L. Grigorjeva, K. Smits, D.Millers, Dz.Jankoviča
Abstract. The nanoparticles of hydroxiapatite and fluorapatite doped with
Er/Yb and Tm/Yb were synthesized and characterized by FTIR, XRD, SEM and
TEM methods. The results of up-conversion luminescence studies were
presented for the samples as prepared, annealed at 500°C and at 900-1000 °C.
At annealing above 800°C the ceramic state was formed. It is shown that
fluorapatite host is more appropriate than hydroxiapatite host for rare ions
luminescence and up-conversion processes. The post preparing annealing of
nanarticles significantly enhanced the luminescence intensity. The Tm/Yb
doped fluorapatite shows intense up-conversion luminescence in 790-800 nm
spectral region and is potentially useful for biomedical applications.
IOP Conference Series: Materials Science and Engineering 77 (2015) 012036
GRABIS Janis, JANKOVICA Dzidra, STEINS Ints, SMITS Krisjanis,and SIPOLA Inta
Abstract. The characteristics and sinterability of the Al2O3-ZrO2(Y2O3) nanoparticles produced by
simple and effective microwave and molten salts methods and processed by using spark plasma
sintering were studied and compared. The crystalline powders with the specific surface area in the
range of 72–108 m2/g and crystallite size of 5–13 nm were obtained by calcination of samples
prepared by both methods at 800 oC. The content of t-ZrO2 phase depends on concentration of
Al2O3, Y2O3 and on calcination temperature but the impact of the preparation method is
insignificant. The phase transition of tetragonal ZrO2 to monoclinic for the samples without Y2O3
started at 1000 oC though it was incomplete in the case of high content of Al2O3. The bulk materials
with relative density of 86.1–98.7% were fabricated by the spark plasma sintering method at 1500–
1600 oC depending on the content of Al2O3 and Y2O3.
Advances in Science and Technology Vol. 87 (2014) pp 30-35