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Perovskite type lanthanum manganite：Morpho-structural analysis and electrical investigations

Journal of Rare Earths 2018年第5期36卷 499-504页

作者： Paula Sfirloaga Maria Poienar iosif malaescu Antoanetta Lungu Paulina Vlazan Institute for Research and Development in Electrochemistry and Condensed Matter P. Andronescu Street No.1 300224 Timisoara Romania West University of Timisoara Vasile Parvan 4 300223 Romania

Perovskite-type oxides of LaMnO3 were synthesized by means of the sol-gel method, in the presence of citric acid as gelling agent. The precursors used were Mn（NO3）2·H2O, La2O3, and NaOH,mixed in the stoichiometric ratio to obtain perovskite materials. The obtained gel was heat-treated at 400, 600 and 800 ℃ respectively, for 6 h. X-ray diffraction and FT-IR spectroscopy were used to analyze the phase transformation as a function of temperature, and the Rietveld refinement was used in order to characterize the materials obtained structurally. The average crystallite size of the products was calculated from XRD data and the average particle size was measured from the TEM micrographs. At 600 ℃, the synthesized compound is well-crystallized, showcases a perovskite structure（Pm-3m space group）, and exhibits uniform and homogeneous hexagonally-shaped particles, with sizes in the 20-50 nm *** impedance measurements in the 20-2 × 10^6 Hz frequency range were carried out at different temperatures（26-115 ℃）, and the electrical conduction mechanism is discussed.

关键词： Rare earths Sol-gel method Physico-chemical properties Electrical investigations

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Comparative Study on the Surface Dose of Some Bolus Materials

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International Journal of Medical Physics, Clinical Engineering and Radiation Oncology 2015年第4期4卷 348-352页

作者： iosif malaescu Catalin Nicolae Marin Marius Spunei Department of Physics West University of Timisoara Timisoara Romania High Energy Radiotherapy Center Timisoara Romania

In order to investigate the possibility of using different materials as bolus in radiotherapy, five samples denoted by S2 - S6 were prepared and analyzed by comparison with one available commercial bolus denoted by S1. Sample S1 was a thermoplastic material from Qfix;S2 was a moldable silicon rubber (RTV-530 from Prochima);S3 and S4 were obtained by adding micrometric particles of Al and Cu respectively (at the same mass concentration of 5.5%);S5 was another moldable silicon rubber (GSP400 from Prochima) and S6 was a mixture of GSP400 and micrometric particles of Cu (at the mass concentration of 5.5%). The measurements of normalized transmitted dose as a function of sample thickness were performed for all samples (S1 - S6) at two values of electron beam energy (6 and 9 MeV) produced by a linear accelerator VARIAN 2100SC. The results showed that the maximum of the normalized transmitted dose of manufactured samples (S2 - S6) is registered at smaller sample thicknesses than for the analyzed commercial bolus (sample S1). The smallest sample thickness corresponding to normalized maximum point dose is obtained for sample S2 (RTV-530). Measurements performed for electron beam energy of 6 and 9 MeV have proven the possibility of using the manufactured samples as bolus in radiotherapy.

关键词： Bolus Materials Surface Dose Build-Up Region Moldable Silicon Rubber Electron Beams

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