氧化还原反应条件对二氧化锰粉体晶型和形貌的影响

摘要

Manganese dioxide powder was prepared by redox precipitation using KMnO4and MnSO4as raw materials. The composition and morphology of the samples were analyzed by XRD and FESEM. The effects of redox conditions on the crystal form and morphology of manganese dioxide were investigated, and the crystal transformation mechanism was discussed. The results show that nano flower-like δ-type, nanowire α-type and nano-particulate γ-type MnO2powders can be prepared by changing the process parameters. The crystal form of different products is affected primarily by K+concentration, while the reaction temperature and reaction time are the secondary influencing factors. When the molar ratios of KMnO4to MnSO4are 2:1.5 and 2:3, the MnO2powders are δ-type and α-type, respectively; and when the molar ratio of KMnO4to MnSO4is less than 2:3, the MnO2powder transforms into γ-type. At reaction temperatures of 40 ℃, 60 ℃ and 80 ℃, the MnO2powders are all γ-type, which transform into α-type when the temperature rises to 90 ℃. When the reaction time is 0.5 h and 1 h, the MnO2powders are δ-type and γ-type, respectively;and when the reaction time exceeds 2 h, the MnO2powder transforms into α-type.%采用氧化还原沉淀法,以KMnO4和MnSO4为原料制备了二氧化锰粉体.利用XRD和FESEM对样品的组成和形貌进行分析,研究了氧化还原反应条件对二氧化锰晶型和形貌的影响,并对晶型转变机理进行了讨论.结果表明,改变工艺参数,可以制备出纳米球花状的δ型、纳米线状的α型和纳米颗粒状的γ型MnO2粉体.不同产物的晶型主要受K+浓度的影响,而反应温度与反应时间是次要影响因素.其中,当KMnO4与MnSO4的摩尔比为2:1.5和2:3时,MnO2粉体分别为δ型和α型,而当摩尔比为小于2:3时,MnO2粉体转变为γ型;当反应温度为40,60,80 ℃时,MnO2粉体均为γ型,而当温度升高至90 ℃时,MnO2粉体变为α型;当反应时间为0.5和1 h时,MnO2粉体分别为δ型和γ型,当反应时间超过2 h时,MnO2粉体则变为α型.