Y2O3 and Yb+3:Y2O3 particles production and characterization

In the last decades the development in nanotechnology was going in several directions: Development of the new nanomaterials, testing their characteristics, search for their new implementation and testing of the various synthesis methods in order to achieve the target quality, characteristics and quantity of the nanomaterial. Development of the new nanomaterials, testing their characteristics, search for their new implementation and testing of the various synthesis methods. The development in this category of the nanoparticles moves in the direction to be able to achieve the target morphology such as dense, hollow, spherical and to create nanoparticles with a multicomponent structure. One of the very interesting ways to improve the structural and the functional characteristics of the nanoparticles is the synthesis of the multicomponent nanoparticles with a controlled structure (composites, core-shell, etc.). Today, a very high number of the nanoparticles are synthesized and tested in laboratories, but there are still challenges in respect of their industrial scale production and commercial application, especially due to the process control challenges and the relatively high production costs. Sub-micron and nano-sized metal, alloy, and metal oxide particles are indispensable raw materials for advanced technology materials. The nanoparticles are one of the most important nanostructures. Depending on the large surface area, the small size of the metal oxide particles makes them attractive to many areas. Nowadays, produced particles are used in various sectors such as medicine, chemistry, optics, communication especially in electronic sector. The powders have applications such as insulators, conductors, medicines, information storage media, water treatment systems, catalysts, sensors, self-cleaning paints and antimicrobial materials. Yttrium oxide (Y2O3) has a high melting temperature, high refractivity index (~2), high thermal conductivity (13,6Wm-1K-1), high bandwidth (5,72eV) and broad transmission range (280-8000 nm) high corrosion resistance and high mechanical resistance. Thanks to these features, they are used in applications such as lasers, projection tubes, fiber optic cables, ultra-fast sensors, transmission electron microscope fluorescents and high temperature coatings. Y2O3 particles show up-conversion and down-conversion properties with the doped of elements such as erbium, ytterbium, terbium, and europium to Y2O3. Thanks to its luminescence properties, it is used in led displays, flammable labels, safety marks, temperature sensors and solar. There are different approaches to the production of Y2O3 particles in the literature. Ultrasonic spray pyrolysis (USP) and Sol-gel method described in the up-down approach provide significant advantages than other powder production techniques due to homogeneous composition and wide chemical composition range. Also, the production of Y2O3 can be carried out both lower temperature and short residence time in the furnace. The USP technique is a versatile method that allows the production of nano-sized particles with a wide range of chemical compositions, sizes and morphologies that are spherical and non-agglomerated. In this method, high purity metal salts and cleaned leach solutions of secondary raw materials are used in many areas. The USP method takes place in four stages. First, aerosol droplets composed of the initial solution are transported to the furnace with carried gas by means of ultrasonic waves and then particles were formed by thermal decomposition and reduction. In the sol-gel method, the precursor to be dissolved is hydrolyzed then ıt is obtained the network structure (gel) by various reactions. After the gel-form heat treatment, the material with the desired properties is produced. In both techniques, cleaned / purified leach solutions of high purity metal salts or secondary raw materials can be used for several materials. In this thesis study, it is aimed to produce Y2O3 and Yb3+: Y2O3 nanostructured particles with Ultrasonic Spray Pyrolysis (USP) and Sol-jel method from their high purity salts. Investigating the effects of the precursor solution concentration and temperature parameters on particle morphology, sizes and crystallite size. Also, it is aimed to Y2O3 and Yb3+: Y2O3 were characterized by using X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy and Raman analysis. According to X-ray diffraction analysis, crystallite size, lattice strain and stress, energy density were measured by Williamson-Hall analysis. The production parameters of Y2O3 and Yb + 3: Y2O3 particles were determined in order to optimize them. In the USP technique, initial solutions were prepared at different solution concentrations (0,1 - 0,4M)). Then, depending on the thermodynamic investigations with HSC Chemistry 5.11 software, 700, 800 and 900 oC defined as process temperatures. In addition to all these, the experiments performed using an ultrasonic atomizer endowed with 1.7 MHz ultrasound frequency and 0.5 L/min carrier gas. In the characterization of the produced nanoparticles, particle properties such as size, morphology, crystal structure and crystalite size were investigated depending on the production parameters. It was determined that C-bixibite cubic structure of Y2O3 and Yb+ 3: Y2O3 particles by X-ray diffraction analysis method. Also, morphology and size of particles analysis were performed by scanning electron microscopy (SEM). As the concentration of the solution increased, the average particle size increased. Characteristic raman peaks of cubic Y2O3 were obtained from the Raman analysis. Crystallite size and strain were measured by uniform deformation model (UDM). As the initial molarity of solution and the calcination temperature increased, the crystallite size and lattice strain increased. In the Uniform Stress Deformation Model (USDM), lattice strain and stress were measured assuming that lattice strain is not same all crystallographic direction. Also, energy density in lattice were analyzed by Uniform deformation energy density model (UDEDM). As the reaction temperature and solution molarite increase, the energy density of the lattice increases. Y2O3 and Yb3+: Y2O3 Particles were produced by the sol-gel method at different solution concentrations (0,1M - 0,4M). Y(NO3)3.6H2O and Yb(NO3)3.xH2O were dissolved in deionized water. Subsequently, citric acid and ammonia (NH3) or NaOH were added to solution in determined amounts. Prepared solution was stirred by using a magnetic stirrer for 2h at room temperature. After precipitation, the solution was filtered and dried. After drying, powders were calcined at 700 oC - 900 oC for 3h and finally cooled to room temperature. The particles were produced with 5,10 and 15 mole percentage of Yb. The morphologies and structures of powders produced using different precipitating agents (NaOH, NH4OH) have been investigated by several characterization methods. As the initial molarity of solution and the calcination temperature increased, the particle size increased. Different precipitating agents have also lead to changing the morphology of the powders. It has been observed that the powders produced with NaOH have spherical morphology while the powders produced with NH4OH have sponge morphology. Synthesized particles by sol-gel method were analyzed by uniform deformation model (UDM), uniform stress deformation model (USDM) and uniform deformation energy density model (UDEDM). According to UDM, USDM and UDEDM, crystallite size, strain and energy density increase with increased calcination temperature and solution concentration. Also, crystallite size, strain and energy density of Yb doped Y2O3 particles decrease due to the smaller lattice parameter of ytterbium than yttrium.