Synthesis of Y₂O₃: Eu Nanosized Phosphor Using Hydrothermal Technique and Rapid Thermal Annealing (RTA)

Abstract

The application of special nanomaterials is promising for the development of new methods for the diagnostics and treatment of cancer. Photodynamic therapy (PDT) is a well-known and recognized method of cancer treatment. This type of therapy is less carcinogenic and mutagenic compared to radiation and chemotherapy, since the applied photosensitizers do not bind to DNA of the cells. However, currently this technique is only applicable to skin cancer, while its extension to the treatment of abdominal tumors requires the creation of pharmacological drugs for PDT, which along with a photosensitizer include a colloidal solution of nanosized luminescent phosphor emitting visible light with the required wavelength under the influence of infrared, X-ray or γ-radiation, which easily penetrates the body tissues. Since photosensitizers are already available as commercial products, the most important goal is the development of nanosized phosphors providing the required radiation convertion. In this study, the effects of hydrothermal synthesis, duration and the conditions of rapid thermal annealing (RTA) on Y2O3:Eu phosphor particle size were studied. The hydrothermal synthesis technique was carried out in two ways: chloride (precipitation from a chloride solution using NaOH and NH4OH precipitators) and acetate (decomposition of mixed acetate either without a dispersant at 230° C for 24 hours, or using PEG-200 and PEG-2000 as dispersants at 230 °C for 12 hours). The rapid thermal annealing was performed either at 600 °C for 20 minutes, or at 800 °C for 5 minutes. The developed synthetic approaches afforded Y2O3:Eu nanosized phosphor samples with the particle size not exceeding 200 nm.

Synthesis of Y₂O₃: Eu Luminescent Phosphor with Increased Dispersion for Use in Medical Purposes

“…Rapid thermal annealing (RTA) at 800 °C within 5 min. These conditions were selected according to the results of our previous studies [16,17] indicating that annealing at lower temperatures does not allow the required phase composition, while reduced treatment time results in remaining of unburnt carbon in the samples.…”

“…However, the particle size of thus prepared materials exceeded 100 nm. The most promising method was found to be a hydrothermal procedure involving the initial components solution treatment in an autoclave [9][10][11][12][13][14][15][16][17]. However, the subsequent studies revealed that in order to obtain the target yttrium oxide phase the hydrothermal treatment must be followed by a high temperature annealing at the temperature of at least 800 °C, which in turn can lead to the agglomeration and undesirable growth of the phosphor nanoparticles.…”