ISSN 1070-4272, Russian Journal of Applied Chemistry, 2008, Vol. 81, No. 6, pp. 1000!1003. + Pleiades Publishing, Ltd., 2008.
Original Russian Text + S.M. Karabanov, O.G. Lokshtanova, 2008, published in Zhurnal Prikladnoi Khimii, 2008, Vol. 81, No. 6, pp. 961!964.
AND CORROSION PROTECTION OF METALS
A Study of the Complex Composition of Sulfamate
S. M. Karabanov and O. G. Lokshtanova
Ryazan Plant of Metal-Ceramic Devices Open Joint-Stock Company, Ryazan, Russia
Received October 11, 2007
Abstract-Varying-with-time complex composition of a sulfamate ruthenium-plating electrolyte was
studied. Recommendations are given concerning the working modes and adjustment conditions in pro-
longed operation of the electrolyte.
The sulfamate electrolyte is the most widely used
industrial ruthenium-plating electrolyte . It is
prepared from a complex salt, ammonium m-ni-
]. In a prolonged use of the ruthenium-
plating electrolyte, it is necessary to maintain its
technical characteristics (e.g., the deposition rate,
within the prescribed limits) and the stability of
characteristics of electroplated coatings. To accom-
plish this task, it is necessary to know the varia-
tion dynamics of the complex composition of both
the electrolyte and the adjusting solutions in pro-
longed storage and use during accumulation of
products of chemical and electrochemical reactions.
The aim of this study was to examine the vary-
ing-with-time complex composition of ruthenium-
plating electrolytes and adjusting solutions.
In the study, IR spectroscopy, powder X-ray dif-
fraction analysis, electronic absorption spectros-
copy (EAS) of aqueous salt solutions, and gel-chro-
matography of aqueous solutions on Sefadex gels
The commonly used ruthenium-plating electro-
lyte has the following composition (g l
(in terms of the metal) and ammonium sulfamate
30380. The pH value was maintained in the range
1.532.0. The electrodeposition was performed at
a temperature of 60370oC and cathode current
density of 132Adm
with the use of Pt/Ti anodes.
Originally, the starting complex salt of rutheni-
um was studied. IR spectroscopy revealed the fol-
lowing absorption bands (cm
): 1060, vibrations
of the Ru3N3Ru bond; 1450, vibrations of NH
bonds; 1543, vibrations of uncoordinated water;
and 1040, vibrations of coordinated water, which
is trans to the bridging nitrogen.
The complex salt was subjected to X-ray diffrac-
tion analysis. The resulting X-ray diffraction pat-
tern is in good agreement with published data for
] . It was found that
the ruthenium compound used to prepare electro-
lytes fully corresponds to this formula, but contains
hydration water: (NH
(according to a calculation, n < 1).
It was of interest to check whether the composi-
tion of the complex changes when the electrolyte
and adjusting solutions are prepared by dissolving
the starting salt in water. The EAS spectra of aqu-
eous solutions of the salt, measured immediately
after the substance is dissolved, contain four ab-
sorption bands at 205, 2903292, 350, and 435 nm,
in full agreement with published data [5, 6].
Solutions of the complex ruthenium salt in water
and a 0.1 M solution of hydrochloric acid were
subjected to chromatography on a column packed
with Sefadex G-15 gel. Chromatograms of the fresh-
ly prepared aqueous and hydrochloric acid solu-
tions are shown in Fig. 1. The chromatograms con-
tain only a single broad brown zone containing
ruthenium. The EAS spectrum of separate fractions
of the zone coincides with that of the starting com-