What will be the effect on the lattice parameter on the substitution of Zr4+ by Zn2+ in the crystal structure of 3YSZ? The ionic radius of Zn2+, Y3+ , and Zr4+ are 90, 101.9, 84 pm respectively. Is there is any possibility of the substitution of Yttrium by Zinc?
Answer to your first question is:
If we substitute Zr4+ by Zn2+ in the crystal structure of 3YSZ then the lattice parameter should increase. Since the Coloumbic force between the ions will decrease as it is dependent on the amount of charge. This is, in turn, will lead to an increase in bond length. As the bond length will increase there will be a decrease in the lattice parameter.
Dear Ammar,
Zirconium 4+ has crystal ionic radii in pm as a function of ionic charge and spin (ls = low spin, hs= high spin) of 86 pm. I am considering 6-coordinate ion. Zn2+ has its crystal ionic radii of 88 pm. So, by increasing the amount of Zn2+, the lattice parameters increase a bit.
This expected behavior occurs if the substitution is isomorphic.
However, depending on the route of syntheses, you may face an interstitial substitution; it depends on the amount of Zn2+ (stoichiometric or excess ) available at the synthesis procedure, temperature, pressure, and the substitution pathway (in solution at the synthesis or in solid-state by intimate solid mixture).
In this case, you face a final lower Zr4+ amount (decreased in quantity at the synthesis to clear space for Zn2+) and an interstitial Zn2+. In such a case, the lattice parameters may decrease or still unaltered, once Zn2+, or part of it, did not occupy Zr4+ sites in the lattice, now with lower stoichiometric Zr4+ available.
Best regards,
WNM
I don't think that Zn2+ can replace Zr4+ in zirconia because of the difference in the charges. However, zinc cations may be doped in aninterstitial fashion, in this case significant changes in the lattice parameters are not expected.