Extreme phonon anharmonicity underpins superionic diffusion and ultralow thermal conductivity in argyrodite AgSnSe.

Ultralow thermal conductivity and fast ionic diffusion endow superionic materials with excellent performance both as thermoelectric converters and as solid-state electrolytes. Yet the correlation and interdependence between these two features remain unclear owing to a limited understanding of their complex atomic dynamics. Here we investigate ionic diffusion and lattice dynamics in argyrodite AgSnSe using synchrotron X-ray and neutron scattering techniques along with machine-learned molecular dynamics.

Concomitant Thermochromic and Phase-Change Effect in a Switchable Spin Crossover Material for Efficient Passive Control of Day and Night Temperature Fluctuations.

The increasing environmental protection demand has prompted the development of passive thermal regulation systems that reduce temperature fluctuations in buildings. Here, it is demonstrated that the heat generated by the sun can trigger a spin crossover (SCO) in a molecule-base material, resulting in a concomitant color variation (from pink to white) and a phase transition. This leads to a cooling effect with respect to other thermochromic materials.

Structural, Magnetic, and Electronic Properties of CaBaCoM O (M = Fe, Zn).

The effect of substituting iron and zinc for cobalt in CaBaCoO was investigated using neutron diffraction and X-ray absorption spectroscopy techniques. The orthorhombic distortion present in the parent compound CaBaCoO decreases with increasing the content of either Fe or Zn. The samples CaBaCoZnO and CaBaCoFe O with x ≥ 1.

The magnetic structure of β-cobalt hydroxide and the effect of spin-orientation.

Synchrotron X-ray and neutron diffraction experiments at various temperatures, down to 3 K, along with ab initio calculations, are carried out to elucidate the magnetic order of layered β-cobalt-hydroxide. This combination of techniques allows for the unambiguous assignment of the magnetic structure of this material. Our results confirm that below the Néel temperature high-spin cobalt centers are ferromagnetically coupled within a layer, and antiferromagnetically coupled across layers (magnetic propagation vector k = (0,0,½)), in agreement with the indirect interpretation based on magnetic susceptibility measurements.

Influence of Li(+) and H(+) Distribution on the Crystal Structure of Li(7-x)H(x)La3Zr2O12 (0 ≤ x ≤ 5) Garnets.

With appropriate doping or processing, Li7La3Zr2O12 (LLZO) is an excellent candidate to be used in Li batteries either as a solid electrolyte or as a separator between the Li anode and a liquid electrolyte. For both uses, the reactivity with water either from the air or in aqueous media is a matter of interest. We address here the structural changes undergone by LLZO as a result of H(+)/Li(+) exchange and relate them with the amount of H content and atomic distribution.

Homoleptic Iron(II) Complexes with the Ionogenic Ligand 6,6'-Bis(1H-tetrazol-5-yl)-2,2'-bipyridine: Spin Crossover Behavior in a Singular 2D Spin Crossover Coordination Polymer.

Deprotonation of the ionogenic tetradentate ligand 6,6'-bis(1H-tetrazol-5-yl)-2,2'-bipyridine [H2bipy(ttr)2] in the presence of Fe(II) in solution has afforded an anionic mononuclear complex and a neutral two-dimensional coordination polymer formulated as, respectively, NEt3H{Fe[bipy(ttr)2][Hbipy(ttr)2]}·3MeOH (1) and {Fe[bipy(ttr)2]}n (2). The anions [Hbipy(ttr)2](-) and [bipy(ttr)2](2-) embrace the Fe(II) centers defining discrete molecular units 1 with the Fe(II) ion lying in a distorted bisdisphenoid dodecahedron, a rare example of octacoordination in the coordination environment of this cation. The magnetic behavior of 1 shows that the Fe(II) is high-spin, and its Mössbauer spectrum is characterized by a relatively large average quadrupole splitting, ΔEQ = 3.

Neutron diffraction study of the BiFeO₃ spin cycloid at low temperature.

The reported observation of two anomalies in the intensity of the magnon Raman peaks of BiFeO₃ at 140 and 200 K (Singh et al 2008 J. Phys.: Condens.

Thermal, pressure and light induced spin transition in the two-dimensional coordination polymer [Fe(pmd)2[Cu(CN)2]2].

A complete structural, calorimetric, and magnetic characterisation of the 2D coordination spin crossover polymer [Fe(pmd)(2)[Cu(CN)(2)](2)] is reported. The crystal structure has been investigated below room temperature at 180 K and 90 K, and at 30 K after irradiating the sample at low temperature with green light (lambda = 532 nm). The volume cell contraction through the thermal spin transition is only 18 A(3) which is lower than the usually observed value of around 25-30 A(3) while the average Fe-N bond distances decrease by the typical value of about 0.