Abstract
An investigation of MgAl2O4 spinel and Y3Al2O5 (YAG) materials sintered by spark plasma sintering (SPS) was performed. The optical properties of the materials are modified depending on the powder source and the SPS sintering conditions. Spectrophotometer and Raman analysis are presented in this work, along with optical and scanning electron microscope (SEM) observations and cathodoluminescence analysis. The results show a correlation between carbon contamination and the optical properties of the materials. Herein, the source of the contamination is explained, along with its genesis and diffusion. The carbon contamination originates from the powder itself (carbonates), as well as the SPS environment (papiex® graphite foil, graphite die, graphite felt) to form carbon clusters. During the high-temperature SPS process, carbon from those carbon clusters diffuses, resulting in an increase in the contamination volume, thereby increasing the light absorption.
Highlights
High-density polycrystalline ceramics are regarded as promising materials due to their optical properties, such as their high transparency in the near ultraviolet (0.16 μm) to the mid-infrared (10 μm) range
Carbon contamination originates from carbon clusters which are formed by carbon originating from the powder itself and from the spark plasma sintering (SPS) environment
Longer SPS time and a higher temperature are responsible for carbon diffusion from the carbon
Summary
High-density polycrystalline ceramics are regarded as promising materials due to their optical properties, such as their high transparency in the near ultraviolet (0.16 μm) to the mid-infrared (10 μm) range. (YAG) are the most widely used transparent ceramics materials, as they are used for several optical applications, including transparent armor for air and ground vehicles, optical lenses, windows for lasers, high-pressure arc lamps, and refractories and electronic ceramics [6,7,8,9,10]. The fabrication of these materials by spark plasma sintering (SPS) possesses some advantages over classical techniques such as hot pressing and hot isostatic pressing. Transparent and dense MgAl2 O4 can be obtained at a temperature of 1300 ◦ C after only a 20 min soak, without sintering aids [11]
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