Faculty of Natural Sciences and Mathematics

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The environmental and health damage caused by the use of coal
(Springer Science and Business Media LLC, 2025-01-22)
Tasev, Goran
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Životić, Dragana
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Boev, Ivan
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Crossroads of vibrational (infrared and Raman) spectroscopy and X-ray powder diffraction in identification and characterization of some minerals – advantages and limitations. A review
(Society of Chemists and Technologists of Macedonia, 2024-05-19)
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Pejov, Ljupco
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Jovanovski, Gligor
<jats:p>Many analytical methods have been successfully employed for the study of minerals, in particular, vibrational infrared (FTIR) and Raman spectroscopies and X-ray powder diffraction (XRPD). The advantages of the vibrational spectroscopic techniques for identifying and characterizing minerals include: rapid and versatile use; qualitative and quantitative chemical signatures; distinctive chemical fingerprint of a material; indirect determination of the crystal features (polymorphism, isomorphism, coordination, degree of deformation of structural polyhedra); small sample quantity (area less than 1 μm2 for Raman); wide coverage of 4,000 – 50 cm−1 region in a single scan; in situ and direct measurements without sample preparation; nondestructive use; etc. On the other hand, XRPD is a destructive technique that, depending on the method used and the density of the material, requires from a few micrograms up to around 5 grams of sample quantity for analysis. In spite of that, it is a rapid and powerful technique used in mineral studies with relatively straightforward interpretation of the results. During the last decade, portable X-ray powder diffractometers for the nondestructive analysis of art and archeological materials have been developed along with the portable and hand-held vibrational spectroscopy instrument. Here, some advantages and limitations in the process of the complementary use of FTIR and Raman vibrational spectroscopy and XRPD for identification and characterization of minerals are outlined.</jats:p>
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Solid-State Phase Transformation of Monohydrate and Anhydrous Form II of Sitagliptin Phosphate into a Novel Anhydrous Form IV – Solvent-Driven, Temperature-Induced and Stress Testings
(Elsevier BV, 2024-02)
Chachorovska, Marina
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Lefton, Jonathan B.
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Petrushevski, Gjorgji
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Geskovski, Nikola
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Coal: exploration, reserves, and utilization
(Springer Science and Business Media LLC, 2024-02-12)
Životić, Dragana
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Jovanovski, Gligor
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Simić, Vladimir
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Boev, Ivan
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Cvetkov, Vesna
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The restored opus sectile panel from the luxurious episcopal residence in the ancient city of Stobi–mineralogical and chemical findings
(Wiley, 2022-11-06)
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Šijakova‐Ivanova, Tena
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Georgiev, Zoran
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Balabanova Aleksova, Dafinka
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Reka, Arianit A.
<jats:title>Abstract</jats:title><jats:p>Samples from the opus sectile panel excavated from the Episcopal Residence building at the archaeological site of Stobi were examined using X‐ray powder diffraction, SEM‐EDS, and Raman spectroscopy. The analyzed samples, exhibiting plentiful color and surface variations, comprise the reconstructed sectile panel as well as represent the in situ ground remains. The complementary techniques revealed dominant amorphous phase in five samples, whereas the remaining seven specimens confirmed the presence of magnesite, quartz, dolomite, ankerite, cuprite, wüstite, and hematite. The work represents the first systematic attempt to determine the mineral phases in the restored opus sectile panel, assembled by decorative minerals forming a geometric net of polychrome crosses. Furthermore, the mineral characterization has revealed an origin of mineral species not typical for Macedonian terrain (ankerite, wüstite, cuprite, transparent quartz) that lead to the conclusion that the samples were likely imported from other early‐Christian communities.</jats:p>
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Rapid and in-situ determination of epoxy equivalent weight of bisphenol-based epoxides by micro-Raman spectroscopy
(Springer Science and Business Media LLC, 2023-02)
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Ivanoska-Dacikj, Aleksandra
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Geskovski, Nikola
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Gigopulu, Olga
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Bogoeva-Gaceva, Gordana
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Chemistry and geology of coal: nature, composition, coking, gasification, liquefaction, production of chemicals, formation, peatification, coalification, coal types, and ranks
(Springer Science and Business Media LLC, 2023-01-19)
Jovanovski, Gligor
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Boev, Blazo
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Voltammetry of Solid Microparticles of Some Common Iron-and Copper-IronSulfide Minerals
(Elsevier BV, 2022-03)
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Vasilevski, Hristijan
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Mirceski, Valentin
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Thermal analysis assisted by spectra-structure studies of BCS class II active pharmaceutical ingredients: ezetimibe and lercanidipine hydrochloride. The concept of preformulation
(Springer Science and Business Media LLC, 2022-01-13)
Chachorovska, Marina
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Petrushevski, Gjorgji
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Stojanovska Pecova, Monika
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Ugarkovic, Sonja
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A Unique Mechanochemical Redox Reaction Yielding Nanostructured Double Perovskite Sr2FeMoO6 With an Extraordinarily High Degree of Anti-Site Disorder
(Frontiers Media SA, 2022-03-16)
Tóthová, Erika
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Düvel, André
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Witte, Ralf
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Brand, Richard A.
