I prepared undoped ZnO, AZO (Al-doped ZnO), and MZO(Mg doped Zno) thin films. After SEM analysis I noticed that the particle size decreased for Al doping compared to undoped but particle size increased for Mg doping.
Hi Md Mahamud Hasan Tusher
First compare the crystallite sizes using XRD analysis of the both samples using Serrer's formula. The ionic radius of Mg2+ is 66pm and ionic radius of Al3+ is 53pm. The increase in the size may be due to the larger size of the Mg2+ w.r.t. Al3+.
From my side I can say this.
Waiting for other response from the RG experts.
Regards
This can be explained by the cationic field strength (CFS) value, which can be expressed as the Z/r2 value. For dopants like Al+3 which have higher CFS values as +3 oxidation state and approx. 54pm ionic radii. This leads to increase strain in the lattice as a result it squeezes the lattice. As a result of that particle size decreases.
Now for Mg+2, the cationic radius is approx. 67pm which is comparatively larger than Zn+2. As a result, the CFS value is quite low. So, particle size increases for doping of Mg+2
Al doping in the synthesis of ZnO thin film leads to reduced particle size due to the decrease in crystallinity. This is because Al atoms replace some of the Zn atoms in the crystalline lattice, creating structural defects and disrupting the growth of the lattice. On the other hand, Mg doping causes the particle size to increase because Mg atoms are larger than Zn atoms, resulting in increased interparticle spacing which allows for bigger particles to form.
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