Magnetic and Mössbauer Study of Cerium-Based Reactive Sorbent

Abstract

A new kind of magnetically separable composite consisting initially of magnetite and cerium carbonate nanograins was investigated using magnetic and Mössbauer methods at room and low temperatures. Various stages of calcination treatment in air resulted in a transformation of the cerium carbonate into cerium dioxide and magnetite into more complicated iron oxide compositions. The final CeO2 nanograins on the surface of α-Fe2O3 were obtained after calcination at 973 K.

Effect of Iron Impurities on Magnetic Properties of Nanosized CeO2 and Ce-Based Compounds

“…Therefore, the present study is concentrated on ceria prepared by different technological procedures. It continues our previous investigations [9,10] in order to shed more light on the magnetic behaviours of ceria and Ce-compounds. The nano-sized CeO 2 powders were prepared from the same cerium (III) nitrate hexahydrate using three precipitation procedures with different chemicals.…”

“…A sharp magnetisation reversal at lower magnetic fields seen at the RT hysteresis loops in Figure 4 (left panel) is indicative of the ferromagnetic contribution. This can originate in a large number of structural defects, particularly surface oxygen vacancies mentioned by some authors [17][18][19][20][21], and/or magnetic impurities, namely iron [9,10] contributing to small values of RT ferromagnetic saturation magnetisation of an order of 10 −3 Am 2 /kg, detected also in other usually nonmagnetic compounds [22]. The analysis of the present magnetic measurements of the S4, S5, and S6 samples has resulted in the detection of a small amount of iron impurities, in units of ppm as seen in Table 2.…”

“…A slightly better effect, observed at CeN, corresponds to the higher Fe content followed from the ICP-AES. The spectra of the samples were evaluated using one double-line component with hyperfine parameters (isomer shift, δ, and quadrupole slitting, ∆) not too different in the frame of experimental errors: S4: δ = 0.229 10 [9,10].…”