Revista MexIcana de FísIca 38, Suplemento 1 (1992) 15-17

The development of high pressure physics in MexicoC. RENERO AND F.E. PIUETO

Instituto de Física, Universidad Nacional Autónoma de MéxicoApartado postal 20-364, 01000 México, D.F., México

Recibido el 15 de agosto de 1991; aceptado el 14 de Cebrerode 1992

ABSTRACT. A review oC the deveJopment oC high pressure physics in Mexico is presented. Thehistory began in 1962 during a Latin American Sehool oC Physics. From then on a theoreticalgroup has developed and two laboratories are in operation: a light gas gun Cordynamieal studiesand an underwater shock wave device working in the low intensity range of shock pressures.

RESUMEN. Se presenta el desarrollo de la física de altas presiones en México desde sus principiosen 1962 durante la Escuela Latinoamerica de Física. En la actualidad, además de un grupo teórico,se cuenta con dos laboratorios diseñados y construidos en el Instituto de Física de la UniversidadNacional Autónoma de México: un cañón de gas para estudios dinámicos y un aparato para producirondas de choque débiles por rompimiento eléctrico en agua.

PAes: 62.50.+p

l. 1NTRODUCTION

The history of high pressure physics in Mexico begins when ProL F.E. Prieto presents atwenty hour course of lectures [1] during the Latin American Schoo! of Physics, he Id inMexico City from July 3 lo August 3,1962. Frorn then on, a group ofphysicists interestedin high pressure physics has deveJoped. In the beginning, only theoretical work was done.Currently, two experimental facilities, designed ami constructed at the Institute of Physicsof the National University of Mexico (IFUNAM), are in operation: A 75 mm light gas gunfor dynamic high pressure research, and an underwater shock wave deviee working in thelow intensity range of shoek pressures.

2. TIIEORETlCAL \YORK

The theoretical work has been centered on the study of the thermodynamical behaviorof matter under high pressure. Early \Vork concerned mainly the equations of state forspecific material [2-4], silver, copper ami sodiulTl chloride in particular. Later the interestshifted lo the properties ofshock loaded mallero Studies oflhe shock profile, and the shockadiabat in solids \Vere published [5,6]. Exlensive \Vork \Vas done, in collaboralion betweenC. Renero and F.E. Prieto, on tite conscqucnccs of t1sing cithcr a linear fit (Us = a +bUp),

or a quadralic fit (U, = a + bUp + cU~) to the experimental data on shock and particlevelocilies. A paper was published on lhe form of lhe equation for lhe I1ugoniol in theP-V representation when a quadratic fit for v"'"cilies is used 15].

16 C. RENERO AND F.E. PRIETO

In 1971, lhe firsl of a long series of papers using reduced variables lo describe highpressure lhermodynamics was published [7]. It was shown lhallhe equalion far lhe Hugo-niol in lhe linear case could be lransformed in such a way lhal lhe resulling equalionis universal. This means lhal il lakes nol only lhe same form for all malerials, bul inaddilion, il is syslcm-independenl if lhe appropriale reduced or scaled variables are usedfor pressure and compression [8]. It was also shown lhal in lhe quadralic case lhe equationfor lhe Hugoniol can nol be lransformed inlo a universal form [9]. This paper markedlhe beginning of a new period and a new goal for lhe work of our group: The search fora syslem-independenl represenlalion for lhe lhermodynamics of high pressures. The firslclue in lhe sojulion of lhis problem was lhe formulalion of a law of corresponding slales formalerials al high pressures [8]. It was shown lhal lhere is only one lransformalion of vari-ables leading lo a universal form of lhe equalion for lhe Hugoniol, in lhe linear case, whenexpressed in scaled pressure and relalive compression. This made il possible lo expressall lhe mechanical variables of lhermodynamics in Jcaled form, and if possible achievingsyslem-independency. An adequale lransformalion for lelllperalures was however lacking.The sludy of release adiabals from shocked slales resulled in a reduced form for lhe le m-peralure [ID]. It was shown in parlicular lhal by lhe use of lhe so called "o-reduced le m-perature" lhe equation for lhe release adiabats could be expressed in systelll-independenlformo This provided the way lo lhe formulalion of a system-independenl thermodynamicsof high pressures. An imlllediale consequence was a universal equation of state for solids athigh pressure [llj. This equalion, originally demonslraled for solids, turned out to be alsovalid for liquids ami for gases at high pressures, as reporled in a paper in collaboralionwith ProL A. Mondragón [12]. Thus, lhis equation is in fact a universal equation of state,or a universal PVT correlation for maller al high pressure [13-16].Having succeeded in oblaining a syslelll-independenl formulation of the thermodynam-

ics of high pressures, and a universal equation of stale correlation, lhe n~ed of experimentalfacilities for comparison belween lheorelical results and experimenlal data was sleadilygrowing.

