X-Ray Phase Analysis of Composites after Temperature Modification of Titanium Dioxide with Melamine at Different Quantities of Initial Components

Composites based on melamine and titanium dioxide at different initial ratios 4 : 1, 6 : 1, 8 : 1, and 10 : 1 were obtained by polymerization in air at a temperature of 550°C. The morphology of the samples was investigated, and the elemental mapping of the sample composition was carried out using scanning electron microscopy. It was found that the initial melamine particles have a size of more than 20 μm, and its polymerization leads to the formation of g-C₃N₄ layers up to 5 μm in size. TiO₂ particles have an average size of 150 nm, and the resulting g-C₃N₄/TiO₂ heterostructures consist of particles with a size of 20–30 nm, which form agglomerates of about 2 μm in size. It was shown that the specific surface area decreases from 67 to 41 m²/g with increasing melamine content in the initial mixture. A single-phase composition TiN_0.24O_1.88 was formed when the initial components were mixed at a ratio of 4 : 1. When the ratio of the initial melamine and titanium dioxide was increased to 8 : 1 and 10 : 1, a two-phase system was formed, which consisted of Ti_0.72O₂ in an amount from 12 to 13% and C₃N₄ in an amount from 87 to 88%. During synthesis at a ratio of 6 : 1, two phases were also formed, but the C₃N₄ content in it was significantly less, up to 5%.