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In conclusion, the present study not only extends the scope of NTE families and rare high-temperature isotropic ZTE compounds but also proposes a new method to design systematically controllable isotropic thermal expansion frameworks from the perspective of atomic linkage flexibility.
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#Volumetrix thermal expansion ideal gas units series
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The future studies on NTE functional materials will definitely promote the development of NTE materials. There remains a challenge more » to discover a “perfect” NTE material for each specific application for chemists. Finally, challenges and questions are discussed for the development of NTE materials. Chemical modification has been proved to be an effective method to control thermal expansion. In NTE functional materials, a multi-way to control thermal expansion can be established through the coupling roles of ferroelectricity-NTE, magnetism-NTE, change of electron configuration-NTE, open-framework-NTE, and so on. There is a general nature of NTE for both ferroelectrics and magnetics, in which NTE is determined by either ferroelectric order or magnetic one. The NTE functional materials present a general physical picture to reveal a strong coupling role between physical properties and NTE. Zero thermal expansion (ZTE) of functional materials is emphasized due to the importance for practical applications. In the present review article, NTE is reviewed in functional materials of ferroelectrics, magnetics, multiferroics, superconductors, temperature-induced electron configuration change and so forth. In the last two decades good progress has been achieved to discover new phenomena and mechanisms of NTE. Interestingly, a large number of NTE materials have been found in various types of functional materials. Negative thermal expansion (NTE) is an intriguing physical property of solids, which is a consequence of a complex interplay among the lattice, phonons, and electrons.