PORE STRUCTURES OF THE THERMAL-DECOMPOSITION PRODUCTS OF DELTA-FEOOH PARTICLES DOPED WITH NI(II), CO(II) AND CU(II)

Particles of delta-FeOOH doped with various divalent metal ions such a s Ni(II), Cu(II) and Co(II) were generated by oxidation of Fe(OH)(2) c ontaining various amounts of these ions by H2O2. The particle sizes we re not influenced by doping Co(II) but reduced by Ni(II) and Cu(II). T he t-plot and the pore size distribution obtained from N-2 adsorption isotherms showed that micropores develop in the particles doped with N i(II) and Co(II) on outgassing above 200 degrees C. All the materials with and without doping gave rise to a similar maximum specific surfac e area of 140-160 m(2) g(-1) despite their different particle sizes fr om 0.2 to 2 mu m. It was inferred that the thermal decomposition produ cts are agglomerates of thin plate-shaped microcrystals with a constan t thickness. The microporous materials doped with Ni(II) and Co(LT) in an atomic ratio of 0.333 were ferrimagnetic ferrites. (C) 1998 Elsevi er Science B.V.