Co effect on zinc blende-rocksalt phase transition in CdS nanocrystals

The influence of Co doping on zinc blende-to-rocksalt (ZB-RS) phase transformation in CdS nanocrystals (NCs) has been investigated. Analysis is performed using in situ high pressure X-ray powder diffraction with synchrotron radiation. Pure cadmium sulphide (CdS) and cobalt-doped cadmium sulphide (CdS:Co) are prepared by gas-liquid phase chemical deposition. The experimental data indicates that doping with Co ions reduces the phase transition pressure ( P T ) (CdS = 4.89 GPa and CdS:Co = 4.06 GPa) and increases the bulk modulus ( B 0 ) of the initial and high-pressure phases. The phase transitions of all samples are reversible. Density functional theory calculations are also performed to study the phase transition. The enthalpy variation is in accord with the experimental data. The Co dopant significantly promotes the zinc blende to rocksalt phase transition and increases the bulk modulus compared with CdS nanocrystals.