Microwave dielectric properties of (1 - x)(Mg0.95Co0.05)TiO3–x(Na0.5La0.5)TiO3 ceramic system

Cheng-Liang Huang,Jhih-Yong Chen,Yen-Hsing Wang,Bing-Jing Li 한국물리학회 2009 Current Applied Physics Vol.9 No.6

The microstructures and the microwave dielectric properties of the (1 - x)(Mg0.95Co0.05)TiO3– x(Na0.5La0.5)TiO3 ceramic system were investigated. Two-phase system was confirmed by the XRD patterns and the EDX analysis. A co-existed second phase (Mg0.95Co0.05)Ti2O5 was also detected. The microwave dielectric properties are strongly related to the density and the matrix of the specimen. A new microwave dielectric material 0.88(Mg0.95Co0.05)TiO3–0.12(Na0.5La0.5)TiO3, possessing an excellent combination of dielectric properties: εr ~22.36, Q × f ~ 110,000 GHz (at 9 GHz), τf ~ 2.9 ppm/℃), is proposed as a candidate dielectric for GPS patch antennas. The microstructures and the microwave dielectric properties of the (1 - x)(Mg0.95Co0.05)TiO3– x(Na0.5La0.5)TiO3 ceramic system were investigated. Two-phase system was confirmed by the XRD patterns and the EDX analysis. A co-existed second phase (Mg0.95Co0.05)Ti2O5 was also detected. The microwave dielectric properties are strongly related to the density and the matrix of the specimen. A new microwave dielectric material 0.88(Mg0.95Co0.05)TiO3–0.12(Na0.5La0.5)TiO3, possessing an excellent combination of dielectric properties: εr ~22.36, Q × f ~ 110,000 GHz (at 9 GHz), τf ~ 2.9 ppm/℃), is proposed as a candidate dielectric for GPS patch antennas.

Bi₄Ti₃O₁₂ 박막의 구조적 특성과 유전 특성에 미치는 산소 열처리 효과

차유정,성태근,남산,정영훈,이영진,백종후,Cha, Yu-Jeong,Seong, Tae-Geun,Nahm, Sahn,Jeong, Young-Hun,Lee, Young-Jin,Paik, Jong-Hoo 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.4

$Bi_{4}Ti_{3}O_{12}$ (BiT) thin films were grown on the Pt/Ti/$SiO_2$/si substrate using a metal organic decomposition (MOD) method. Effects of oxygen annealing on the structural properties and dielectric properties of the BiT thin films were investigated. The BiT films were well developed when rapid thermal annealed at $>500^{\circ}C$ in oxygen ambient. For the film annealed at $700^{\circ}C$, no crystalline phase was observed under oxygen free annealing atmosphere while its crystallinity was significantly enhanced as the oxygen pressure increased. The BiT film also exhibited a smooth surface with defect free grains. A high dielectric constant and a low dielectric loss were achieved satisfactory in the frequency range from 75 kHz to 1 MHz. Especially, the BiT film, annealed at $700^{\circ}C$ and 10 torr oxygen pressure, showed good dielectric properties: dielectric constant of 51 and dielectric loss of 0.2 % at 100 kHz. Its leakage current was also considerably improved, being as $0.62\;nA/cm^2$ at 1 V. Therefore, it is considered that the oxygen annealing has effects on an enhancement of crystallinity and dielectric properties of the BiT films.

Dielectric Properties of Orthorhombic Dysprosium Manganites

Wang, Wei Tian Materials Research Society of Korea 2019 한국재료학회지 Vol.29 No.12

Orthorhombic dysprosium manganite DyMnO₃ with single phase is synthesized using solid-state reaction technique and the crystal structure and dielectric properties as functions of temperature and frequency are investigated. Thermally activated dielectric relaxations are shown in the temperature dependence of the complex permittivity, and the respective peaks are found to be shifted to higher temperatures as the measuring frequency increases. In Arrhenius plots, activation energies of 0.32 and 0.24 eV for the high- and low-temperature relaxations are observed, respectively. Analysis of the relationship between the real and imaginary parts of the permittivity and the frequencies allows us to explain the dielectric behavior of DyMnO₃ ceramics by the universal dielectric response model. A separation of the intrinsic grain and grain boundary properties is achieved using an equivalent circuit model. The dielectric responses of this circuit are discerned by impedance spectroscopy study. The determined grain and grain boundary effects in the orthorhombic DyMnO₃ ceramics are responsible for the observed high- and low-temperature relaxations in the dielectric properties.

Electrical Properties of Copper Substituted Nickel Ferrites

G. Ravi Kumar,Y. C. Venudhar,A. T. Raghavender,K. Vijaya Kumar 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.7

The Ni-Cu ferrites, Ni1−xCuxFe2O4 (0.0 ≤ x ≤ 1.0) were prepared by using the sol-gel method. The X-ray diffraction patterns of all the samples showed the formation of a single-phase spinel structure. The lattice parameter was found to increase with increasing copper concentration. The electrical properties, such as the d. c. conductivity as a function of the temperature, and the dielectric constant, the dielectric loss factor and the dielectric loss tangent as function of the frequency were investigated. The d. c. conductivity was found to increase with increasing temperature in accordance with the Verwey hopping mechanism. The dielectric constant, the dielectric loss factor and the dielectric loss tangent were found to decrease with increasing frequency. The dielectric constant followed the Maxwell-Wagner interfacial polarization. A suitable explanation was given for the frequency and the composition dependences of the dielectric properties.

