The photo is sourced from rscf.ru
Apart from medical applications, X radiation is used in studies of crystalline structures and chemical composition of various substances and isolated molecules. For this purpose, researchers apply radiation which is hundreds of thousands times stronger than that emitted by conventional X-ray equipment. This, as well as the invisibility of rays to the human eye, makes it especially difficult to focus them on the designated target.
X-ray material visualization was achieved earlier by RAS General Physics Institute researchers. For this purpose, they created a composite material with europium fluoride and strontium fluoride nanoparticles embedded in diamond. In order to place nanoparticles inside the diamond “shell”, the authors alternately synthesized layers of diamond and europium-containing material, and then repeated the procedure with diamond layers. The experiment was conducted in microwave plasma, that is, methane-hydrogen mixture, heated to thousands of degrees. When the resulting material was hit by X-ray beams, nanoparticles exhibited luminescence, thus allowing for X radiation detection. Notably, the luminescence spectrum of diamond-embedded nanoparticles was different from that of the source material.
In the new research project, the joint team of RAS General Physics Institute and Institute of Physics aimed to find why europium luminescence changes when embedded into diamond using the microwave method. To this end the authors imitated the microwave plasma synthesis environment by heating powders to temperatures between 600 and 900 degrees Celsius and then keeping them under the same conditions for different periods of time (from five minutes to three hours).
Nanoparticles luminescence was found to be modified by chemical interaction between nanoparticles and plasma hydrogen. The reaction produces europium and strontium hydrides, which affects the optical properties of the whole material. The authors also discovered that, by varying the temperature and duration of nanoparticles treatment, their luminescence can be “fine-tuned”, e.g., set within a narrow or broad spectrum (i. e. on a single or multiple wavelengths).
“Our results will make it possible to fine-tune the luminescence spectrum of existing composite materials, thus making them more efficient. In addition, knowing how nanoparticles are modified in microwave plasma will enable us to substantially broaden the choice of substances that can be embedded in diamond. This, in turn, can help improve the productivity and safety of scientific and medical X-ray systems,” says Artem Martyanov, Candidate of Physical and Mathematical Sciences, cited by the Russian Science Foundation.
