비열살균기술로서 저온플라즈마 활용 가능성을 탐색하고자 유전체장벽 방전 플라즈마(DBDP)생성장치를 제작하여 최적 플라즈마생성 조건을 도출하고 Staphylococcus aureus를 대상으로 살균성능을 조사하였다. DBDP생성장치는 전력공급장치, 변압기, 전극, 시료처리부 등 네 부분으로 구성하였다. 인가전압은 단상 200 V AC를 사용하고, 변압기를 통하여 10.0-50.0 kV로 변환하고 10.0-50.0 kHz의 주파수의 펄스 구형파를 유전체인 세라믹 블록 내에 장치한 전극에 투입함으로써 상압에서 플라즈마를 생성하였다. 주파수를 올림에 따라 높은 전류가 유입되었고, 이에 비례하여 전력소비량이 증가하였다. 전류세기 1.0-2.0 A, 주파수 32.0-35.3 kHz 범위에서 균일하고 안정적인 플라즈마 발생이 이루어졌으며 시료를 투입하지 않은 상태에서의 최적 전극간격은 1.85 mm 이었다. 전극간격을 높임에 따라 소비 전력이 증가하였으나 시료 처리에 적합한 전극간격은 2.65 mm였다. DBDP 처리에 의한 온도상승은 최대 20oC에 불과하여 열에 의한 생물학적 효과는 무시할 수 있었으며 따라서 비열기술임이 확인되었다. Staphylococcus aureus를 대상으로 DBDP 처리할 경우 초기 5분 동안은 살균치가 직선적인 증가를 보이다가 이후 다소 완만해지는 경향을 보였으며 1.25 A에서 10분간 처리 시 살균치는 5.0을 상회하였다.

The structure and dielectric properties of poled<001>-oriented 0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (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.

Thermoelectric power, dc conductivity, and the dielectric relaxation properties of La2NiO4.03 are reported in the temperature range of 77 K - 300 K and in a frequency range of 20 Hz - 1 MHz. Thermoelectric power was positive below 300K. The measured thermoelectric power of La2NiO4.03 decreased linearly with temperature. The dc conductivity showed a temperature variation consistent with the variable range hopping mechanism at low temperatures and the adiabatic polaron hopping mechanism at high temperatures. The low temperature dc conductivity mechanism in La2NiO4.03 was analyzed using Mott's approach. The temperature dependence of thermoelectric power and dc conductivity suggests that the charge carriers responsible for conduction are strongly localized. The relaxation mechanism has been discussed in the frame of the electric modulus and loss spectra. The scaling behavior of the modulus and loss tangent suggests that the relaxation describes the same mechanism at various temperatures. The logarithmic angular frequency dependence of the loss peak is found to obey the Arrhenius law with activation energy of ~ 0.106eV. At low temperature, variable range hopping and large dielectric relaxation behavior for La2NiO4.03 are consistent with the polaronic nature of the charge carriers.

Polysilazane and silazane-based precursor films were deposited on stacked TiN/Ti/TEOS/Si-substrate by spin-coating, then annealed at 150~400oC, integrated further to form the top electrode and pad, and finally characterized. Theprecursor solutions were composed of 20% perhydro-polysilazane (SiH2NH)n, and 20% hydropolymethyl silazane(SiHCH3NH)n in dibutyl ether. Annealing of the precursor films led to the compositional change of the two chemicals intosilicon (di)oxides, which was confirmed by Fourier transform infrared spectroscopy (FTIR) spectra. It is thought that thedifferent results that were obtained originated from the fact that the two precursors, despite having the same synthetic routeand annealing conditions, had different chemical properties. Electrical measurement indicated that under 0.6MV/cm, a largercapacitance of 2.776×10−11 F and a lower leakage current of 0.4pA were obtained from the polysilazane-based dielectric films,as compared to 9.457×10−12 F and 2.4pA from the silazane-based film, thus producing a higher dielectric constant of 5.48compared to 3.96. FTIR indicated that these superior electrical properties are directly correlated to the amount of Si-O bondsand the improved chemical bonding structures of the spin-on dielectric films, which were derived from a precursor without C.The chemical properties of the precursor films affected both the formation and the electrical properties of the spin-on dielectricfilm.

