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c-BN color change with bonded water added into the h-BN–Mg system
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Diamond & Related Materials 17 (2008) 258 – 261 www.elsevier.com/locate/diamond
c-BN color change with bonded water added into the h-BN–Mg system X.C. Wang a,b,⁎, T.C. Zhang b , H.A. Ma b , X.P. Jia b a
b
Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080, China National Key Laboratory for Superhard Materials, Jilin University, Changchun 130012, China
Received 27 January 2007; received in revised form 6 December 2007; accepted 11 December 2007 Available online 23 December 2007
Abstract Cubic boron nitride (c-BN) crystals were synthesized in conditions of high temperature and high pressure (HTHP) when different kinds of bonded water were respectively added into the system of h-BN–Mg. All bonded water used in this work could reduce the temperature of growing c-BN compared to that in the system of h-BN–Mg. The c-BN color could change from black to yellow when certain amounts of bonded water, such as NiSO4·6H2O and CuSO4·5H2O, Mg(OH)2, were added. However, c-BN color remained black no matter how much bonded water, such as NiCl2·6H2O, CuCl2·2H2O, and SnCl2·2H2O, was added. The bonded water can be classified into Chlorine-containing bonded water (Cl-BW) and Chlorine-free bonded water (ClF-BW) according to their different characters and effects on the synthesized c-BN color. © 2007 Elsevier B.V. All rights reserved. Keywords: c-BN; Bonded water; Chloric; Color
1. Introduction Cubic boron nitride (c-BN) has been applied in many fields because of its outstanding properties. c-BN is the second hardest material. Its high hardness and high thermal conductivity make it useful as a cutting tool and as an abrasive. In addition, its high thermal conductivity and the possibility of appropriate doping make it a potential material for applications in electric fields. At HTHP conditions, c-BN crystals can be synthesized from hexagonal boron nitride (h-BN) with the catalysts such as the alkali metals, alkaline earth metals, their nitrides, and their boric nitrides [1–6]. The color of the synthesized c-BN crystals varies according to the types of the catalysts used. Generally, black cBN crystals are synthesized from h-BN when alkali metals or alkaline earth metals are used. With their nitrides or their boric nitrides as the catalysts, the color of synthesized c-BN is yellow [1,4]. Also, the color may be white when water, boric acid, or urea is used [7]. If M' (M' = Al, B, Si, Ti) is doped into the mixture of h-BN and M xN y (M xN y = Ca3N2, Li3N, Mg3N2), ⁎ Corresponding author. Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080, China. Tel.: +86 010 62554408. E-mail address: [email protected] (X.C. Wang). 0925-9635/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.diamond.2007.12.037
the synthesized c-BN color can change from yellow to black with increasing proportions of M' [4,8]. The effect of bounded water on the c-BN transformation from h-BN in the presence of magnesium (Mg) has been heavily studied [9–15]. It was reported that when the amount of bonded water increased in the mixture of h-BN and magnesium, the synthesized c-BN color would change from black to yellow [9]. However, our work demonstrates that only ClF-BW can make the color change. When Cl-BW is added into the mixture of h-BN and Mg, the synthesized c-BN color remains black, regardless of the amount. 2. Experiment The c-BN crystal was synthesized at HTHP in a cubic anvil high-pressure apparatus. The pressure was estimated by an oil press load, which was calibrated by the pressure-induced phase transitions of bismuth, thallium, and barium metals. The temperature was estimated by the relationship between applied electrical power and temperature, which was measured by using the platinum–rhodium thermocouple. The assembly used in this work is shown in Fig. 1. In sample column A, the mixture of h-BN, Mg and different kinds of bonded water such as NiSO4·
X.C. Wang et al. / Diamond & Related Materials 17 (2008) 258–261
259
Fig. 1. High pressure cell assembly of c-BN crystal synthesis. (1) pyrophyllite; (2) graphite (3) sample column; (4) h-BN; (5) steel ring.
