The relationships governing variation of the photoluminescence of graphitic carbon nitride synthesized by heat treatment of melamine in a closed air medium containing oxygen in the temperature range of 10–300 K were investigated. It was shown that the concentration of oxygen in the obtained material 4–5 at.% increases with increase of temperature and decreases with increase in the duration of the synthesis process. By measurements at reduced temperatures right down to 10 K it was possible to resolve bands due to radiative recombination processes in the photoluminescence spectra of the graphitic carbon nitride. It was found that increase of the synthesis temperature from 500 to 600°C and also increase of the duration at the given temperature from 30 to 240 min shift the maximum in the photoluminescence spectrum from 2.74 eV into the region of lower energies to 2.71–2.67 eV. This is due to the bigger role of the molecular system formed by the π bonds of carbon and nitrogen atoms with sp² hybridization and characterized by a smaller forbidden band width in the emission of light. Transitions due to recombination through oxygen-induced levels in the forbidden band of the semiconductor lead to the appearance of a "tail" in the photoluminescence spectra in the region of low energies (2.40–2.33 eV). Increase of the carbon nitride synthesis temperature to 600°C leads to a change in the structure of the energy bands and to increase of the energy of the radiative transitions as a result of increase in the degree of doping with oxygen atoms and thermal stratifi cation.

中文翻译：

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氧掺杂石墨氮化碳的光致发光光谱结构

研究了在密闭的含氧空气中（温度范围为10–300 K）通过三聚氰胺热处理合成的石墨氮化碳的光致发光变化的关系。结果表明，所获得的材料中4-5 at。％的氧浓度随温度升高而增加，而随着合成过程时间的延长而降低。通过在低至10 K的降低温度下进行测量，可以分辨出石墨氮化碳的光致发光光谱中由于辐射复合过程而产生的谱带。发现合成温度从500℃增加到600℃，并且在给定温度下持续时间从30分钟增加到240分钟，光致发光光谱的最大值从2移开。74 eV进入低能量区域至2.71–2.67 eV。这是由于碳和氮原子的π键与sp形成的分子系统的作用更大。²杂交，其特征在于发光中的禁带宽度较小。由于在禁带的半导体中通过氧诱导的水平的复合而引起的跃迁导致在低能量（2.40–2.33 eV）区域的光致发光光谱中出现“尾巴”。氮化碳合成温度升高到600℃导致能带结构的改变，并且由于增加了氧原子和热分层的掺杂度而导致辐射跃迁的能量增加。