Tunable thermal expansion in framework materials through redox intercalation

Abstract

Thermal expansion properties of solids are of fundamental interest and control of thermal expansion is important for practical applications but can be difficult to achieve. Many framework-type materials show negative thermal expansion when internal cages are empty but positive thermal expansion when additional atoms or molecules fill internal voids present. Here we show that redox intercalation offers an effective method to control thermal expansion from positive to zero to negative by insertion of Li ions into the simple negative thermal expansion framework material ScF3, doped with 10% Fe to enable reduction. The small concentration of intercalated Li ions has a strong influence through steric hindrance of transverse fluoride ion vibrations, which directly controls the thermal expansion. Redox intercalation of guest ions is thus likely to be a general and effective method for controlling thermal expansion in the many known framework materials with phonon-driven negative thermal expansion.

Switching Between Giant Positive and Negative Thermal Expansions of a YFe(CN)6‐based Prussian Blue Analogue Induced by Guest Species

“…[40] Thermal expansion changes substantially after the insertion of H 2 Oi nto ZnPt(CN) 6 . [44] Herein, we demonstrate that the thermal expansion of YFe(CN) 6 -based Prussian blue analogues can be switched substantially from negative to positive by introduction of guest molecules (H 2 O) and ions (K + )tothe void spaces of its framework structure.C rystal structures and thermal expansions were determined by high-resolution synchrotron X-ray diffraction (SXRD), neutron powder diffraction (NPD), and from the temperature dependence of XRD.T he role of the guest ions and molecules upon switching of the thermal expansion is explained by the solid state structure and the characteristics of the lattice dynamics.T he present approach permits tailoring of thermal expansion and may be extended to many other NTE framework materials. [42] Similar interesting phenomena were also observed in MOFs.…”

Perovskite-related ReO3-type structures

“…98 It has also been found that NTE in ScF 3 can be essentially turned off by doping with a small amount of Fe and intercalating an equal amount of Li into the vacant A-sites. 99 The inclusion of Li ions limits the transverse vibrations of the fluoride ions, much the same way that guest molecules can dampen NTE in other porous NTE materials. [100][101][102][103][104] Redox active MF 3 materials that have been examined as intercalation materials for batteries include those where M = Ti, V, Mn, Co, and Fe.…”

Progress of Research in Negative Thermal Expansion Materials: Paradigm Shift in the Control of Thermal Expansion

“…In addition to cyanides (Chapman et al, 2006; Phillips et al, 2008), the fluoride group (Greve et al, 2010; Attfield, 2011; Chatterji et al, 2011; Chen et al, 2017), such as ScF 3 and ZnF 2 , has attracted attention recently. Particularly, Cd(CN) 2 · x CCl 4 shows large NTE of α L = −34 × 10 −6 K −1 and Δ V / V = 2.1% at T = 175–375 K (Phillips et al, 2008).…”