(中南大學(xué) 冶金科學(xué)與工程學(xué)院，長沙 410083)
摘 要: 以可溶性氯化鎳、氯化鈷和草酸或草酸銨為原料，氨水為pH值調(diào)節(jié)劑，采用液相共沉淀法合成草酸鎳鈷共沉淀產(chǎn)物，借助X射線衍射(XRD)、熱重−差熱分析(TG-DTA)和掃描電鏡(SEM)對(duì)共沉淀產(chǎn)物進(jìn)行表征，并將結(jié)果與機(jī)械混合物進(jìn)行比較。結(jié)果表明：在共沉淀過程中，當(dāng)溶液pH≤5.0時(shí)，鈷離子易進(jìn)入草酸鎳晶格中形成置換固溶體，得到的共沉淀產(chǎn)物為草酸鎳鈷單相固溶體，其熱分解行為明顯不同于具有相同配比的機(jī)械混合物；當(dāng)pH＞5.0時(shí)，鎳離子和鈷離子與草酸根離子的共沉淀過程為分步沉淀，得到的共沉淀產(chǎn)物為組分分布均勻的復(fù)雜混合物，而非單相固溶體。
關(guān)鍵字: 草酸鎳鈷；固溶體；共沉淀產(chǎn)物；分步沉淀；機(jī)械混合物
（School of Metallurgical Science and Engineering, Central South University, Changsha 410083, China）
Abstract:The Ni-Co oxalate coprecipitates were synthesized by liquid coprecipitation reaction using soluble nickel chloride, cobalt chloride and ammonium oxalate or oxalic acid as raw material and ammonia as pH value regulator. The coprecipitates were characterized by X-ray diffractiometry (XRD), scanning electron microscopy(SEM) and thermogravimetry-differential thermal analysis(TG-DTA), and the results were compared with those of mechanical mixtures. The results show that when pH≤5.0, the cobalt ion enters the lattice of nickel oxalate and forms a substitution solid solution. The obtained coprecipitate is a single-phase solid solution with characteristics which exhibit distinctly different thermal decomposition behavior from those of the mechanical mixture with the same stoichiometry. However, when pH＞5.0, the coprecipitation process of nickel ions, cobalt ions and oxalate ions is a fractional precipitation process, and the obtained coprecipitate is a complex mixture with uniform component distribution, not a single-phase solid solution.
Key words: Ni-Co oxalate; solid solution; coprecipitates; fractional precipitation; mechanical mixtures
