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Diamond synthesis by electric discharge shock technique
Carbon
1964, Vol. 1, pp. 127-131.
DIAMOND
Pergamon
Press Ltd.
SYNTHESIS
BY ELECTRIC
SHOCK
DISCHARGE
TECHNIQUE
H. HONDA Resources Research
Printed in Great Britain
and Y. SANADA
Institute,
Kawaguchi-Saitama,
Japan
and K. INOUE Japax Inc., Sakato, Kawasaki-Kanagawa,
Japan
(Received 19 March 1963)
Abstract-A new apparatus of diamond synthesis by electric discharge shock in oil was completed. Synthetic diamonds were made by a spark discharge shock between nickel and iron and an artificial graphite electrode in high pressure kerosene. The discharge energy was about 4000 joules. The identification was made by hardness tests and by an X-ray diffraction pattern. The growth rate of synthetic diamonds is very high. The synthetic diamonds are transparent and slightly yellowish.
1. INTRODUCTION early
to strong shock phenomena produced by high explosives, have been reported, though the details of experimental methods were not explained.(12-r4) On the other hand, the synthesis of diamonds using an electric arc between carbon electrodes was attempted by many investigators in the past, but no one has ever succeeded in making diamonds by this method. The present authors tried to make diamonds by using electric discharge shock in oil.
attempts
of HANNAY and MOBSAN to synthesize diamonds were outstanding and created a great excitement. HANNAY obtained purported diamonds in 1880 by heating paraffin and bone oil with metallic lithium under extremely hazardous conditions. MOISSAN prepared his diamonds by dissolving sugar carbon in molten iron and quenching it to generate the high pressure required for the transformation. Unfortunately, their attempts preceded the days of the unequivocal X-ray test and their claims resulted in inconclusive disputes. Thermodynamic studies of the equilibrium between diamond and graphite forms of carbon have indicated that diamond should be the stable form of carbon under higher pressure(3-5). In 1955 the General Electric Research Laboratory in Schenectady reported the production of synthetic diamonds under conditions of high pressure and high temperature.(6, 7, Also, the success in production of synthetic diamonds was announced from Sweden@), Russia(9), South Africa(“)) and Japan. (11) All of these diamond syntheses, however, succeeded under mechanical high pressure. Recently, successful conversion of graphite to the diamond phase, when the former is subjected THE
2. EXPERIMENTAL
PROCEDURE
The apparatus used in the synthesis of diamonds is shown schematically in Fig. 1. Nitrogen gas is sent from a bomb to SCP (fully automatic compression and constant volume pump) through OPC (fully automatic pressure volume controller). Flow rates of nitrogen gas into SCP is controlled by means of a stop valve and an electromagnetic valve. Oil is sent from a reservoir to the secondary device for increasing pressure by the action of SCP. Then the spark discharge is initiated between the charged electrodes in the insulating oil. A general view and diagram of the synthetic apparatus are shown in Figs. 2 and 3, respectively. SCP is mounted on the high pressure equipment and the secondary device for increasing pressure is fitted out in the high pressure equipment. Figure 4 shows a diagram of high pressure capsule. 127
H. HONDA,
128
“pper
block
,z---._-
Y. SANADA
and K.
INOUE Plunger
(die steel)
Plunger
guide
Punch
(stainless
(die
steel)
steel)
plastic)
~.__,\
Insulator
Block
(epoxy
(nickel
reinforced
plastic)
chromium
block (f-21 Insulator(polycorbonote)
FIG.
1. Schematic diagram of electric discharge shock system.
The upper electrode is a nickel or iron rod of 6 mm dia., the lower electrode is an artificial graphite rod of 6 mm diameter, and packing is a polyoxymethylene resin. The pressure in the capsule becomes about 3000 kg/cm2 by the actions of SCP and the secondary device for increasing pressure when the electrode gap is 4-5 mm and the insulating oil is kerosene. Figure 5 shows a circuit diagram of electric sources. The capacity of condenser is 20,000~ F. The charging voltage of this experiment was 600 V. After the discharge was completed, the capsule was opened and the contents in the capsule were removed. The kerosene was washed out by methyl
acetate. The metal in the residue was removed by boiling with hydrochloric acid. Graphite and soot were removed by oxidation in air or in hot nitric and sulphuric acid. Thereafter, the synthetic diamonds were isolated by the float-or-sink method using methylene iodide. 3. RESULTS
AND
DISCUSSION
Obtained synthetic diamonds are shown in Fig. 6. These diamonds are transparent and slightly yellowish. X-ray diffraction pattern of a synthetic diamond is shown in Fig. 7 with those of natural and G. E. man-made diamonds. The lattice distance and the lattice constant of the synthetic
FIG. 6.
