• Current Photovoltaic Research
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• v.3 no.1
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• pp.5-9
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• 2015

Absorption and luminescence characteristics of disperse red-19 (DR-19) and $TiO_2$ composite have been investigated with various poling electric field strengths. Two step synthetic processes were employed to employ the DR-19 to the $TiO_2$ sol-gel. Firstly, urethane bond formation between DR-19 (-OH) and 3-isocyanatopropyl triethoxysilane (ICPTES, -N=C=O) performed (ICPDR) prior incorporation to the $TiO_2$ sol-gel. Secondary, the hydrolysis of the ethoxy group from the ICPTES and condensation reaction between silanol groups from ICPTES and $TiO_2$ sol-gel were performed. The ICPDR and $TiO_2$ sol-gel ($DRTiO_2$) were mixed and stirred for several days. The composite was coated to the ITO coated glass substrate. Corona poling were performed before drying the composite with various electric field strengths. The absorption intensity decreased with the increase of the poling field strength, which resulted in the increase of poling efficiency. The photoluminescence also decreased as the poling field strength increased. There is long luminescence tail for the poled $DRTiO_2$ film compared with unpoled $DRTiO_2$ film. The luminescence long tail indicates that the self-trapped excitons and polarons were generated when the $DRTiO_2$ film was poled with electric field.

• Polymer(Korea)
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• v.28 no.5
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• pp.361-366
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• 2004

The poling characteristics of PVDF (poly(vinylidene fluoride)) film was investigated by measuring the electric voltage generated by the external load for the distributed tactile sensor applications. The poling conditions for the PVDF films were controlled by changing temperature and electric field, and the resulting crystal structure of the $\beta$-phase crystal was confirmed by FT-IR, DSC, and XRD experiments. The $\beta$-phase crystal was increased with the poling temperature and poling voltage, and subsequently the permittivity of the Poled PVDF films was increased. Finally, the prototype tactile sensor was tested by a 8 $\times$ 8 may circuit exhibiting high voltage signal for the highly poled PVDF films.

• Korean Journal of Materials Research
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• v.21 no.7
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• pp.391-395
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• 2011

The structure and dielectric properties of poled <001>-oriented 0.7Pb($Mg_{1/3}Nb_{2/3})O_3-0.3PbTiO_3$ (PMN-0.3PT) crystals have been investigated for orientations both parallel and perpendicular to the [001] poling direction. An electric field induced monoclinic phase was observed for the initial poled sample. The phase remained stable after the field was removed. A quite different temperature dependence of dielectric constant has been observed between heating and cooling due to an irreversible phase transformation. The results of mesh scans and temperature dependence of the dielectric constant demonstrate that the initial monoclinic phase changes to a single domain tetragonal phase at 370K and to a paraelectric cubic phase at 405K upon heating. However, upon subsequent cooling from the unpoled state, the cubic phase changes to a poly domain tetragonal phase and to a rhombohedral phase. In the ferroelectric tetragonal phase with a single domain state, the dielectric constant measured perpendicular to the poling direction was dramatically higher than that of the parallel direction. A large dielectric constant implies easier polarization rotation away from the polar axis. This enhancement is believed to be related to dielectric softening close to the morphotropic phase boundary and at the phase transition temperature.

• Korean Journal of Optics and Photonics
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• v.32 no.2
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• pp.62-67
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• 2021

We have experimentally demonstrated sum-frequency generation (SFG) in a periodically poled lithium niobate (PPLN) crystal, using a mode-locked picosecond-pulsed fiber laser and a continuous-wave (CW) diode laser with a narrow linewidth. The mode-locked fiber laser had a center wavelength of 1560.7 nm and a spectral width of 1.1 nm, and the CW diode laser had a center wavelength of 1551.0 nm and a spectral width of 6 MHz. To effectively realize SFG, both of the spatial modes of the two lasers were made to overlap in the PPLN crystal by using a single-mode optical fiber. The pulse-mode SFG with pulsed- and CW-mode lasers was successfully observed in the spectral and time domains. These results are expected to be applicable in various ways, such as optical frequency measurement and high-resolution laser spectroscopy studies using optical frequency combs.

• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.82-86
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• 2013

A poled lead zirconate titanate (PZT) cube specimen is subjected to impulse-type compressive stress with increasing magnitude in parallel to the poling direction at four room and high temperatures. During the ferroelastic domain switching induced by the compressive stress, electric displacement in the poling direction and longitudinal and transverse strains are measured. Using the measured responses, linear material properties, namely, the piezoelectric and elastic compliance coefficients, are evaluated by a graphical method, and the effects of stress and temperature are analyzed. Finally, the dependency of the evaluated linear material properties on relative remnant polarization is analyzed and discussed.

