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Thermal Properties of 0.9CaMgSi2O6-0.1MgSiO3 Glass-Ceramics
전창준,선귀남,이종규,주한새,김응수 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.1
Dependencies of thermal properties on the crystallization behavior of 0.9CaMgSi2O6-0.1MgSiO3 glass-ceramics were investigated as a function of heat-treatment temperature from 750oC to 950oC. The crystallization behavior of the specimens depended on the heat-treatment temperature, which could be evaluated by differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FT-IR), and X-ray diffraction (XRD) analysis by the Rietveld-reference intensity ratio (RIR) combined procedure. With an increase of the heat-treatment temperature, the thermal conductivity and thermal diffusivity of the heat-treated specimens increased. These results could be attributed to the increase of crystallization with heat-treatment temperature. However, the specific heat capacity of the heat-treated specimens was not affected by the heat-treatment temperature. The thermal conductivities measured from 25oC to 100oC were also discussed for application to lighting-emitting diode (LED) packages and substrate materials.
Microwave Dielectric Properties of MgTiO3, MgTa2O6 / Polytetrafluoroethylene Composite
전창준,김응수 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.3
Effects of ceramics on the microwave dielectric properties of polytetrafluoroethylene (PTFE) composites filled with MgTiO3 (MTi) and/or MgTa2O6 (MTa) were investigated. The dielectric constant (K), quality factor (Qf), and temperature coefficient of resonant frequency (TCF) of the composites were dependent on the type and volume fraction (Vf) of the ceramics. For the composites mixed with MTa and MTi, the K and TCF values decreased with increasing MTi content. The Qf values of the composites were affected by relative density. The measured K values of the composites were compared with those predicted by several theoretical models. Good microwave dielectric properties with values of K =3.6, Qf = 7,788 GHz, and TCF = −0.19 ppm/oC were obtained for the composites with 0.1 Vf ceramics (mixed 0.025MTa and 0.075MTi).
전창준,황하나,정영훈,윤지선,남중희,조정호,백종후,임종봉,남산,김응수 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.9
0.72Pb(Zr0.47Ti0.53)O3-0.28Pb[(Zn0.45Ni0.55)1/3Nb2/3]O3 (0.72PZT-0.28PZNN) thick films wereprepared by using a tape casting method to develop new materials with high energy-density applicableto energy-harvesting devices. The piezoelectric strain constant (d33), dielectric constant("T33/"0), piezoelectric voltage constant (g33) and transduction coefficient (d33·g33) of the films wereaffected by the sintering temperature. These results could be attributed to the crystal structure,microstructures and secondary phases. However, the dielectric loss (tan) of the films was notchanged remarkably with increasing sintering temperature. Typically, a d33 of 452 pC/N, εT33/ε0 of 1444, d33·g33 of 20,340 × 10−15 m2/N and tanδ of 0.15% were obtained for the films sintered at 1050 ℃ for 1 h. The power generation performance of the piezoelectric unimorph cantilever wasassessed to demonstrate the feasibility of the 0.72PZT-0.28PZNN piezoelectric thick film. Also,theoretical models were employed to predict the resonance frequency of the unimorph cantilevergenerator, and the predicted values were compared with experimental data.
전창준,김응수 한국세라믹학회 2011 한국세라믹학회지 Vol.48 No.3
Dependencies of dielectric properties on MgTa_2O_6, MgNb_2O_6, and MgWO4 (Mg-based ceramics) fillers of the polystyrene (PS) matrix composites were investigated as a function of frequency. With increasing frequency from 1 GHz to 7.3 GHz, the dielectric constant (K) of the composites was not changed significantly, while the dielectric loss (tanδ) of the composites was slightly decreased. The K, tanδ, and temperature coefficient of resonant frequency (TCF) of the composites were dependent on the type and amount of ceramics at 11 GHz. Also, several theoretical models have been employed to predict the effective dielectric constant of the composites and the results were compared with experimental data. Typically, a K value of 6.67, tanδ of 0.56×10^(−3), and TCF of −4.99 ppm/℃ were obtained for the PS composites with 0.4 volume fraction of MgNb_2O_6 at 11 GHz.
마이크로볼로미터 응용을 위한 스핀 스프레이로 증착된 스피넬 박막
전창준,이귀웅,레득탕,정영훈,윤지선,백종후,조정호,Jeon, Chang Jun,Lee, Kui Woong,Le, Duc Thang,Jeong, Young Hun,Yun, Ji Sun,Paik, Jong Hoo,Cho, Jeong Ho 한국전기전자재료학회 2014 전기전자재료학회논문지 Vol.27 No.12
Spinel thin films were prepared by the spin spray technique to develop new thermal imaging materials annealed at low temperature for uncooled microbolometer applications. The spinel thin films were deposited from $[(Ni_{0.30}Co_{0.33}Mn_{0.37})_{1-x}Cu_x]_3O_4$ ($0.1{\leq}x{\leq}0.2$) solutions and then annealed at $400^{\circ}C$ for 1 h in argon. Effects of Cu content (x) and deposition time on the electrical properties of the annealed films were investigated. With increasing deposition time, the resistivity of the annealed films increased. For the annealed films deposited for 1 min, the resistivity of x=0.15 films was lower than that of x=0.1 films due to the different grain sizes. The high temperature coefficient of resistance (TCR) of the annealed films could be obtained at temperature below $50^{\circ}C$. Typically, the resistivity of $127{\Omega}{\cdot}cm$ and TCR of -5.69%/K at $30^{\circ}C$ were obtained for x=0.1 films with deposition time of 1 min annealed at $400^{\circ}C$ for 1 h in argon.
스핀 스프레이 법으로 제조한 망가나이트 박막의 전기적 특성
전창준,정영훈,윤지선,박운익,백종후,홍연우,조정호,Jeon, Chang Jun,Jeong, Young Hun,Yun, Ji Sun,Park, Woon Ik,Paik, Jong Hoo,Hong, Youn Woo,Cho, Jeong Ho 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.1
Effects of pH value and deposition time on the electrical properties of (NMC) Ni-Mn-Cu-O and (NMCC) Ni-Mn-Cu-Co-O thin films were investigated. The NMC and NMCC films were prepared by spin spray method. The crystal structure and thickness of the annealed films were changed by the pH value and deposition time, respectively. A single phase of cubic spinel structure was confirmed for the annealed films deposited from solutions with pH 7.6. The resistivity of the annealed films was affected by the crystal structure and microstructure. The TCR (temperature coefficient of resistance) was dependent on the $Mn^{3+}/Mn^{4+}$. Typically, the resistivity of $70.5{\Omega}{\cdot}cm$ and TCR of -3.56%/K at room temperature were obtained for NMCC films deposited from solutions with pH 7.6 for 5 min, and annealed at $450^{\circ}C$ for 3 h.