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Sodium Potassium Niobium Tantalate계의 압전성에 미치는 Ag와 Li 치환효과
강동헌 水原大學校 2019 論文集 Vol.33 No.-
Lead free piezoelectric specimen, Ag or Li doped NKMNT ((Na0.5K0.5)1-X(M)x](Nb1-XTaX)O3) (M = Ag, Li) were prepared by the conventional ceramic process. Their crystal structures, microstructures, dielectric and piezoelectric properties were investigated with different dopant contents and sintering temperatures. For all specimens, a typical perovskite structure was observed, except for the results that for Li doped ceramics, apparent peak split between (002) and (200) planes and a trace of secondary phase identified as K3Li2Nb5O15 was observed. Sinterability was apparently changed with doping concentration and sintering temperature. Maximum density was obtained for x=0.1 (Ag) and x=0.075 (Li), sintered at 1100℃ for 2h and 1080℃ for 2h, respectively. At that condition, apparent improvements in ɛr, kp and d33 were observed. Among them, doping effect on sinterability and electrical properties clearly revealed for M = Li, implying more contribution of Li doping due to its smaller ionic radius and crystal phase transition.
LTCC적층형 대역통과필터의 공정 및 특성 최적화 연구
강동헌,차훈주 수원대학교 산업기술연구소 2003 산업기술연구소논문집 Vol.18 No.-
Multi-layered ceramic chip bandpass filter for 2.4 GHz ISM band was fabricated by using LTCC (Low Temperature Co-fired Ceramics) technology, and related processing parameters such as lamination condition, sintering temperature, time and electrode condition were investigated in terms of filters characteristics. The BPF consists of coupled stripline resonators and coupling capacitors. The sintering shrinkages was affected substantially by lamination pressure and sintering temperature. And insertion loss with inner conductor thickness has been discussed and realized. Insertion losses in the passband were less than 2 dB and the attenuation more than 25 dB at 2.1 GHz. The frequency response characteristics of the chip BPF is well acceptable for bluetooth application.
Pb(Mg1/3 Nb2/3)O3 세라믹스의 전기적 특성
강동헌,윤기현 한국세라믹학회 1989 한국세라믹학회지 Vol.26 No.5
PMN ceramics with excess MgO addition in the range of 0 to 70m/o were prepared, and their electrical properties, such as dielectric constant, tan$\delta$, diffuseness coefficient, remanent polarization, coercive field and electrical conductivity were measured. Dielectric constant and remanent polarization increased with up to 5m/o excess MgO and then decreased presumely due to the precipitation of second phase, etc. Electrical conductivity slightly increased with the addition of excess MgO.
Lead Magnesium Niobate 계 세라믹스의 전왜성에 미치는 미세구조 의존성
姜東憲 수원대학교 산업기술연구소 1993 산업기술연구소논문집 Vol.8 No.-
Pb(Mg_1/3Nb_2/3)O_3 and Pb(Mg_1/3Nb_2/3)O_3 - PbTiO_3 ceramics were prepared by the columbite precursor method and their electrostrictive properties were investigated as a function of sintering temperature and excess MgO content. For the PMN ceramics, the longitudinal field induced strain, x increased with increasing sintering temperature and the addition of 5 mol% excess MgO led to the further increases in the maximum dielectric constant and electrostrictive strain. For the PMN-PT ceramics, larger strain value, compared to that of the PMN ceramics, was induced at room temperature and also electrostrictive coefficient, Q slightly increased with the addition of PbTiO_3. These results were explained by microstructure analysis.
무연계 (Bi0.5Na0.5)TiO3 박막의 강유전특성 연구
강동헌 水原大學校 2013 論文集 Vol.27 No.-
(Bi0.5Na0.5)TiO3 (BNT) is well known as an excellent candidate for the lead free ferroelectric and piezoelectric materials due to its relatively high Tc, Pr and Ec, compared with other lead free materials. For BNT material, it is well known that Bi and Na have relatively low melting and boiling points compared with those of other elements, and are vaporized easily. In this study, BNT thin films were fabricated by the sol-gel method and their dielectric properties were investigated as a function of excess Bi and Na contents. As the content of excess Bi and Na increased, their properties were improved. For 0.1 mol addition, it showed the highest dielectric constant, remanant polarization and pyroelectric coefficient regardless annealing condition. While their properties were degraded with further excess Bi and Na addition. These results were explained in terms of phase present by XRD and surface morphology by SEM and AFM
친환경 비납계 Sodium potassium niobate 압전세라믹스의 조성 최적화
姜東憲 水原大學校 2012 論文集 Vol.26 No.-
Lead-free piezoelectric [(Na0.5K0.5)1-x(A)x][(Nb)1-y-z(B)y(Mn)Z]O3 (A:Ag or Li, B=Ta) specimens prepared by the conventional ceramic processing. Their crystal structure, microstructure, dielectric and piezoelectric properties were investigated with different compositions (substituents and contents). Electrical properties of the specimens increased up to 0.075 mol Ag or Li addition and Ta addition improved their piezoelectric properties. The maximum values, d33, Qm, kp obtained were 153(pC/N), 351, 0.43 for Ag/Ta and 201(pC/N), 141, 0.4 for Li/Ta based NKN systems, respectively. When 0.005 mol Mn was added in Ag/Ta or Li/Ta based specimens, dielectric loss was effectively suppressed below 1.5% and piezoelectric constant, d33 was improved, although dielectric constant and Qm were somewhat lowered. These results were explained in terms of the formation of morphotropic phase boundary, sinterability, grain size, formation of oxygen vacancy and change of transition temperature.
PCFN-PZW계의 마이크로파 유전 특성에 미치는 Pb계 Flux의 영향
강동헌,설충의,차훈주,김영호,길상근,조봉희 한국전기전자재료학회 2002 전기전자재료학회논문지 Vol.15 No.12
(Pb$\_$0.4/Ca$\_$0.6/)(Fe$\_$1/2/Nb$\_$1/2/)O$_3$ system was modified by 10 mol% Pb(Zn$\_$1/2/W$\_$1/2/)O$_3$ addition and their sinterability and microwave properties were investigated as a function of the amount of flux (0.975PbO-0.025SnO$_2$). With increasing flux content, single perovskite phase was maintained up to 3 wt% flux addition and further addition led to the presence of Pb-rich second phase which was confirmed by EDS analysis. The apparent densities of PCFN-PZW specimen increased and showed maximum values at 2.5 wt% flux addition for the Ts=1000$^{\circ}C$ and 2.0wt% flux addition for the Ts=1050$^{\circ}C$, respectively. The dielectric constant and Q$.$f values strongly depended on the variation of density and microstructure, where the optimum values of $\varepsilon$$\_$r/ = 91.95, Q$.$f = 5938GHz, TCF = +8.15ppm/$^{\circ}C$ were obtained for the 2.5wt% flux added PCFN-PZW specimen sintered at 1000$^{\circ}C$ for 4h.