"Babes-Bolyai" University

"Raluca Ripan" Institute for Research in Chemistry

NANOPHOSPHORS BASED ON YTTRIUM SILICATE FOR OPTOELECTRONICS


STAGE 2

Objective 1
Preparation and characterisation of NP-YSO mono-doped with rare earth (Ce, Eu, Tb) with enhanced morphostructural and luminescent characteristics


* Synthesis of NP-YSO ( effect of fuel)
* Synthesis of NP-YSO (ratio of reagents)
*Morpho-structural characteristaion of NP-YSO by FT-IR ICP-OES, XRD, SEM si BET
* PL characterisation of NP-YSO.


Objective 2
Synthesis of mono-doped NP-YSO with modified host lattice


* Preparation of Y2-xGdxSiO5:Ce and/or Y2-xLuxSiO5:Ce * PL chaacterisation of modified NP-YSO

Objective 3
Elucidation of some physical-chemical aspects regarding the formation of YSO phosphors


* Correlation preparative conditions-morphology-structure-luminescence
* Studies regarding luminescent processes in NP-YSO

Objective 4
Increasing the national and international visibility


*Dissemniation and mobilities


    RESULTS AND DISSEMINATION



* Based on TG-DTA curves correlated with EGA investigations it was found that threonine, arginine and glycine leads to precursors with similar thermal behaviour with a mass loss up to 10% mainly due to decomposition of yttrium carbonate based compounds.
* The precursors prepared with citric acid has a high mass loss of 36.4 % indicating that during gelling process, citrates compounds are formed that inhibit the combustion process.
* Unreacted yttrium nitrate was identified in precursors prepared with 0.5 mole threonine. Combustion with 1.25 mole or 1.5 mole threonine determine the appearance of new decomposition stages due to burning of organic residues.
* The best luminescence was obtained for combustions with 1 mole threonine and fired at 14000C for 4 h in air atmosphere.


* The conversion of precursors to well crystallised silicate was observed in FTIR spectra by the changes of band vibration at ~1000 cm-1 specific for ?as(Si-O-Si) into three well structured bands at ~997 cm-1, ~916 cm-1 and ~878 cm-1 specific for vibration in SiO4 group.
* According to XRD measurements, aspartic acid forms single phase X2-type phosphors while glutamic acid leads to a mixture of phases containing X2- Y2SiO5 and Y2O3.
* According to thermal analysis correlated with FTIR and XPS investigations, the combustion process occurs differently depending on the fuel amount; unreacted nitrate compounds have been identified in fuel lean conditions and carbonate based compounds along with organic residue in rich fuel conditions
* A positive effect of residual carbon on the luminescence have been observed for samples prepared with glutamic acid fired in air. The best luminescence was obtained for combustions with 0.75 mole aspartic acid and 1.25 mole glutamic respectively, fired at 14000C for 4 h in air atmosphere.

    Images during the combustion process

Combustion set-up Begining of the ignition
The maximum of the ignition proces The ash after combustion


Dissemination Stage 2 (2014)

Published Papers:
1. Studies on Y2SiO5: Ce phosphors prepared by gel combustion using new fuels, Muresan L.E., Oprea B.F., Cadis A.I, Perhaita I., Ponta O., Journal of Alloys and Compounds 615, 5 dec.2014, pp. 795-803, 2014, DOI 10.1016/j.Jallcom.2014.07.036. (ISI= 2.999 2014)

2. Thermal behavior of precursors for synthesis of Y2SiO5:Ce phosphor via gel combustion, L. E. Muresan, A.I. Cadis, I. Perhaita, O.Ponta, D.T. Silipas, Journal of Thermal Analysis and Calorimetry, 119, 2015, pp. 1565-1576, DOI: 10.1007/s10973-014-4315-0 Accepted in 19 Nov 2014, (ISI= 2.04 2014)


Conferences:
1. L.E. Muresan - Yttrium based silicate phosphors synthesized by combustion of gels prepared in ultrasonic conditions - 17th International Conference on Luminescence and Optical Spectroscopy of Condensed Matter (ICL2014)- Wroclaw, Polonia, 13-18 July, 2014.
2. I. Perhaita - Studies on structural and luminescent characteristics of y2sio5:ce prepared by combustion using new fuels - 17th International Conference on Luminescence and Optical Spectroscopy of Condensed Matter (ICL2014)- Wroclaw, Polonia, 13-18 July, 2014.