Are you sure that there are some MoO3 crystals in PDMS? You may need to check using either X ray diffraction or Raman spectrophotometer.

Dear Md Kazi Rokunuzzaman many thanks for sharing this very interesting technical question on RG. In this context, please have a look at the following potentially useful literature reference which might help you in your analysis. The authors here report that (citation): "Mechanical exfoliation of MoO3 crystals was conducted using polydimethylsiloxane (PDMS) as an alternative to the conventional scotch-tape method."

Two-dimensional MoO3 via a top-down chemical thinning route

The article is freely available as public full text on the internet (please see attached pdf file). Of course it is difficult to judge from the outside what perhaps went wrong in your experiment.

Good luck with your work and best wishes!