OS2-11
融液の熱物性と原子配列をベースとした機能性高充填密度
ガラスの設計指針の確立
Materials design of functional densely packed glasses
using thermophysical properties and atomic
arrangements of melts
増野敦信
Atsunobu MASUNO
京都大学大学院工学研究科，Graduate School of Engineering, Kyoto University

1. Introduction
Oxide glasses are generally considered to be materials in which the so-called network former oxides, such as
SiO2, B2O3, and P2O5, serve as the main components, forming corner-sharing three-dimensional random
network structures (Figure1(a)). However, we have recently succeeded in synthesizing a variety of highlydensely packed glasses without corner-shared networks by using a levitation technique1,2) (Figure 1(b)). These
glasses exhibit fascinating physical properties compared to conventional glasses, including a high refractive
index with low wavelength dispersion, strong luminescence, high elastic modulus, high cracking resistance,high dielectric constant, and a large magneto-optical effect3–5). It is suggested that these remarkablefunctionalities arise from the high packing density; however, the structure-property relationship remains
unclear. Additionally, the structural and thermophysical origin of glass formation in the absence of network
formation, despite high packing density, are still not well understood. Given that glasses are obtained bycooling melts, it is crucial not only to clarify the structural features responsible for functionality of these glasses
but also to understand the glass formation process by which such characteristic atomic arrangements areformed. To achieve this, it is first necessary to investigate the correlation between the structure of melts andsupercooled liquids and their thermophysical properties such as viscosity.

Figure 1 Atomic arrangements of (a) conventional network glass and (b) densely packed glass.
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2. Purpose of the projectThis research project builds on the FY2022 project titled "Physical property measurements of functional
densely packed oxide glass melts by using ELF for understanding the atomistic origin of the functionality".
The current project’s objective is to develop guidelines of materials design of functional densely packed glasses
by examining the thermophysical properties and atomic arrangements of melts. This represents a more indepth investigation compared to the previous study, which primarily aimed to elucidate mechanism behindthe functionalities of these glasses. In the FY2022 project, we focused on understanding the mechanisms
underlying the functionalities of densely packed glasses, shown in Table 1. Thermophysical properties(density and viscosity) and diffraction data of the glass melts will be obtained. Building on these results, thisstudy will explore a wider composition range to examine the composition dependence of these functionalities
and their glass forming abilities. By adjusting the chemical compositions, specifically by altering the size ofcations in modifier oxides and the concentration of modifier oxides, we aim to identify characteristic atomic
arrangements that contribute to functionalities and structural factors that enhance glass formation.

Table 1. Chemical compositions of samples for FY2022 and FY2023 projects.

FY2022

Refractive index

Thermal expansion

Transparency

50La2O3–50B2O3

25La2O3–75MoO3

30La2O3–70SiO2

50Y2O3–50B2O3

25Er2O3–75MoO3

30Y2O3–70SiO2

30La2O3–70B2O3

20La2O3–80WO3

FY2023To evaluate glass formation and calculate the Fragility Index—a parameter that quantifies glass-forming
ability of melts—we will measure the temperature dependence of density and viscosity in space. The use of
the electrostatic levitation furnace (ELF) on the ISS Kibo is crucial for accurately measuring the density andviscosity across a wide temperature range, from above the melting point to significantly supercooledtemperatures6). On the ground, Raman scattering spectroscopy, along with X-ray and neutron diffraction
experiments, will be conducted to analyze the structure of the melts. Structural models that reproduce theexperimental data will be prepared using molecular dynamics simulations. The reliability of these models will
be significantly enhanced by incorporating the densities obtained from space experiments. The structuralmodels will be analyzed using various geometrical methods to extract characteristic atomic arrangements
responsible for the functionality7–10). Combining thermophysical data with structural information of these
unconventional oxide glass melts, we aim to uncover important insights into the atomistic origin offunctionality and the glass formation process.

References
1)
2)

A. Masuno: Structure of Densely Packed Oxide Glasses Prepared Using a Levitation Technique. J. Phys. Soc. Jpn, 91,(2022) 091003, DOI: 10.7566/JPSJ.91.091003.
H. Inoue et al.: Nearly close-packed atomic arrangements in BaTi2O5 glass. Scr. Mater., 252, (2024) 116271, DOI:
10.1016/j.scriptamat.2024.116271.
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3)A. Masuno: Functionalities in unconventional oxide glasses prepared using a levitation technique. J. Ceram. Soc. Jpn.,
130, (2022) 563, DOI: 10.2109/jcersj2.22073.
4) A. Masuno et al.: Crystal-Like Atomic Arrangement and Optical Properties of 25La2O3−75MoO3 Binary Glasses
Composed of Isolated MoO42−. Inorg. Chem., 63, (2024) 5701, DOI: 10.1021/acs.inorgchem.4c00176.
5) S. Sasaki et al.: Magneto-optical effect of rare-earth-rich borate glasses prepared using a levitation technique. J. Am.
Ceram. Soc., in press, DOI: 10.1111/jace.20065.
6) H. Tamaru et al.: Status of the Electrostatic Levitation Furnace (ELF) in the ISS-KIBO. Microgravity Sci. Technol., 30,(2018) 643, DOI: 10.1007/s12217-018-9631-8.
7) C. Koyama et al.: Very sharp diffraction peak in nonglass-forming liquid with the formation of distorted tetraclusters.
NPG Asia Mater., 12, (2020) 43, DOI: 10.1038/s41427-020-0220-0.
8) Y. Onodera et al.: Structure and properties of densified silica glass: characterizing the order within disorder. NPG
Asia Mater., 12, (2020) 85, DOI: 10.1038/s41427-020-00262-z.
9) S. Kohara: Probing order within disorder in oxide glasses and liquids by quantum beam diffraction. J. Ceram. Soc.
Jpn., 130, (2022) 531, DOI: 10.2109/jcersj2.22030.
10) Y. Shuseki et al.: Atomic and Electronic Structure in MgO−SiO2. J. Phys. Chem. A, 128, (2024) 716, DOI:
10.1021/acs.jpca.3c05561.

© 2024 by the authors. Submitted for possible open access publication under theterms and conditions of the Creative Commons Attribution (CC BY) license(http://creativecommons.org/li censes/by/4.0/).

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