TY - JOUR
T1 - Structure and electrical properties of molybdenum-containing diamond-like carbon coatings for use as fatigue sensors
AU - Kosukegawa, Hiroyuki
AU - Berkani, Sophia
AU - Miki, Hiroyuki
AU - Takagi, Toshiyuki
N1 - Funding Information:
This work was partly supported by a Grant-in-Aid for Scientific Research (A) ( 23240638 ), a Grant-in-Aid for Scientific Research (B) ( 16H04287 ), and the JSPS Core-to-Core Program, A . Advanced Research Networks, “International research core on smart layered materials and structures for energy saving.” Extensive studies on TEM and EELS by Mr. Kobayashi (Tohoku University) is gratefully acknowledged.
Publisher Copyright:
© 2017 Elsevier B.V.
PY - 2017/11
Y1 - 2017/11
N2 - Electrically conductive diamond-like carbon coatings containing metal grains (Me-DLC) have recently been suggested for use in sensors. We found that the electrical resistance of molybdenum-containing DLC (Mo-DLC) varies with increasing cycles of cyclic bending. Because of this aging property, Mo-DLC has potential as a fatigue sensor. In this paper, we analyzed the variation of nanoscopic structure of Mo-DLC by various spectroscopic techniques and clarified the mechanism underpinning the variation of the electrical properties of Mo-DLC in terms of the hopping conduction in Me-DLC. In the Raman spectra, the intensity ratio between the D-band and G-band of Mo-DLC gradually decreased with bending, which means that the sp2 carbon in aromatic rings decreases in number. XPS indicates that carbide bonding (C–Mo) increased after bending for 107 cycles. Furthermore, EELS showed a decrease in π* bonding in the a-C:H matrix with increasing cyclic bending. From these results, we assume a mechanism that the bonding condition of carbon in the matrix changes from sp2 to carbide because the repeated bending stress changed the electrical properties of Mo-DLC. This knowledge can be useful for controlling the electrical and mechanical properties of Mo-DLC for sensing application. Furthermore, the characteristics of Mo-DLC, such as the variation in electrical properties, can be applied to sense fatigue in severe environments.
AB - Electrically conductive diamond-like carbon coatings containing metal grains (Me-DLC) have recently been suggested for use in sensors. We found that the electrical resistance of molybdenum-containing DLC (Mo-DLC) varies with increasing cycles of cyclic bending. Because of this aging property, Mo-DLC has potential as a fatigue sensor. In this paper, we analyzed the variation of nanoscopic structure of Mo-DLC by various spectroscopic techniques and clarified the mechanism underpinning the variation of the electrical properties of Mo-DLC in terms of the hopping conduction in Me-DLC. In the Raman spectra, the intensity ratio between the D-band and G-band of Mo-DLC gradually decreased with bending, which means that the sp2 carbon in aromatic rings decreases in number. XPS indicates that carbide bonding (C–Mo) increased after bending for 107 cycles. Furthermore, EELS showed a decrease in π* bonding in the a-C:H matrix with increasing cyclic bending. From these results, we assume a mechanism that the bonding condition of carbon in the matrix changes from sp2 to carbide because the repeated bending stress changed the electrical properties of Mo-DLC. This knowledge can be useful for controlling the electrical and mechanical properties of Mo-DLC for sensing application. Furthermore, the characteristics of Mo-DLC, such as the variation in electrical properties, can be applied to sense fatigue in severe environments.
KW - Diamond-like carbon
KW - Electrical properties characterization
KW - Nanostructures
KW - Sensors
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U2 - 10.1016/j.diamond.2017.09.018
DO - 10.1016/j.diamond.2017.09.018
M3 - Article
AN - SCOPUS:85031719398
VL - 80
SP - 38
EP - 44
JO - Diamond and Related Materials
JF - Diamond and Related Materials
SN - 0925-9635
ER -