6H2O, CuSO4·5H2O, Mg(OH)2, NiCl2·6H2O, CuCl2·2H2O, and SnCl2·2H2O, was directly pressed into the column. In sample column B, when the mixture powder of h-BN and Mg was pressed into the column, a lump of bonded water was packed into it. Then, the assembled cell was treated for 5 min at a high pressure (5.0 GPa) and a high temperature (1300 °C). After being quenched, sample column A was measured by X-Ray diffraction, and sample column B was observed by an optical microscope. 3. Results c-BN crystals were synthesized from the mixture of h-BN, Mg and bonded water at HTHP. Table 1 shows that the synthesized c-BN color would change from black to yellow when the amount of NiSO4·6H2O increases, while the synthesized c-BN color is independent of the amount of NiCl2·6H2O. Fig. 2 (a), (b) shows the photographs of synthesized c-BN crystals when NiCl2·6H2O (10 wt.%) and NiSO4·6H2O (10 wt.%) are added into the mixture of h-BN and Mg (15 wt.%), re-
Fig. 2. (a), (b) Photographs of c-BN crystals synthesized with the mixture of h-BN, Magnesium (15 wt.%) and bonded water at 5.0 GPa and 1300 °C. (a) NiCl2· 6H2O (10 wt.%); (b) NiSO4·6H2O (10 wt.%).
spectively. The c-BN color is black when NiCl2·6H2O (10 wt.%) is added and is yellow when NiSO4·6H2O (10 wt.%) is added. Fig. 3 shows the sketch map of samples with a lump of different bonded water packed into it, after these samples are quenched at HTHP. When the lump of ClF-BW is packed into the mixture of h-BN and Mg, the quenched sample would have three sections shown in Fig. 3 (a). Section A is close to the lump, in which c-BN crystals exist and their color is yellow. Section B is near section A, in which black c-BN grains exist. The outer place is section C and no c-BN crystals are synthesized there. If the lump of Cl-BW is packed into it, then the quenched sample would have two sections: a growing black
Table 1 Content of bonded water dependence of the c-BN crystal color in the h-BN–Mg and bonded water system h-BN (wt.%) (content of Mg is fixed at 15 wt.%)
c-BN crystal color
(a) NiSO4·6H2O (wt.%) 80: 5 75: 10 65: 20
Black Yellow No c-BN forms
(b) NiCl2·6H2O (wt.%) 80: 5 75: 10 65: 20
Black Black No c-BN forms
Fig. 3. (a), (b) Sketch map of samples with a lump of different bonded water packed into, after these samples are quenched at 5.0 GPa and 1300 °C. (a) NiSO4·6H2O, CuSO4·5H2O and Mg(OH)2 was packed into respectively; (b) NiCl2·6H2O, CuCl2·2H2O and SnCl2·2H2O was packed into respectively.
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c-BN grains section (Section D) and non-growing c-BN grains section (Section E). Fig. 4 shows the XRD patterns of samples quenched at HTHP. From Fig. 4, we can see that h-BN remains the main phase and that a lot of MgO and a little boric magnesium are produced. The peak of c-BN can only be seen from the local region of the diffraction pattern.
5.0 GPa and 1300 °C, c-BN would not be synthesized due to the lack of bonded water. The synthesized c-BN color is black in section B because the section is not far away from the lump and the bonded water could reach there, reducing the c-BN synthesized temperature. In Fig. 3 (b), there exist two sections: a black c-BN grains section and a non-growing c-BN grains section. It means that the bonded water reduces the temperature of c-BN synthesis and the color is independent of its amount. According to the results above, we can classify the bonded water into Cl-BW and ClF-BW. From Fig. 4, we can see that all the quenched samples contain medium productions of MgO and Mg–B–O compounds. However, Mg3BN3, which is considered as the catalyst/ solvent for synthesis of c-BN in the B–N–Mg system, is not found. This means that the c-BN synthesis process in the mixture of h-BN, Mg and bonded water is different from that in the system of h-BN–Mg. In this work, some metal lumps can be observed in quenched samples because nickel or copper would be dissociated from the bonded water compounds at that condition of HTHP. Therefore, the cations in bonded water compounds would have little effect on the synthesis of c-BN. Because both Cl-BW and ClF-BW have the similar characters in the process of c-BN synthesis, it