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Submitted on 1 Jan 1974
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MÖSSBAUER STUDY OF CoO AT VERY LOW TEMPERATURES
T. Shinjo, K. Okada, T. Takada
To cite this version:
T. Shinjo, K. Okada, T. Takada. MÖSSBAUER STUDY OF CoO AT VERY LOW TEMPERATURES. Journal de Physique Colloques, 1974, 35 (C6), pp.C6-323-C6-323.
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CHEMICAL EFFECTS OF NUCLEAR TRANSFORMA TION.
MOSSBAUER STUDY OF CoO AT VERY LOW TEMPERATURES
T. SHINJO, K. O K A D A (*) and T. T A K A D A
Institute for Chemical Research, Kyoto University, Uji, Kyoto-fu, Japan
Resume. — Le spectre Mossbauer d'emission de 5 'Co dans CoO a ete mesure a de tres basses temperatures allant jusqu'a 80 mK. La polarisation nucleaire du noyau parent 57Co apparait alors et le spectre devient asymetrique. Du rapport des intensites des pics externes on deduit que le signe du champ hyperfin est positif et que son intensite est de 590 kOe. Une quantite considerable de Fe3 +
est observee simultanement et le champ hyperfin au noyau de 57Co deduit du spectre de Fe3 + est approximativement identique a la valeur precedente. A des temperatures moderees, le rapport ato- mique Fe^/Fe2 4" diminue progressivement avec la temperature mais il en est independant entre 4,2 K et 80 mK. Les details ont ete publies ailleurs [1].
Abstract. —• The Mossbauer source spectrum for Co5 7 in CoO was measured at very low tempe- ratures down to 80 mK. Then the nuclear polarization of the parent nucleus, Co5 7, occurred and the spectrum became asymmetric. From the intensity ratio of the outermost peaks it was derived that the sign of the hyperfine field is plus and the magnitude is 590 kOe. A considerable amount of Fe3 +
coexisted and the hyperfine field at Co37 nucleus estimated from the Fe3 + spectrum was nearly the same as the above value. Although at moderate temperatures, the atomic ratio, Fe 3 +/Fe2 +, decreased gradually with a decrease of temperature, it had no temperature dependence between 4.2 K and 80 mK. Details have been published elsewhere [1].
(*) Present address : Department of Physics, Kumamoto University, Kumamoto, Japan.
References
[1] OKADA, K. and SHINTO, T., / . Phys. Soc. Japan 36 (1974) 1017.
[1] OKADA, K. et SHINJO, T., / . Phys. Soc. Japan 36 (1974) 1017.
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1974653
