• 한국세라믹학회지
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• 제44권11호
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• pp.627-632
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• 2007

We have studied the ac conductivity of insulating $La_{0.7}Sr_{0.3}FeO_3$ in the frequency range 20 Hz-l MHz and in the temperature range 80-300 K. We have analyzed experimental results in the frame works of the quantum-mechanical tunneling mechanism (QMT) and the hopping of barrier mechanism (HOB). We observed that small polaron QMT model is the most suitable mechanism for the low temperature ac conductivity of $La_{0.7}Sr_{0.3}FeO_3$.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1995년도 하계학술대회 논문집 C
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• pp.1016-1018
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• 1995

In this paper, we studied the electrical and the microwave properties of the amorphous $As_{10}Ge_{15}Te_{75}$ thin film. The electrical properties of a-$As_{10}Ge_{15}Te_{75}$ thin film were examined d.c. and a.c. bias with annealing condition. As the result of the electrical properties, we observed the physical characteristics of a-$As_{10}Ge_{15}Te_{75}$ thin film such as the density of defect states, characteristic relaxation time, localized density of states, and localized wave function by using CBH and QMT model. We also examined the microwave conduction properties before and after d.e. switching.

• 한국전기전자재료학회논문지
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• 제19권3호
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• pp.228-232
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• 2006

In this paper, in order to develop low temperature sintering $PbTiO_3$-system piezoelectric ceramics for thickness-vibration-mode piezoelectric transformer, $Pb_{0.76}Ca_{0.24}[(Mn_{1/3}Sb_{2/3})_{0.04}Ti_{0.96}]O_3$ ceramics using $0.25\;wt\%\;CaCO_3$ and $0.2\;wt\%\;Li_{2}CO_3$ as sintering aids were manufactured according to the variation of poling field. The specimens could be sintered at $930\;^{\circ}C$. The piezoelectric properties were investigated according to the poling field. The maximum properties showed at the field of 6.5 kV/mm, which had kt of 0.49, Qmt of 1816, and $d_{33}$ of 81.4 pC/N.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
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• pp.176-177
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• 2005

In this paper, in order to develop low temperature sintering $PbTiO_3$-system piezoelectric ceramics for thickness-vibration-mode piezoelectric transformer, $Pb_{0.76}Ca_{0.24}[(Mn_{1/3}Sb_{2/3})_{0.04}Ti_{0.96}]O_3$ ceramics using $0.25wt%CaCO_3$ and 0.2wt%$Li_2CO_3$ as sintering aids were manufactured according to the variation of poling field. Specimens could be sintered at the sintering temperature of $930^{\circ}C$. The piezoelectric properties increased according to the increase of poling field and showed the maximum values (kt=0.49, Qmt=1816, and $d_{33}$=81.4pC/N) under 6.5kV/mm.

• 한국안광학회지
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• 제6권1호
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• pp.111-117
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• 2001

BB-계열에서 $Bi_2O_3$ 함량이 증가할수록 비저항의 peak는 낮은 온도로 이동하였다. 비저항에 대한 완화현상을 설명하기 위한 등가회로는 G-C의 병열회로이고, 전기전도과정은 체적전도이며, 완화의 형태는 non-Debye 형이었다. 그리고 BB-계열의 전기전도 현상은 일반적으로 s가 거의 일정한 (s=0.8) QMT 모델에 잘 맞는 것으로 판명되었다.