Synthesis, crystal structure, and electrochemical properties of hollandite-type K0.008TiO2

Temperature‐dependent electrical transport behavior and structural evolution in hollandite‐type titanium‐based oxide

“…Electron paramagnetic resonance (EPR, JEOL JES-FA200) was taken to further determine the presence of Ti 3+ . The spacing of adjacent lattice planes is approximately 0.751 nm ( Figure 2B), which was assigned to the (1 1 0) plane of K 1.36 Ti 8 O 16 . The thermal expansion coefficient (TEC) of the sintered sample bars was measured using a dilatometer (Netsch DIL 402C) at temperatures ranging from 40 to 1000°C at a heating rate of 5°C/min in air.…”

“…To determine the temperature-dependent structural evolution of the obtained sample, in situ XRD was conducted at 200, 400, 450, 500, 550, 600, 650, 700, 750, 800, and 900°C in air with a heating rate of 2°C/min and a 5 min holding time at each temperature prior to collecting the data. Thus, the obtained sample can be described as K 1.36 Ti 8 O 16 . Electron paramagnetic resonance (EPR, JEOL JES-FA200) was taken to further determine the presence of Ti 3+ .…”

“…A decreased half-life time corresponds to a fast polarization process and a high mobility of potassium ions. Hence, when compared to K 1.36 Ti 8 O 16 , it is more difficult for the potassium to transfer in K 2 Ti 6 O 13 . 57 Therefore, it can be concluded from Figure 8 that potassium ion conductivity should increase when the temperature varies from 25 to 800°C.…”

“…For example, Xu et al studied the conductivity of hollandite Ba x Cs y Ga 2x + y Ti 8-2xy O 16 in a temperature range from 600 to 800°C and found that atomistic scale structural features effectively limit the mobility of large cations, like Ba 2+ and Cs + , in the hollandite structure. For example, Xu et al studied the conductivity of hollandite Ba x Cs y Ga 2x + y Ti 8-2xy O 16 in a temperature range from 600 to 800°C and found that atomistic scale structural features effectively limit the mobility of large cations, like Ba 2+ and Cs + , in the hollandite structure.…”

Sol-gel synthesis and leaching of potassium hollandites

“…The use of hollandites as electrode materials for lithium-ion batteries was also suggested. As shown in [14,15], chemical treatment of titanates of the compositions K x TiO 2 (0.125 < x < 0.25) in a mixture of H 2 SO 4 and H 2 O 2 allows virtually complete extraction of alkali metal cations from the crystal lattice. As a result, the amount of Li ions intercalated into this material considerably increases, with the corresponding increase in its energy capacity.…”