• • CE0.4MO exhibits NTE over 100–830 K and ZTE up to 1100 K, outperforming most reported ZTE materials; this wide window enables precision components in aerospace and high-temperature instrumentation where dimensional stability is critical.
• • Configurational entropy reduction from CE1.0MO to CE0.4MO suppresses structural evolution, directly reducing structural flexibility; higher ADPs of O atoms in CE1.0MO confirm enhanced flexibility, linking entropy to thermal expansion behavior.
• • Raman FWHM in the 750–900 cm-1 range positively correlates with configurational entropy, indicating lattice disorder; blue shift of modes within 750–1050 cm-1 as entropy decreases confirms progressive lattice stiffening, providing a spectroscopic handle for quality control.
• • ELF and charge density analyses reveal that Mg/Mn/Co/Ni/Sc–O bonds are ionic, with ionicity weakening as configurational entropy decreases; this enhances constraints on atomic vibrations, offering a design principle for tuning thermal expansion via bond ionicity.