Page 36 - PR 2014 2016 10 Materials and Nanotechnology

312 Materials and Nanotechnology | Progress Report

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crystalline Cr C –25(Ni20Cr) powders milled at room temperature, in one single step. The
3
for different times were determined by X-ray novel and stable Mg:β-TCP resulted in a crys-
diffraction measurements. talline and spherical nanoparticles (diameter
of approximately 20nm), with mesoporous
Calcium phosphates, including hydroxyap- structures and a high specific surface area
atite [HA, Ca (PO ) (OH) ] and beta-trical- (about 574m /g). These special characteristics
2
10 4 6 2
cium phosphate [β-TCP, Ca (PO ) ], are the make this novel crystalline mesoporous Mg:
3 4 2
main mineral component of bone tissue and β-TCP nanoparticles ideal candidates for drug
teeth. The synthetic calcium phosphates are delivery system and a promising non-viral
of special interest in medicine because of their vector for gene therapy.
biocompatibility, bioactivity and non-toxici-
ty. Europium-doped hydroxyapatite (HA), be- Texture
ta-tricalcium phosphate (β-TCP) and biphasic
phosphate nanopowders were synthesized We studied the influence of particle size from
by co-precipitation method and their crystal powders and addition of sintering additives
structures and fluorescence properties were in- Al O (0.25 to 1 wt.%), H BO (0.25 and 0.50
2 3 3 3
vestigated depending on the pH of the starting wt.%) and SiO (1 wt.%) on strontium ferrite
2
solution. In the range of pH 6–10, HA and β-TCP permanent magnets magnetic properties. The
phases coexist. The β-TCP proportion increased milling step was carried out in a planetary ball
as the pH of the solution decreased, while HA mill with milling time between 30 and 360
yields decreased. At pH below 6, monopha- minutes using 30 ml and 12 ml of deionized
sic β-TCP powder was obtained after thermal water as grinding media with and without
treatment. In particular, HA and β-TCP can be sintering additives. After this process, powders
used as luminescent materials when activated were characterized through average particle
by Eu ions in substitution of Ca ions. Herein, size using Fisher Sub Sieve Sizer equipment
3+
2+
the Eu ions doped HA and β-TCP phase com- and laser granulometry method, average
3+
position were analyzed in order to investigate crystallite size through x-ray diffraction, and
the fluorescence emission of the HA, β-TCP and morphology using scanning electron micros-
biphasic compounds. Eu-doped HA exhibited copy images. These powders were aligned to
a red-orange emission at 575 nm with several a 6 T magnetic field, isostatically pressed and
minor peaks at 610–640 nm, while Eu-doped sintered at 1220°C during 25 minutes and 60
β-TCP had an unexpected strong red emis- minutes. The sintered magnets were charac-
sion at 610–620 nm and a secondary band at terized by its density, pole figures, alignment
590–600 nm. In fact, the Eu:β-TCP integrated degree and magnetic properties through de-
emission area is almost 20-fold higher than magnetization curves.
Eu:HA for the same europium ion concentra-
tion. These results demonstrate the potential of The aluminum alloy 3104, H19 temper, is com-
Eu:β-TCP as biomarker for medical applications, monly used in the production of two-pieces
as drug release and targeting based on their beverage cans. The objective of the present
luminescent properties. study is to compare three different rolled
sheets of this alloy. All three of them are rou-
A nanosized magnesium-substituted beta-tri- tinely used in production lines dedicated to
calcium phosphate (Mg:β-TCP) was synthe- can manufacturing. The yield strength for all
sized by an aqueous precipitation method, three was found around 265 MPa, the ultimate

Instituto de Pesquisas Energéticas e Nucleares