is suggested that these processes of c-BN synthesis would be the same as that of h-BN– Mg and Mg(OH)2, which has been discussed in our previous work [9]. When c-BN is synthesized in the h-BN–Mg system at HTHP, h-BN reacts with Mg and forms MgB2 and Mg3BN3. In this flux, Mg3BN3 dissolves h-BN and crystallizes into c-BN [1,6]. In that process of c-BN synthesis, MgB2 or Mg may be doped in c-BN crystals and make the c-BN color black [1,4]. When bonded water is added into the h-BN–Mg system, the decomposed water can react with Mg and produce MgO. The consumption of Mg may lead to the reduction of MgB2 and a light c-BN color. Therefore, when increasing the amount of ClF-BW, c-BN color can change from black to yellow. However, the synthesized c-BN color is still black, no matter how much Cl-BW is added. The difference between ClF-BW and Cl-BW suggests that chlorine might be the cause for the independence of c-BN color on the Cl-BW amount. Perhaps, ClBW can be decomposed at HTHP conditions. For example:
4. Discussion
NiCl2 d 6H2 O þ 2e → 6 H2O þ Ni þ 2Cl−
At the condition of fixed 5.0 GPa, c-BN cannot be synthesized from the mixture of h-BN and Mg at the temperature of 1300 °C [9]. However, c-BN can be synthesized at that temperature when ClF-BW or Cl-BW is added into the mixture. This means that both ClF-BW and Cl-BW could reduce the temperature of the growing c-BN. Another result from this work is that ClF-BW and Cl-BW have different effects on the c-BN color. Fig. 3 (a) and (b) can clearly demonstrate those results. As far as Fig. 3 (a) is concerned, the amount of bonded water would be higher in section A because it is close to the lump. Therefore, the c-BN color is yellow. In section C, no c-BN crystal forms because it is far away from the lump. At the conditions of
and the dissociated Chlorine might be doped in the c-BN crystal and make the c-BN color remain black. Nevertheless, further work is needed to research the effect of bonded water on c-BN synthesis from h-BN with the presence of Mg.
Fig. 4. (a), (b) XRD patterns of samples quenched at 5.0 GPa and 1300 °C, which different bonded water was added into. (a) Full scale (b) Local region showing the diffraction peaks of c-BN.
5. Conclusion When bonded water is added into a system of h-BN–Mg, it changes the process of c-BN synthesis and reduces the temperature of the growing c-BN crystal. According to the character of bonded water and its effect on the synthesized c-BN color, it can be classified into ClF-BW and Cl-BW. When increasing the amount of ClF-BW, the synthesized c-BN color
X.C. Wang et al. / Diamond & Related Materials 17 (2008) 258–261
changes from black to yellow. The c-BN color remains black no matter how much Cl-BW is added. It is suggested that Chlorine might be the cause of c-BN color's independence to the Cl-BW amount. References [1] R.H. Wentorf Jr., J. Chem, Physics 34 (1961) 809. [2] R.C. Devries, J.F. Fleisher, J. Cryst. Growth 13/14 (1972) 88. [3] T. Sato, T. Endo, S. Kashima, O. Fukunaga, M. Iwata, J. Mater. Sci. 18 (1983) 3054. [4] G. Bocquillon, C. Loriers-susse, J. Loriers, J. Mater. Sci. 28 (1993) 3547. [5] H. Lorenz, I. Orgzall, E. Hinze, Diamond Relat. Mater 4 (1995) 1050. [6] H. Lorenz, T. Peun, I. Orgzall, Appl. Phys., A 65 (1997) 487.
261
[7] T. Kobayashi, J. Chem Phys. 70 (1979) 5898. [8] Yonghui Du, Zuopeng Su, Dapeng Yang, Xuxin Yang, Xiaorui Ji, Xiliang Gong, Tiechen Zhang, Mater. Lett. 16 (2006) 1475. [9] X.C. Wang, X.P. Jia, T.C. Zhang, G.Z. Ren, H.J. Liu, C.Y. Zang, P.W. Zhu, H.A. Ma, G.T. Zou, Diamond Relat. Mater 12 (2003) 57. [10] T.-C. Zhang, X.-C. Wang, Y.-H. Du, Z.-P. Su, G.-T. Zou, Chin. J. High Press. Phys. 18 (2004) 17. [11] A.I. Prikhna, A.A. Shulzhenko, V.D. Yakimenko, The USSR Author's Certificate of Invention 452162 (1968). [12] N.V. Novikov, A.I. Prikhna, A.A. Shulzhenko, et al., The USSR Author's Certificate of Invention 707070 (1978). [13] N.V. Novikov, A.I. Prikhna, A.A. Shulzhenko, et al., The USSR Author's Certificate of Invention 799279 (1979). [14] V.S. Lysanov, V.V. Digonskij, L.I. Felgun, et al., DOS 3030362 (1990). [15] A.A. Shulzhenko, A.N. Sokolov, J. Chem. Vapor Depos. 4 (1996) 318.
