can you provide data file and PCR file?

Try to read the following two papers. I hope they will be helpful.

Particle Size Effect on the Crystal Structure of Y2O3 Particles Formed in

a Flame Aerosol Process, 

J. Am. Ceram. Soc., 91 [5] 1653–1658 (2008)

http://onlinelibrary.wiley.com/doi/10.1111/j.1551-2916.2008.02341.x/pdf

and 

Real Structure of Undoped Y203 Single Crystals, Acta Cryst. (1984). B40, 76--82, BY FRANTI~EK HANIC

see this article you may finde in it wath benefit can download from the link

http://www.up-00.com/?UK6g

It is just Y-(O)3-Y, where ecah oxygen atom has two lone pair electrons and each Yttrium atom has two p vacant orbitals

thank you for your answers it help me

https://materialsproject.org/materials/mp-558573/

Dear Samira Lalaooa:

You can find many crystal structures and properties using the following link:

http://www.springermaterials.com/,

You just need to imput the formula of the compound, e.g., Y2O3.

The C2/m structure of Y2O3 in the paper below

A. E. Solov’eva, Neorg. Mater. 21, 808 1985

https://doi.org/10.1016/j.jallcom.2020.154405