Mechanochemical synthesis of multiferroic yttrium manganite

Multiferroic yttrium manganite (YMnO3) is known as a material that exhibits both ferromagnetic and ferroelectric properties making it interesting for various technological applications. In this work single-phased YMnO3 was prepared for the first time by mechanochemical synthesis in a planetary ball mill. The YMnO3 can be formed directly from the highly activated constituent oxides, Y2O3 and Mn2O3, after 60 min of milling time and subsequently grows during prolonged milling. The cumulative energy introduced into the system during milling for 60 min was 86 kJ/g. X-ray analysis indicates that the as-prepared samples crystallize majority with hexagonal (P63cm) and minorly with orthorhombic (Pnma) YMnO3 structure. The morphology, structure and chemical composition of the powder were investigated by SEM with EDS and TEM. The magnetic properties of the obtained YMnO3 powders were found to change as a function of milling time in a manner consistent with the variation in the nanocomposite microstructure

Industrial control measurements of high chromium steel rolls heat treatment

In this paper, industrial control measurements of the heat treatment of high chromium steel (HCS) rolls is presented. Measurements of the gas fired car bottom chamber furnace Bosio PP-KP 70/1150 were carried out in the company Valji d. o. o., Štore, Slovenia. Temperature in the individual heating zones of the furnace, temperatures of the roll surface, furnace external walls, and gas consumption was monitored throughout the whole process of heat treatment. The temperature profile of the rolls cross-section was calculated using computer simulation. Periodical measurements of CO and NOx emissions were also carried out with the aim of combustion evaluation and ecological integrity. The successfulness of heat treatment was examined through microstructure observation, hardness measurement, and the amount of retained austenite in the heat treated rolls

Adsorptive, catalytic and antimicrobial applications of Serbian natural clinoptilolite

Clinoptilolite is the most abundant natural zeolite in Serbia, and the Zlatokop deposit (near Vranjska Banja) is the largest deposit. The zeolitic tuff (CT) from Zlatokop contains >70 wt. % clinoptilolite with quartz and feldspar as major mineral impurities. Considering the high clinoptilolite content in the CT, this tuff has been studied in detail as an adsorbent, catalyst carrier and antimicrobial agent. We evaluated the cation-exchange capacity for several toxic metal cations, the sorption efficiency for several anions, the catalytic activity in the processes of valorization of biomass, and the antimicrobial activity of the CT

Structural and magnetic properties of nanocrystalline bismuth manganite obtained by mechanochemical synthesis

We have studied the formation of BiMnO3 (BMO) nanocrystalline perovskite powder produced by high-energy milling of the constituent oxides. The crystal structure and the amount of crystalline and amorphous phases in the powder as a function of the milling time were determined with XRPD using Rietveld refinement. BMO perovskite formed directly from highly activated nano-sized constituent oxides after 240 min of milling and subsequently grew during prolonged milling. The morphology, structure, and chemical composition of the powder were investigated by SEM and TEM. A clear ferromagnetic transition was observed at T C ~66 K for a sample milled for 240 min and increased with milling time. The magnetic hysteresis behavior is similar to that of a soft ferromagnet. The magnetic properties of the obtained BMO powders were found to change as a function of milling time in a manner consistent with variations in the nanocomposite microstructure