It is known that the relative dielectric constant of insulating polyethylene matrix composites with conducting materials (such as carbon black and metal powder) increases as the conducting material content increases below the percolation threshold. Below the percolation threshold, dielectric properties show an ohmic behavior and their value is almost the same as that of the matrix. The change is very small, but its origin is not clear. In this paper, the dielectric properties of carbon black-filled polyethylene matrix composites are studied based on the effect medium approximation theory. Although there is a significant amount of literature on the calculation based on the theory of changing the parameters, an overall discussion taking into account the theory is required in order to explain the dielectric properties of the composites. Changes of dielectric properties and the temperature dependence of dielectric properties of the composites made of carbon particle and polyethylene below the percolation threshold for the volume fraction of carbon black have been discussed based on the theory. Above the percolation threshold, the composites are satisfied with the universal law of conductivity, whereas below the percolation threshold, they give the critical exponent of s = 1 for dielectric constant. The rate at which the percentages of both the dielectric constant and the dielectric loss factor for temperature increases with more volume fraction below the percolation threshold.

For the aim of low-temperature co-fired ceramic microwave components, sintering behavior and microwave properties (dielectric constant , quality factor Q, and temperature coefficient of resonant frequency ) are investigated in [BCZN] ceramics with addition of . The specimens are prepared by conventional ceramic processing technique. As the main result, it is demonstrated that the additives () show the effect of lowering of sintering temperature and improvement of microwave properties at the optimum additive content. The addition of 0.25 wt% lowers the sintering temperature to utilizing liquidphase sintering and show the microwave dielectric properties (dielectric constant = 75, quality factor = 572 GHz, temperature coefficient of resonance frequency ). The estimated microwave dielectric properties with addition (increase of , decrease of , shift of to negative values) can be explained by the observed microstrucure (sintered density, abnormal grain structure) and possibly high-permittivity (BZN) phase determined by X-ray diffraction.

MgTiO3 thin films were prepared by r.f. magnetron sputtering in order to prepare miniaturized NPO type MLCCs.MgTiO3 films showed a polycrystalline structure of ilmenite characterized by the appearance of (110) and (202) peaks. Theintensity of the peaks decreased with an increase in the chamber pressure due to the decrease of crystallinity which resultedfrom the decrease of kinetic energy of the sputtered atoms. The films annealed at 600oC for 60min. showed a fine grainedmicrostructure without micro-cracks. The grain size and roughness of the MgTiO3 films decreased with the increase of chamberpressure. The average surface roughness was 1.425~0.313nm for MgTiO3 films prepared at 10~70mTorr. MgTiO3 films showeda dielectric constant of 17~19.7 and a dissipation factor of 2.1~4.9% at 1MHz. The dielectric constant of the films is similarto that of bulk ceramics. The dielectric constant and the dissipation factor decreased with the increase of the chamber pressuredue to the decrease of grain size and crystallinity. The leakage current density was 10−5~10−7A/cm2 at 200kV/cm and this valuedecreased with the increase of the chamber pressure. The small grain size and smooth surface microstructure of the filmsdeposited at high chamber pressure resulted in a low leakage current density. MgTiO3 films showed a near zero temperaturecoefficient and satisfied the specifications for NPO type materials. The dielectric properties of the MgTiO3 thin films preparedby sputtering suggest the feasibility of their application for MLCCs.

BaTiO3/epoxy composites have been widely investigated as promising materials for embedded capacitors in printed circuit boards. It is generally known that the dielectric constant (K) of the BaTiO3/epoxy composites increases with improvement of the dispersion of BaTiO3 particles in the epoxy matrix that comes from adding surfactant. The influences of surfactant addition on the dielectric properties of the BaTiO3/epoxy composites are reported in the present study. The dielectric constant of the BaTiO3/epoxy composites is not significantly affected by the surfactant addition. However, the temperature coefficient of capacitance increases and the peel strength decreases as the amount of added surfactant increases. The influences of surfactant addition on the dielectric properties of the neat epoxy are also very similar to those of the BaTiO3/epoxy composites. The residual surfactant in the BaTiO3/epoxy composites affects the temperature coefficient of capacitance and the peel strength of the epoxy matrix, which in turn affects the temperature coefficient of capacitance and the peel strength of the BaTiO3/epoxy composites.