Photograph
of synthetic
diamonds.
[fncin.g p.
t 2x
FIG. 7.
X-ray
diffraction
patterns
of synthetic
and natural
diamond.
DIA~~OND
SYNTHESIS
BY ELECTRIC
DISCHARGE
SHOCK
~ut~rna~i~ compresslon and constant volume pump) ’
c\
2_8,Ptunger guide
29 Elect rode _ 0 30 Arr 0
relief vo~ve
QRase----. @Termhot (iower)
rod
FIG. 3 Diagram of synthetic apparatus.
c
TECHNIQUE
129
H. HONDA,
130
Y. SANADA
and K. INOUE
Full outamatic compression ond cansiant pump -
--ARemote Control 4-22
Nitrogen
gos
:m2mox
bomb
, Primary
device
for increasing
econdory
device
for increasing
ac3 Regulating ronge O-20 Flow quonlity 300-50
pressure
phase 2OOT
kg/cm’ cc/min
‘Oil Cell
FIG. 4. Diagram of high pressure capsule. Main switch
Lnorgmg Voltage
regulator
resIsTor
Mg,
W,
+P +Terrrinol _to
Capacitor
Magnet switch
Limit
switch3
iompoMagnet
valve S v
? PllOf lomp
FIG. 5. Circuit diagram of electric sources.
DIAMOND
SYNTHESIS
BY
ELECTRIC
TABLE 1. LATTICE DISTANCEAND
Value of A.S.T.M.
W)
I
DISCHARGE
SHOCK
TECHNIQUE
131
LATTICE CONSTANTOF SYNTHETIC DIAMOND
Natural diamond
Man-made diamond
Synthetic diamond
by G.E.
by electric discharge
A
A
a
A
(111)
2.060
2.06
2.06
2.06
(220)
I.261
I.259
I.260
1.263
(311)
1.0754
I.074
I.075
I.077
(400)
0.8916
0890
0.891
0.894
(331) Lattice const.
0.8180
0817
0.817
0.820
3.567
3,562
3.565
3.572
diamond are shown in Table 1 with those of natural and G. E. man-made diamonds. The mirror finished surface of titanium carbide is scratched by these synthetic diamonds. The direct measurements of pressure and temperature in the capsule at the moment of the spark discharge were not done in this work. It is believed, however, that the temperature of a stationary arc column is about 5000-6000”K, while the temperature of a transitory spark discharge is above 10,OOO”K. Furthermore, spark discharge in oil produces a pressure of about 150,000-200,000 kg/cm2 at the electrode gap. Therefore, it is possible to create an ideal environment of adequate pressure and temperature for synthesizing diamond by means of applying spark discharge shock in a high pressure capsule. The pulse duration of spark discharge was about 5 -6 m sec. The growth rate of synthetic diamonds is very high. The rapidity of reaction under spark discharge shock seems to be associated with the extremely large forces in the shock front and the estremely steep temperature gradients.
REFERENCES 1. HANNAY J. B., PYOC.Roy. SW 30, 450 (1880). 2. MOISSANH., C. R. Acad. Sci., Paris 140, 277 (1905). 3. BERMAN R. and THEWLIS J., Nature, Lond. 176, 834 (1955). 4. BERMAN R. and SIMON F., Z. Elektrochem. 59, 333 (1955). 5. BUNDY F. P., BOVENKERKH. P., STRONGH. M. and WENTORF R. H., r. Chem. Phys. 35, 383 (1961). 6. BUNDY F. P., HALL H. T., STRONG H. M. and WENTORF R. H., Nature, Lond. 176, 51 (1955). 7. BOVENKERK H. P., BUNDY F. P., HALL H. T., STRONGH. M. and WENTORF R. H., Nature, Lond. 184, 1094 (1959). 8. LIAND~R H. and LUNDBLAI) E.. Ark. Kemi. 16, 139 (1960). 9. VERESHCHACINL. F., Progress in VeryHigh Pressure Research (Bolton Landing Conference), p.290. Wiley, New York (1961). 10. Industr. Diam. Reo. 21, 186 (1961). 11. WAKAMATSUN.. TAKASU S. and WAKATSUKI M., Kagaku-Asahi, Japan. 124 (1962). 12. LIPSCHUTZ M. E. and ANDERS E.. Geochim. et Cosmochim. Acta. 24, 83 (1961). 13. ALDER B. J. and CHRISTI.~NR. H., Phys. Rev. Ixtters 7, 367 (1961). 14. DE CARLI P. S. and JAMII.SON J. C., Science 133, 1821 (1961).