Diamond & Related Materials 17 (2008) 258 – 261 www.elsevier.com/locate/diamond
c-BN color change with bonded water added into the h-BN–Mg system X.C. Wang a,b,⁎, T.C. Zhang b , H.A. Ma b , X.P. Jia b a
b
Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080, China National Key Laboratory for Superhard Materials, Jilin University, Changchun 130012, China
Received 27 January 2007; received in revised form 6 December 2007; accepted 11 December 2007 Available online 23 December 2007
Abstract Cubic boron nitride (c-BN) crystals were synthesized in conditions of high temperature and high pressure (HTHP) when different kinds of bonded water were respectively added into the system of h-BN–Mg. All bonded water used in this work could reduce the temperature of growing c-BN compared to that in the system of h-BN–Mg. The c-BN color could change from black to yellow when certain amounts of bonded water, such as NiSO4·6H2O and CuSO4·5H2O, Mg(OH)2, were added. However, c-BN color remained black no matter how much bonded water, such as NiCl2·6H2O, CuCl2·2H2O, and SnCl2·2H2O, was added. The bonded water can be classified into Chlorine-containing bonded water (Cl-BW) and Chlorine-free bonded water (ClF-BW) according to their different characters and effects on the synthesized c-BN color. © 2007 Elsevier B.V. All rights reserved. Keywords: c-BN; Bonded water; Chloric; Color
1. Introduction Cubic boron nitride (c-BN) has been applied in many fields because of its outstanding properties. c-BN is the second hardest material. Its high hardness and high thermal conductivity make it useful as a cutting tool and as an abrasive. In addition, its high thermal conductivity and the possibility of appropriate doping make it a potential material for applications in electric fields. At HTHP conditions, c-BN crystals can be synthesized from hexagonal boron nitride (h-BN) with the catalysts such as the alkali metals, alkaline earth metals, their nitrides, and their boric nitrides [1–6]. The color of the synthesized c-BN crystals varies according to the types of the catalysts used. Generally, black cBN crystals are synthesized from h-BN when alkali metals or alkaline earth metals are used. With their nitrides or their boric nitrides as the catalysts, the color of synthesized c-BN is yellow [1,4]. Also, the color may be white when water, boric acid, or urea is used [7]. If M' (M' = Al, B, Si, Ti) is doped into the mixture of h-BN and M xN y (M xN y = Ca3N2, Li3N, Mg3N2), ⁎ Corresponding author. Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080, China. Tel.: +86 010 62554408. E-mail address: [email protected] (X.C. Wang). 0925-9635/$ - see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.diamond.2007.12.037
the synthesized c-BN color can change from yellow to black with increasing proportions of M' [4,8]. The effect of bounded water on the c-BN transformation from h-BN in the presence of magnesium (Mg) has been heavily studied [9–15]. It was reported that when the amount of bonded water increased in the mixture of h-BN and magnesium, the synthesized c-BN color would change from black to yellow [9]. However, our work demonstrates that only ClF-BW can make the color change. When Cl-BW is added into the mixture of h-BN and Mg, the synthesized c-BN color remains black, regardless of the amount. 2. Experiment The c-BN crystal was synthesized at HTHP in a cubic anvil high-pressure apparatus. The pressure was estimated by an oil press load, which was calibrated by the pressure-induced phase transitions of bismuth, thallium, and barium metals. The temperature was estimated by the relationship between applied electrical power and temperature, which was measured by using the platinum–rhodium thermocouple. The assembly used in this work is shown in Fig. 1. In sample column A, the mixture of h-BN, Mg and different kinds of bonded water such as NiSO4·
X.C. Wang et al. / Diamond & Related Materials 17 (2008) 258–261
259
Fig. 1. High pressure cell assembly of c-BN crystal synthesis. (1) pyrophyllite; (2) graphite (3) sample column; (4) h-BN; (5) steel ring.
