Achieving near‐linear thermal expansion and in situ interfacial regulation in Li ₂ O–ZnO–SiO ₂ sealing glass–ceramics

Abstract A key challenge in high‐expansion Li 2 O–ZnO–SiO 2 glass–ceramics is the sudden change in the thermal expansion curve caused by the α–β phase transformation of cristobalite near ∼220°C, which results in a nonlinear thermal strain response. This abrupt thermal strain can cause a transient mismatch between the glass–ceramic and the metal during sealing, ultimately compromising interfacial reliability. In this study, a novel and efficient regulation method was found that the near‐linear thermal expansion of Li 2 O–ZnO–SiO 2 (LZS) glass–ceramics was obtained by adjusting the precipitation of quartz and cristobalite with the addition of Sm 2 O 3 . FTIR and Raman results showed that the addition of Sm 2 O 3 increased the content of bridging oxygen in the LZS glass network structure, enhancing the glass structure and increases the crystallization activation energy. Correspondingly, the increase of bridging oxygen content could inhibit the precipitation of cristobalite in LSZ glass–ceramics, which reduced the abrupt change in the thermal expansion curve around 220°C. When the addition of Sm 2 O 3 exceeds 6 wt%, the thermal expansion curve with 15.2 × 10 −6 K −1 (30–300°C) becomes near‐linear, with a Pearson correlation coefficient of .9951. At 500°C, the electrical resistivity of LSZ glass–ceramics reaches as high as 10 8 Ω cm, demonstrating excellent high‐temperature electrical insulation. Additionally, an in‐situ Zn–Si–Cu–O transition layer with a thickness of ∼2 µm was observed at the sealing interface between high Sm 2 O 3 content LSZ glass–ceramics and copper. This study was useful for controlling optimal the near‐linear thermal expansion and in situ interfacial regulation of Li 2 O–ZnO–SiO 2 ‐based glass–ceramic sealant for efficient and stable glass–ceramic to metal seal.