Evolution of CdS:Mn nanoparticle properties caused by pH of colloid solution and ultrasound irradiation

Abstract

The effects of pH value and precursors concentrations in the growth solution as well as of ultrasound irradiation on the properties of CdS:Mn nanoparticles in PVA matrix are studied. Analysis of the photoluminescence spectra indicates that the increase of the pH value in the growth solution leads to the increase of the density of surface electron states that participate in radiative transitions and to the enlargement of CdS:Mn nanoparticles.We discuss a stabilization of the sizes of CdS:Mn nanoparticles at pH=6 and change of nanoparticle size with decreasing pH value at elevated concentrations of ions HS- . It is shown that in the ultrasound-treated samples the size of the particles does not depend on pH value. The effects of ultrasound result primarily from acoustic cavitation. It is demonstrated that the action of two external factors (the value of the medium pH and ultrasound treatment) on the characteristics of nanoparticles is correlated.