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Inner Stress Induced by Cu Metal Precipitation at Grain Boundaries in Low‐Temperature‐Fired Ni‐Zn‐Cu Ferrite
Author(s) -
Fujimoto Masayuki
Publication year - 1994
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1994.tb04517.x
Subject(s) - materials science , grain boundary , ferrite (magnet) , metallurgy , grain size , sintering , metal , composite material , microstructure
Multilayer chip inductors were characterized using analytical electron microscopy. The chip inductors consist of silver internal electrode sandwiched between low‐temperature‐fired, Ni‐Zn‐Cu ferrite layers. It was found that the cooling rate affected the inductance of the chip inductor. Elastic strain fields were observed at the grain boundaries in the rapidly cooled samples, causing degradation of the inductance. The strain field causing a decrease in the effective permeability of the ferrite was found to be due to interstitial‐type Cu precipitates at the grain boundaries. The occurrence of Cu metal precipitates was dependent on the starting chemical composition, oxygen partial pressure, and thermal equilibrium during cooling after the sintering process.