(中南大学 冶金科学与工程学院,长沙 410083)
摘 要: 以NiCl2∙6H2O和MnCl2∙4H2O为主盐,分别与(NH4)2C2O4∙H2O、NaOH和Na2CO3∙10H2O经室温固相合成相应的镍锰化合物,然后分别在400、300、500 ℃温度下煅烧分解3 h得到镍锰氧化物。结合已知的热力学数据,对室温固相反应的吉布斯自由能变和焓变进行计算,从热力学的角度出发,研究不同的反应类型对产物结构的影响。采用DSC-TGA、XRD等方法对煅烧分解过程、氧化物的物相和微观形貌进行了分析与表征。结果表明:镍锰草酸盐分解得到NiMn2O4和MnNi2O4;镍锰氢氧化物分解只得到MnNiO3;镍锰碳酸盐分解得到NiMn2O4、MnNi2O4和MnNiO3。镍锰氧化物粒径依次增大的顺序为:镍锰氢氧化物、镍锰草酸盐、镍锰碳酸盐的产物
关键字: 镍锰氧化物;固相反应;热力学分析
(School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China)
Abstract:Using NiCl2∙6H2O and MnCl2∙4H2O as major reactants, nickel-manganese composites were synthesized by the solid state reaction at room temperatures with three difference reactants ((NH4)2C2O4∙H2O, NaOH, NaCO3∙10H2O). The nickel-manganese oxides were synthesized by calcining three precursors at 400, 300, 500 ℃ for 3 h. and for three solid state reactions at room-temperature were estimated by the thermodynamic data. The effects of difference reaction on the oxides were studied. The processes, particle size and crystallography characters were studied by means of DSC-TGA, XRD and TEM. The results show that spinel NiMn2O4 and MnNi2O4 are obtained by decomposing nickel-manganese oxalic acid; Ilmenite-type MnNiO3 is obtained by decomposing nickel-manganese hydroxide; Ilmenite-type MnNiO3, spinel NiMn2O4 and MnNi2O4 are obtained by decomposing nickel-manganese carbonate. The particle size of nickel-manganese oxide products increases by turn of nickel-manganese hydroxide, oxalic acid, carbonate
Key words: nickel-manganese oxide; solid state reaction; thermodynamic analysis