The new matrix method for deriving counting rate equations describing coincidence summing of gamma and X-rays for germanium spectrometers

The method for deriving counting rate equations in coincidence summing of gamma and X-rays that we have developed has made it much easier to obtain the results as well as the measurement process itself. This method allows us to determine the activity of a radioactive source directly without calibration of the detector and also to simultaneously to determine the efficiency of detection. We have successfully applied the method to the radionuclide with a simpler decay scheme such as 139Ce, 57Co, 133Ba. The application of this method to the 152Eu as a radionuclide with a much more complex decay scheme has also been equally successful. We are applying the method to 235U and 231Th and the preliminary results show that it is possible to apply this method to these radionuclides as well.IX International Conference on Radiation in Various Fields of Research : RAD 2021 : book of abstracts; June 14-18, 2021; Herceg Novi, Montenegr

Investigations of Yttrium Oxisulfide (Y2O2S)

Rare-earth oxysulfides have many applications such as solar energy, wind turbines, batteries for electric vehicles and mobile phones, cathode ray tubes, metal alloys, ceramic materials and so on. Their important feature is that those materials are wide-gap semiconductors. Yttrium oxide is one of the most important compounds of yttrium and is widely used in many ceramic materials[1] RE element-doped oxysulfides has been utilized for effcient luminescent use e.g., Eu-activated Y2O2 S emits bright red-light under cathode-ray excitation and has been widely used for televisions[2]. In this study we perform crystal structure prediction and investigate energy landscape of Yttrium Oxisulfide (Y2 O2 S). In order to predict new crystal structures, global optimizations on the energy landscape of Y2O2 S has been performed. Afterwards, a local optimization has been performed using ab initio calculations. In particular various quantum mechanical methods have been applied: Density Functional Theory (DFT) with Local-Density Approximations (LDA) and Generalised Gradient Approximation (GGA), and hybrid B3 LYP (Becke, three-parameter, Lee-Yang-Parr) functional.IX Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 20-21, 2021; Belgrad

Application of the new matrix method to coincidence summing effects in gamma spectroscopy

A new method has been developed for deriving counting rate equations describing coincidence summing of gamma and X-rays for germanium spectrometers. The coincidence summing effects occur whenever two or more cascading photons are emitted from the same nucleus and detected within the resolving time of spectrometer. The application of analytical approaches to coincidence summing effects makes it possible to predict all summation peaks that occur in the spectrum. Our work includes solving the problems of coincidence summarizing by introducing the new method with simpler algebra. The new analytical approach that we have developed also allows us to determine the activity of radioactive sources directly without calibration of the detector, which is very important in metrology of radionuclides. Accordingly, based on the value of the peak area in the spectrum and knowledge of probability transitions between excited states of a nucleus, it is possible to determine the efficiency of detection. This method is successfully applied to the decay of radionuclides 139Ce, 57Co, 133Ba and 152Eu. Results, obtained using the proposed method, are achieved in a much clearer and simpler wayVIII International Conference on Radiation in Various Fields of Research : RAD 2020 : book of abstracts; Virtual Conferenc

Theoretical and experimental study of polycrystalline phases obtained by the nanometric ZnTiO3 powder sintering

In this study we have combined two research methods: structure prediction of ZnTiO3 using computational SPuDS software, and the characterization of binary oxides obtained from ZnO TiO2 system. Pure nanosized ZnTiO3 (99.5%), was compacted in cylindrical shape specimens by uniaxial double sided compaction and then sintered in air atmosphere in a dilatometric device [1,2]. One compact was sintered up to 915 °C to retain metastabile ZnTiO3 and held 5 minutes on that temperature, and another one at the same conditions, but now up to 970 °C to induce phase transition and to obtain stabile Zn2TiO4 and TiO2 according to phase diagram [2]. Reheated samples obtained at different characteristic temperatures in air were analyzed by X-ray diffraction (XRD). The infrared attenuated total reflectivity measurements confirmed XRD results. In order to estimate theoretical stability of these perovskite structure, Goldschmidt tolerance factor Gt and global instability index GII were calculated. Furthermore, the Ti valence states were determined by bond valence calculations (BVC). Also, we have investigated the formation of new phases (Zn2Ti3O8, TiO2 and Zn2TiO4) originating from ZnTiO3 with temperature change, as well as the relation between the crystal structures which have been predicted and the structure of the phases we have experimentally observed

New method for determination of temperature in spallation reactions

We propose a new method for determination of temperature in spallation events. It is shown that temperature can be determined by applying the friction model of energy dissipation in participant-spectator model of a spallation process. First order estimate of temperature dependence of the participant zone on reaction Q-value is obtained from the Fermi gas model considerations. The heat diffusion process is also discussed

Enhancement of weak ferromagnetism, exotic structure prediction and diverse electronic properties in bismuth ferrite and holmium-substituted multiferroic bismuth ferrite

Program and book of abstracts / 2nd International Conference on Innovative Materials in Extreme Conditions i. e. (IMEC2024), 20-22 March 2024 Belgrade, Serbia

Preparation of Ca0.9Er0.1MnO3 nanopowders by combustion method

Program and book of abstracts / 2nd International Conference on Innovative Materials in Extreme Conditions i. e. (IMEC2024), 20-22 March 2024 Belgrade, Serbia

Theoretical Investigations of Electronic Properties of Predicted Y2O2S

Program and book of abstracts / 2nd International Conference on Innovative Materials in Extreme Conditions i. e. (IMEC2024), 20-22 March 2024 Belgrade, Serbia

Synthesis and characterization of BiFeO3 fine powders

Bismuth ferrite (BiFeO3) is one of the most studied multiferroic system with a large number of published articles. This is mainly because BiFeO3 material possesses both ferromagnetic and ferroelectric properties observed at room temperature, which opens great possibility for industrial and technological applications. Well-crystallized single-crystal BiFeO3 nanopowder has been successfully synthesized with the hydrothermal method. Structural analysis showed that non-annealed powder can be perfectly fitted to rhombohedral space group R3c and contains a very small amount of secondary phase, whereas the final product (annealed at 800 °C) represents single-phase perovskite powder with high crystallinity. HRTEM analysis confirmed existence of twin stacking faults, which are responsible for enhanced magnetic properties. EPR measurements suggested existence of electrons trapped by vacancies or defects. It has been proposed that existence of Fe3+ −OV defect complex could be generated at elevated temperatures followed by formation of trivalent Fe ions, which intensely provide local 3d moments.V Serbian Ceramic Society Conference : program and the book of abstracts; June 11-13, 2019; Belgrad

First principles investigations of structural, electronic, elastic and mechanical properties of barium sulfide from standard to extreme high pressures

Barium sulfide (BaS) is an important precursor to other barium compounds with applications from ceramics and flame retardants to luminous paints and additives, and recent research shows potential technological applications in advanced electrical and optical devices. Pressure induced phase transitions of barium sulfide has been investigated. Novel BaS modifications have been calculated on ab intio level using Hartree-Fock, DFT and the hybrid B3LYP functional. We predict metastable BaS polymorphs which have not-yet been observed in the experiment or previous calculations. We investigate the electronic, mechanical, elastic, vibrational and thermodynamical properties of BaS and our calculations were in very good agreement with previous experimental and theoretical observations. Furthermore, we investigate the electronic properties of experimentally known struc-tures, as well as novel predicted modifications of BaS at extreme pressure conditions. In this way, we address new possibilities of synthesizing BaS and possible band gap tuning which can have great applications in opto-electrical technologies