期刊
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
卷 111, 期 2, 页码 1121-1127出版社
SPRINGER
DOI: 10.1007/s10973-011-2177-2
关键词
Chromites; Carboxylate; Bichromate; Thermal analysis
资金
- European Social Fund-Investing in People, within the Sectoral Operational Programme Human Resources Development
- [POSDRU/88/1.5/S/50783]
- [ID50783]
This paper presents a study regarding the obtaining of NiCr2O4 by two new unconventional synthesis methods: (i) the first method is based on the formation of Cr(III) and Ni(II) carboxylate-type precursors in the redox reaction between the nitrate ion and 1,3-propanediol. The thermal decomposition of these complex combinations, at similar to 300 degrees C, leads to an oxide mixture of Cr2O3+x and NiO, with advanced homogeneity, small particles and high reactivity. On heating this mixture at 500 degrees C, Cr2O3 reacts with NiO to form NiCr2O4, which was evidenced by FT-IR and X-ray diffractometry (XRD) analysis; (ii) the second method starts from a mechanical mixture of (NH4)(2)Cr2O7 and Ni(NO3)(2)center dot 6H(2)O. On heating this mixture, a violent decomposition at 240 degrees C with formation of an oxides mixture (Cr2O3 + CrO3) and NiO takes place. On thermal treatment up to 500 degrees C, an intermediary phase NiCrO4 is formed, which by decomposition at similar to 700 degrees C leads to NiCr2O4, evidenced by FT-IR and XRD analysis. NiCr2O4 is formed, in both cases, starting with a temperature higher than 400 degrees C, when the non-stoichiometric chromium oxide (Cr2O3+x) loses the oxygen excess and turns to stoichiometric chromium oxide (Cr2O3), which further reacts with NiO.
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