The biaxial texturing ((001)[100], cube texture) behavior of Ni electrodeposit by applying the magnetic field has been studied. The approaching method for biaxial texturing of Ni electrodeposit includes two stages ; the first stage is to investigate the plating condition for Ni electrodeposit having perfect c-axis alignment with (002) fiber texture, at the second stage, magnetic field is applied to th e electroplating cell performed under the same condition, in order to lead to in-plane align in the a-b plane. The texture of electrodeposit is analysed by texture fraction (TF) and pole figure. The degree of out-of-plane and in-plane alignment is expressed by full width of half maximum values of rocking curve (Δω) and phi-scan curve (Δφ). A modified Watts bath has been used for DC and PR platings. In order to obtain optimum parameters for maximum texture fraction of (002) plane, Taguchi method is applied with three-level L9 orthogonal array. In case of DC plating, the optimum condition is i=5A/d ㎡, T=50℃, pH=2, and distance between anode and cathode is 3cm, and in case of PR plating, that is 70℃, $i_c=10A/d ㎡$, $i_a=1A/d ㎡$, $t_a=5msec$ and pH=2 . TF(002) obtained under thess parameters is higher than 0.96 and Δω is 8° indicating good aligned (002) fiber texture.
In order to investigate the variation of in-plane alignment with magnetic field, magnetic fields of 0～ 0.4T are applied to plating cell using bipolar type electromagnets. During the electroplating at 0.3T, the angle between the direction of magnetic field and normal direction of cathode is changed to 0, 45, 90, 135 and 180° by moving the position of magnets. The pole figure of Ni electrodeposit changed from ring pattern indicating (002) fiber texture to complicate one. Especially the trend from (002) fiber texture to form (001)[100] cube texture at the angle of 45° was found in only in-plane alignment rotating at c-axis . As the magnetic field increased from 0 to 0.4T, the degree of in-plane alignment only increased without variation of out-of-plane alignment. However, degree of in-plane alignment was saturated at 0.4T and was not improved any more even though above 5T produced by superconductor electromagnet. The maximum values of ΔΦ were 30° and 15° in DC and PR platings, respectively.
Heat treatment for the two kinds of Ni electrodeposits with (002) fiber texture and cube texture have been performed at 400, 600, 800 and 1,000℃ for 1 hour, in order to investigate the variation of texture. Until 600℃, there is no texture change in (002) fiber textured Ni deposits, however (111) peak is appeared above 800℃ disappearing (002) peak at 1,000℃. On the contrary, cube textured Ni electrodeposit was not entirely changed even at 1,000℃. It means that the biaxial texture can keep its texture during the coating of the buffer layer at 600～800℃.
$CeO_2$ film with 600Å thickness was epitaxially deposited by thermal evaporation as a buffer layer. Even though the temperature of deposition is 650℃, it proved that biaxial texture of Ni electrodeposit was not broken after evaporating the buffer layer.
The epitaxial orientation observed is $CeO_2<110>∥Ni<100>$ and value of Δφ in both of Ni and $CeO_2$ is about 10°, indicating good in-plane alignment and epitaxy.
In order to investigate the mechanism of biaxial texturing of Ni electrodeposit, polarization, cyclic voltammetry and AC impedance methods were applied under no magnetic field and 0.4T. however, there is no difference in each result. It means that there is no significant magnetic field effect on the motion of the ions through solution as well as the kinetics of the electrode reactions.
It is calculated that the magnetic force exerting to adatom is higher than adatom-lattice bonding force. On the basis of this result, it is suggested that in-plane alignment of electrodeposit can be developed by directional surface diffusion of adatoms induced by magnetic field rather than random-walk on the cathode surface.
