N-doped Na2Ti6O13@TiO2 (denoted as N-NTO@TiO2) composites are successfully synthesized using a simple two-step process: 1) ball-milling of TiO2 with Na2CO3 followed by heat treatment at 900oC; 2) mixing of the prepared Na2Ti6O13 with titanium isopropoxide and calcining with urea at 500oC. The prepared composites are characterized using XRD, SEM, TEM, FTIR, and BET. The N-NTO@TiO2 composites exhibit well-defined crystalline and anatase TiO2 with exposed {101} facets on the external surface. Moreover, dopant N atoms are uniformly distributed over a relatively large area in the lattice of the composites. Under visible light irradiation, ~51% of the aqueous methylene blue is photodegraded by N-NTO@TiO2 composites, which is higher than the values shown by other samples because of the coupling effects of the hybridization of NTO and TiO2, N-doping, and presence of anatase TiO2 with exposed {101} facets.

The ZnO–Na2Ti6O13 composites were synthesized by facile solution combustion method with different molar concentrations of sodium titanate which is prepared by hydrothermal route. The formation of the composites was confirmed by the X-ray diffraction (XRD) analysis. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) results revealed that the synthesized composites exhibit porous morphology, whereas the pristine Na2Ti6O13 nanoparticles have whisker like morphology. Diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) studies were utilized to compute the bandgap and the presence of defects in the composites respectively. The photocatalytic activity of ZnO–Na2Ti6O13 catalyst was investigated through the degradation of 4-nitrophenol under solar light over a period of 180 min and the composite with 0.05 M of Na2Ti6O13 showed higher degradation efficiency (96%) than the other concentrations of Na2Ti6O13 and pristine ZnO. The reduced bandgap, high charge transfer, more oxygen vacancies and the production of high superoxide anion radicals have profound effect on the higher photocatalytic efficiency of the composite with 0.05 of M Na2Ti6O13.

The microstructure and positive temperature coefficient of resistivity (PTCR) characteristics of 0.1mol%Na2Ti6O13doped 0.94BaTiO3-0.06(Bi0.5Na0.5)TiO3 (BBNT-NT001) ceramics sintered at various temperatures from 1200oC to 1350oC wereinvestigated in order to develop eco-friendly PTCR thermistors with a high Curie temperature (TC). Resulting thermistors showeda perovskite structure with a tetragonal symmetry. When sintered at 1200oC, the specimen had a uniform microstructure withsmall grains. However, abnormally grown grains started to appear at 1250oC and a homogeneous microstructure with large grainswas exhibited when the sintering temperature reached 1325oC. When the temperature exceeded 1325oC, the grain growth wasinhibited due to the numerous nucleation sites generated at the extremely high temperature. It is considered that Na2Ti6O13 isresponsible for the grain growth of the 0.94BaTiO3-0.06(Bi0.5Na0.5)TiO3 ceramics by forming a liquid phase during the sinteringat around 1300oC. The grain growth of the BBNT-NT001 ceramics was significantly correlated with a decrease of resistivity.All the specimens were observed to have PTCR characteristics except for the sample sintered at 1200oC. The BBNT-NT001ceramics had significantly decreased ñrt and increased resistivity jump with increasing sintering temperature at from 1200oC to1325oC. Especially, the BBNT-NT001 ceramics sintered at 1325oC exhibited superior PTCR characteristics of low resistivityat room temperature (122Ω·cm), high resistivity jump (1.28×104), high resistivity temperature factor (20.4%/oC), and a highTc of 157.9oC.