Synthesis of Nanocrystalline Lanthanum Strontium Manganite Powder by the Urea–Formaldehyde Polymer Gel Combustion Route |
| |
Authors: | Kuttan Prabhakaran Jorly Joseph Nitin Madhusudan Gokhale Suresh Chandra Sharma Ramji Lal |
| |
Affiliation: | Naval Materials Research Laboratory, Thane 421 506, India |
| |
Abstract: | Nanocrystalline lanthanum strontium manganite (LSM) powder has been synthesized by combustion of a transparent gel obtained by the polymerization of methylol urea and urea in a solution containing La3+, Sr2+, and Mn2+ (LSM ions). Chemistry of the transparent urea–formaldehyde (UF) polymer gel formation and structure of the gel have been proposed such that the LSM ions act in between the growing UF polymer chains by interacting through NH, OH, and CO groups by co-ordination and prevent polymer self-assembly through inter-chain hydrogen bonding as evidenced from infrared spectrum. Thermally stable structures formed by the decomposition of UF polymer below 300°C undergo combustion in the presence of nitrate oxidant in a temperature range from 350°–450°C. A perovskite LSM phase has been formed by self-sustained combustion of the dried gel initiated with little kerosene. The powder obtained after deagglomeration and calcination at 600°C for 2 h has a D 50 value of 0.19 μm, and the particles are aggregates of crystallites 10–25 nm in size. |
| |
Keywords: | |
|
|