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하종윤,김진상,정대용,김현재,윤석진 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.3
The piezoelectric properties of tetragonal 0.88Pb(Zn1/3Nb2/3)O3-0.12PbTiO3 single crystals are characterized along the <111> direction, which composed the engineering domain configuration in the tetragonal phase. The <111>-oriented crystal possessed smaller d33 values compared to the crystal along the <001> spontaneous polarization direction. Based on phenomenological theory, it is shown that the engineering domain configuration does not enhance the piezoelectric constant in tetragonal 0.88Pb(Zn1/3 Nb2/3)O3-0.12PbTiO3 single crystals. In addition, the electrostrictive coefficients of Q12=−0.03706 m4/C2, Q11=0.10765 m4/C2, and Q44=0.02020 m4/C2 of tetragonal 0.88PZN-0.12PT single crystals were calculated. The piezoelectric properties of tetragonal 0.88Pb(Zn1/3Nb2/3)O3-0.12PbTiO3 single crystals are characterized along the <111> direction, which composed the engineering domain configuration in the tetragonal phase. The <111>-oriented crystal possessed smaller d33 values compared to the crystal along the <001> spontaneous polarization direction. Based on phenomenological theory, it is shown that the engineering domain configuration does not enhance the piezoelectric constant in tetragonal 0.88Pb(Zn1/3 Nb2/3)O3-0.12PbTiO3 single crystals. In addition, the electrostrictive coefficients of Q12=−0.03706 m4/C2, Q11=0.10765 m4/C2, and Q44=0.02020 m4/C2 of tetragonal 0.88PZN-0.12PT single crystals were calculated.
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IMT-2000용 초소헝 적층형 대역 통과 칩 필터 설계 및 제작
임혁,하종윤,심성훈,강종윤,최지원,최세영,오영제,김현재,윤석진,Lim Hyuk,Ha, Jong-Yoon,Sim, Sung-Hun,Kang, Chong-Yun,Choi, Ji-Won,Choi, Se-Young,Oh, Young-Jei,Kim, Hyun-Jai,Yoon, Seok-Jin 한국세라믹학회 2003 한국세라믹학회지 Vol.40 No.10
BiN $b_{0.975}$S $b_{0.025}$ $O_4$저온 동시 소결 세라믹 후막 및 적층 세라믹(Multi-Layer Ceramic, MLC) 공정 기술을 이용한 소형 마이크로파 필터를 설계 및 제작하였다. MLC 칩 대역 통과 필터(BPF)는 소형화와 낮은 가격이라는 장점을 가지고 있다. 제안된 필터는 stripline 공진기와 결합 캐패시터로 구성되며, IMT-2000용 단말기의 수신단 통과 대역에 적합하며 통과 대역 아래쪽 저지 대역에 감쇠극이 형성되도록 설계하였다. 상용 마이크로파 회로 및 구조 설계 tool를 이용하여 제안된 MLC칩 대역 통과 필터의 공진기 전자기적 결합량 변화 및 결합 캐패시턴스에 따른 필터의 주파수 특성, 특히 감쇠극의 위치 변화에 대해 살펴보았다. 제작된 MLC 칩 BPF의 주파수 특성은 시뮬레이션 결과와 매우 일치하였다. A Multi-Layer Ceramic (MLC) chip type Band-Pass Filter (BPF) using BiNb$\_$0.975/Sb$\_$0.025/ $O_4$ LTCC (Low Temperature Co-fired Ceramics) and MLC processing is presented. The MLC chip BPF has the benefits of low cost and small size. The BPF consists of coupled stripline resonators and coupling capacitors. The BPF is designed to have an attenuation pole at below the passband for a receiver band of IMT-2000 handset. The computer-aided design technology is applied for analysis of the BPF frequency characteristics. The attenuation pole depends on the coupling between resonators and the coupling capacitance. An equivalent circuit and structure of MLC chip BPF are proposed. The frequency characteristics of the manufactured BPF is well acceptable for IMT-2000 application.
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결정구조와 이온 분극률에 따른 (Al,Mg,Ta)O<sub>2</sub>고용체의 마이크로파 유전상수 특성
최지원,하종윤,안병국,박용욱,윤석진,김현재 한국전기전자재료학회 2003 전기전자재료학회논문지 Vol.16 No.2
The calculated and measured dielectric constants of (1-x)(A $l_{1}$2/ T $a_{1}$2/) $O_2$-x(M $g_{1}$3/ T $a_{2}$3/) $O_2$ (0$\leq$x$\leq$1.0) solid solutions were investigated by variations of ionic polarizability and crystal structure. (A $l_{1}$2/ T $a_{1}$2/) $O_2$ and (M $g_{1}$3/ T $a_{2}$3/) $O_2$ were orthorhombic and tetragonal trirutile structure, respectively. When (A $l_{1}$2/ T $a_{1}$2/) $O_2$ was substituted by (M $g_{1}$3/ T $a_{2}$3/) $O_2$, the phase transformed to tetragonal structure over 60 mole. Because the total ionic radius of [(Mg+2Ta)/3]$^{4+}$ was slightly bigger than one of [(Al+Ta)/2]$^{4+}$, the lattice parameters increased with an increase of (M $g_{1}$3/ T $a_{2}$3/) $O_2$ substitution. The measured dielectric constant increased with an increase of (M $g_{1}$3/ T $a_{2}$3/) $O_2$ substitution and coincided with dielectric mixing rule and the calculated dielectric constant with the molecular additivity rule. There were some differences between the measured and the calculated dielectric constant. The reason of the lowered dielectric constant comparing with the calculated one was compressed stress due to the electronic structure of tantalum.
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Characteristics of (Ba,Sr)TiO3 Thin Films for Microwave Tunable Device Applications
K. H. Cho,C. Y. Kang,J. S. Kim,최지원,하종윤,이영백,윤석진 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.3
Ferroelectric (Ba0.5Sr0.5)TiO3 (BST) thin films with thicknesses of 500 nm were deposited on LaAlO3 (LAO) substrates by RF magnetron sputtering at 800 C. The BST films were characterized for structure by using X-ray diraction (XRD). The surface morphologes and the thicknesses of BST films were characterized by using atomic force microscopy (AFM) and field-emission scanning electron microscope (FESEM), respectively. We measured the dielectric properties at microwave frequencies (1 – 3 GHz) by using a symmetrical stripline resonator with shorted ends at room temperature. The tunability of the as-deposited and the annealed BST films were 1 % and 27 % at a field of 40 kV/mm and values of tan of 0.0038 and 0.0050, respectively. Through a post-annealing process, we were able to improve the dielectric constant and tunability, although the dielectric loss was slightly increased. The change in the dielectric properties after annealing could be attributed to a change in the film strain.
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