Hello,
I have synthesized silver nanoparticles using PVA as encapsulating and stabilizing agent. From XRD i could get 25 and 28 nm crystallite size for 400 C and 500 C annealed samples.
The lattice parameter were 0.4072 nm and 0.4060 nm. I was expecting the parameter to increase with temperature due to crystal growth.
Is defect free crystal at higher temperature the possible reason or something else ?
Dear Bhasker, 25 and 28 nm are quit close sizes. I think you need more information about your samples. for example if you had PDI from DLS or TEM analysis you can see if there is a real difference between your samples or not.
I agree with previous answers... Why it happens may be explained by means of some facts…Generally, when temperature is increased, the lattice parameters are increased due to the materials expansion.
However, nanocrystallites may have a number of defects, during annealing these defects migrate and the lattice is decreased.
At the same time, phase transformations at annealing process can lead to decreasing and increasing lattice.
In this grain size. could be called a nanoparticle the lattice is effectively affected by the particle size which increases wi the decrease of the particle size. That is what your results are
for more information you can see the article published by M. S. Omar In the journal of thermophysics 2016
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