Dear Frank With regard to accurately determining the size of small particles or nano-crystallites, have you seen this article on "Pitfalls in the characterization of nanoporous and nanosized materials" by Claudia Weidenthaler?
https://pubs.rsc.org/en/content/articlelanding/2011/nr/c0nr00561d Best regards, Darren > -----Original Message----- > From: [email protected] > Sent: Thu, 6 Jun 2019 12:39:29 +0200 > To: [email protected] > Subject: Literature on Rietveld limitations in nano materials > > Dear fellow Rietvelders, > > Could anyone point me to some nice literature which critically discusses > the limitations of the Rietveld method when it comes to nano-crystalline > materials (specifically in the 1 to 3 nm range)? > As far as I'm aware, the core Rietveld literature seems to touch this > point only in the passing. > > Background: > To the best of my knowledge, Rietveld-derived parameters (like lattice > constants or domain sizes) should not be trusted as being "physically > meaningful" anymore when you fit the powder pattern of a material in > the few nm range with standard Rietveld tools. > My naive understanding of this problem is that the physical principles > of diffraction (or rather the best way to model it) gradually change > when you go from long-range ordered to medium-/short-range ordered > materials. > Being a Rietveld practitioner rather than a theoretician, and having no > first-hand experience with WPPM and PDF methods, I am often confronted > with the problem to explain to my "customers" why I can't extract > trustworthy lattice constants or domain sizes from their > nano-crystalline samples, especially if it seems technically possible to > fit the pattern with a Rietveld program. > I think it would be nice if I could cite some critical discussion, or > overview article with further references, to put my finger on the > problem. > Especially in the catalysis community literature, my impression is that > the applicability of the Rietveld method is sometimes overestimated, > leading to overinterpretation of the results. > > Any suggestions? > > Best wishes, > Frank Girgsdies > > > > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > Please do NOT attach files to the whole list > <[email protected]> > Send commands to <[email protected]> eg: HELP as the subject with no body > text > The Rietveld_L list archive is on > http://www.mail-archive.com/[email protected]/ > ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Please do NOT attach files to the whole list <[email protected]> Send commands to <[email protected]> eg: HELP as the subject with no body text The Rietveld_L list archive is on http://www.mail-archive.com/[email protected]/ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
