A New Chemical-Mechanical Polishing Method Based On Colloids Silica and MgO Was Developed For Polishing Y3Al5O12 Material

The material yttrium aluminum oxide (Y3Al5O12) is one of the materials commonly used in laser devices. For application in optical devices, it is necessary to produce ultra-precise surface quality, however, Y3Al5O12 material belongs to the group of difficult-to-machine materials with high brittleness and hardness. Therefore, it is very difficult to ensure that the main criterion when finishing this material to produce a quality surface in the nanometer form with the ability to remove the material is very difficult. To solve this problem, this work provided a new chemical - mechanical polishing mixture. The proposed polishing mixture of ZrO2, Na2SiO3–5H2O, and MgO abrasives has a weight ratio of 8%, 5% and 1% respectively, with the remainder being deionized water. The surface result after polishing is obtained with a material removed rate of 38 (nm/min) along with an ultra-smooth surface produced with Ra = 0.41 nm. With the help of X-ray photoelectron spectroscopy (XPS) method before and after polishing by CMS, the reaction mechanisms were elucidated. Analytical results show that Y3Al5O12 material produces YOOH and AlOOH in Na2SiO3 solution, then combines with –Si–OH to form (Y-Si) and (Al-Si) with significantly reduced hardness compared to other Y3Al5O12 materials, these products combine with MgO to form montmorillonites (3MgO–Al2O3–3SiO2–3Y2O3–5Al2O3). With this formation, the surface layer of Y3Al5O12 material becomes soft and is easily removed by ZrO2 abrasive particles under the influence of mechanical polishing, resulting in superfine surfaces are generated from the proposed CMS model.

Erratum: Development of a simultaneous imaging system to measure the optical and gamma ray images of Ir-192 source for high-dose-rate brachytherapy

The gamma camera has a 1-mm-thick cerium-doped yttrium aluminum perovskite (YA1O_3: YAP(Ce)) scintillator plate optically coupled to a position-sensitive photomultiplier (PSPMT), and a 0.1-mm-diameter pinhole collimator was mounted in front of the camera to improve spatial resolution and reduce sensitivity.

LUMINESCENCE OF YAG:Ce DOPED WITH SILVER NANOPARTICLES

В работе впервые было исследовано влияние наночастиц серебра на люминесценцию иттрий-алюминиевого граната, легированного церием. С помощью метода химического восстановления был синтезирован золь с размером наночастиц серебра ≈100 нм. Керамический порошок люминофора иттрий-алюминиевого граната, легированного церием, был получен методом двухстадийного осаждения в уротропин. Золь наночастиц серебра в концентрациях от 0,125 до 0,1 мл вводили в порошок-прекурсор перед прокаливанием. Было показано, что при данном способе введения наночастиц серебра интенсивность фотолюминесценции возрастала по сравнению с эталоном. Оптимальной концентрацией в рамках исследования являлась концентрация 0,25 мл. При данной концентрации увеличение интенсивности фотолюминесценции на длине волны 540 нм составило порядка 10%. Проведенные исследования показали, что наночастицы серебра могут с успехом применяться для увеличения яркости люминофора иттрий-алюминиевого граната, легированного церием, без искажения и ухудшения спектральных характеристик. This work was the first to study the effect of silver nanoparticles on the luminescence of cerium doped yttrium-aluminum garnet. A sol with the size of silver nanoparticles of ≈100 nm was synthesized using the method of chemical reduction. Phosphor ceramic powder of the yttrium-aluminum garnet doped with cerium was obtained by the two-stage precipitation method. The silver nanoparticles sol was introduced into the precursor powder before calcination in concentrations from 0,125 to 0,1 ml. It was shown that the photoluminescence intensity increased in comparison with the reference when we used this method of introducing silver nanoparticles. The optimal concentration within the study was 0,25 ml. At this concentration, the increase in the photoluminescence intensity at a wavelength of 540 nm was about 10 %. Studies have shown that silver nanoparticles can be successfully used to increase the brightness of the phosphor of the yttrium-aluminum garnet doped with cerium without distortion and deterioration of spectral characteristics.

Luminescence efficiency of cerium-doped yttrium aluminum garnet ceramics formed by radiation assisted synthesis

The variety of applications of yttrium-aluminum garnet (YAG)-based luminescent materials and the morphology necessary for these purposes required the development of many technologies for their synthesis. All synthesis technologies used are complex. The structural phase of yttrium-aluminum garnet is formed with any technology, at temperatures exceeding 1,500 °C. The starting materials for the synthesis are metal oxides of aluminum, yttrium and other oxides for activation and modification. It seems possible to use hard radiation to form a new phase. Radiation synthesis of ceramics is realized in less than 1 s, without the use of any additives and influences. The synthesis was carried out at the electron accelerator of the Institute of Nuclear Physics (Novosibirsk). In this work, we studied the spectral-kinetic and quantitative characteristics of luminescence for the first time obtained by the method of radiation synthesis of ceramic samples of yttrium-aluminum garnet doped with cerium with statistical processing of their values. The dependences of the reproducibility of the spectral characteristics of the luminescence of the samples on the preliminary preparation of the charge for synthesis have been investigated. Several cycles of luminophore brightness studies have been performed. It is shown that the obtained ceramics based on yttrium-aluminum garnet doped with cerium possesses the required spectral-kinetic properties, and the efficiency of conversion of the chip radiation into luminescence is achieved, which is comparable to that available in commercial phosphors. The maximum measured values of the position of the bands are from 553.5 to 559.6 nm. Brightness values range from 4,720 to 1,960 cd/m2. It was found that the main reason for the scatter in the characteristics of the luminescent properties of ceramics of yttrium-aluminum garnet, activated by cerium obtained by radiation assisted synthesis is the high rate of synthesis and, especially, the high rate of cooling of the samples.

Antifungal Activity of a Neodymium-Doped Yttrium Aluminum Garnet 1,064-Nanometer Laser against Sporothrix globosa by Inducing Apoptosis and Pyroptosis via the NLRP3/Caspase-1 Signaling Pathway: In Vitro and In Vivo Study

Nd:YAG 1,064-nm laser irradiation is a useful alternative for the treatment of sporotrichosis, especially in patients with liver dysfunction, pregnant women, and children, for whom the administration of antifungal drugs is not suitable. It may improve the overall treatment effect by shortening the duration of antifungal treatment and reducing tissue inflammation.