Hello everyone,
I am synthesizing BiFeO3 using sol-gel method but there are some peaks for Bismuth oxides. I want to remove these oxides so if anyone have experience for this kind of problem please guide me. Here I attached the XRD patteren and from XRD its very clear there is only Bi2O3. SO kindly share your great experience that how can I remove these oxides? your response will be highly appreciated.
Dear Jafar,
Can you please share more information about the synthesis method you adopted, like temperature of annealing, etc. The melting point of BiFeO3 is 960 Degree Celsius. Below this temperature, rhombohedral phase exists and an intermediate phase in the region 830-925 Degree Celsius. Cubic phase in the region 925-933 Degree Celsius. As melting point of Bi2O3 is 817 Degree Celsius. Therefore to get single phase BiFeO3, you have to anneal your samples at 925 Degree Celsius to get Cubic phase and so on. My suggestion is to go for annealing the samples at 925 Degree Celsius in order to get single phase BiFeO3.
woww great Dear Rupesh Talewar great information about it. But I think if I go to high temperature like this it may effect Bi amount as it is volatile and it cause defeciency and there will appear second phase like Bi2Fe4O9 etc. Anyway I take 10mmol Tartaric acid and dissolve it in 100ml EG at 80C. then i add Bi nitrate and Iron nitrate equimolar and I also tried 10% excess of Bi and let it stirr untill it get completely dry then after grinding, I keep this powder at 550C for 2 hours. This is the whole procedure but I am getting Bi2O3 and other Bi base oxides.
and when I use 10% excess of Bi there is no second phase for BFO but only Bi oxides while in equimolar ratio I get also other phases of BFO alongwith oxides of Bi.
Dear Sir,
550 Degree Celsius for 2 hours is not enough to prepare BiFeO3 single phase. Kindly anneal the same sample at 925 Degree Celsius and take XRD again. By doing this all the secondary phases along with Bi2O3 may disappear. Try it
could you suggest some time intervals for this temperature? I mean for how long time I should calcinate at this temperature?
No this was not a good temperature. it totally destroyed the whole sample. May be you didn't consider the point that I used sol-gel method using nitrates precursors that I mentioned clear in above answer. Usually this kind of high temperature used for metal oxides when we used as a precursors. so this temperature was not useful.
Destroyed means what happen to the sample. Does it got melted or something else? Can you share the XRD of BiFeO3 in which you have got Bi2O3 phase?
Hi, jafar you can sintering your material in increasing temperature but be carful dont exceed the melting point of raw elements of sample in the first and second sintering stepes.
Hello Mr Jafar,
Have you got pure phase material. For Sol-gel based BFO the calcination temperature should be between 400-500 C and calcination time only 1 hour is enough. the calcination temperature and time also depends on furnace type so you have to optimize calcination temp in a range 400- 550 and also vary the temperature 30 min to 120 min. May be you need to do re-calcination.
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