H.J. Zhang et al. / Journal of Alloys and Compounds 419 (2006) 220–226
225
Table 3
Inversed parameters and experimental results of ultrafine Ni powders synthesis
Sample no.
Coordinate
Test parameters obtained with inversion projection program
Experiment results
X
Y
T (◦C)
pH
10
Ni (mol/l)
0.18
NN (molar ratio)
3.0
SN (molar ratio)
0.1
t (min)
Relative content of Ni (%)
Point 1
0.06
−0.36
0.53
0.51
0.4
0.35
0.13
0.33
90
73
>90
<90
Point 2
Point 3
Point 4
Point 5
Point 6
Point 7
0.03
−0.1
55
65
45
50
55
55
7.8
8.3
8.0
6.8
7.0
7.0
0.34
0.098
0.06
0.10
0.01
0.15
1.13
5.87
5.84
4.37
4.51
3.71
1.9
2.0
1.8
1.4.
1.2
1.2
50
35
55
40
35
35
−0.04
−0.07
−0.02
−0.06
T: temperature; Ni: [Ni2+]; NN: [N2H4·H2O]/[Ni2+]; SN: [Na3Cit]/[Ni2+]; t: time.
[Ni2+]: [Ni2+] = 0.20 M is recommended. The Ni powders pre-
pared by electroless plating are ultrafine grained, mostly with
sizes of approximately 1.0 m.
The dielectric loss of prepared Ni ultrafine powders is small
with values less than 0.2 in 8.2–12.4 GHz. The magnetic loss
of synthesized Ni powders with values about 2 in the frequency
region below 9 GHz, decrease appreciably with increasing fre-
quency. Patternrecognitionbasedonprincipalcomponentanaly-
sis is used to optimize the parameters and to predict the expected
values. This method gave 100% reliable recognition.
region (area B) were obviously separated, and absolutely all
the ‘optimum points’ located in target optimum region (in the
quadrangle, area A), the correctness prediction rate was 100%.
The values of projection coordinates (X, Y) corresponding to
each sample point are also shown in Table 2, the relationship
between the values of projection coordinates (X, Y) and temper-
ature (T), the concentration of NiSO4 ([Ni2+]), the molar ratio of
N2H4·H2O to NiSO4 ([N2H4·H2O]/[Ni2+]), pH of the solution,
bathing time (t) and the molar ratio of sodium citric to NiSO4
([Na3Cit]/[Ni2+]) is as following:
X = −0.0039T + 0.0725pH − 0.609[Ni]
− 0.0811([N2H4 · H2O]/[Ni2+])
Acknowledgement
This work was supported by “The Henan Province Science
Fund for Distinguished Young Scholars, China (Contract No.
0512002400)”.
+ 0.528([Na3Cit]/[Ni2+]) − 0.0004t
(7)
Y = −0.0015T − 0.0153pH + 1.0167[Ni]
− 0.0403([N2H4 · H2O]/[Ni2+])
References
[1] T. Kobayashi, J. Ishibashi, S. Mononobe, M. Ohtsu, H. Honma, J. Elec-
trochem. Soc. 147 (3) (2000) 1046.
[2] L.M. Ang, T.S.A. Hor, C.Q. Xu, C.H. Tung, S.P. Zhao, J.L.S. Wang,
Carbon 38 (2000) 363.
[3] F.Z. Kong, X.B. Zhang, W.Q. Xiong, F. Liu, W.Z. Huang, Y.L. Sun, J.P.
Tu, X.W. Chen, Surf. Coat. Technol. 155 (2002) 33–36.
[4] H. Liu, G. Cheng, R. Zheng, Y. Zhao, J. Mol. Catal. A: Chem. 225
(2005) 233–237.
[5] C. Zhanga, G.P. Linga, J.H. He, Mater. Lett. 58 (2003) 200–204.
[6] G. Wen, Z.X. Guo, C.K.L. Davies, Scripta Mater. 43 (2000) 307–311.
[7] S.G. Lua, K. Li, H.L.W. Chan, C.L. Choy, Mater. Chem. Phys. 88 (2004)
113–118.
[8] H.F. Chang, M.A. Saleque, W.S. Hsu, W.H. Lin, J. Mol. Catal. A: Chem.
109 (1996) 249–260.
[9] Q.Y. Zhang, M. Wu, W. Zhao, Surf. Coat. Technol. 192 (2005) 213–219.
[10] S. Shukla, S. Seal, Z. Rahaman, K. Scammon, Mater. Lett. 57 (2002)
151–156.
+ 0.4558([Na3Cit]/[Ni2+]) − 0.001t
(8)
As to any giving parameters to prepare Ni ultrafine powders, the
expected yield ratio can be predicted by pattern recognition anal-
ysis. In addition, the proper parameter can also be determined
by an inverse projection. In order to verify the correctness of the
pattern recognition program, 1 point in ‘optimum’ region and
6 points in ‘inferior’ region are chosen, respectively, and also
defined as ‘inverse points’. The corresponding technological
parameters of those ‘inverse points’ can be calculated by inverse
projection. The experimental results based on these technolog-
ical parameters show that this pattern recognition program is
reliable. The corresponding technological parameters and exper-
imental results are shown in Table 3.
[11] Z. Aixiang, X. Weihao, X. Jian, Mater. Lett. 59 (2005) 524–528.
[12] N. Vassal, E. Salmon, J. Fauvarque, J. Electrochem. Soc. 146 (1999)
20–26.
5. Conclusions
[13] D. Laughlin, B. Lu, Y. Hsu, J. Zou, D. Lambeth, IEEE. Trans. Magn.
36 (2000) 48–53.
[14] S. Illy, O. Tillement, F. Machizaud, J.M. Dubois, Philos. Mag. A 79 (5)
(1999) 1021.
[15] J. Gao, F. Guan, Y. Zhao, W. Yang, Y. Ma, X. Lu, J. Hou, J. Kang,
Mater. Chem. Phys. 71 (2001) 215–219.
[16] S. Komarneni, R. Pidugu, Q.H. Li, R. Roy, J. Mater. Res. 10 (7) (1995)
1687.
Ultrafine Ni powders were formed by electroless plating pro-
cess using hydrazine hydrate, NiSO4, etc., as studying materials.
The principal factors influencing ultrafine Ni powder synthesis
are—(1) pH of bathing solution: pH 9–10 is recommended; (2)
bathing temperature: 90 ◦C is effective for ultrafine Ni powders
synthesis; (3) molar ratio of [N2H4·H2O]/[Ni2+]: the suitable
molar ratio of [N2H4·H2O]/[Ni2+] is 2.0; (4) the concentration of
[17] D. Chen, S. Wu, Chem. Mater. 12 (2000) 1354.