Thermal expansion, mechanical and optical properties of gallium and aluminum substituted Zn2TiO4 spinels

Publication from Materials

Lukas Perfler, Volker Kahlenberg, Georg Jakopic, Andreas Schaur, Martina Tribus, Daniela Schmidmair, Reinhard Kaindl

Materials Research Bulletin Volume 95, Pages 367-379, 11/2017


Polycrystalline samples of new Zn1.75Ti0.75Ga0.5O4, Zn1.5GaTi0.5O4, and Zn1.75Ti0.75Al0.5O4 spinel were prepared by solid-state reactions. Phase analysis and structural investigations were carried out by powder X-ray diffraction and Raman spectroscopy. In situ high-temperature powder X-ray diffraction experiments enabled the investigation of the thermal expansion of the spinel-type compounds. To determine the mechanical properties, nanoindentation experiments were performed with a Berkovich diamond indenter tip. Analyses of the load–displacement curves revealed a high hardness ranging from 10.2 ± 0.4 GPa to 11.8 ± 0.5 GPa and a reduced elastic modulus of 162 ± 5 GPa up to 178 ± 6 GPa. Furthermore, the optical properties of the spinel-type materials were studied by spectroscopic ellipsometry in the wavelength range of 250–1000 nm. All materials exhibit a high refractive index ranging from n = 2.20 to n = 2.10 at 430.8 nm (Fraunhofer G line) with a similar low dispersion (0.09 to 0.07).