RESUMO
Zinc/cobalt aluminates with spinel-type structure were prepared by a polymeric route, leading to a pure phase with controlled grain size. The prepared pigments were characterized by powder X-ray diffraction Rietveld analyses in order to determine structural features, scanning electron microscopy for morphological investigation, helium pycnometry and (27)Al MAS NMR in order to highlight the occurrence of defects inside the structure, and UV-visible-near-IR spectroscopy to identify electronic transitions responsible for the compounds' color. The green-blue coloration of these pigments is known to be dependent on the sample thermal history. Here, for the first time, the Zn(1-x)Co(x)Al(2)O(4) color is newly interpreted. The pigment is green once synthesized at low temperature (i.e., with diminution of the pigment grain size); this variation was attributed to the appearance of a new absorption band located at about 500 nm, linked to a complex network feature involving Co ions in octahedral sites as well as oxygen and cationic vacancies. Hence, this work shows the possibility of easily getting a nonstoichiometric network with an abnormal cationic distribution from "chimie douce" processes with moderate synthesis temperature, and so various colorations for the same composition.
RESUMO
Zn1-xCuxAl2O4 (0
RESUMO
This article exposes the work realised by a child psychiatry organization of prevention cares in pre- or post-partum, based on an intricately articulated network of professionals. The author mentions the signals likely to induce the establishment of a well-coordinated network whose effects will make care easier and allow for the creation of new links between professionals/parents; parents/child. We founded our observations on the practical case of a mother granted complete follow-up and attention from the beginning of pregnancy. The quality of exchanges demonstrates how these links between professionals can create a positive step into evolution of parenthood.