6H2O, CuSO4·5H2O, Mg(OH)2, NiCl2·6H2O, CuCl2·2H2O, and SnCl2·2H2O, was directly pressed into the column. In sample column B, when the mixture powder of h-BN and Mg was pressed into the column, a lump of bonded water was packed into it. Then, the assembled cell was treated for 5 min at a high pressure (5.0 GPa) and a high temperature (1300 °C). After being quenched, sample column A was measured by X-Ray diffraction, and sample column B was observed by an optical microscope. 3. Results c-BN crystals were synthesized from the mixture of h-BN, Mg and bonded water at HTHP. Table 1 shows that the synthesized c-BN color would change from black to yellow when the amount of NiSO4·6H2O increases, while the synthesized c-BN color is independent of the amount of NiCl2·6H2O. Fig. 2 (a), (b) shows the photographs of synthesized c-BN crystals when NiCl2·6H2O (10 wt.%) and NiSO4·6H2O (10 wt.%) are added into the mixture of h-BN and Mg (15 wt.%), re-
Fig. 2. (a), (b) Photographs of c-BN crystals synthesized with the mixture of h-BN, Magnesium (15 wt.%) and bonded water at 5.0 GPa and 1300 °C. (a) NiCl2· 6H2O (10 wt.%); (b) NiSO4·6H2O (10 wt.%).
spectively. The c-BN color is black when NiCl2·6H2O (10 wt.%) is added and is yellow when NiSO4·6H2O (10 wt.%) is added. Fig. 3 shows the sketch map of samples with a lump of different bonded water packed into it, after these samples are quenched at HTHP. When the lump of ClF-BW is packed into the mixture of h-BN and Mg, the quenched sample would have three sections shown in Fig. 3 (a). Section A is close to the lump, in which c-BN crystals exist and their color is yellow. Section B is near section A, in which black c-BN grains exist. The outer place is section C and no c-BN crystals are synthesized there. If the lump of Cl-BW is packed into it, then the quenched sample would have two sections: a growing black
Table 1 Content of bonded water dependence of the c-BN crystal color in the h-BN–Mg and bonded water system h-BN (wt.%) (content of Mg is fixed at 15 wt.%)
c-BN crystal color
(a) NiSO4·6H2O (wt.%) 80: 5 75: 10 65: 20
Black Yellow No c-BN forms
(b) NiCl2·6H2O (wt.%) 80: 5 75: 10 65: 20
Black Black No c-BN forms
Fig. 3. (a), (b) Sketch map of samples with a lump of different bonded water packed into, after these samples are quenched at 5.0 GPa and 1300 °C. (a) NiSO4·6H2O, CuSO4·5H2O and Mg(OH)2 was packed into respectively; (b) NiCl2·6H2O, CuCl2·2H2O and SnCl2·2H2O was packed into respectively.
260
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c-BN grains section (Section D) and non-growing c-BN grains section (Section E). Fig. 4 shows the XRD patterns of samples quenched at HTHP. From Fig. 4, we can see that h-BN remains the main phase and that a lot of MgO and a little boric magnesium are produced. The peak of c-BN can only be seen from the local region of the diffraction pattern.
5.0 GPa and 1300 °C, c-BN would not be synthesized due to the lack of bonded water. The synthesized c-BN color is black in section B because the section is not far away from the lump and the bonded water could reach there, reducing the c-BN synthesized temperature. In Fig. 3 (b), there exist two sections: a black c-BN grains section and a non-growing c-BN grains section. It means that the bonded water reduces the temperature of c-BN synthesis and the color is independent of its amount. According to the results above, we can classify the bonded water into Cl-BW and ClF-BW. From Fig. 4, we can see that all the quenched samples contain medium productions of MgO and Mg–B–O compounds. However, Mg3BN3, which is considered as the catalyst/ solvent for synthesis of c-BN in the B–N–Mg system, is not found. This means that the c-BN synthesis process in the mixture of h-BN, Mg and bonded water is different from that in the system of h-BN–Mg. In this work, some metal lumps can be observed in quenched samples because nickel or copper would be dissociated from the bonded water compounds at that condition of HTHP. Therefore, the cations in bonded water compounds would have little effect on the synthesis of c-BN. Because both Cl-BW and ClF-BW have the similar characters in the process of c-BN synthesis, it