LTCC 기판의 60 GHz 대역 유전특성 및 LTCC 위에 구현된 전송선로의 전달특성 측정

김동영 ( Dong Young Kim ),문재경 ( Jae Kyoung Mun ),김해천 ( Hae Cheon Kim ),유현규 ( Hyun Kyu Yu ) 대한금속재료학회 ( 구 대한금속학회 ) 2008 ELECTRONIC MATERIALS LETTERS Vol.4 No.1

The dielectric properties at millimeter-wave band(MMW) of commercially available LTCC substrate were measured using cavity resonance method. A6S substrate from Ferro has best dielectric properties at MMW bands, and the other substrates also have good dielectric properties. CBCPW (Conductor backed coplanar waveguid) lines for MMW were designed and measured. The transmission losses of CBCPW lines on LTCC substrate with tand less than 0.002 were 0.1dB/mm. As the tand of LTCC substrate increases to 0.004, the losses of CBCPW lines at 60 GHz increase to 0.15dB/mm. However, this transmission loss of 0.15dB/mm is sufficiently low in the application of LTCC as a packaging technology at MMW band. As expected, the transmission losses of lines were critically dependant on the dielectric properties of the substrate used.

Structural, Optical and Electrical Properties of PVA/PEO/SnO2 New Nanocomposites for Flexible Devices

Aseel Hadi,Ahmed Hashim,Yahya Al-Khafaji 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.3

Fabrication of polyvinyl alcohol (PVA)–polyethylene oxide (PEO) blend doped with tin dioxide (SnO 2 ) nanocomposites has been investigated for flexible electrical and optical applications. The prepared nanocomposites have low cost, lightweight, flexible, high corrosion resistance, good optical and electrical properties. These properties of fabricated nanocomposites make it useful for diff erent optoelectronics applications such as: sensors, solar cells, transistors, diodes, capacitors, energy storage etc. The structural, optical and electrical properties of (PVA–PEO–SnO 2 ) nanocomposites have been studied. The experimental results of optical properties for (PVA–PEO–SnO2) nanocomposites showed that the nanocomposites have higher absorbance in UV region at wavelength range (200–280) nm. This behavior makes the nanocomposites may be used for optoelectronics applications. The absorbance, absorption coeffi cient, extinction coeffi cient, refractive index, real and imaginary dielectric constants and optical conductivity of polymer blend are increased with the increase in SnO2 nanoparticles concentrations while the transmittance and energy band gap are decreased with the increase in SnO2 nanoparticles concentrations. The decrease in energy band gap is useful for diff erent optoelectronics devices industries. Also, the results showed that the dielectric constant and dielectric loss decrease while the conductivity increases with the increase in frequency. The dielectric constant, dielectric loss and conductivity are increased with the increase in SnO2 nanoparticles concentrations. The electrical properties showed that the (PVA–PEO–SnO2) nanocomposites have good dielectric parameters which it may be used for different electronics applications.

Surface and Dielectric Properties of Oriental Lacquer Films Modified by UV-Curable Silicone Acrylate

홍진후,김현경 한국고분자학회 2006 Macromolecular Research Vol.14 No.6

In order to achieve an oriental lacquer (OL) film with a thick consistency, UV-curable silicone acrylate (SA) was added to OL by a dual curing process. The addition of 5wt% UV-curable SA to the OL formulation enabled the preparation via a single drying step of a 77m-thick film exhibiting excellent surface properties. FTIR-ATR was used to investigate the effect of UV-curable SA on the behavior of film formation during curing, and the relaxation behavior of the produced films was investigated by dielectric spectroscopy. Dielectric properties were measured in the frequency range 10-2-105Hz at various temperatures between -100 and 200C. The results demon strated that OL modified by UV-curable SA has a higher glass transition temperature and stronger secondary relaxation at a lower temperature than the conventional OL system. The OL film modified with UV-curable SA was presumed to be harder at the surface and tougher than conventional OL film.

