Synthesis of lscf by Sol-gel method

Synthesis of Nano-Structured La_0.6Sr_0.4Co_0.2Fe_0.8O₃ Perovskite by CoPrecipitation Method
Ebrahim Mostafavi, Alireza Babaei* Ataie School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, P.O. Box 14395-553, Tehran, Iran
Received: 1 December 2014 ; Accepted: 1 March 2015 * Corresponding author E-mail: [e-mail], Tel.: [phone]; fax: [phone]
Nano-structured lanthanum strontium cobalt ferrite, La0.6Sr0.4Co0.2Fe0.8O3 (LSCF), was successfully synthesized via co-precipitation method using metal nitrates as starting materials. Effects of precipitating agent and calcination temperature on the phase composition and morphology of synthesized powders were systematically studied using X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM), respectively. XRD analysis revealed that a single phase La0.6Sr0.4Co0.2Fe0.8O3 perovskite was obtained in the processed sample using ammonium carbonate as precipitating agent with a NH4 + /NO3 -molar ratio of 2 after calcination at 1000C for 1 h. The phase composition of products was also affected by changing pH values. Moreover, using sodium hydroxide as a precipitant resulted in a mixture of La0.6Sr0.4Co0.2Fe0.8O3 and cobalt ferrite (CoFe2O4) phases. Careless washing of the precursors can also led to the formation of mixed phase after calcination of final powders. Mean crystallite size of the obtained powders was not noticeably affected by varying calcination temperature from 900 to 1050C and remained almost the same at 10 nm, however increasing calcination temperature to 1100C resulted in sharp structural coarsening. FESEM studies demonstrate that relatively uniform particles with mean particle size of 90 nm were obtained in the sample processed with a NH4 + /NO3 - molar ratio of 2 after calcination at 1000C for 1 h.

Nano-strukturali lantan stronsiy kobalt ferriti, La_0.6Sr_0.4Co_0.2Fe_0.8O₃ (LSCF) boshlang'ich material sifatida metall nitratlar yordamida birgalikda cho'ktirish usuli orqali muvaffaqiyatli sintez qilindi. Cho'ktiruvchi vosita va kalsinlanish haroratining sintezlangan kukunlarning fazaviy tarkibi va morfologiyasiga ta'siri rentgen nurlari difraksiyasi (XRD) va maydon emissiyasini skanerlash elektron mikroskopiyasi (FESEM) yordamida tizimli ravishda o'rganildi. XRD tahlili shuni ko'rsatdiki, qayta ishlangan namunada bir fazali La_0.6Sr_0.4Co_0.2Fe_0.8O₃ perovskit 1000°C da 1 soat davomida kalsinlangandan so'ng NH₄⁺/NO₃^- -molyar nisbati 2 bo'lgan cho'ktiruvchi vosita sifatida ammoniy karbonat yordamida olingan. Mahsulotlarning fazaviy tarkibiga pH qiymatlarining o'zgarishi ham ta'sir ko'rsatdi. Bundan tashqari, cho'ktiruvchi sifatida natriy gidroksiddan foydalanish La_0,6Sr_0,4Co_0,2Fe_0,8O₃ va kobalt ferrit (CoFe₂O₄) fazalarining aralashmasiga olib keldi. Prekursorlarni ehtiyotkorlik bilan yuvish, shuningdek, yakuniy kukunlarni kalsifikatsiya qilishdan keyin aralash faza hosil bo'lishiga olib kelishi mumkin. Olingan kukunlarning o'rtacha kristallit o'lchamiga 900 dan 1050 °C gacha bo'lgan o'zgaruvchan kalsinlanish harorati sezilarli ta'sir ko'rsatmadi va 10 nm da deyarli bir xil bo'lib qoldi, ammo kalsinlanish haroratining 1100 °C ga ko'tarilishi strukturaning keskin qo'pollashishiga olib keldi. FESEM tadqiqotlari shuni ko'rsatadiki, o'rtacha zarracha hajmi 90 nm bo'lgan nisbatan bir xil zarrachalar NH₄⁺/NO₃^- molyar nisbati 2 ga teng bo'lgan 1 soat davomida 1000°C da kalsinlangandan keyin qayta ishlangan namunada olingan.