• KSBB Journal
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• v.13 no.5
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• pp.477-482
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• 1998

A biosensor with PZT piezoelectric ceramic crystal was developed for the detection of formaldehyde gas. Poled PZT piezoelectric ceramic disk was made from ZrO2, TiO2 and Nb2O5, together with the addition of PbO and polyvinyl alcohol, through various processes of mixing, calcination drying, crushing, forming, sintering, polishing, ion coating and poling. Oscillator circuit of sensor was made of operational amplifier(AD811AN). Formaldehyde dehydrogenase was immobilized onto a piezoelectic ceramic crystal, together with the cofactors, reduced glutathione and nicotinamide adenine dinucleotide. The effect of flow rate on the sensitivity was determined by varing the flow rate of carrier gas from 24.7mL/min to 111.7mL/min through detector cell. The results indicated that as the flow rate was increased, the recovery rate was increased. And a significant increase in the sensitivity was observed in enhanced flow rate of carrier gas. Frequency difference(ΔF) of immobilized PZT piezoelectic disk increased proportionally to the concentration gas and reproduced to repeated exposures of formaldehyde gas(28ppm, Δ68Hz).

• Journal of the Korean Ceramic Society
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• v.31 no.8
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• pp.829-834
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• 1994

The aim of this study is to investigate the changes in dielectric properties, Young's modulus and remnant compressive strength with compressive cyclic loading in PZT of tetragonal, MPB and rhombohedral composition. Higher relative dielectric constants appeared in the poled condition than the unpoled condition for all the compositions. After poling treatment remarkably higher relative dielectric constants were observed particularly in MPB, tetragonal compositions. Until five percent of the expected fatigue life was exhausted, the dielectric constant increased with compressive cyclic stress in MPB and rhombohedral while it remained nearly constant in tetragonal. During the subsequent compressive cyclic stress, dielectric constant decreased in all the three compositions. As the compressive cyclic stress is applied the change of Young's modulus was coincided with the change of remnant compressive strength.

• Korean Journal of Materials Research
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• v.4 no.4
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• pp.439-444
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• 1994

The influence of the direction of applied compressive stress on degradation mechanism ofpoled PZT sample was studied. When compressive stress perpendicular to poling direction was appliedon poled PZT sample, the degradation phenomena was explained by the diffusion of space chargepolarization. On the contrary, compressive stress parallel to poling direction was applied, it wasexplained by the rearrangement of 90" domains. As the grain size increased, the degradation phenomenawas promoted. It is attributed to different internal stress due to difference of grain size. of grain size.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.6
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• pp.464-470
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• 2010

A new method for the poling of piezoelectric ceramics with an air insulation medium in stead of silicon oil is described. A similar variation of electromechanical coupling coefficient $K_t$, for an air medium is observed in comparison to that of the material poled by the conventional poling method using a silicon oil medium. Different poling parameters such as dielectric constant $\varepsilon^T$ and frequency deviation ${\Delta}f$ are studied as well as the influence on the aging effect. The required poling factors to achieve the optimal piezoelectric characteristics are electric field, 2 kV/mm, temperature $100^{\circ}C$, and poling time 30 Min. From this result electric field 3 kV/mm atmosphere airs there being will be able to use with the polarization insulation medium about the piezoelectric material, confirmed.

• Journal of the Korean Graphic Arts Communication Society
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• v.14 no.1
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• pp.1-15
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• 1996

In this paper, the preparation of lead zirconium titanate(PZT) thin film by sol-gel processing was descried. Thin film coated with thickness of 4${\mu}{\textrm}{m}$ on the stainless steel substrates using the multiple spin-coating process. The crystalline phases of PZT powder and film were investigated by X-ray diffraction pattern and PZT thin film has perovskite structure over 600 C annealing temperature. Corona charging characteristics of the ferroelectric PZT thin film at 600 C were investigated by electrophotographic measurement. A difference in the charging characteristics between positive and negative corona charging was found. The charge acceptance depended in the polarity of corona and the poling of film. According to the D-E hysteresis measurment, PZT thin film can be poled by corona charging without use of top electrode. The remnant polarization in the PZT thin film is generally in the order of 48$\mu$C/$\textrm{cm}^2$. From this results, the ferroelectric PZT thin film will be possible to apply for the add-on type imaging formation.