Mukerjee, A K

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A. K. MUKER.1EKDepartment of Maqnetihm, Indian Association for the (U i.tivation of Rciench,CALCt7TTA-32, India(Received N o v cm h e r 11, ll)(i7)1 ho temporaluI(' variation ol monetisation and susce.ptibilit.y of specular hematite (~99.1%  a-Fe..O.„ origin Mt. Popa, Buima; obtained from (he collec­tions in the laboratory) has been studied in the rang*' of 100 K to JOlMl' K. for fresh as well as samples hi'ut treated to a temiM intnre of ]000'1\. The results are shown in fig. 1 .25THE MAGNETIC PROPERTIES OF SPECULAR HEMATITEflSd6lOO Vio wo soo wo bOO '00 BtJO <JCX) lOtxfKPig. 1. Magnetisation (a) and susceptibility (X) at different temperatures of single crystals of hematite for fresh end heat treated samples. (1) along the basal plane (2) along the trigonal axis.781782 Letters to the EditorFor fresh samples the temperature variation of field independent susceptibi­lities both along the r>axis'and in the basal plane agree well with the findings of Tasaki and lida (1963) on syntlu'tio hematite, but there the ferromagnetism, unlike ours, appears only along the plane above Morin temperature (~250'^K) and at lower temperatures no ferromagnetism exists at all in either of the direc­tions. In respect of the tempei ature variations of both the susceptibilities and the fiuToinagnotisrn in the plane, the present obs(Tvations resemble those? of Ne< J et al (1952) and Lin (1959), on very pure natural crystals, but differ with their observations of fcrromagntd-isni along tlie c-axis. Lin (1959) observed consider­able ferromagnetism along the axis below th<‘ Morin temperatun* (~250®K) which falls sharply to a low value at liiglier ti niperatures. Neel cf al., (1952) no doubi observed consi(hu*able ferromn.gri<dism at Jowcu* f<un]H‘ratures (belov'~250''K) but its temperature variation unlike tlu' observation of Lin (1959) was ratlui slow. In onr case on the eontrary the ferromagned-ism a^ong the c-ax s vanislu s beloM' ~25()^K and appears rather sharply abovt* this temperature.The measurements on l)eat treated samples agree closely with those of Milker j(‘c(1967), the magnitude of magnetisat ion and snseeptibilitv increasing eonsiderahlx and the sharp changes at ~250^K vanishing altogether.The author is thankful to Shri A. K. Dutta for his constant guidance and Professor A. Bose for his kind interest in the work.R K F K Ji K NT C FSLin, S. T., 1959, Phys. Pev., 116, 1447.Mukerjee, A. K., 1967, Indian •/. Phys., 41, 466.N6el, L. and Pauthenet, R., 1952, Compt. Pend. 234, 2172.Tasaki, A. and Ii<la, S,, 196,3 J. Phys. Soc. Japan. 18, 1148,26A SIM PLE EXPERIM ENTAL DEM ONSTRATION OF THE BREAKDOWN OF FARADAY’S LAW OF ELECTROLYSISSANTl R. PALITDepartment of Physicai. CJhkmistry, Indian association fob the Citetivation OF Science, J adavpub, Cai,cutta-32, India.The author adduced experimental evidence (Palit, 1967) indicating wifie deviation from Faraday’s law in the electrolysis of weakly conducting solutions, particularly conductivity water. Since this fact runs counter to a long accepted idea, the author presents here a simple experimental device which conclusively demonstrates the failure of Faraday’s law.

The Magnetic Properties of Specular Hematite

http://arxiv.iacs.res.in:8080/jspui/bitstream/10821/5307/1/The%20magnetic%20properties_A%20K%20Mukerjee.pdf

The Magnetic Properties of Specular Hematite

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