Simulation of powder diffraction patterns of mixed-layer compounds in the restacked binary nanosheet system Ti0.91O2-MnO2

Two-component colloidal nanosheets in a Ti0.91O2-MnO2 system with different compositions were restacked by flocculation with K ions. X-ray powder diffraction patterns of the products showed remarkably broad reflections. The structures suggested the presence of mixed layers of Ti0.91O2 and MnO2 connected by K ions. Powder pattern simulation was conducted using the matrix method, in an approach similar to that used for analyzing layered composite crystals with one-directional disorder. The following were considered: (1) stacking disorder in layered K-Ti-oxide, (2) stacking disorder in layered K-Mn-oxide, and (3) sequence probabilities of K-Ti-oxide and K-Mn-oxide sheets. Taking into consideration chemical composition, three types of probability tables were unified into one large probability table. For 00 zeta calculation, z coordinates of all atoms were used. For h(1)k(1)zeta calculation except 00 zeta, atom coordinates of the K-Ti-oxide sheet were used on an orthorhombic cell (a(1) = 2.96, b(1) = 3.77, c(1) = 9.32 angstrom), and for h(2)k(2)zeta calculation except 00 zeta, those of the K-Mn- oxide sheet were used on a trigonal cell (a(2) = b(2) = 2.84, c(2) = 7.10 angstrom). The agreement in pattern fitting between the experimental and calculated intensities was satisfactory in all composition ranges. From the results, the phase relationship of the misfit mixed-layer material in the binary restacked nanosheet system of Ti0.91O2-MnO2 flocculated with K ions was clarified.