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On intermetallic compound Bi2Zr
Solid State Communications,
Vol. 7, pp. 1803—1804, 1969.
Pergamon Press.
Printed in Great Britain
ON INTERMETALLIC COMPOUND Bi2Zr Arunsingh* and B. Dayal Department of Physics, Banaras Hindu University, Varanasi-5, India (Received 3 June 1969 by A.R. Verma)
The method recently proposed by us (Ziet für Metalikunde, 1969) has been utilised to produce intermetallic compound Bi2Zr. The interdiffusion coefficient has been estimated to be of the order of i0~cm~/secat 600°Kand this explains the reason why this intermetallic is formed so easily.
WE HAVE recently reported 1,2 a method by which alloys of Cd and Zr could be prepared easily. The same method has been used to prepare the alloy of Bi and Zr. Here again like Cd—Zr system the conventional method would fail as both the metals have widely differing melting points, Bi boils at 1560°Cand Zr melts at 1852°C.
that in 30 mm time the alloy product was formed. The product was recovered in the form of fine powder and was kept for annealing for 72 hr at 360°C. The powder pattern of this alloy was obtained and in all 52 lines were recorded. All the lines were indexed by taking an orthorhombic unit cell with a = 10. i9A ±0.O1A, b = 15.06A ±o.oiA and pattern c = 4.OOA For interpreting this powder we ±o.oiA. have adopted 4 procedure but instead of the Hesse Lipson taking sin2O values we have taken l/d2 values.5 This procedure has certain superiority and is more straightforward.
The only reported work on Bi—Zr 3system They had seems to be of Bykov and Kazarnikov. prepared single crystal of Bi 2Zrmethod by dipping liquid Bi. As the details of the are Zr notin available, we decided to prepare this compound by the method recently reported ~ by us. Zr powder was obtained by filing with a fine jeweller’s file the specpure rod of metal. After doing magnetic separation for iron contaminated particles and screening through a ‘Jayant sieve’ of 200 mesh (B.S.S.) the particles smaller than 75/h were collected for use. This is the size of the particles quoted by the manufacturer of the sieve. Si powder was obtained by crushing the ingots in agate pestle and mortar. Appropriate quantities of both were packed in a capillary tube and small pressure by hand was applied to bring them together. A current through the compact was passed at 4V 9A and it was found *
Pearson’s6 compilation quotes the following values of the lattice parameters from the work of Bykov and Kazarnikov a = 10.2A b = 15.15A and c = 4.OA. However the translated version of this paper of the above authors gives the value of b slightly different i.e. 15.5A. Our values are in agreement with Pearson’s values. On indexing the lines we found that in the reflections of hkO, oki and hO! types the extinction condition h + k = k + I = h + I = 2n was satisfied, hence in agreement with Bykov and Kazarnikov the space group Pnnn or may be assigned to this structure.
On leave from Government College, Shahdol (M.P.) India. 1803
1804
ON INTERMETALLIC COMPOUND Bi2Zr
In our view the alloy formation in the present process takes place through thermal diffusion via vacancies. The great convenience by which Bykov and Kazarnikov could prepare single crystal of Bi2Zr suggests that interdiffusion coefficient between7 these two a metals must high. proposed solution ofbe Fick’s We have recently diffusion equation in the form D
=
Vol.7, No.24
out by these authors one interesting consequence of this model is that the rate of interdiffusion is independent of the Cu particle size but sensitive to the size of the Ni particle. It is in this context that we believe that Bi diffuses into Zr and that theoninterdiffusion dependent the size of Zrcoefficient particle. is only
.~!!_1og~ C 0
where a is the particle size, t is the time to get the alloy product formed C 0 = 100 and c is the atom % of the second constituent which diffuses in the parent matrix. The above equation has been derived on the basis of the 8shell model These authors proposed by Fisher and Rudman. have discussed the Cu—Ni system and assume that prior to any appreciable interdiffusion, the Ni particles are surrounded by a shell of Cu. In our view this is due to the fact that Cu has a lower melting point than Ni and hence Cu lattice becomes effectively more loose and is likely to smear easily around the Ni particle. As pointed
Putting a 75/h and t = 302/sec minutes we get D~3.6 x l0~cm This is reasonable but a few order of magnitude higher than usually observed for metals at 600°K. This seems to be the reason why Bi2Zr is formed so easily. Acknowledgements The authors are grateful to Dr. O.N. Srivastava for discussions. One of us is further grateful to the Principal Government College, Shahdol, M.P. (India) for permitting the work to be undertaken in the Physics Department. He is also grateful to U.G.C. India for giving financial assistance, under the scheme meant for college teachers. —
REFERENCES 1.
