ISSN:
1573-9171
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Summary 1. An investigation was made of the effect of component ratio and thermal treatment conditions on the phase composition and magnetic properties of coprecipitated ferric oxide-alumina gels containing up to 57 mol. percent of 2. Gels fired at 400° contained only one crystalline phase, namely, a saturated solid solution of Fe2O3 (8 mol. %@#@) inγ-Al2O3, while those fired at 600 and 750° also contained a solid solution of Al2O3 inα-Fe2O3. Noγ-Fe2O3 was detected either by x-ray diffraction or magnetic methods. 3. Fe2O3 reduced the temperature of the phase transition ofγ-Al2O3, in which it was dissolved, toα-Al2O3 and this transition occurred even at 1000°. 4. All gels fired at 400°, gels with 7 and 18 mol. % of Fe2O3 fired at 600°, and the gel with 8% of Fe2O3 fired at 750° were paramagnetic and obeyed the Curie-Weiss law with a positive value for the Weiss constant. Their paramagnetism is explained by the formation ofβ-Fe2O3 or more complex transition phases. All the other gels were ferromagnetic. 5. Catalytic reactions of isopropyl alcohol on the gels studied at 260–290° led to an increase in the ferromagnetism as a result of the formation of Fe3O4.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00942883