1964, Vol. 1, pp. 127-131.
DIAMOND
Pergamon
Press Ltd.
SYNTHESIS
BY ELECTRIC
SHOCK
DISCHARGE
TECHNIQUE
H. HONDA Resources Research
Printed in Great Britain
and Y. SANADA
Institute,
Kawaguchi-Saitama,
Japan
and K. INOUE Japax Inc., Sakato, Kawasaki-Kanagawa,
Japan
(Received 19 March 1963)
Abstract-A new apparatus of diamond synthesis by electric discharge shock in oil was completed. Synthetic diamonds were made by a spark discharge shock between nickel and iron and an artificial graphite electrode in high pressure kerosene. The discharge energy was about 4000 joules. The identification was made by hardness tests and by an X-ray diffraction pattern. The growth rate of synthetic diamonds is very high. The synthetic diamonds are transparent and slightly yellowish.
1. INTRODUCTION early
to strong shock phenomena produced by high explosives, have been reported, though the details of experimental methods were not explained.(12-r4) On the other hand, the synthesis of diamonds using an electric arc between carbon electrodes was attempted by many investigators in the past, but no one has ever succeeded in making diamonds by this method. The present authors tried to make diamonds by using electric discharge shock in oil.
attempts
of HANNAY and MOBSAN to synthesize diamonds were outstanding and created a great excitement. HANNAY obtained purported diamonds in 1880 by heating paraffin and bone oil with metallic lithium under extremely hazardous conditions. MOISSAN prepared his diamonds by dissolving sugar carbon in molten iron and quenching it to generate the high pressure required for the transformation. Unfortunately, their attempts preceded the days of the unequivocal X-ray test and their claims resulted in inconclusive disputes. Thermodynamic studies of the equilibrium between diamond and graphite forms of carbon have indicated that diamond should be the stable form of carbon under higher pressure(3-5). In 1955 the General Electric Research Laboratory in Schenectady reported the production of synthetic diamonds under conditions of high pressure and high temperature.(6, 7, Also, the success in production of synthetic diamonds was announced from Sweden@), Russia(9), South Africa(“)) and Japan. (11) All of these diamond syntheses, however, succeeded under mechanical high pressure. Recently, successful conversion of graphite to the diamond phase, when the former is subjected THE
2. EXPERIMENTAL
PROCEDURE
The apparatus used in the synthesis of diamonds is shown schematically in Fig. 1. Nitrogen gas is sent from a bomb to SCP (fully automatic compression and constant volume pump) through OPC (fully automatic pressure volume controller). Flow rates of nitrogen gas into SCP is controlled by means of a stop valve and an electromagnetic valve. Oil is sent from a reservoir to the secondary device for increasing pressure by the action of SCP. Then the spark discharge is initiated between the charged electrodes in the insulating oil. A general view and diagram of the synthetic apparatus are shown in Figs. 2 and 3, respectively. SCP is mounted on the high pressure equipment and the secondary device for increasing pressure is fitted out in the high pressure equipment. Figure 4 shows a diagram of high pressure capsule. 127
H. HONDA,
128
“pper
block
,z---._-
Y. SANADA
and K.
INOUE Plunger
(die steel)
Plunger
guide
Punch
(stainless
(die
steel)
steel)
plastic)
~.__,\
Insulator
Block
(epoxy
(nickel
reinforced
plastic)
chromium
block (f-21 Insulator(polycorbonote)
FIG.
1. Schematic diagram of electric discharge shock system.
The upper electrode is a nickel or iron rod of 6 mm dia., the lower electrode is an artificial graphite rod of 6 mm diameter, and packing is a polyoxymethylene resin. The pressure in the capsule becomes about 3000 kg/cm2 by the actions of SCP and the secondary device for increasing pressure when the electrode gap is 4-5 mm and the insulating oil is kerosene. Figure 5 shows a circuit diagram of electric sources. The capacity of condenser is 20,000~ F. The charging voltage of this experiment was 600 V. After the discharge was completed, the capsule was opened and the contents in the capsule were removed. The kerosene was washed out by methyl
acetate. The metal in the residue was removed by boiling with hydrochloric acid. Graphite and soot were removed by oxidation in air or in hot nitric and sulphuric acid. Thereafter, the synthetic diamonds were isolated by the float-or-sink method using methylene iodide. 3. RESULTS
AND
DISCUSSION
Obtained synthetic diamonds are shown in Fig. 6. These diamonds are transparent and slightly yellowish. X-ray diffraction pattern of a synthetic diamond is shown in Fig. 7 with those of natural and G. E. man-made diamonds. The lattice distance and the lattice constant of the synthetic
FIG. 6.
