Aqueous electrodeposition of rare earth and transition metals

Details Aqueous electrodeposition of rare earth and transition metals Aqueous electrodeposition of rare earth and transition metals

1999-12-10

2001-10-23

Valentine, Donald R. (Department: 1741)

Electrolysis: processes, compositions used therein, and methods

Electrolytic coating

Depositing predominantly alloy coating

C205S261000, C205S270000, C205S271000, C205S269000

Reexamination Certificate

active

06306276

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to the electrodeposition of transition metal and rare earth alloys from aqueous solutions to form thin films. In particular, this invention relates to the application of an aqueous based electrodeposition process for producing magneto-optical systems and permanent magnets.
Bulk alloys of transition metals-rare earths are important permanent magnet materials. There have been considerable recent efforts to develop new high performance magnets that achieve substantial weight and size reductions when compared to traditional permanent magnets used in electrical devices. Recent developments have focussed on cobalt-rare earth and, more recently, on iron-rare earth permanent magnets. Substantially improved magnetic properties have been achieved by appropriate heat treatment of these new alloys.
Sputtered thin films of binary, ternary and quaternary transition metal-rare earth alloys have recently been utilized as magneto-optical reading media.
Therefore, there is a need for an electrochemical process capable of depositing thin films of Fe, Ni and Co-rare earth alloys which would substantially reduce the manufacturing costs of these alloys compared to vacuum processes. Furthermore, electrodeposition of Co, Ni and Fe-rare earth thin film alloys will enable fabrication of nano-dimensional permanent magnet and magneto-optical materials. In addition, ultra-high frequency electrodeposition techniques and addition of light elements show exceptional promise to produce nano-structured amorphous permanent magnet and magneto-optical systems.
SUMMARY
These needs are met by the present invention which comprises the preparation of suitable mixtures of water soluble compounds containing the desired transition metal (TM) and rare earth (RE) elements, establishing appropriate bath conditions and applying specific current densities across the bath solution to cause a film with the desired properties to be deposited on a target substrate.
A number of plating solutions consisting of mixtures of ferrous, cobalt, nickel, lanthanum, neodymium and cerium salts, as well as other rare earth salts were prepared. Under certain current density and bath conditions mirror-bright metallic films were deposited on substrates.
BACKGROUND
Rare earth-transition metal alloys, such as Nd
2
Fe
14
B and solid solution of interstitial N and C atoms in Sm
2
Fe
17
, have coercivities, remanances and energy product greater than prior state of the art compositions. The makes them promising materials for high powered permanent magnets used in automotive, aerospace, information technology and consumer electronic industries.
In 1973, P. Chaudhari, J. J. Cuomo and R. J. Cambino, IBM J. Res. Develop., 17, 66 (1973) discovered that sputtered Gd—Co and Gd—Fe thin films have perpendicular magnetic anisotropy, which resulted from antiferromagnetic coupling between Gd and Co or Fe atoms. Since then, rare earth-transition metal (RE-TM) thin films have been prepared by various vacuum deposition processes to investigate the electrical and magnetic properties of these films. These include binary Gd—Fe, Gd—Co, Tb—Co, Tb—Fe (Y. Mimura and N. Imamura, Appl. Phys. Lett., 28, 746 (1976), Y. Sakurai and K. Onishi, J. Magn. Magn. Mat., 35, 183 (1983), A. Forkl, H. Herscher, T. Mizoguchi, H. Kronmuller and H-U. Haberometer, J. Magn. Magn. Mat., 93, 261 (1991)), ternary Gd—Tb—Fe (M. Takahashi, T. Niharra and N. Ohta, J. Appl. Phys., 64,262 (1988), P. Hansen and K. Witter, IEEE