No abstract

Single crystals of LiIn 2 SbO 6 (LIAO) have been synthesized using a Li 2 MoO 4 flux and characterized with X-ray diffraction. The compound crystallizes in a new structure type with a rutile-related framework. Like others in the rutile-related family, LIAO is formed of chains of edge-sharing octahedra. The chain structure, with a width that alternates between single and double octahedra, has not previously been reported in a rutile-related material. The framework is formed via corner sharing by the chains in a checkerboard arrangement, with Li + residing in tetrahedral sites in the resulting, identically-alternating channels. Solid-state 6/7Li NMR spectroscopy and ab initio spectral calculations verify the presence of tetrahedrally coordinated lithium. The solution determined here contradicts previous reports of this material as a cation-ordered variant of LiSbO 3 . The relationship between this new structure and LiSbO 3 and others in the rutile-related family is discussed. Variable temperature powder X-ray diffraction and diffuse reflectance show that LIAO has high thermal stability and a large direct band gap of 3.9 eV. AC impedance spectroscopy reveals that LIAO is a relatively poor Li conductor, displaying a conductivity of 1.3 × 10 −7 S/cm at 623 K, along with an activation energy for charge transport of 1.1 eV. This material presents an opportunity to explore a new subfamily of rutile-related materials in which alternating-width chains may provide an independent avenue for tuning desired properties.

We report the discovery of a new superprotonic compound, Cs 7 (H 4 PO 4 )(H 2 PO 4 ) 8 , or CPP, which forms at elevated temperatures from the reaction of CsH 2 PO 4 and CsH 5 (PO 4 ) 2 . The structure, solved using high-temperature single-crystal X-ray diffraction and confirmed by high-temperature 31 P NMR spectroscopy, crystallizes in space group Pm3̅ n and has a lattice constant of 20.1994(9) Å at 130 °C. The unit cell resembles a 4 × 4 × 4 superstructure of superprotonic CsH 2 PO 4 , but features an extraordinary chemical moiety, rotationally disordered H 4 PO 4 + cations, which periodically occupy one of every eight cation sites. The influence of this remarkable cation on the structure, thermodynamics, and proton transport properties of the CPP phase is discussed. Notably, CPP forms at a temperature of 90 °C, much lower than the superprotonic transition temperature of 228 °C of CsH 2 PO 4 , and the compound does not appear to have an ordered, low-temperature form. Under nominally dry conditions, the material is stable against dehydration to ∼151 °C, and this results in a particularly wide region of stability of a superprotonic material in the absence of active humidification. The conductivity of Cs 7 (H 4 PO 4 )(H 2 PO 4 ) 8 is moderate, 5.8 × 10 −4 S cm −1 at 140 °C, but appears nevertheless facilitated by polyanion (H 2 PO 4 − ) group reorientation.

We report the discovery of a new superprotonic compound, Cs7(H4PO4)(H2PO4)8, or CPP, which forms at elevated temperatures from reaction of CsH2PO4 and CsH5(PO4)2. The structure, solved using high temperature single crystal x-ray diffraction and confirmed by high temperature 31P NMR spectroscopy, crystallizes in space group Pmn and has lattice constant 20.1994(9) Å at 130 °C. The unit cell resembles a 4  4  4 superstructure of superprotonic CsH2PO4, but features an extraordinary chemical moiety, rotationally disordered H4PO4+ cations, which periodically occupy one of every eight cation sites. The influence of this remarkable cation on the structure, thermodynamics, and proton transport properties of the CPP phase is discussed. Notably, CPP forms at a temperature of 90 C, much lower than the superprotonic transition temperature of 228 C of CsH2PO4, and the compound does not appear to have an ordered, low temperature form. Under nominally dry conditions the material is stable against dehydration to ~ 151 C, resulting in a particularly wide region of stability of a superprotonic material in the absence of active humidification. The conductivity of Cs7(H4PO4)(H2PO4)8 is moderate, 5.8  10-4 S cm-1 at 140 C, but appears nevertheless facilitated by polyanion (H2PO4-) group reorientation. Figure 1

Stainless steel and battery manufacturing industries can be united for mutual economic and environmental benefits by utilizing stainless steel pickling liquor waste as a precursor for high energy iron fluoride based positive electrode materials in batteries.