Synthesis and Characterization of LTC x(Ni0.90 Mg0.10 )Fe2O4-(1-x)(Ba0.88 Sr0.10 Ca0.02)(Ti0.95 Zr0.05)O3 Ceramic Composites for Antenna Application

Sk. Saddam Hossain,Deepshikha Shekhawat,P. K. Roy 한국전기전자재료학회 2023 Transactions on Electrical and Electronic Material Vol.24 No.6

The objective of the work is to synthesize low-temperature co-fired (LTC) biphasic ceramic composites of dielectric (Ba0.88 Sr0.10 Ca0.02)(Ti0.95 Zr0.05)O3 and spinel ferrite (Ni0.90 Mg0.10 )Fe2 O4 with diff erent fractions by a standard ceramic route and to study the effects on physical, magnetic, dielectric and electrical properties for antenna application. The respective ferrite and dielectric powders are prepared by two different techniques, i.e., sol–gel auto combustion and solid–state route, respectively. Dielectric-ferrite mixed powder is pressed into pellets and toroids by uniaxial pressure, and the pellets are sintered at 950°C. The X-ray diff raction (XRD) & FTIR analysis disclose the coexisting of perovskite and spinel phases in the composite without interacting with each other. The SEM analysis displays a compact structure with few porosities. The changes in dielectric constant and loss tangent of composite specimens with frequency are also investigated. The dielectric constant is continuously increased, and permeability is decreased with increasing dielectric content. Observations of M-H hysteresis loops and dielectric measurements support the magnetic and dielectric nature of the composite specimens. The magnetoelectric voltage coefficient is confi rmed to monitor the interaction between magnetic and dielectric phases. The high-performance composites are useful for antenna applications as they have almost equal permittivity and permeability.

Effect of nanofillers on the dielectric properties of epoxy nanocomposites

Wang, Q.,Chen, G. Techno-Press 2012 Advances in materials research Vol.1 No.1

Epoxy resin is widely used in high voltage apparatus as insulation. Fillers are often added to epoxy resin to enhance its mechanical, thermal and chemical properties. The addition of fillers can deteriorate electrical performance. With the new development in nanotechnology, it has been widely anticipated that the combination of nanoparticles with traditional resin systems may create nanocomposite materials with enhanced electrical, thermal and mechanical properties. In the present paper we have carried out a comparative study on dielectric properties, space charge and dielectric breakdown behavior of epoxy resin/nanocomposites with nano-fillers of $SiO_2$ and $Al_2O_3$. The epoxy resin (LY556), commonly used in power apparatus was used to investigate the dielectric behavior of epoxy resin/nanocomposites with different filler concentrations. The epoxy resin/nanocomposite thin film samples were prepared and tests were carried out to measure their dielectric permittivity and tan delta value in a frequency range of 1 Hz - 1 MHz. The space charge behaviors were also observed by using the pulse electroacoustic (PEA) technique. In addition, traditional epoxy resin/microcomposites were also prepared and tested and the test results were compared with those obtained from epoxy resin/nanocomposites.

두께 변화에 따른 (111) 방향으로 성장된 PZT 후막의 미세구조와 전기적 특성

조삼연,양선아,부상돈 한국물리학회 2011 새물리 Vol.61 No.10

Pb(Zr,Ti)O₃ (PZT) thick films have attracted considerable attention because they are widely used in micro-electromechanical systems (MEMS), micro-power harvesting systems and high frequency ultrasonic transducers for higher imaging resolution. Their popularity is based on their high ferroelectric and piezoelectric properties. However, these properties are closely related to the film's thickness. Therefore, we investigated the thickness dependent ferroelectric and dielectric properties of PZT films. The PZT thick films were fabricated on (111) Pt/Ti/SiO2₂/Si (Pt/Si) substrats by using a sol-gel method with a multi-coating process. Their orientation was controlled by using a layer(s) by layer(s) annealing process. The X-ray diffraction (XRD) analysis showed that all the films were highly oriented along the (111) direction. Increases in the remnant polarization and the dielectric constant with increasing film thickness were observed in the thickness range from 0.3㎛to 1.7㎛. However, thicker films greater than (2.3㎛)showed abrupt decreases in the remnant polarization and the dielectric constant. Thickness dependent of the ferroelectric and the dielectric properties can be explained in terms of the domain structure, non-switching interface layer, and grain size. 솔-젤 (sol-gel) 방법으로 Pt(111)/Ti/SiO₂/Si(100) (Pt/Si) 기판위에 (111) 방향으로 Pb(Zr_(0.52)Ti_(0.48)O₃ (PZT) 후막을제작하였다. 박막 증착시 각 층들을 반복 열처리 방법으로 배향성을조절하였으며, X-선 회절 분석으로부터 0.3~2.3㎛의두께에서 PZT 후막은 (111) 방향으로 성장 되었다. 이와 같이 후막증착시 증착된 한 층을 반복 열처리 방법으로 후막의 배향성에 따른전기적 특성 변화를 최소화 한 후, 두께 변화에 따른 PZT 후막의 전기적특성을 조사하였다. PZT 후막은 두께 증가에 따라 강유전 및 유전 특성이향상되었으며, 1.7㎛ 두께에서 PZT 후막의 잔류분극 및 유전상수값은 29.2μC/cm², 1279로 최대값을 나타내었다. 그러나 후막의두께가 2.3㎛ 일 때 25.42μC/cm², 1065로 감소하였다. 이현상은 두께 변화에 따른 PZT 후막의 구역 (domain) 구조 변화, 계면의non-switching 층의 존재와 낟알 크기 (grain size) 변화에 기인한것이다.