Electrical resistivity of NiAℓ

Electrical resistivity of NiAℓ

Solid State Communications, Vol. 20, No. 8, pp. 741—742, 1976 Pergamon Press. Printed in Great Britain ELECTRICAL RESISTIVITY OF NiM. T. Yoshitomi,...

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Solid State Communications, Vol. 20, No. 8, pp. 741—742, 1976

Pergamon Press.

Printed in Great Britain

ELECTRICAL RESISTIVITY OF NiM. T. Yoshitomi, Y. Ochiai and J. 0. Brittain Materials Research Center and Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60201, USA (Received 24 August 1976 by H. Suhl)

Resistivity-temperature measurements on annealed near sto ich lometric NiAt. showed the absence of a resistivity minimum and confirms that the reported anomalous transport properties are an extrinsic effect not observed in high purity NiAL. Thermal treatments on NW. designed to effect the order did not produce a resistivity—temperature minimum.

The intrinsic magnetic property of stoi— chiometric or near stoichiometric NW. has been recently as simple paramagne— 4 reported From a study of thePauli extrinsic nature tism.’ of NW.5’6 we believe the previously observed temperature dependent susceptibility results from the magnetic impurity contamination; namely Cr, Mn or Fe. The purpose of this paper is to report the intrinsic nature of NiAt. in terms of the resistivity measurement. The NiAt. specimens were prepared from

high purity Ni and M (both 99. 99~) by arc melting in high purity, gettered argon. The charge contained an additional amount of At. (~O.O5 w~) to compensate for the M. loss due to the high vapor pressure of M in the arc melting. The button shaped ingots (-..l0 g) were made by repeated breaking and melting followed by anneal at 1100°C in vacuum (....lO_6 mmllg) for 40 to 80 hours. Thin rectan— gular prisms were cut from the sliced ingots by a spark machine and polished by mechanical and

ii

$‘—NiAI

LI I

1.5 2

NORMALIZEODEPTN OF THE RESISTIVITY MINIMUM O•SERV(D SY YANASUCHI El~ AL. FOR N1509A1411

5

10

Ni 50AI50

II

20

1%

30

1.5

T(K)

2

0

NA-I

x NA-2

5

10

20

T(K)

Fig. 1. Temperature dependence of resistivity ratio of NW..

Fig. 2. Temperature dependence of resistivity ratio of N150M50. 741

30

742

ELECTRICAL RESISTIVITY OF NiAI

chemical means. The four probe method was utilized for resistivity measurement. The details7 of the measurements are described else— where. Figure 1 shows the resistivity ratio vs. temperature for the stoichionietric and off— stoichiometric NW.. Six different Ni50A.~ alloys were prepared in order to produce a well ordered stoichiometric specimen. The best sam— ple (NA—i) had an RR1~a p(300)/p(4.2) = 14.3 and p(4.2) = 0.ôSji.Ocm and the second sample (NA—2) had an RRR = 12.9 and p(4.2)0.597~cm. The RRR and p(4.2) for these samples are among pies are well ordered indicating and very close stoi— the highest reported that to these sam— chiometry. The RRR of Nieg.sAtbOe, Ni 50 ~ and Ni51,6M.48 ~4.2) were was2.90, 3.5l~1cm, 5.17 2.3i4i~cmand 4.89t~C2cmrespectively. In Fig. 1, and 3.38 respectively and p( the normalized depth of the resistivity minimum [p(2) — P(Tmin)]/p(4•2) observed by Yamaguchi et al.7 for Ni 50 9At49 ~ is shown for the corn—

Vol. 20, No. 8

parison; clearly our high purity annealed sam— pies have no resistivity minimum. In order to check the effect resistivity of Niof order on the low temperature 50At~0, neasurenents were made after different thermal treatment on several samples, one of which was quenched from 1000°C to OOC and the other was an as arc—melted sam— ple. The results are shown in Fig. 2, again no resistivity mini’mum was observed. RRR’s of the quenched and as—melted samples were 4.2 and 2.6 respectively, while p(4.2) was 2.4j.~Qcmand 5~cm respectively. 8 x(ppm) = The amount of crystal disorder, x, can be l0~/RRRfor l0~. rule, Therefore, the estimated by 1theRRR empirical specimens we studied contained crystal disorder of in them the range showedof resistivity from 700 ppm minimum. to 3800 observation is quite consistent with sults of susceptibility measurements above. Thus the ~reviously reported anomalies in NiAt. ~

ppm. This None the re— described transport

was an extrinsic effect

due to the presence of magnetic impurities. REFERENCES

1. 2. 3. 4. 5. 6. 7. 8. 9.

ZELENIN, L.P., BASHKA1DV, A.N., SIDORENKO, F.A. and GEL’D, P.V., Fiz. metal. metalloved. 30, 740 (1970). — MIYATANI, K. and IIDA, S., J. Phys. Soc. Japan 25, 1008 (1968). WILLHITE, J.R., WELSH, L.B., YOSHITOMI, T. and BRITTAIN, J.0., Solid State Commun. 13, 1907 (1973). — FORT, D., KILNER, J.A. and HARRIS, I.R., Met. Sci. 9, 305 (1975). YOSHIIOMI, T., Ph.D. Thesis 1974, Northwestern University; the work of 3d transition metal impurity effect was submitted to J. Phys. Chem. Solids. WILLHITE, J.R., YOSHITOMI, T., WELSH, L.B. and BRITTAIN, J.0., AlP Conf. Proc. 19th Conf. on Magnetism and Magnetic Materials (1973); also WILLHITE, J.R., Ph.D. Thesis 1975, North— w”stern University. YAJ.L~CUCHI,Y., AOKI, T. and BRITTAIN, J.0., J. Phys. Chem. Solids 31, 1325 (1970). STEINER, A. and KOMAREK, K.L., Trans. AIME 230, 786 (1969). — C~SKEY,G.R., FRANZ, J.M. and SELU1YER, D.J., J. Phys. Chern. Solids 34, 1179 (1973).