3. EXPEIUMENTAL WORK

The light gas gun

At lhe lime M. de Ieaza, one of ProL Prielo's former students, was coming back fromPoiliers (France), where he received a PhO under PraL J. Jacquesson. After many dis-cussions involving members of our group, and also the administration of lhe IFUNAM, theproposed project for a light gas gun, to be entirely designed, constructed and operatedat the IFUNAM, was accepted. This work took more than five years, and it is now inoperation (17-19]. It has a barrel with 75.4 mm inside and 130 mm outside diameters,and a total length of 13 m. The breech can be filled up to ,10 MPa pressure with a lightgas such as helium and the gun can then accelerate ¡ Kg projectiles up to I Km/s. Themain experimental interests are the use of conlrolled initial temperature targets to testprevious theorctical work on thc universal equation of state, and also mcasuring shockinduccd pha..'ic transitions.

THE DEVELOPMENT OF HIGH PRESSURE. • • 17

Underwater low intensity shock wave generator

This device was also designed and built at the IFUNAM[20-22], with imported electroniccomponents. Shock waves are generated by dielectrical breakdown of water. Electrodes arepositioned in the neighborhood of the primary focus of an ellipsoidal metalJic mirror andthe shock wave is concentrated at the second focus. Shock intensity attained is between1000 ami 2000 atmospheres. This is a research device that has applications for physical,biophysical, chemical, and clinical investigations of the behavior of materials vnder theinfluence of shock waves.

REFERENCEs

1. F.E. Prieto, "Equation oC state oC metals al high prcssures" I Escuela Latino Americana deFísica, July 2 - August lO, 1962, UNAM.

2. F.E. Prielo, Phys. Rev. 129 (1963) 37.3. G.S. Oyarzabal and F.E. Prieto, Rev. Mex. Fis. 12, (1963) 43.4. F.E. Prielo and C. Renero, Rev. Mex. Fis. 13 (196.1) 15.5. F.E. Prielo and C. Renero, J. Appl. Phys. 41 (1970) 3876.6. F.E. Prielo and C. Renero, J. Appl. Phys. 44 (1973) 4013.7. F.E. Prielo and C. Renero, J. Appl. Phys. 42 (1971) 296.8. F.E. Prielo, J. Phys. Chem. Solids 35 (1974) 279.9. F.E. Prielo and C. Renero, C.R. Aead. Seí. 2793 (1974) 601.lO. F.E. Prielo. J. Phys. Chem. Solíds 36 (1975) 871.11. F.E. Prieto and C. Renero, J. Phys. Chem. Solids 37 (1976) 151.12. F.E. Prielo, C. Renero and A. Mondragón. Proe. Fjfth Peaeeful Nuclear Explosíon Conf.

IAEA, TC81 (1978) 511.13. F.E. Prielo and C. Renero, in lligh P,'Cssure Seí. and Teeh., Vol. 1, Plenum Press (1979).14. F.L. Yarger, F.E. Prielo and C. Renero, in lligh Pressure Sej. and Teeh., Vol. 11, Plenum

Press (1979).15. F.E. Prielo and C. Renero, C.R. Aead. Seí. 289B (1979) 5.16. F.E. Prieto and C. Renero, J. Phys. Chem. Solids 43 (1982) 147.17. M. de !caza, C. Renero and F.E. Prielo, Physies 139B (1986) 599.18. M. de !caza, C. Renero and F.E. Prielo, Rev. Sej. Inst. 60 (1989) 3284.19. M. de !caza, C. Renero and F.E. Prielo, Rev. Sej. Inst. 62 (1991) 431.20. A.M. Loske, M. Se. Thesis, Facullad de Ciencias, UNAM (1991).21. F.E. Prieto, A.M. Loske and F.L. Yarger, llevo Seí. Inst. 62 (1991) 1849.22. F.L. Yarger, F.E. Prielo and A.M. L""ke, Pme. APD Topíeal Conf. Shock Compro of

Condenscd Matler, Eds. S.C. Schmidt, R.D. Diek, J.\V. Forbes and D.G. Tasker, ElsevierSeience Pub. (1991).