Oxygen nonstoichiometry and dielectric evolution of BaTiO3. Part I—improvement of insulation resistance with reoxidation

Yang, Guang; Dickey, Elizabeth C.; Randall, Clive A.; Barber, D. E.; Pinceloup, Pascal; Henderson, Matthew A.; Hill, Richard A.; Beeson, J. J.; Skamser, Daniel J.

doi:10.1063/1.1809267

Cited by 195 publications

(191 citation statements)

References 31 publications

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“…Because of this, a capacitive device of higher performance is obtained by higher resistivity. 25 Figure 5 illustrates that resistivity is very similar among the four BNT-BT-KNN materials from 100 to 400°C.…”

Section: Figmentioning

confidence: 97%

Lead-free high-temperature dielectrics with wide operational range

Dittmer

Damjanović

et al. 2011

Journal of Applied Physics

186

119

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The dielectric, electrical and structural properties of (1–x)(0.94Bi1/2Na1/2TiO3–0.06BaTiO3)–xK0.5Na0.5NbO3 (BNT–BT–xKNN) with x=0.09, 0.12, 0.15, and 0.18 were investigated as potential candidates for high-temperature capacitors with a working temperature far beyond 200 °C. Temperature dependent dielectric permittivity (ε) showed two local broad maxima that at the optimal composition of KNN (x=0.18) are combined to form a plateau. This then results in a highly temperature-insensitive permittivity up to ∼300 °C at the expense of a small reduction in absolute permittivity values. High-temperature in situ x-ray diffraction study showed pseudocubic symmetry without obvious structural changes, which implies that the dielectric anomalies observed could only be a consequence of a slight change in space group. BNT–BT–0.18KNN showed a permittivity of ∼2150 at the frequency of 1 kHz at 150 °C with a normalized permittivity ε/ε150 °C varying no more than ±10% from 43 to 319 °C. With very good electrical properties persisting up to 300 °C, i.e., a resistivity on the order of magnitude of 108 Ω m and the RC constant of about 1 s, the examined BNT–BT–xKNN compositions present a good starting point for the development of high-temperature capacitor materials.

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Section: Figmentioning

confidence: 97%

Lead-free high-temperature dielectrics with wide operational range

Dittmer

Damjanović

et al. 2011

Journal of Applied Physics

186

119

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“…Therefore, alloying is thermodynamically possible if BaTiO 3 undergoes significant reduction [16][17][18][19]. In fact, we recently identified the formation of discrete interfacial alloy layers consisting of Ni, Ba and Ti with a thickness of 5-15 nm between Ni electrodes and BaTiO 3 in commercial MLCCs [16][17][18][19]. The appearance of this alloy was attributed to the local reduction of the BaTiO 3 by residual carbon remaining from the binder burnout process.…”

Section: Introductionmentioning

confidence: 96%

Effect of Cr additions on the microstructural stability of Ni electrodes in ultra-thin BaTiO3 multilayer capacitors

et al. 2007

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Microstructural control in thin-layer multilayer ceramic capacitors (MLCC) is one of the present day challenges to maintain an increase in capacitive volumetric efficiency. This present paper opens a series of investigations aimed to engineer the stability of ultra-thin Ni electrodes in BaTiO 3 -based multilayer capacitors using refractory metal additions to Ni. Here, pure Ni and Ni-1 wt.% Cr alloy powders are used to produce 0805-type BME MLCCs with 300 active layers and with dielectric and electrode layer thickness around 1 μm. To investigate the continuity of Ni electrodes, both MLCC chips with pure and doped electrodes were sintered at different temperatures for 5 h. It is found that the continuity of Ni electrodes is improved most likely due to the effect of Cr on the lowmelting point (Ni,Ba,Ti) interfacial alloy layer formation. The interfacial alloy layer is not observed when Cr is segregated at Ni-BaTiO 3 interface in the Cr-doped samples, while it is found in all undoped samples. The interfacial alloy layer is believed to increase mass-transfer along the Ni-BaTiO 3 interfaces facilitating an acceleration of Ni electrodes discontinuities.

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“…The p-type BaTiO 3 -Ni interface will have a hole accumulation and would show an ohmic contact [14]. Previous studies of BME-MLCC chips before and after the reoxidation treatment confirmed the formation of blocking Schottky barrier in either case [3,5]. This means that the BaTiO 3 -based dielectric is still n-type semiconducting even after the reoxidation treatment and different from the airfired cases.…”

Section: Introductionmentioning

confidence: 52%

“…One of the current issues in state-of-the-art base-metal electrode multilayer ceramic capacitors (BME MLCCs) with dielectric and electrode layer thicknesses around or below 1 μm is the discontinuity of Ni electrodes, which can affect the electrical performance and reliability of final products [1,2]. Recently, our investigations revealed the formation of an interfacial low-melting point (Ni,Ba,Ti) alloy with a melting point as low as 1000-1150°C at Ni-BaTiO 3 interfaces [3][4][5][6]. The reduction process to produce the metallic Ti and Ba components results from the presence of residual carbon content from the organics used in the tape casting and screen printing process steps.…”

Section: Introductionmentioning

confidence: 99%

Effect of Cr additions on the electrical properties of Ni–BaTiO3 ultra-thin multilayer capacitors

et al. 2008

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Multilayer ceramic capacitors based on BaTiO 3 dielectric compositions and Ni inner electrodes have complex interfacial reactions that impact the continuity of the inner electrode microstructure. Previously we demonstrated that through the addition of Cr to Ni, a significant improvement in the continuity of ultra-thin Ni electrodes in Ni-BaTiO 3 multilayer capacitors could be achieved. Here, the effect of the Cr addition to the nickel electrode pastes is studied with regard to the electrical properties. Low-field electrical measurements demonstrate no major differences between Cr doped Ni and undoped Ni. However, high-field measurements show a significant decrease to the total capacitor resistance. Under a critical electrical bias the conductivity significantly increases due to a FowlerNordheim tunneling conduction though the interfacial Schottky barrier at the dielectric-electrode interface; the onset voltage of this conduction is much lower than with the undoped nickel. Based on these results, we evaluate criteria for the selection of an appropriate refractory metal in order to improve the Ni electrode continuity.

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Oxygen nonstoichiometry and dielectric evolution of BaTiO3. Part I—improvement of insulation resistance with reoxidation

Cited by 195 publications

References 31 publications

Lead-free high-temperature dielectrics with wide operational range

Lead-free high-temperature dielectrics with wide operational range

Effect of Cr additions on the microstructural stability of Ni electrodes in ultra-thin BaTiO3 multilayer capacitors

Effect of Cr additions on the electrical properties of Ni–BaTiO3 ultra-thin multilayer capacitors

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