Synthesis and characterization of lithium-ion-conductive glass-ceramics of lithium chloroboracite Li₄₊<i>_x</i>B₇O₁₂₊<i>_x</i>_/2Cl (<i>x</i> = 0&ndash;1)

Abstract

Nearly single-phase and almost fully-crystallized glass-ceramics of lithium chloroboracite Li 4+x B 7 O 12+x/2 Cl (x = 01) were prepared by crystallization of precursor glasses derived from the Li 2 OB 2 O 3 LiCl ternary system. The crystal structure of Li 4 B 7 O 12 Cl (x = 0) was refined by the Rietveld method in the space group F 43c (no. 219).

Li4B4M3O12Cl (M = Al, Ga): An Electrochemically Stable, Lithium-Ion-Conducting Cubic Boracite with Substituted Boron Sites

“…Table 3 lists the selected interatomic distances for these compounds. These results confirmed the indexing of the three peaks at 2326°to the 222 reflections of the cubic boracite phases with different lattice parameters, i.e., the end members, Li 4 20 In contrast, only one exothermic peak was found in the Al-and Ga-doped samples and the onset temperature (T x ) was ³475°C for both samples. The glass transition of the Aldoped sample was recorded at ³405°C, whereas it was not obvious in the Ga-doped sample.…”

“…This value was an order of magnitude larger than that of glass-ceramic 20 where phase transitions near room temperature do not occur. These samples were further characterized by conductivity measurements with Li electrodes.…”

“…The main crystalline phase in the undoped (y = 0) sample was cubic Li 4 B 7 O 12 Cl, and the strongest peak was located at ³25.4°, attributed to the 222 reflection. 20 In the Al-and Gadoped samples LiAl 5 O 8 and LiGa 5 O 8 were also found as impurity phases at large y values. Replacement of B in the constituent phase with Al or Ga caused a distinct shift of the 222 reflection to lower angles, and the shift was larger for the Ga-doped samples.…”

“…The quenched undoped sample was amorphous and the heat treatment generated Li 2 B 4 O 7 . 20 The quenched Aldoped sample was amorphous but contained a small amount of LiAl 5 Figure 7 shows Arrhenius plots of ac conductivity measured with Au electrodes. Although the conductivity of the doped samples was smaller than the undoped sample at y .…”

“…20 at 35 mmol. The mixture was melted in a platinum crucible for 60 min (Al-doped, y¯0.15) or 30 min in an electric furnace preheated to 1100°C (Al-doped, y = 0.43), 1150°C (Al-doped, y = 0.50 and Ga-doped, y = 0.43), 1250°C (Ga-doped, y = 0.50), 1300°C (Al-doped, y = 0.57), or 1000°C.…”