Melt‐quenched oxide glasses with ultrahigh Young's modulus and small thermal expansion coefficient
Katsuki Hayashi, Kazuki Mitsui, Tatsuki Shimizu, Rikiya Kado, Takumi Umada, Akio Koike, Satoshi Yoshida, Seiji Inaba, Akira Saitoh
Abstract
Abstract The well‐known Makishima–Mackenzie relationship, consisting of two terms of the dense packing structure and dissociation energy regarding bonding in constituent oxides, enables fabricating oxide glasses with ultrahigh Young's modulus (∼140 GPa) and a small coefficient of thermal expansion (CTE) (∼4 ppm/K). The effects of increasing MgO and Ta 2 O 5 contents in an MgO–Ta 2 O 5 –Al 2 O 3 –SiO 2 –B 2 O 3 glass system using a conventional melt‐quenching method are revealed. The essential oxides of Al 2 O 3 and Ta 2 O 5 are primarily suitable for dense packing structures dominated by a large coordination number of oxygens. The substitution of CaO by MgO results in high dissociation energy when the glass composition falls in the peraluminous regime (Al 2 O 3 /[MgO + CaO] > 1). A small CTE is realized by increasing the molar ratio of Al 2 O 3 /MgO. According to magic‐angle spinning‐nuclear magnetic resonance spectra, mechanically and thermally functional oxide glasses depend on their structures. These findings facilitate the development of glass substrate applications without thermal dilatation.