Hi Rishabh,

I think the best thing for this question would be to post the spectra you are referring to.

I agree qith Jeremy. Without seeing the spectra however I would say that you are talking about the bandgap absorption (~190 nm in bulk YAG) and any kind of possible defect absorption in the Vis. The defects would be related to e.g. strain resulting from nano-effects, could be contaminants etc. Seeing spectra would help, also other data.

HERE IS UV-VIS SPECTRA OF YAG NAOCRYSTALS WITH ETHANOL SOVLVENT. What could be reason for peak?

I have uploaded the uv results .Please check it in my answer.

Dear Rishabh, The experimentally determined optical band gap of YAG is at about 7.1. eV = 175 nm (Cryst. Growth Des., 2017, 17 (4), pp 1863–1869

DOI: 10.1021/acs.cgd.6b01822), which means that your absorption band at about 210 nm is not related to the optical band gap of YAG. I assume that the solvent ethanol is already strongly absorbing below 220 nm and thus governing the shape of the absorption spectrum. The decline of the band below 210 nm is caused by the deviation from the Lambert-Beer law due to the large ethanol concentration. The absorption edge of clean and dry ethanol is at about 205 nm. Advice: The best solvent for the deep UV range is water (~ 190 nm), but this is yet not good enough for the determination of the optical band gap of YAG.