Solid StateCommunicationsVol. 2, P. 123, 1964. PergamonPress,Inc. Printed in the UnitedStates

SUPERCONDUCTWITYOF Mo3AI2C

JeanJohnston,Louis Toth, Kurt KennedyandEarl R. Parker

Inorganic MaterialsResearchDivision, LawrenceRadiationLaboratoryandDepartmentof Mineral Technology, University of California, Berkeley, California

(Received16 March1964 by J.A. Krumhansl)

AN investigationof ternarycompoundsof the form TABLE 1M3A12C (M = Mo, Nb, Tp., V, Ti or Cr) recently ______________________________________

found by Jeitschkoetal.’’ 2, hasled to the dis- H-phaselatticecoveryof a new superconductor,Mo3~kl2C,which Compound parametersforcrystallizesin 8-Mn (A13) structure. hexagonalsubcell

The samples,with the exceptionof V3A12C, Nb3A12C a = 2. 67werepreparedby hot-pressingthe metalpowders c = 8.02in graphicmolds; V3A12C wasmadeby arc-mel- Ta3A12C a = 2. 6öting powdercompactsin an argon atmosphere. c = 7. 97In addition, sinteredsamplesof Nb3A12C andTa3 V3A12C a = 2. 52A12C werepreparedfrom powdercompacts. All c = ‘1. 52sampleswere annealedat 1000°Cin vacuumand Ti3A12C a~ 2.63furnacecooled. C = 7. 87

Cr3A12C a2.47A superconductingtransitionwas observed c = 7. 39

at 10.0°Kfor the compoundM03A12C. The latticeDaramet~rfor the B-Mn cubic cell wall was a =

6. 867A, which is in good agreementwith the value given in Taole 1.reportedby Jetlschkoetal.

4 TheseInvestigatorsalsofound the B-Mn structureat the compositions To our knowledge, this is the secondNb3A1

2C andTa3A12C, but reportedthat the phase compoundof the B-Mn typefoundto showacrystallizedwith asecondphase,the “H-phase,” superconductingtransition, the first beingwhich hasahexagonalsubcell. In thepresent Nb3A1O.5GeO.5, which hasa transitiontern-investigation, only the H-phasecould be identi- peratureof 12.60K. The occurrenceof super-fied in bothhot-pressedandsinteredsamples; conductivity in both compoundsat 10°Korhigh-latticeparametersfor the hexagonalsubcellof er indicatesthat the B-Mn structureis favorablethe H-phaseare shown in Table 1. Neither for theoccurrenceof superconductivityat rela-compoundwas superconductingabove4. 2°K. tively hightemperatures.Also, only the H-phaseswereobservedfor thecompoundsV3A12C, T13A12C and Cr3A12Cand We are grateful to Dr. Erwin Rudyofno transitionswere foundfor thesecompounds Aerojet-GeneralCorporation,Sacramento,above 4. 2°K. The lattice parametersfor the Californiafor his assistancein making the hot-hexagonalsubcellsof thesecompoundsare also pressedsamples.

Reference.s

1. JEITSCHKOW., NOWOTNY H. andBENESOVSKY F., Mh. Chem. 94, 247 (1963).

2. JEITSCHKOW., NOWOTNY H. andBENESOVSKY F., Mh. Chem. 94, 332 (1963).

3. REEDT. B., GATOSH. C., LA FLEUR W. J. andRODDY J.T., Superconductorsp. 143,Interscience,New York (1962).

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