is suggested that these processes of c-BN synthesis would be the same as that of h-BN– Mg and Mg(OH)2, which has been discussed in our previous work [9]. When c-BN is synthesized in the h-BN–Mg system at HTHP, h-BN reacts with Mg and forms MgB2 and Mg3BN3. In this flux, Mg3BN3 dissolves h-BN and crystallizes into c-BN [1,6]. In that process of c-BN synthesis, MgB2 or Mg may be doped in c-BN crystals and make the c-BN color black [1,4]. When bonded water is added into the h-BN–Mg system, the decomposed water can react with Mg and produce MgO. The consumption of Mg may lead to the reduction of MgB2 and a light c-BN color. Therefore, when increasing the amount of ClF-BW, c-BN color can change from black to yellow. However, the synthesized c-BN color is still black, no matter how much Cl-BW is added. The difference between ClF-BW and Cl-BW suggests that chlorine might be the cause for the independence of c-BN color on the Cl-BW amount. Perhaps, ClBW can be decomposed at HTHP conditions. For example:
4. Discussion
NiCl2 d 6H2 O þ 2e → 6 H2O þ Ni þ 2Cl−
At the condition of fixed 5.0 GPa, c-BN cannot be synthesized from the mixture of h-BN and Mg at the temperature of 1300 °C [9]. However, c-BN can be synthesized at that temperature when ClF-BW or Cl-BW is added into the mixture. This means that both ClF-BW and Cl-BW could reduce the temperature of the growing c-BN. Another result from this work is that ClF-BW and Cl-BW have different effects on the c-BN color. Fig. 3 (a) and (b) can clearly demonstrate those results. As far as Fig. 3 (a) is concerned, the amount of bonded water would be higher in section A because it is close to the lump. Therefore, the c-BN color is yellow. In section C, no c-BN crystal forms because it is far away from the lump. At the conditions of
and the dissociated Chlorine might be doped in the c-BN crystal and make the c-BN color remain black. Nevertheless, further work is needed to research the effect of bonded water on c-BN synthesis from h-BN with the presence of Mg.
Fig. 4. (a), (b) XRD patterns of samples quenched at 5.0 GPa and 1300 °C, which different bonded water was added into. (a) Full scale (b) Local region showing the diffraction peaks of c-BN.
5. Conclusion When bonded water is added into a system of h-BN–Mg, it changes the process of c-BN synthesis and reduces the temperature of the growing c-BN crystal. According to the character of bonded water and its effect on the synthesized c-BN color, it can be classified into ClF-BW and Cl-BW. When increasing the amount of ClF-BW, the synthesized c-BN color
X.C. Wang et al. / Diamond & Related Materials 17 (2008) 258–261
changes from black to yellow. The c-BN color remains black no matter how much Cl-BW is added. It is suggested that Chlorine might be the cause of c-BN color's independence to the Cl-BW amount. References [1] R.H. Wentorf Jr., J. Chem, Physics 34 (1961) 809. [2] R.C. Devries, J.F. Fleisher, J. Cryst. Growth 13/14 (1972) 88. [3] T. Sato, T. Endo, S. Kashima, O. Fukunaga, M. Iwata, J. Mater. Sci. 18 (1983) 3054. [4] G. Bocquillon, C. Loriers-susse, J. Loriers, J. Mater. Sci. 28 (1993) 3547. [5] H. Lorenz, I. Orgzall, E. Hinze, Diamond Relat. Mater 4 (1995) 1050. [6] H. Lorenz, T. Peun, I. Orgzall, Appl. Phys., A 65 (1997) 487.
261
[7] T. Kobayashi, J. Chem Phys. 70 (1979) 5898. [8] Yonghui Du, Zuopeng Su, Dapeng Yang, Xuxin Yang, Xiaorui Ji, Xiliang Gong, Tiechen Zhang, Mater. Lett. 16 (2006) 1475. [9] X.C. Wang, X.P. Jia, T.C. Zhang, G.Z. Ren, H.J. Liu, C.Y. Zang, P.W. Zhu, H.A. Ma, G.T. Zou, Diamond Relat. Mater 12 (2003) 57. [10] T.-C. Zhang, X.-C. Wang, Y.-H. Du, Z.-P. Su, G.-T. Zou, Chin. J. High Press. Phys. 18 (2004) 17. [11] A.I. Prikhna, A.A. Shulzhenko, V.D. Yakimenko, The USSR Author's Certificate of Invention 452162 (1968). [12] N.V. Novikov, A.I. Prikhna, A.A. Shulzhenko, et al., The USSR Author's Certificate of Invention 707070 (1978). [13] N.V. Novikov, A.I. Prikhna, A.A. Shulzhenko, et al., The USSR Author's Certificate of Invention 799279 (1979). [14] V.S. Lysanov, V.V. Digonskij, L.I. Felgun, et al., DOS 3030362 (1990). [15] A.A. Shulzhenko, A.N. Sokolov, J. Chem. Vapor Depos. 4 (1996) 318.