ABSTRACT
In the investigation reported in this paper a modified thermal decomposition method was developed to produce very small Er2O3 nanoparticles (NPs). Particles structure, shape and size were characterized by x-ray diffraction and transmission electron microscopy which showed that the synthesis by thermal decomposition under O2 atmosphere produced very small and monodisperse NPs, allowing the investigation of finite-size and surface effects. Results of magnetization measurements showed that the smallest particles present the highest values of susceptibility that decrease as particle size increases. Specific heat measurements indicate that the sample with the smallest NPs (diameter â¼5 nm) has a Néel temperature of 0.54 K. The local structure of particles was investigated by measurements of hyperfine interactions with perturbed angular correlation spectroscopy using 111Cd as probe nuclei replacing the cationic sites. Results showed that the relative population of sites 8b increases in both the core and surface layer of particles.
ABSTRACT
In this work the peak kilovoltage (kVp), practical peak voltage (PPV) and air kerma rate were measured with the noninvasive meters Radcal Accu-kV® Diagnostic Sensor™ model 40×12-W, and PTW Diavolt. The results were compared in order to ensure the quality control, compare the meters and establish the new quantity PPV, at the Calibration Laboratory of IPEN. These tests were performed using the standard diagnostic radiology quality beam RQR5, and the results are in good agreement.
