T. Osaka et al., Effects of saccharin and thiourea on sulfur inclusion and coercivity of electroplated soft magnetic CoNiFe film, J ELCHEM SO, 146(9), 1999, pp. 3295-3299
During the course of our recent work performed to develop an electroplated
CoNiFe ternary alloy with high saturation magnetic flux density and low coe
rcivity for use in magnetic recording heads, it was observed that two commo
n sulfur-containing additives, saccharin and thiourea, behave differently w
ith respect to the dependence of sulfur inclusion and coercivity of the all
oy film on the additive concentration in the plating bath. To understand th
e cause of this difference, scanning tunneling microscopy (STM) was perform
ed, using Au(111) as the substrate, to examine the structure of the adsorbe
d layers of the additive molecules. The result revealed that the nature of
adsorption is fundamentally different for the two different additives; i.e.
, the adsorption of saccharin is physical and reversible, whereas thiourea
undergoes irreversible chemisorption. This finding is consistent with the k
nown behaviors of the two additives in the electroplating of nickel. In thi
s paper the different effects of saccharin and thiourea in the electrodepos
ition of CoNiFe alloy are interpreted based on the STM results and relevant
information available in the literature on the electrodeposition of nickel
. (C) 1999 The Electrochemical Society. S0013-4651(98)12-087-6. All rights
reserved.