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Nahm, Choon-Woo; Park, Choon-Hyun; Yoon, Hwajoung

doi:10.1023/a:1006739421559

Cited by 34 publications

(6 citation statements)

References 8 publications

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“…However, they possess a few drawbacks (Lee and Tseng 1992) caused by high volatility and reactivity of Bi 2 O 3 . In recent years, Pr-doped ZnO varistors have been studied to overcome these problems (Alles and Burdick 1991;Lee et al 1996;Chun et al 1999;Nahm et al 2000;Chun and Mizutani 2001). Nahm et al reported that the ternary system ZnO-Pr 6 O 11 -CoO-based varistors have highly nonlinear properties when rare earth metal oxides, R 2 O 3 (R = Er, Dy, Nd) are doped (Nahm et al 2000;Nahm 2003).…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, Pr-doped ZnO varistors have been studied to overcome these problems (Alles and Burdick 1991;Lee et al 1996;Chun et al 1999;Nahm et al 2000;Chun and Mizutani 2001). Nahm et al reported that the ternary system ZnO-Pr 6 O 11 -CoO-based varistors have highly nonlinear properties when rare earth metal oxides, R 2 O 3 (R = Er, Dy, Nd) are doped (Nahm et al 2000;Nahm 2003). To develop the varistors of high performance, it is very important to comprehend the effects of the individual additives on varistor characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Nonlinear electrical properties and aging characteristics of (NiO, MgO, Cr2O3)-doped Zn-Pr-Co-R (R = Y, Er) oxide-based varistors

Nahm

2008

Bull Mater Sci

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The electrical properties and stability of the varistors, which composed of (NiO, MgO, Cr 2 O 3 )-doped Zn-Pr-Co-R (Y, Er) oxide-based ceramics, were investigated for different additives. The breakdown voltage of the varistors increased in order of NiO→undoped→MgO→Cr 2 O 3 : 1200→1551→1691→1959 V/cm for ZPCY system and undoped→NiO→MgO→Cr 2 O 3 : 1024→1041→1500→1668 V/cm for ZPCE system, respectively. The nonlinear coefficient value increased in order of undoped→NiO→MgO→Cr 2 O 3 : 21→ 25→38→50 in ZPCY system and NiO→undoped→MgO→Cr 2 O 3 : 27→32→35→38 in ZPCE system, respectively. In ZPCY and ZPCE systems, the Cr 2 O 3 -additives most greatly improved the nonlinear properties. In Cr 2 O 3 -doped system, ZPCY system exhibited higher nonlinear properties than that of ZPCE system. The stability against d.c. accelerated aging stress was higher in Cr 2 O 3 -additives than in NiO-and MgO-additives for ZPCY system and was higher in NiO-additives than in MgO-and Cr 2 O 3 -additives for ZPCE system.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Nonlinear electrical properties and aging characteristics of (NiO, MgO, Cr2O3)-doped Zn-Pr-Co-R (R = Y, Er) oxide-based varistors

Nahm

2008

Bull Mater Sci

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“…Not only the existence of two liquid phases adds to the amount of liquid phases, but also their difference at melting point remarkably widens the temperature range of films' liquid phase annealing. The compatible of the two liquid phases effectively avoids distributing uniformity of the component [13][14][15]. Figure 5 shows Xray diffraction pattern of ZnO films doped with 0.25, 0.5, 0.75, 1.0 mol.% B 2 O 3 , respectively.…”

Section: Study Of Microstructure Compactnessmentioning

confidence: 99%

Study on the ZnO-based ceramic films for low-voltage varistors with high stability

et al. 2007

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ZnO-based ceramic films for low-voltage varistors were fabricated by a novel sol-gel process. The stability of ZnO-based ceramic films has been studied by improving the degradation properties and increasing the microstructure compactness of the films. The degradation of the film varistors was improved via doping with Na + and heat-treating in oxygen ambient. The microstructure compactness was increased via eliminating the microspores and improving uniformity of the grain size of ZnO by doping with B 2 O 3 . The results indicated that ZnO-based ceramic films for lowvoltage varistors with high stability can be obtained while the concentration of doped Na + is 20-40 ppm, B 2 O 3 is 0.25-0.5 mol.% and being heat-treated in oxygen ambient for 2 h.

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“…And the stability against aging stress or electrostatic is somewhat weak compared with Pr-based varistors. Recently, Zn-Pr-based ceramics have been studied in order to improve a few drawbacks associated with Bi (Alles and Burdick 1991;Lee et al 1996;Chun et al 1999;Nahm et al 2000;Chun and Mizutani 2001). Nahm et al reported that the quaternary system ZnO-Pr 6 O 11 -CoOCr 2 O 3 (ZPCC)-based varistors have highly nonlinear properties when Er, Y, Dy, La, and Tb are added (Nahm 2006(Nahm , 2007Nahm and Ryu 2002;Nahm et al 2003Nahm et al , 2004.…”

Section: Introductionmentioning

confidence: 99%

Effect of aluminum addition on electrical properties, dielectric characteristics, and its stability of (Pr, Co, Cr, Y)-added zinc oxide-based varistors

Nahm

2010

Bull Mater Sci

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The electrical properties, dielectric characteristics, and its stability against d.c. accelerated aging stress of (Pr, Co, Cr, Y)-added zinc oxide-based varistors were investigated for different aluminum concentrations under a sintering temperature of 1280°C. As the aluminum concentration increased, the average grain size (d) increased in the range of 4⋅3-5⋅5 μm and the sintered density increased in the range of 5⋅63-5⋅67 g/cm 3 . As the aluminum concentration increased, the breakdown field decreased in the range of 6327-710 V/cm and the maximum nonlinear coefficient (46⋅9) was obtained for 0⋅005 mol% in aluminum concentration, further additions impaired the nonlinear properties. As the aluminum concentration increased, the apparent dielectric constant increased in the range of 500⋅5-1327⋅4 and dissipation factor increased in the range of 0⋅00493-0⋅0724. The varistor added with 0⋅001 mol% Al exhibited the highest stability for E-J characteristics in which %ΔE 1 mA is +1⋅4% and %Δα is -5⋅7%, under stress state of 0⋅95 E 1 mA /150°C/24 h.

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Untitled

Cited by 34 publications

References 8 publications

Nonlinear electrical properties and aging characteristics of (NiO, MgO, Cr2O3)-doped Zn-Pr-Co-R (R = Y, Er) oxide-based varistors

Nonlinear electrical properties and aging characteristics of (NiO, MgO, Cr2O3)-doped Zn-Pr-Co-R (R = Y, Er) oxide-based varistors

Study on the ZnO-based ceramic films for low-voltage varistors with high stability

Effect of aluminum addition on electrical properties, dielectric characteristics, and its stability of (Pr, Co, Cr, Y)-added zinc oxide-based varistors

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