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The hitherto unknown title compound is prepared from a homogeneous melt of Na2O and P2O5 containing more than 25 wt.% of TiO2, which is slowly cooled down starting from 930 °C. An X‐ray analysis of this compound reveals that its space group is P21a; Z=4.

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We have investigated the changes in the morphology and microstructure of carbon nanotubes (CNTs) brought about by acetylene in the buffer gas of helium in arc discharge. Observations using scanning electron microscopy and transmission electron microscopy indicate that, with the introduction of acetylene, on the one hand, the diameters of spots in the central pattern region decrease markedly and CNTs are embellished with nanoparticles on the top surface of cathode deposit; and, on the other hand, the outer and inner diameters of CNTs decrease evidently. These results indicate that the outer diameter and innermost empty space of the nanotubes are related to growth conditions such as the density of carbon species and temperature in the growth region. This suggests that the outer and inner diameters of CNTs are adjustable by controlling the growth conditions in the growth region.