High Elastic Moduli of a 54Al2O3-46Ta2O5 Glass Fabricated via Containerless Processing.

Gustavo A Rosales-Sosa,Atsunobu Masuno,Teruyasu Mizoguchi,Katsuyoshi Kato,Takumi Umada,Hiroyuki Inoue,Kohei Okamura,Yuji Higo,Yasuhiro Watanabe,Yutaka Yanaba

doi:10.1038/srep15233

Abstract

Glasses with high elastic moduli have been in demand for many years because the thickness of such glasses can be reduced while maintaining its strength. Moreover, thinner and lighter glasses are desired for the fabrication of windows in buildings and cars, cover glasses for smart-phones and substrates in Thin-Film Transistor (TFT) displays. In this work, we report a 54Al2O3-46Ta2O5 glass fabricated by aerodynamic levitation which possesses one of the highest elastic moduli and hardness for oxide glasses also displaying excellent optical properties. The glass was colorless and transparent in the visible region, and its refractive index nd was as high as 1.94. The measured Young’s modulus and Vickers hardness were 158.3 GPa and 9.1 GPa, respectively, which are comparable to the previously reported highest values for oxide glasses. Analysis made using 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS NMR) spectroscopy revealed the presence of a significantly large fraction of high-coordinated Al in addition to four-coordinated Al in the glass. The high elastic modulus and hardness are attributed to both the large cationic field strength of Ta5+ ions and the large dissociation energies per unit volume of Al2O3 and Ta2O5.

Highlights

Glasses with high elastic moduli have been in demand for many years because the thickness of such glasses can be reduced while maintaining its strength
The glass transition temperature Tg is located at 858 °C, and the first TP1 and second TP2 crystallization peak are observed at 912 °C and 1054 °C, respectively
X-ray Diffraction (XRD) analysis confirmed that glass was totally amorphous and that the main phase of the crystallized sample after Differential Thermal Analysis (DTA) was AlTaO4

Summary

Introduction

Glasses with high elastic moduli have been in demand for many years because the thickness of such glasses can be reduced while maintaining its strength. The high elastic modulus and hardness are attributed to both the large cationic field strength of Ta5+ ions and the large dissociation energies per unit volume of Al2O3 and Ta2O5. In order to achieve high elastic moduli and high hardness values, the use of components with large dissociation energies and a high atomic packing density are key factors. High elastic modulus and high hardness glasses generally include large quantities of Al2O3, as is found in R2O3-Al2O3-SiO2 glasses (R = r are earth ion, Y, or Sc)8–11 These glasses have high atomic packing densities. Al2O3-based glasses have attracted interest as high elastic moduli and high hardness materials The properties of such glasses should be enhanced through the incorporation of additional components other than Al2O3 with high dissociation energies and high packing volumes. An approach to the design of glasses with higher elastic moduli and higher hardness is proposed on the basis of the results of the local structure analysis around aluminum performed using 27Al MAS NMR spectroscopy

Methods

Results

Conclusion