Unveiling the presence of mixed oxidation states of Europium in Li_7+δEu_xLa_3−δZr_2−δO_12−δ garnet and its impact on the Li‐ion conductivity

Abstract

Since the discovery of Li 7 La 3 Zr 2 O 12 (LLZO), many attempts have been made to improve the characteristics of this important group of materials. In this regard, various dopant ions have been proposed to convert the tetragonal phase (t-LLZO) to cubic (c-LLZO) because the latter is of crucial importance for having a highly functional electrolyte. [1][2][3][4][5][6] The c-LLZO has many advantages over t-LLZO such as higher ionic conductivity, better mechanical strength, and higher safety. These properties arise from the structural nature of it. 7 When assembled to a battery, c-LLZO plays a pivotal role in essence that it preserves the interfacial stability between electrode and electrolyte, it provides an enhanced ionic conductivity, it induces higher cyclability with preserving specific capacity, and also it is safe and nonflammable. Up to today, two different polymorphs have been reported for LLZO, namely, c-LLZO and t-LLZO. 8 The most common symmetry proposed for c-LLZO is centric Ia3d (No.230). However, in a few studies performed on Ga and Fe doped LLZO, acentric I43d (No.220) has also been reported. 6,9 In Ia3d (No.230) symmetry, there are various positions available for the occupancy of

Inhibiting Formation and Reduction of Li2CO3 to LiCx at Grain Boundaries in Garnet Electrolytes to Prevent Li Penetration

“…As shown in Figure 4f, the 6 Li spectrum of LLZO contains two peaks at 0.28 ppm and 1.31 ppm, corresponding to the tetrahedral (24d) and octahedral coordination (96 h/48 g) of LLZO, respectively. [ 34,35 ] Moreover, an additional component is observed at 0.84 ppm in the 6 Li spectra of LAO‐LLZOF (Figures 4g,h), which corresponds to the resonance of LAO (Figure 4i). The low‐angle resonance peak at 0.98 ppm observed in the 7 Li spectrum of LAO‐LLZOF (Figure S20a, Supporting Information) is attributed to LAO rather than LAF.…”

Synthesis and photoluminescence of novel blue‐emitting phosphor of Eu2+‐activated fluoroborate BaGaBO3F2

“…[1][2][3][4] Among them, Eu 2+ is known for the strong luminescence, which is attributed to the lowest state of 4f 6 5d 1 to ground state 8 S 7/2 (5d→4f) due to the strong interaction between the 4f and 5d orbitals. [5][6][7][8] Eu 2+ ions typically exhibit broad luminescence transitions strongly depending on their electronic configuration and the crystal field environment, 9 consequentially its luminescence chromaticity changes from ultraviolet to near-infrared. Eu 2+ has the applications in solid-state lighting, biomedical imaging, X-ray fluorescence, plasma display panels, sensors, etc.…”