresis loop is desired for obtaining the Off state by zero electric field.

• Korean Journal of Materials Research
• /
• v.16 no.11
• /
• pp.705-709
• /
• 2006

Nb was doped to Pb-free $(Bi_{0.5}Na_{0.5})TiO_3$ (BNT) by a solid state mixing process to form $(Bi_{0.5}Na_{0.5})Ti_{1-x}Nb_xO_3\;(x=0{\sim}0.05)$ (BNTNb) and its doping effects on ferroelectric and piezoelctric properties of BNT were investigated. The BNTNb solid solutions were formed up to x=0.01 with no apparent second phases while grain sizes decreased. As x increased, coercive field ($E_c$) and mechanical quality factor ($Q_m$) decreased but piezoelectric constant ($d_{33}$) increased, which indicates Nb acts as a donor for BNT.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.05d
• /
• pp.72-76
• /
• 2003

The $Sr_{0.7}Bi_{2.6}Ta_2O_9$(SBT) thin films are deposited on Pt-coated electrode(Pt/$TiO_2/SiO_2$/Si) using RF magnetron sputtering method. The structural and electrical properties of SBT capacitors were influenced with annealing atmosphere. In the XRD pattern, the SBT thin films in all annealed atmosphere had (105) orientation. In the SEM images, Bi-layered perovskite phase was crystallized in all annealing atmosphere and grains largely grew in oxygen annealing atmosphere. The maximum remanent polarization and the coercive electric field in oxygen annealing atmosphere are $12.40[{\mu}C/cm^2]$ and 30[kV/cm] respectively. The fatigue characteristics of SBT capacitors did not change up to $10^{10}$ switching cycles.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.16 no.3
• /
• pp.207-213
• /
• 2003

The Sr$\_$0.7/Bi$\_$2.6/Ta$_2$O$\_$9/(SBT) thin films are deposited on Pt-coated electrode(Pt/TiO$_2$/SiO$_2$/Si) using RF magnetron sputtering method. The structural and electrical properties of SBT capacitors were influenced with annealing atmosphere. In the XRD pattern, the SBT thin films in all annealed atmosphere had (105) orientation. In the SEM images, Bi-layered perovskite phase was crystallized in all annealing atmosphere and grain largely grew in oxygen annealing atmosphere. The maximum remnant polarization and the coercive electric field in oxygen annealing atmosphere are 12.40[${\mu}$C/cm$^2$] and 30[kV/cm] respectively. The dielectric constant and leakage current density of capacitors annealed oxygen atmosphere are 340 and 2.13${\times}$10$\^$-9/ [A/cm$^2$] respectively. The fatigue characteristics of SBT capacitors did not change up to 10$\^$10/ switching cycles.