ARUNSINGH and DAYAL B., Z. Melalik. (In press).
2.
ARUNSINGH and DAYAL B., Acta Crystallogr. B25, 1010 (1969).
3.
BYKOV V.N. and KAZARNIKOV V.V., Soy. Phys. Crystallogr. 4, 880 (1960).
4.
HENRY N.F.M., LIPSON H. and WOOSTER W.A., The Interpretation of X-ray Diffraction Photograph, p. 183, Macmillan, (1953).
5. 6.
AZAROFF L.V. and BURGER V.J., The Powder Method, p. 117, McGraw Hill, (1958). PEARSON W.B., A handbook of lattice spacings and structures of metals and alloys, p. 730, Pergamon Press, (1967). ARUNSINGH and DAYAL B., Z. Mettallk. (In press). FISHER B. and RUDMAN P.S., J. appi. Phys. 32, 1904 (1961).
7. 8.
Mii npe~~iarae~ fl~$D4O~ o~iapyzeime 9~KTOBOTKJIOH~HM$i CIHIHOB
B
O~1OOCHUM
$ppoMarliemloM npH H~JIbOM~e~nepa~yp~ 11pM EaJIWWE 6o~woroMarHxmoro IlOjisi UepneH~fl(yJ1HpHoYHMX~AbHOMY OCIO. Oflpe~eAeaMOTKJIOH6HMe ommoB 11 I1~O~OJ1bH~~ BOCI1~MXMt1MBOCTb K~K~~HKI~M$I OT qacTom, H npe~no.~1oze~ CrBr
3 MJIM Cr1 3~iu 9KCflO~HM~HT~J1bHO~O ~iccie~o~anna.
Vol. 7, pp. 1803—1804, 1969.
Pergamon Press.
Printed in Great Britain
ON INTERMETALLIC COMPOUND Bi2Zr Arunsingh* and B. Dayal Department of Physics, Banaras Hindu University, Varanasi-5, India (Received 3 June 1969 by A.R. Verma)
The method recently proposed by us (Ziet für Metalikunde, 1969) has been utilised to produce intermetallic compound Bi2Zr. The interdiffusion coefficient has been estimated to be of the order of i0~cm~/secat 600°Kand this explains the reason why this intermetallic is formed so easily.
WE HAVE recently reported 1,2 a method by which alloys of Cd and Zr could be prepared easily. The same method has been used to prepare the alloy of Bi and Zr. Here again like Cd—Zr system the conventional method would fail as both the metals have widely differing melting points, Bi boils at 1560°Cand Zr melts at 1852°C.
that in 30 mm time the alloy product was formed. The product was recovered in the form of fine powder and was kept for annealing for 72 hr at 360°C. The powder pattern of this alloy was obtained and in all 52 lines were recorded. All the lines were indexed by taking an orthorhombic unit cell with a = 10. i9A ±0.O1A, b = 15.06A ±o.oiA and pattern c = 4.OOA For interpreting this powder we ±o.oiA. have adopted 4 procedure but instead of the Hesse Lipson taking sin2O values we have taken l/d2 values.5 This procedure has certain superiority and is more straightforward.
