Actually i found that with Zr doping in TiO2, particle size decreases but d spacing increases.
Dear Inderjeet Singh
Have a nice time and good day
Yes,the d values may be increased due to insertion of the doping atom in the host material. Increasing of d values may be within the range 10-2 to 10-3 Angstrom. This increasing leads to increase the volume of the lattice. Consequently the crystallite size will be increased.
On the other hand, the particle is consists of an agglomeration of many crystallites. The smaller of the particle size is not dependent upon of (d) values only but it strongly dependent upon the preparative conditions which have been followed and the agglomerated crystallites.
May this help you
Good Luck.
The crystallite size is assumed to be the size of a coherently diffracting domain and it is not necessarily the same as particle size. In your case overall particle size is decreasing but surely crystallize size is increasing as depicted by "d" values.
By substituting titanium zirconium d spacings should increase in any case, regardless of whether or nanoparticle or bulk material. This is due to the fact that the larger size of zirconium atom amount of titanium atom.
However, you ask an interesting question: is it possible to increase the d spacings not due to changes in the chemical composition, but by reducing the particle size. I strongly believe this is possible. Moreover, it should be observed as a rule!
The interatomic distances determined by the interaction of atoms in the crystal. If the interatomic potential interaction would be symmetrical, the heating would not result in thermal expansion of the crystal. However, most of the body expands when heated. This is due to the asymmetry of the interaction potential, which characterizes the anharmonicity of the thermal vibrations of the atoms. The surface of the crystal is a defect that is associated with excess free energy. The free energy during the deformation due to the formation of the defect increases the same way as for heating. This effect we have observed for TiSe2:
https://www.researchgate.net/publication/256858187_Characterization_of_1T-TiSe2_surface_by_means_of_STM_and_XPD_experiments_and_model_calculations
It is therefore not surprising increase in the interatomic distance near such a defect. By reducing the size of the crystal you increase the contribution of the surface in the total volume of the crystal, and therefore, increase the volume of the crystal.
Article Characterization of 1T-TiSe2 surface by means of STM and XPD...
Dear Inderjeet Singh
Good day
I forgot to tell you that I could overcome a similar situation. I found the (d) values increased but the crystallite size decreased. The attached paper treat this concerning issue. It may help you.
https://www.researchgate.net/publication/277004252_Microstructure_and_crystal_imperfections_of_nanosized_CdS_x_Se_1-x_thermally_evaporated_thin_films
Article Microstructure and crystal imperfections of nanosized CdS x ...
Dear Inderjeet Singh
You are welcome. I hope that my answer and my article paper have been helped you
My greetings
Yours,
Ahmed
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