Perovskite compound LaFeO3 was prepared by solution combustion synthesis using lanthanum nitrate and ferric nitrate as oxidants ,citric acid as organic fuel Effect of pH value of precursor solution on phase composition and morphology of LaFeO3 employing ethylenediamine and NaOH solution as pH regulator,respectively,was investigated by using X-ray diffraction(XRD) and scanning electron microscopo(SEM).The results showed that the pH regulator and the pH value of precursor solution had significant effect on the phase composition, crystallite size and morphology of LaFeO3.When the pH value of precursor solution was adjusted to the range of 3-12 by ethylenediamine,only amorphous products were obtained at 300 ℃ ,while pure phase LaFeO3 could be obtained at 600 ℃.In contrast to this,using NaOH solution as pH regulator,pure phase LaFeO3 could be obtained in the pH range of 5 to 13 at 300 ℃, and the LaFeO3 nanocrystal prepared at pH = 7 had a net-like porous structure with the largest crystallite size of 30.5 nm.However,under the acidic and basic conditions,the obtained LaFeO3 products were an aggregate of irregular particles.%以硝酸镧和硝酸铁为氧化剂,柠檬酸为燃料,采用溶液燃烧法制备了钙钛矿型LaFeO3.通过XRD和SEM表征,分别研究了以乙二胺和NaOH溶液为pH调节剂,前驱物溶液在不同pH值条件下,对制备的纳米LaFeO3粉体的晶相组成和微观形貌的影响.结果表明:前驱物溶液pH值对燃烧产物的晶相组成、晶粒大小和微观相貌都有显著的影响.乙二胺调节前驱物溶液pH值为3至12时,在300℃燃烧条件下获得为无定形产物,而在600℃均可制得纯相LaFeO3纳米晶体.NaOH溶液为pH调节剂,前驱物溶液在pH值5至13范围内,在300℃的条件下均能制得纯相LaFeO3纳米晶体;其中pH=7的中性环境中产物为蓬松多孔网状纳米结构,具有最大的晶粒尺30.5 nm,而在酸性和碱性环境中制得的产物均为无规则颗粒的聚集体.
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