Investigation of the surface centers of Cr3+ ions in nanosized aluminum oxide by luminescent spectroscopy.

R&D registration number in UkrISTEI: 0117U004136

What priority area of ​​science and technology does it correspond to: fundamental scientific research on the most important problems of developing scientific, technical, socio-economic, socio-political, human potential to ensure Ukraine’s competitiveness in the world and sustainable development of society and the state.

Research: fundamental

Funding source: state budget funds

Prospect for further implementation in 2021-2022: to be continued as a targeted fundamental

Research level: no analogues in Ukraine.

Patent: no.

What additional actions require further research: synthesis of experimental samples of composites based on nanosized Al2O3 and testing of the obtained materials in prototypes of optoelectronic devices.

Brief description, advantages, further prospects for application.

Samples of doped Cr3+ δ*-Al2O3 with an average particle size of ~35 nm were obtained by gas-phase combustion. It has been shown that Cr3+ ions in δ*-Al2O3 occupy octahedral positions in the volume and surface of nanoparticles, which leads to the appearance of relatively narrow luminescence lines (R lines) in the range of 680–720 nm, which are due to 2Eg → 4A2g transitions in the impurity ion. The local structure around the Cr3+ ions inside the nanoparticles differs from the environment of the Cr3+ ions in the surface layer, which causes significant differences in the width of the R lines and their shift to the red region with an increase in temperature from 77 to 293 K. It is shown that, compared with regular surface Cr+ centers, are characterized by a lower strength of the crystal field and a higher degree of covalence of the bond between the Cr3+ ion and their environment. It is concluded that the features of Al2O3 condensation in the high-temperature reaction zone and the high cooling rate of combustion products will contribute to a high concentration of surface Cr3+ centers in the obtained samples. The results of the study are promising for obtaining new luminescent ceramics and composites for optoelectronics.

More details…