Is there any strain in the nanostructures synthesized by chemical precipitation route (e.g. Ca(OH)2, Ni(OH)2, Cu(OH)2 nanostructures and etc)? What causes this strain?
Normally you cannot generalised whether there will or will not be any strain in particles synthesised by a specific route. This is because there are many factors that can effect the strain in crystal structure including synthetic protocols, individual ways of handling synthesis steps (human errors), impurities in your system, variations in crystal phases by slight differences in synthetic routes and so on.
So if you really want to analyse the strain within your crystal structures then the only option for you would be to actually do the analyses yourself. You can try williamson hall analysis by XRD as a starting point.