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Sarkar, Abhishek
<jats:p>Strontium ferromolybdate, Sr<jats:sub>2</jats:sub>FeMoO<jats:sub>6</jats:sub>, is an important member of the family of double perovskites with the possible technological applications in the field of spintronics and solid oxide fuel cells. Its preparation <jats:italic>via</jats:italic> a multi-step ceramic route or various wet chemistry-based routes is notoriously difficult. The present work demonstrates that Sr<jats:sub>2</jats:sub>FeMoO<jats:sub>6</jats:sub> can be mechanosynthesized at ambient temperature in air directly from its precursors (SrO, α-Fe, MoO<jats:sub>3</jats:sub>) in the form of nanostructured powders, without the need for solvents and/or calcination under controlled oxygen fugacity. The mechanically induced evolution of the Sr<jats:sub>2</jats:sub>FeMoO<jats:sub>6</jats:sub> phase and the far-from-equilibrium structural state of the reaction product are systematically monitored with XRD and a variety of spectroscopic techniques including Raman spectroscopy, <jats:sup>57</jats:sup>Fe Mössbauer spectroscopy, and X-ray photoelectron spectroscopy. The unique extensive oxidation of iron species (Fe<jats:sup>0</jats:sup> → Fe<jats:sup>3+</jats:sup>) with simultaneous reduction of Mo cations (Mo<jats:sup>6+</jats:sup> → Mo<jats:sup>5+</jats:sup>), occuring during the mechanosynthesis of Sr<jats:sub>2</jats:sub>FeMoO<jats:sub>6</jats:sub>, is attributed to the mechanically triggered formation of tiny metallic iron nanoparticles in superparamagnetic state with a large reaction surface and a high oxidation affinity, whose steady presence in the reaction mixture of the milled educts initiates/promotes the swift redox reaction. High-resolution transmission electron microscopy observations reveal that the mechanosynthesized Sr<jats:sub>2</jats:sub>FeMoO<jats:sub>6</jats:sub>, even after its moderate thermal treatment at 923 K for 30 min in air, exhibits the nanostructured nature with the average particle size of 21(4) nm. At the short-range scale, the nanostructure of the as-prepared Sr<jats:sub>2</jats:sub>FeMoO<jats:sub>6</jats:sub> is characterized by both, the strongly distorted geometry of the constituent FeO<jats:sub>6</jats:sub> octahedra and the extraordinarily high degree of anti-site disorder. The degree of anti-site disorder <jats:italic>ASD</jats:italic> = 0.5, derived independently from the present experimental XRD, Mössbauer, and SQUID magnetization data, corresponds to the completely random distribution of Fe<jats:sup>3+</jats:sup> and Mo<jats:sup>5+</jats:sup> cations over the sites of octahedral coordination provided by the double perovskite structure. Moreover, the fully anti-site disordered Sr<jats:sub>2</jats:sub>FeMoO<jats:sub>6</jats:sub> nanoparticles exhibit superparamagnetism with the blocking temperature <jats:italic>T</jats:italic><jats:sub>B</jats:sub> = 240 K and the deteriorated effective magnetic moment <jats:italic>μ</jats:italic> = 0.055 <jats:italic>μ</jats:italic><jats:sub>B</jats:sub> per formula unit.</jats:p>

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