Enhancement of ZnSe stability during optical composite processing via atomic layer deposition

This study evaluates the impact and stability behavior of a candidate protective shell of Al2O3 which aims to hinder the dissolution of ZnSe in As-S-Se glass systems during the so-called ‘grinding-remelt’ process. Atomic Layer Deposition (ALD) was chosen as the route to conformal shell coating and the role of resulting film attributes on powder and bulk composite properties were assessed to ascertain how ALD film attributes aided stability in the chalcogenide glass melt environment. It is shown that an ozone pre-treatment, performed on the ZnSe powders prior to the ALD, improves particle stability, resulting in a significant decrease of the dissolution behavior of coated powders. This enhanced stability increases with shell thickness and with the use of ozone pretreatment step on the powders. Coating chemistry and structure evaluated via XPS and HR-TEM illustrates the mechanism of dissolution for different ZnSe coated particles at varying loading levels in the glass matrix.