Dear respected RG members,
Recently, we tried to prepare Ni doped MgO nanoparticles using co-precipitation method. The XRD pattern of pure MgO-NPs is going well with five peaks (20-80 degree). We encountered unusual peak at around (64 degree) 2theta for 3% doped MgO-NPs. We follow the same procedure of preparing pure MgO. Stiocheiometric amount of magnesium nitrate hexahydrate (0.097 mol) and nickel nitrate hexahydrate (0.003 mol ) were dissolved in 200 ml water and the aqueous solution heated to 70 Celsius. Then, 0.2 mol of NaOH was add to the mixture as fast as possible till the precipitate occur (pH 10 ) and stirred for another 2 hrs at 70 C. The precipitate dried and crushed (using pestle and mortar) and calcined at 500 C for 2 hrs with a heating rate of 10 degree/min.
Our main concerns are:
1- The unknown peak at (64 degree) may come from impurity during grinding using pestle and mortal.
2- Is the incorrect calculation ( nonstoichiometric ) of the main precursor and the reagent cause this issue?
3- The Ni show very high solubility in MgO host lattice without phase separation, so we do not believe that the impurity is related to Ni, NiO or Ni2O3.
Please we are looking for your recommendation and help
Dear Mohammed,
Generally the materials preparation is depends on various factors.
We should take care in each and every step. Otherwise we get lots of impurities or some times the samples may contaminate.
You are telling MgO is nanoparticle. How about Ni. Is it bigger than MgO or not?
While taking/weighing the chemicals...have you taken exactly according to the Stiocheiometric.
Mix the NaOH slowly to the solution, not fast.
Have you cleaned thoroughly mortor and pestle with acetone.
If the particles are nanomaterials, we need not to go for high temperatures.
I feel this presintering temperature is high for this work.
The heating and cooling process in presintering process, make 5oC/min.
In the materials science research, we must do so many trail and error methods to get high quality materials. We must have some patience. I hope you will get good materials for your research.
I wish you good luck.
I would try to measure FWHM of the peak; for example, if you can an unrealistic little value it could be a detector spike
Hello @Natale Perchiazzi,
Yes, I can measure FWHM, but how can I know if the value is unrealistic?
Further, undoped sample has been shown only five peaks without impurities.
Measure a known diffraction standard snd compare. As a rule of thumb Fwhms less than 0.03 are suspicious in my opinion
Hello D. Fruchart ,
We have Shimadzu-6000 diffractometer with Cu-Kα radiation (λ = 1.5406 Å) in our Lab.
Hello Fabrizio Guzzetta ,
Thanks for sharing your experience here. I checked out the Ni and NiO XRD patterns. Ni has no peak at this position (around 64 degree), and NiO (cubic, S.G #225) has almost the same diffraction pattern as MgO. Thus, If there is any diffraction from NiO, their peaks must overlap with MgO reflections.
Yes, we found only this anomalous. Further, when we doped the MgO with higher doses of Ni (6%) , we found that only very small peak spike at 64 degree (2theta). Please, see the attachment of 6% Ni doped MgO host lattice.
Do you think that this impurity arise due the lack of washing the precipitate (We wash it about four times in distilled water)?
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