Unreported dielectrics based on the binary system of MgO-SiO2 were investigated as potential candidates for microwave dielectric applications, particularly those demanding a high fired density and high quality factors. Extensive dielectric compositions having different molar ratios of MgO to SiO2, such as 2:1, 3:1, 4:1, and 5:1, were prepared by conventional solid state reactions between MgO and SiO2. 1 mol% of V2O5 was added to aid sintering for improved densification. The dielectric compositions were found to consist of two distinguishable phases of Mg2SiO4 and MgO beyond the 2:1 compositional ratio, which determined the final physical and dielectric properties of the corresponding composite samples. The increase of the ratio of MgO to SiO2 tended to improve fired density and quality factor (Q) without increasing grain size. As a promising composition, the 5MgO.SiO2 sample sintered at 1400 ˚C exhibited a low dielectric constant of 7.9 and a high Q × f (frequency) value of ~99,600 at 13.7 GHz.

This paper presents a new method for the improvement of color temperature without the change of the driving scheme using transparent dielectric layers with various metal oxides (CeO2, Co3O4, CuO, Fe2O3, MnO2, NiO) in plasma display panels (PDP). In this study, we fabricated ZnO-B2O3-SiO2-Al2O3 glasse with various metal oxides and examined the optical properties of these glasses. As the metal oxides were added to the glasses, the visible transmittances of the dielectric layers decreased and the transmittances in special wavelength regions were reduced at different rates. The change of the transmittance in each wavelength range induced the variation of the visible emission spectra and the change of the color temperature in the PDP. The addition of Co3O4 and CuO slightly decreased the intensity of the blue light, but the intensities of the green and the red light were significantly decreased. Therefore, the color temperature can be improved from 6087K to 7378K and 7057K, respectively.

The development of low-k materials is essential for modern semiconductor processes to reduce the cross-talk, signal delay and capacitance between multiple layers. The effect of the CH4 concentration on the formation of SiOC(-H) films and their dielectric characteristics were investigated. SiOC(-H) thin films were deposited on Si(100)/SiO2/Ti/Pt substrates by plasma-enhanced chemical vapor deposition (PECVD) with SiH4, CO2 and CH4 gas mixtures. After the deposition, the SiOC(-H) thin films were annealed in an Ar atmosphere using rapid thermal annealing (RTA) for 30min. The electrical properties of the SiOC(-H) films were then measured using an impedance analyzer. The dielectric constant decreased as the CH4 concentration of low-k SiOC(-H) thin film increased. The decrease in the dielectric constant was explained in terms of the decrease of the ionic polarization due to the increase of the relative carbon content. The spectrum via Fourier transform infrared (FT-IR) spectroscopy showed a variety of bonding configurations, including Si-O-Si, H-Si-O, Si-(CH3)2, Si-CH3 and CHx in the absorbance mode over the range from 650 to 4000 cm-1. The results showed that dielectric properties with different CH4 concentrations are closely related to the (Si-CH3)/[(Si-CH3)+(Si-O)] ratio.

BaTiO3/epoxy composites can be applied as the dielectric materials for embedded capacitors. The effects of the degree of BaTiO3 particle agglomeration on the dielectric properties of BaTiO3/epoxy composites were investigated in the present study. The degree of particle agglomeration was controlled by the milling of the agglomerated particles. The size and content of the agglomerated BaTiO3 particles decreased with an increase in the milling time. The dielectric constants and polarizations of BaTiO3/epoxy composites abruptly decreased with the increase of the milling time. It was concluded that the dielectric constants and polarizations of BaTiO3/epoxy composites decreased as the degree of particle agglomeration decreased. The degree of agglomeration of BaTiO3 particles turned out to be a very influential factor on the dielectric properties of BaTiO3/epoxy composites.

[ BaO·Nd2O3·5TiO2 ] (BNT) ceramics modified with a borate glass containing Ba, Nd and Ti as glass constituents were investigated with regard to their sintering behavior and microwave dielectric properties. An addition of iso-component glass significantly improved the sinterabilty of the BNT ceramics and lowered the sintering temperature. A maximum density of 5.29 g/cm3 and an x-y shrinkage of 17% were obtained for BNT ceramics containing 10wt.% of the glass sintered at 1100˚C. The dielectric composition without the glass additive was only slightly densified at 1100˚C. The resulting sample exhibited two crystalline phases, BaNd2Ti5O14 and Ba2Ti9O20, regardless of sintering temperature and glass content. When >10wt.% glass was added, exaggerated grain growth with a less uniform microstructure was found, resulting in the subsequent reduction of the fired density and the dielectric properties. BNT ceramics containing 10wt.% of the isocomponent glass sintered at 1100˚C for 4 h showed promising dielectric properties of k = 71.3 and Q = 1,330.