{"title":"Densely packed glass structure caused by seven-coordinated Zr in high elastic modulus Al2O3–SiO2–ZrO2 glasses","authors":"Atsunobu Masuno, Yuki Mikami, Yutaka Yanaba, Yuji Higo, Shunta Sasaki, Io Sato, Toyonari Yaji, Gustavo A. Rosales-Sosa, Hiroyuki Inoue","doi":"10.1016/j.actamat.2024.120549","DOIUrl":null,"url":null,"abstract":"Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub>–ZrO<sub>2</sub> ternary glasses were fabricated using a levitation technique. The addition of ZrO<sub>2</sub> to the Al<sub>2</sub>O<sub>3</sub>–SiO<sub>2</sub> glasses strongly affected their thermal, mechanical, and structural properties. Several compositions were partially vitrified at the laser-melted area without levitation although their melting required temperatures higher than 2000°C. With increasing ZrO<sub>2</sub> content, the elastic moduli linearly increased, and the 50Al<sub>2</sub>O<sub>3</sub>–20SiO<sub>2</sub>–30ZrO<sub>2</sub> glass exhibited a Young′s modulus of 166 GPa and Vickers hardness <em>H</em><sub>V</sub> of 11 GPa. Conversely, crack resistance significantly decreased with the addition of ZrO<sub>2</sub>. Density measurements, Zr <em>L</em><sub>2,3</sub>-edge and <em>K</em>-edge X-ray absorption fine structure analyses, and <sup>27</sup>Al and <sup>29</sup>Si magic-angle spinning nuclear magnetic resonance spectroscopy were performed to investigate the local structure around Zr, Al, and Si in the glasses. Zr formed distorted ZrO<sub>7</sub> as in monoclinic ZrO<sub>2</sub>, which has been rarely found in conventional oxide glasses. The highly oxygen-coordinated Al atoms such as AlO<sub>5</sub> and AlO<sub>6</sub>, were the main components in the glasses rather than AlO<sub>4</sub>. The majority of Si atoms form SiO<sub>4</sub> with four bridging oxygen (Q<sup>4</sup>). Among the four bridging oxygens, the number of oxygens connected to Al or Zr clearly increased with decreasing SiO<sub>2</sub> content. The high packing density of the ternary glasses that resulted in high elastic moduli originated from the highly oxygen-coordinated Zr and Al and their close bonding with SiO<sub>4</sub> without generating nonbridging oxygens.","PeriodicalId":238,"journal":{"name":"Acta Materialia","volume":null,"pages":null},"PeriodicalIF":8.3000,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Materialia","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1016/j.actamat.2024.120549","RegionNum":1,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Al2O3–SiO2–ZrO2 ternary glasses were fabricated using a levitation technique. The addition of ZrO2 to the Al2O3–SiO2 glasses strongly affected their thermal, mechanical, and structural properties. Several compositions were partially vitrified at the laser-melted area without levitation although their melting required temperatures higher than 2000°C. With increasing ZrO2 content, the elastic moduli linearly increased, and the 50Al2O3–20SiO2–30ZrO2 glass exhibited a Young′s modulus of 166 GPa and Vickers hardness HV of 11 GPa. Conversely, crack resistance significantly decreased with the addition of ZrO2. Density measurements, Zr L2,3-edge and K-edge X-ray absorption fine structure analyses, and 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy were performed to investigate the local structure around Zr, Al, and Si in the glasses. Zr formed distorted ZrO7 as in monoclinic ZrO2, which has been rarely found in conventional oxide glasses. The highly oxygen-coordinated Al atoms such as AlO5 and AlO6, were the main components in the glasses rather than AlO4. The majority of Si atoms form SiO4 with four bridging oxygen (Q4). Among the four bridging oxygens, the number of oxygens connected to Al or Zr clearly increased with decreasing SiO2 content. The high packing density of the ternary glasses that resulted in high elastic moduli originated from the highly oxygen-coordinated Zr and Al and their close bonding with SiO4 without generating nonbridging oxygens.
期刊介绍:
Acta Materialia serves as a platform for publishing full-length, original papers and commissioned overviews that contribute to a profound understanding of the correlation between the processing, structure, and properties of inorganic materials. The journal seeks papers with high impact potential or those that significantly propel the field forward. The scope includes the atomic and molecular arrangements, chemical and electronic structures, and microstructure of materials, focusing on their mechanical or functional behavior across all length scales, including nanostructures.