Photograph
of synthetic
diamonds.
[fncin.g p.
t 2x
FIG. 7.
X-ray
diffraction
patterns
of synthetic
and natural
diamond.
DIA~~OND
SYNTHESIS
BY ELECTRIC
DISCHARGE
SHOCK
~ut~rna~i~ compresslon and constant volume pump) ’
c\
2_8,Ptunger guide
29 Elect rode _ 0 30 Arr 0
relief vo~ve
QRase----. @Termhot (iower)
rod
FIG. 3 Diagram of synthetic apparatus.
c
TECHNIQUE
129
H. HONDA,
130
Y. SANADA
and K. INOUE
Full outamatic compression ond cansiant pump -
--ARemote Control 4-22
Nitrogen
gos
:m2mox
bomb
, Primary
device
for increasing
econdory
device
for increasing
ac3 Regulating ronge O-20 Flow quonlity 300-50
pressure
phase 2OOT
kg/cm’ cc/min
‘Oil Cell
FIG. 4. Diagram of high pressure capsule. Main switch
Lnorgmg Voltage
regulator
resIsTor
Mg,
W,
+P +Terrrinol _to
Capacitor
Magnet switch
Limit
switch3
iompoMagnet
valve S v
? PllOf lomp
FIG. 5. Circuit diagram of electric sources.
DIAMOND
SYNTHESIS
BY
ELECTRIC
TABLE 1. LATTICE DISTANCEAND
Value of A.S.T.M.
W)
I
DISCHARGE
SHOCK
TECHNIQUE
131
LATTICE CONSTANTOF SYNTHETIC DIAMOND
Natural diamond
Man-made diamond
Synthetic diamond
by G.E.
by electric discharge
A
A
a
A
(111)
2.060
2.06
2.06
2.06
(220)
I.261
I.259
I.260
1.263
(311)
1.0754
I.074
I.075
I.077
(400)
0.8916
0890
0.891
0.894
(331) Lattice const.
0.8180
0817
0.817
0.820
3.567
3,562
3.565
3.572
diamond are shown in Table 1 with those of natural and G. E. man-made diamonds. The mirror finished surface of titanium carbide is scratched by these synthetic diamonds. The direct measurements of pressure and temperature in the capsule at the moment of the spark discharge were not done in this work. It is believed, however, that the temperature of a stationary arc column is about 5000-6000”K, while the temperature of a transitory spark discharge is above 10,OOO”K. Furthermore, spark discharge in oil produces a pressure of about 150,000-200,000 kg/cm2 at the electrode gap. Therefore, it is possible to create an ideal environment of adequate pressure and temperature for synthesizing diamond by means of applying spark discharge shock in a high pressure capsule. The pulse duration of spark discharge was about 5 -6 m sec. The growth rate of synthetic diamonds is very high. The rapidity of reaction under spark discharge shock seems to be associated with the extremely large forces in the shock front and the estremely steep temperature gradients.
REFERENCES 1. HANNAY J. B., PYOC.Roy. SW 30, 450 (1880). 2. MOISSANH., C. R. Acad. Sci., Paris 140, 277 (1905). 3. BERMAN R. and THEWLIS J., Nature, Lond. 176, 834 (1955). 4. BERMAN R. and SIMON F., Z. Elektrochem. 59, 333 (1955). 5. BUNDY F. P., BOVENKERKH. P., STRONGH. M. and WENTORF R. H., r. Chem. Phys. 35, 383 (1961). 6. BUNDY F. P., HALL H. T., STRONG H. M. and WENTORF R. H., Nature, Lond. 176, 51 (1955). 7. BOVENKERK H. P., BUNDY F. P., HALL H. T., STRONGH. M. and WENTORF R. H., Nature, Lond. 184, 1094 (1959). 8. LIAND~R H. and LUNDBLAI) E.. Ark. Kemi. 16, 139 (1960). 9. VERESHCHACINL. F., Progress in VeryHigh Pressure Research (Bolton Landing Conference), p.290. Wiley, New York (1961). 10. Industr. Diam. Reo. 21, 186 (1961). 11. WAKAMATSUN.. TAKASU S. and WAKATSUKI M., Kagaku-Asahi, Japan. 124 (1962). 12. LIPSCHUTZ M. E. and ANDERS E.. Geochim. et Cosmochim. Acta. 24, 83 (1961). 13. ALDER B. J. and CHRISTI.~NR. H., Phys. Rev. Ixtters 7, 367 (1961). 14. DE CARLI P. S. and JAMII.SON J. C., Science 133, 1821 (1961).