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FIZIKA A 13 (2004) 2 , 53-64
 
STUDY OF UP-CONVERSION LUMINESCENCE IN BaTiO3: Ho3+
NANOCRYSTALS
Y. BADRa, A. SALAHa and I. K. BATTISHAb
aNational Institute of Laser Enhancement Sciences
(NILES), Cairo University, Egypt
bNational Research Center (NRC), Department of Solid State Physics, Cairo,
Egypt
Received 5 May 2003; revised manuscript received 28 January 2004
Accepted 26 April 2004 Online
2 February 2005
Visible up-conversion emissions at 435, 545, 580, 675 and 690 nm and 437, 547, 575 and
675 nm have been obtained from BaTiO3 doped with 4 % Ho3+ ions
in two different forms of the prepared samples, powder and thin film, under 808 nm laser
diode excitation emissions. Combined with the energy level structure of Ho3+
ions and the kinetics of the visible emissions, the up-conversion mechanism has been
analyzed and explained. The blue, green and red emissions of both samples have been
attributed to the ground state-directed transition from 5F1, 5S2
and 5F5 states, respectively, which are populated through excited
state absorption on 808 nm excitation. Nano-structure pure barium titanate and doped with
different concentrations of Ho3+ ions in the form of powder and thin films have
been prepared by so-gel technique, using barium acetate (Ba(CH3CHOO)2)
and titanium isopropoxide (Ti((CH3)2CHO)4) as precursors.
The thin films were prepared by spin-coating sol-gel method. The as-grown thin film and
powders were found to be amorphous, which crystallized to the tetragonal phase after
synthesization at 750 °C in air for 30
minutes. The crystallite size of thin film and powder samples both doped with 4 % Ho3+
ions, were found to be equal to 11 and 16 nm, respectively.
PACS numbers: 81.20.Fw, 78.55.Hx, 78.30.-j
UDC 535.37, 535.375, 539.26
Keywords: BaTiO3, Ho3+ doping, sol-gel, thin film, powder,
up-conversion, FT-Raman, TEM, SEM
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