The only reported work on Bi—Zr 3system They had seems to be of Bykov and Kazarnikov. prepared single crystal of Bi 2Zrmethod by dipping liquid Bi. As the details of the are Zr notin available, we decided to prepare this compound by the method recently reported ~ by us. Zr powder was obtained by filing with a fine jeweller’s file the specpure rod of metal. After doing magnetic separation for iron contaminated particles and screening through a ‘Jayant sieve’ of 200 mesh (B.S.S.) the particles smaller than 75/h were collected for use. This is the size of the particles quoted by the manufacturer of the sieve. Si powder was obtained by crushing the ingots in agate pestle and mortar. Appropriate quantities of both were packed in a capillary tube and small pressure by hand was applied to bring them together. A current through the compact was passed at 4V 9A and it was found *
Pearson’s6 compilation quotes the following values of the lattice parameters from the work of Bykov and Kazarnikov a = 10.2A b = 15.15A and c = 4.OA. However the translated version of this paper of the above authors gives the value of b slightly different i.e. 15.5A. Our values are in agreement with Pearson’s values. On indexing the lines we found that in the reflections of hkO, oki and hO! types the extinction condition h + k = k + I = h + I = 2n was satisfied, hence in agreement with Bykov and Kazarnikov the space group Pnnn or may be assigned to this structure.
On leave from Government College, Shahdol (M.P.) India. 1803
1804
ON INTERMETALLIC COMPOUND Bi2Zr
In our view the alloy formation in the present process takes place through thermal diffusion via vacancies. The great convenience by which Bykov and Kazarnikov could prepare single crystal of Bi2Zr suggests that interdiffusion coefficient between7 these two a metals must high. proposed solution ofbe Fick’s We have recently diffusion equation in the form D
=
Vol.7, No.24
out by these authors one interesting consequence of this model is that the rate of interdiffusion is independent of the Cu particle size but sensitive to the size of the Ni particle. It is in this context that we believe that Bi diffuses into Zr and that theoninterdiffusion dependent the size of Zrcoefficient particle. is only
.~!!_1og~ C 0
where a is the particle size, t is the time to get the alloy product formed C 0 = 100 and c is the atom % of the second constituent which diffuses in the parent matrix. The above equation has been derived on the basis of the 8shell model These authors proposed by Fisher and Rudman. have discussed the Cu—Ni system and assume that prior to any appreciable interdiffusion, the Ni particles are surrounded by a shell of Cu. In our view this is due to the fact that Cu has a lower melting point than Ni and hence Cu lattice becomes effectively more loose and is likely to smear easily around the Ni particle. As pointed
Putting a 75/h and t = 302/sec minutes we get D~3.6 x l0~cm This is reasonable but a few order of magnitude higher than usually observed for metals at 600°K. This seems to be the reason why Bi2Zr is formed so easily. Acknowledgements The authors are grateful to Dr. O.N. Srivastava for discussions. One of us is further grateful to the Principal Government College, Shahdol, M.P. (India) for permitting the work to be undertaken in the Physics Department. He is also grateful to U.G.C. India for giving financial assistance, under the scheme meant for college teachers. —
REFERENCES 1.
ARUNSINGH and DAYAL B., Z. Melalik. (In press).
2.
ARUNSINGH and DAYAL B., Acta Crystallogr. B25, 1010 (1969).
3.
BYKOV V.N. and KAZARNIKOV V.V., Soy. Phys. Crystallogr. 4, 880 (1960).
4.
HENRY N.F.M., LIPSON H. and WOOSTER W.A., The Interpretation of X-ray Diffraction Photograph, p. 183, Macmillan, (1953).
5. 6.
AZAROFF L.V. and BURGER V.J., The Powder Method, p. 117, McGraw Hill, (1958). PEARSON W.B., A handbook of lattice spacings and structures of metals and alloys, p. 730, Pergamon Press, (1967). ARUNSINGH and DAYAL B., Z. Mettallk. (In press). FISHER B. and RUDMAN P.S., J. appi. Phys. 32, 1904 (1961).
7. 8.
Mii npe~~iarae~ fl~$D4O~ o~iapyzeime 9~KTOBOTKJIOH~HM$i CIHIHOB
B
O~1OOCHUM
$ppoMarliemloM npH H~JIbOM~e~nepa~yp~ 11pM EaJIWWE 6o~woroMarHxmoro IlOjisi UepneH~fl(yJ1HpHoYHMX~AbHOMY OCIO. Oflpe~eAeaMOTKJIOH6HMe ommoB 11 I1~O~OJ1bH~~ BOCI1~MXMt1MBOCTb K~K~~HKI~M$I OT qacTom, H npe~no.~1oze~ CrBr
3 MJIM Cr1 3~iu 9KCflO~HM~HT~J1bHO~O ~iccie~o~anna.