Trans. Mag., MAG-24, 2317 (1988), Dy—Fe—Co (P. Hansen, S. Klahn, C. Clausen, G. Much and K. Kitter, J. Appl. Phys., 69, 3196 (1991); K. Naito, T. Numata, K. Nakashima and Y. Namba, J. Magn. Magn. Mat., 104, 1025 (1992), Tb—Fe—Co (M. M. Yang and T. M. Reith, J. Appl. Phys., 71, 3945 (1992) and quaternary GdTbFeCo J. F. Qui, K. N. R. Taylor and G. J. Russell, Mat. Res. Bull., 28, 67 (1993). RE-TM films exhibit strong temperature dependence of coercivity, i.e., higher coercivity at lower temperatures and lower coercivity at higher temperatures. This unique magnetic property makes them ideal candidates for high density storage media in magnetic-optical recording applications (M. H. Kryder, J. Magn. Magn. Mat., 83, 1 (1990); P. Hansen, J. Magn. Magn. Mat., 83, 6 (1990).
Electrodeposition of metallic thin films is usually more cost effective then vacuum deposition. However, prior attempts to electrodeposit RE-TM films has been limited to non-aqueous solutions (ie., water insoluble compounds in organic solvents). Moeller and Zimmerman reported the non-aqueous electrodeposition of rare earth metals of yttrium, neodymium and lanthanum and found that successful deposition could be obtained from ethylenediamine, a highly basic solvent (T. Moeller and P. A. Zimmerman, Science, 120, 539 (1954). Usuzaka et al. electrodeposition Co—Gd alloys from a formamide solution containing ethylenediamine as complexing agent. The resultant films were found to exhibit magnetic anisotropy perpendicular to the film surface (N. Usuzaka, H. Yamaguchi and T. Watanabe, Mat. Sci. Engr., 99, 105 (1988). Y. Sato, H. Ishida, K. Kobayakawa and Y. Abe, Chem. Lett., 1471 (1990), Y. Sato, T. Takazawa, M. Takahashi, H. Ishida and K. Kobayakawa, Plating and Surface Finishing, 4, 72 (1993) electrodeposited SM—Co alloys from formamide solutions and found that higher Co content in Sm—Co films exhibited higher saturation magnetization.
It is well known that rare earth metals are extremely basic metals with a reduction potential over −2V and electroplating of rare earth elements from aqueous solutions is believed to be unattainable due to the onset of hydrogen evolution. This is a common result of attempts to electrodeposit molybdenum or tungsten from aqueous solutions. However, numerous ferrous metal alloys with either Mo or W have been electrodeposited from aqueous solutions (L. O. Case and A. Krohn, J. Electrochem Soc., 105, 512 (1958); V. B. Singh, L. C. Singh and P. K. Tikoo, J. Electrochem. Soc., 127, 590 (1980); M. Schwartz, Unpublished Data (1946); also in discussions in Trans ECS, 94, 382-92 (1948); A. Brenner, P. Burkhead and E. Seegmiller, J. Res. NBS, 93, 351 (1947); M. L. Holt and L. E. Vaaler, Trans. ECS., 94, 50 (1948); W. E. Clark and M. L. Holt, ibid, 94, 244 (1948); M. H. Lietzke and M. L. Holt, ibid, 94, 252 (1948); W. H. Safranek and L. E. Vaaler, Plating, 46 (2), 133 (1959).
We have now discovered that the aqueous electrodeposition of ferrous metal-rare earth (RE) alloys is possible through selective use of added agents, such as complexing agents, current density, solution temperature, and pH.


REFERENCES:
patent: 3914160 (1975-10-01), Fueki et al.
patent: 3947331 (1976-03-01), Kinh et al.
patent: 4101311 (1978-07-01), Aonuma et al.
patent: 4101388 (1978-07-01), Chessin et al.
patent: 4410454 (1983-10-01), Faschingbauer
patent: 4444629 (1984-04-01), Martin
patent: 4529668 (1985-07-01), Croopnick et al.
patent: 4741818 (1988-05-01), Nobel et al.
patent: 4846942 (1989-07-01), Watanabe et al.
patent: 4952557 (1990-08-01), Schmidt
patent: 5302464 (1994-04-01), Nomura et al.
patent: 5470820 (1995-11-01), Hauser et al.
Chen, et al. “Aqueous Electrodeposition of Rare Earth Thin Film Alloys with Ferrous Metals,” Chemical Abstracts, vol. 126, No. 22, Jun. 2, 1997, doc. XP002099433.
Liu, et al. “Study on the Co-Electrodeposition of Lanthanum with Nickel,” Chemical Abstracts, vol. 124, No. 6, Feb. 5, 1996, doc. XP002099434.

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