I have raman spectra of my ferrite based samples, what I observed that, between 100cm-1-1000cm-1, where characterstic peaks should be observed is absent and a broad peak followed by a small peak around 1450 cm-1 are observed. with change in substitution the FWHM of this broad peak varies systematically. What does it mean.
Is it multiphonon relaxation?
(Experimental details: FT-Raman spectra were recorded in backscattering geometry by means of a Varian (Digilab) dedicated FT-Raman spectrometer (Nd-YAG laser, 1064 nm, 500 mW laser power) and corrected to white light background. 1024 spectra were averaged in order to improve the signal to noise ratio)
dear pradeep. K. Jha,
Have you synthesized the sample or purchased? The absence of peaks in the region 100 - 800 cm-1 shows the absence of main functional group. So take IR to get the peaks otherwise theoretical study will be helpful to compare the theoretical spectrum with the spectrum you obtained.
By
T. Karthick
Dear T. Karthick,
I have synthesized the samples, it show very good resemblance in electrical properties, but this raman spectra. Problem is lying with only ferrite sample. Non ferrite sample shows good result.
You may have induced a structural transition by laser heating. You could try to repeat the measure with low laser power. You could also estimate the sample temperature by Stokes - AntiStokes comparison.
Well, that may mean that there is no ferrite in the sample, but rather some other compound. I would suggest to check the Raman spectra of other possible compounds in the literature, and to see if one of them shows a band at 1450... And cross-check with other techniques.
1450 region is already typical for organics, rather than compounds containing such heavy atoms as Fe
It's difficult to give an answer without seeing the actual spectrum but it could be that you burned your sample and got a spectrum of amorphous carbon whose signal is generally a doublet in that region (between 1330 and 1650 cm-1) but can also be a broad undefined band.
In addition, iron compounds are known to be thermo or photo sensitive and change phase and Raman signal when submitted to high laser power/photon density. So using a 500 mW laser on an iron compound is not advisable.
Thanks to All,
The following are the patterns observed when plot to less tha 700 cm-1.
while for higher wave no. it appear like following pattern. (Sample synthesis is fine and it contain Fe.)
I'm not able to identify these spectra but at least I can tell you that they don't look like amorphous carbon obtained after burning an organic sample. So it may not come from thermal degradation. It may be a contaminant, the sample holder, an harmonic band from something else...
- Badges
- Science topic
- Similar topics
- Physical Sciences
- Materials Science
- Materials
- Composites
- Nanocomposites