New data on protonation and hydration of perovskite-type layered oxide KCa2Nb3O10

Protonation and hydration processes of layered perovskite-like oxide KCa 2 Nb 3 O 10 during the reaction with nitric acid solutions with different concentrations were studied by means of TG, STA + MS, XRD, SEM, EDX and ICP methods. It was found that despite the absence of significant changes in crystal structure, treatment of KCa 2 Nb 3 O 10 with water leads to the partial substitution of K + with H + (about 15% exchange), while a number of new hydrated protonated phases H x K 1−x Ca 2 Nb 3 O 10 · y H 2 O with higher exchange (50–90%) may be obtained using moderate acid concentrations (0.1–3 M HNO 3 ) varying reaction time. It was shown that production of the fully protonated form requires the minimum 3 M concentration of the acid and 24 h reaction time.