Zero Thermal Expansion and Ferromagnetism in Cubic Sc_1–xM_xF₃ (M = Ga, Fe) over a Wide Temperature Range

Abstract

The rare physical property of zero thermal expansion (ZTE) is intriguing because neither expansion nor contraction occurs with temperature fluctuations. Most ZTE, however, occurs below room temperature. It is a great challenge to achieve isotropic ZTE at high temperatures. Here we report the unconventional isotropic ZTE in the cubic (Sc1-xMx)F3 (M = Ga, Fe) over a wide temperature range (linear coefficient of thermal expansion (CTE), αl = 2.34 × 10(-7) K(-1), 300-900 K). Such a broad temperature range with a considerably negligible CTE has rarely been documented. The present ZTE property has been designed using the introduction of local distortions in the macroscopic cubic lattice by heterogeneous cation substitution for the Sc site. Even though the macroscopic crystallographic structure of (Sc0.85Ga0.05Fe0.1)F3 adheres to the cubic system (Pm3̅m) according to the results of X-ray diffraction, the local structure exhibits a slight rhombohedral distortion. This is confirmed by pair distribution function analysis of synchrotron radiation X-ray total scattering. This local distortion may weaken the contribution from the transverse thermal vibration of fluorine atoms to negative thermal expansion, and thus may presumably be responsible for the ZTE. In addition, the present ZTE compounds of (Sc1-xMx)F3 can be functionalized to exhibit high-Tc ferromagnetism and a narrow-gap semiconductor feature. The present study shows the possibility of obtaining ZTE materials with multifunctionality in future work.

Zero Thermal Expansion in ZrMgMo3O12: NMR Crystallography Reveals Origins of Thermoelastic Properties

“…101 The Nyquist plots (Supporting Information Figure S17) indicate only one time constant, consistent with a single species as the major contributor to the conductivity. Ionic conductivity is not surprising given the crystal structure; if the Mg 2+ ions are mobile, the structure can be viewed as a network of ZrO 6 and MoO 4 polyhedra with Mg 2+ in cavities that are connected along several directions (see Supporting Information Figure S14). was determined to be 82 kJ mol −1 (Supporting Information Figure S18), which is close to that of HfMgW 3 O 12 (80.6 kJ mol −1 ) 26 and the fast ion conductor LiAlSiO 4 (81 kJ mol −1 ).…”

“…To estimate this attractive force, and the consequent ease of distortion of the ZrO 6 , MgO 6 , and other octahedra, the ionic attractive force, 115 expressed as −k e Z + Z − e 2 / r 0 2 where k e is Coulomb's constant, Z + is the valence of the cation, Z − is the average valence of the anions, e is the elementary charge, and r 0 is the sum of the cation and anion radii, 112 can be used. Instead of using standard valences, these attractive forces were calculated using the bond valence method 116 within IVTON.…”

“…Monoclinic P2 1 /a phases show positive CTEs somewhat higher than the CTEs of traditional ceramics. 2 Thermal expansivity in A 2 M 3 O 12 materials has been shown to correlate negatively with the inherent distortion of the AO 6 polyhedron 31,32 defined as the difference between the volume of the real polyhedron and an ideal polyhedron with the same circumscribed sphere radius. 33 For A 2 M 3 O 12 materials for which atomic positions at various temperatures have been reported, the inherent distortion correlates with the derivative of distortion with temperature, and it has been suggested that nonrigidity of coordination polyhedra enhances NTE in the A 2 M 3 O 12 structure.…”

Hydration and Thermal Expansion in Anatase Nanoparticles

“…[14] All the shorter Ti O bonds intersect with a-or b-axis at a small angle, while the longer Ti O bonds are along c-axis. Pair distribution function (PDF), which is widely recognized to be sensitive to the local structure of nanocrystalline, [15] was extracted from total X-ray scattering for bulk and 4 nm samples. The typical PDF data of 4 nm TiO 2 in the distance from 1.6 to 4.5 Å are depicted in Figure 2a.…”

Negative thermal expansion in isostructural cubic ReO 3 and ScF 3 : A comparative study

“…The coefficient of thermal expansion (CTE) is about an order of magnitude larger than that of ReO 3 . Recently, L. Hu et al fabricated high quality large-scale single crystalline in hydrothermal method [15] and synthesized ScF 3 -based compounds showing zero thermal expansion (ZTE) over a wide temperature range of 300-900 K [16]. By forming Sc 1Àx Ti x F 3 solid solutions [17], C.R.…”