Dear Dr. Yuri Mirgorod, I am familiar with this type of instabilities, what I wanted to say is that in this case of CZTS nanoparticles there is another source of instability, which is the loss of nanoparticles by dissolution due to the existance of polymorphe structures. In this case, even a classical forms of colloid stabilization do not work at prolonged time because it will only slow down the diffusion of the solvent into the nanoparticles to provoke dissolution, hence nanoparticles are lost. According to the aforementioned references increasing reaction time leads to the more resistant crystalline structure to dissolution, and this way the stability from this side is inssured. My Regards

Anchal Yadav

I'd look at a 50 kDa PEG or PEI for steric stabilization. Washing in organic solvents (for what purpose?) is to be avoided.

Anchal Yadav

See the term (topic) ligand below under your question. You don't need a ligand, but a surfactant dispersion stabilizer. You probably got CZTS@Ag by heating the precursor mixture. Use the suggested Alan F Rawle or another surfactant sodium dodecyl sulfate or cetyltrimethylammonium bromide.

Dear all, the file link below attributes this unstability to the thermodynamically metastable kesterite/wurtzite mixture. The XRD profile reveals the formation of this CZTS crystalline phase mixture with a decreasing amount of the wurtzite phase as the synthesis time is increased. So, no stabilization is needed if just the reaction time is increased. My Regards

https://doi.org/10.1155/2016/7486094

Attached is another interesting document. My Regards

Another interesting document. My Regards

https://doi.org/10.1021/acs.chemmater.5b00172

Abdelkader BOUAZIZ

I think we all have different definitions of what is meant by 'stability'...

Dear Dr. Alan F Rawle, yes that's true, it is a matter of the author of the question to tell the stability he is dealing/concerned with. My Regards

Dear Abdelkader BOUAZIZ

The question is asked about colloidal stability or stability of a suspension against aggregation, sedimentation. This is thermodynamic stability and instability of a thermodynamic system called a suspension.

There is another stability - the thermodynamic stability of matter. Allotropic modification of carbon diamond is a thermodynamically unstable compound at room temperature and atmospheric pressure. At high pressure and temperature, diamond is thermodynamically stable.

The kesterite / wurtzite mixture belongs to this type of thermodynamic stability, metastability, absolute instability. A stable substance forms on the binodal. Absolute instability is achieved at the spinodal. Between the binodal and spinodal, CZTS is in a metastable state. A metastable state is a thermodynamically unstable state. After some time, kesterite / wurtzite becomes stable.

Dear Dr. Yuri Mirgorod, I am familiar with this type of instabilities, what I wanted to say is that in this case of CZTS nanoparticles there is another source of instability, which is the loss of nanoparticles by dissolution due to the existance of polymorphe structures. In this case, even a classical forms of colloid stabilization do not work at prolonged time because it will only slow down the diffusion of the solvent into the nanoparticles to provoke dissolution, hence nanoparticles are lost. According to the aforementioned references increasing reaction time leads to the more resistant crystalline structure to dissolution, and this way the stability from this side is inssured. My Regards

Dear Anchal,

As you try to stabilise NPs of a Cu-Zn-Sn sulphide, it might useful to achive thermodynamic stabilisation of these particles by ligands, which tend to react with the involved low-valent metals. Therefore, I would recommend to perform attempts with thioacetamide, dithiocarbamate, cysteine, gluthathione, thioglycerol or similar ligands comprising a R-CS2 or R-CSNH2 unit for coordination.

Success!

Thomas

Although organic ligands have been used as surface‐modifying reagents for nanoparticles to increase their colloidal stability and homogeneity in solution, the structure–function relationships of nanoparticle–ligand complexes remain elusive and controversial. A series of novel amphiphilic small‐molecule ligands were designed, synthesized, and applied as surface‐modifying reagents for aqueous, transparent TiO2 and ZrO2 nanoparticles. The colloidal stability of the resulting nanoparticle–ligand complexes was found to depend not only on the chain length, but also on the relative balance between hydrophobicity and hydrophilicity. The structure of the ligands can be fine‐tuned to achieve “flexible colloidal stability”, thus significantly increasing complex stability in a variety of organic solvents.

https://onlinelibrary.wiley.com/doi/abs/10.1002/chem.201704306

Kindly check https://www.sciencedirect.com/science/article/abs/pii/S074960361733046X

Also check https://pubs.rsc.org/en/content/articlelanding/2015/ta/c5ta03640b#!divAbstract

Abdelkader BOUAZIZ

If you are familiar with the thermodynamic instability of dispersed systems and solid chemical compounds, then why suggest a new one, which is absent in the attached references.

Chinaza Godswill Awuchi

In the process of the synthesis of nanoparticles by the condensation method, nuclei are formed, followed by the growth of nanoparticles. At each stage, they can be modified with additives. Capping with amphiphilic additives or surfactant adsorption works especially well. Adsorption occurs due to the formation of an ionic bond, coordination (with ligands), intermolecular. Ligands (surfactants) are difficult to remove from the surface of nanoparticles.

Dear all, may be I didn't attached the specific reference, I didn't suggested a new instability mechanism of nanoparticles, i.e. dissolotion, it exists and well known and documented, and by the way it is used as a strategy in drug delivery. Sooner I will provide with some references concerning CZTS. My Regards

https://doi.org/10.1103/PhysRevB.46.1198

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6913534/

https://link.springer.com/article/10.1208/s12249-016-0621-0

https://www.researchgate.net/publication/40895063_Stability_of_metal_oxide_nanoparticles_in_aqueous_solutions

https://doi.org/10.1021/la1019229

https://doi.org/10.1039/C9EN00348G

https://www.nature.com/articles/s41598-019-56872-3