Solid StateCommunications,Vol. 18, p. v, 1976. PergamonPress. Printedin GreatBritain

Abstracts of Articles to be Published in The Journal of

Physics and Chemistry of Solids‘J Phys. Chem. Solids (to be published)’ should be citedin references to material quoted from this section prior tothe publication of the relevant article.

1. APPLICATION OFFINITE STRAIN THEORY relationagreeswith the shock-waveHugoniotup toTO NON-CUBIC CRYSTALS 750kbar(P/K0= 1.2),althoughbothcalculatedand

J.ScottWeaver,Departmentof Physics,Queens HugoniotP—V relationsdisagreewith X-ray compres-Collegeof the City Universityof NewYork, sion data.At pressuresgreaterthan 300 kbar, the cal-Flushing,NY 11367,U.S.A. culatedaxial ratio of zinc approachesthat for other

hexagonalmetals(c/a 1.63).The applicationof finite strain theory to a crystal

of orthorhombicor higherelasticsymmetry,which is Received25 August1975subjectedto a purelyextensionaldeformationparallelto thecrystallographicaxes, yieldsstress—strainrela- 2. THE STATE OFFe

57 IN PUREAND OXI-tions and effectiveelasticconstantsfor hydrostatic DIZED TIN CHALCOGENIDESBY MOSS-stresses.Alternativeformulationsof the theoryareob- BAUER SPECTROSCOPYtamedwhenthe freeenergyis written asTaylorseriesin VincenzoFano,MASPEC Laboratoryof the

E, the invariant analogueof theEulerianstrain tensor, C.N.R.,Parma,Italy; and IdaOrtalli, Physicsor ~, the Lagrangianstrain tensor.In most cases,the Institute,University of Parmaand G.N.S.M.,formulation in termsof E providesa betterapproxi- ParmaItaly.mationwhentheTaylorseriesare truncatedat thesecondor third order. In thecaseof cubiccrystals,the A Mossbauerspectroscopystudyhasbeenmadeofstress—strainrelationsreduceto the Birch equation.For thestabilizationstatesof Fe57in puretin chalcogenides.non-cubiccrystals, theF— V relationscalculatedusing The valuesof the isomershifts andthequadrupolesplit-the non-cubicand Birch equationswill differ due to the tingslead to theconclusionthat iron presentstheeffectsof elasticanisotropy.A comparisonbetweenthe electronicconfiguration3d54sxat high spinin the inter-second-orderapproximationsof thenon-cubicstress— stitial position. This result is confirmedvaryingthe Fe57strain relationsand thecubicBirch equationsuggests neighboursby partialsubstitutionof tellurium withthat thedifferencein volume will be lessthan 1% for oxygen.In this case,too, thevaluesof MOssbauerpara-most materials.The differencein volume is reduced metersconfirm thesameresults.The quadrupolewhen the third-orderapproximationsare used.When the momentpresentin pureSnTedopedCo57,andthe shiftthird-ordertermsareretained,the stress—strainrelations of isomershift towardsless positivevaluesfor theoxi-calculatedusingtheEulerian formulationagreewith dizatedsampleshavebeenqualitativelyjustifiedaswell.measuredlinearcompressiondatafor quartzto 150kbar Received2 December1974(P/K

0 = 0.4).Forzinc, the calculatedpressure—volume Revised14 November1975

V