Structural, functional and mechanical properties of spark plasma sintered gadolinia (Gd<inf>2</inf>O<inf>3</inf>)

Powder particles of gadolinia were spark plasma sintered at varied temperatures between 1400 °C and 1600 °C. High-density samples free of any sintering additives were obtained at the highest sintering temperature and the samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) including density measurements. The contact angle measurements and translucence studies implied the sintered samples to be hydrophobic and translucent respectively. The nanohardness values enhanced up to ∼88% with increase in sintering temperature from 1400 °C to 1600 °C. Young's modulii determined using nanoindentation varied from 126 GPa to 169 GPa for the samples sintered at the lowest and highest temperatures respectively. The theoretical Young's modulus was also determined using first principle calculations which were eventually used for fracture toughness calculations. The fracture toughness values of the sintered samples were calculated using the indentation crack length method (ICL) and compared with the crack opening displacement (COD) method.