Top-down synthesis and characterization of exfoliated layered KLnS2 (Ln = La, Ce, Gd, Yb, Lu) nanosheets, their colloidal dispersions and films

• Stable dispersions of KLnS2 can be obtained by ultrasonic treatment.
• In colloids nanoparticles exist as thin nanoplates with high side-to-thickness ratio.
• Films, prepared from dispersions, were high-textured samples of KLnS2.

For the first time the top-down approach was successfully applied to obtaining rare-earth sulfide nanoparticles. In this work we demonstrated that stable dispersions of KLnS2 (Ln = La, Ce, Gd, Yb, Lu) can be prepared by liquid exfoliation by ultrasonic treatment in polar organic solvents. The isopropanol and acetonitrile dispersions demonstrated the highest concentrations and stability among used solvents. The colloids contain thin nanoplates of rhombohedral KLnS2. According to TEM and AFM data, the lateral particles’ sizes were 50–600 nm with thickness 3–15 nm. By filtering the nanoparticles can be reassembled as films, demonstrating strong texture along 00l direction.

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