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Tadic B 《Physical review letters》1996,77(18):3843-3846
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B. Antic A. Kremenovic I. Draganic D. Vasiljevic-Radovic M. Tadic 《Applied Surface Science》2009,255(17):7601-7604
We report the results of ion irradiation influence on rare earth sesquioxides structure, which are materials of practical importance as a radiation resistant ceramics in nuclear applications. Y2O3, Gd2O3 and Er2O3 sesquioxides in the pellet form were irradiated by oxygen ions (O2+) beam with the energy of 30 keV and implantation fluence of 5 × 1020 m−2. Samples are characterized by Grazing Incidence X-ray Diffraction (GIXRD), Raman spectroscopy and atomic force microscopy (AFM). By GIXRD it was found partial transformation from cubic (C) to monoclinic (B) phase only in Gd2O3, induced by O2+ irradiation. This was confirmed by Raman spectroscopy. Although full phase transition from C to B phase in Y2O3 was not observed, the splitting and broadening of the main intensity Raman band for C phase could be explained by the stress and the disorder induced by the quenching. Analysis done by AFM showed changes in surface topology, i.e. values of average roughness (Ra) and root mean squared roughness (RMS) were significantly changed after irradiation for all samples. RMSs in Y2O3 before and after irradiation were 35 nm and 26 nm, respectively. 相似文献
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V. Kusigerski D. Markovic V. Spasojevic M. Tadic M. Zentkova M. Mihalik 《Journal of nanoparticle research》2010,12(4):1299-1306
Pressure effects on magnetic properties of two La0.7Ca0.3MnO3 nanoparticle samples with different mean particle sizes were investigated. Both the samples were prepared by the glycine-nitrate
method: sample S—as-prepared (10 nm), and sample S900—subsequently annealed at 900 °C for 2 h (50 nm). Magnetization measurements revealed remarkable differences in magnetic properties
with the applied pressure up to 0.75 GPa: (i) for S sample, both transition temperatures, para-to-ferromagnetic T
C = 120 K and spin-glass-like transition T
f = 102 K, decrease with the pressure with the respective pressure coefficients dT
C/dP = −2.9 K/GPa and dT
f/dP = −4.4 K/GPa; (ii) for S900 sample, para-to-ferromagnetic transition temperature T
C = 261 K increases with pressure with the pressure coefficient dT
C/dP = 14.8 K/GPa. At the same time, saturation magnetization M
S recorded at 10 K decreases/increases with pressure for S/S900 sample, respectively. Explanation of these unusual pressure effects on the magnetism of sample S is proposed within the scenario
of the combined contributions of two types of disorders present in the system: surface disorder introduced by the particle
shell, and structural disorder of the particle core caused by the prominent Jahn–Teller distortion. Both disorders tend to
vanish with the annealing of the system (i.e., with the nanoparticle growth), and so the behavior of the sample S900 is similar to that previously observed for the bulk counterpart. 相似文献