Supporting Information
Efficient fluorescence emission and photon conversion of LaOF: Eu3+
nanocrystals
Dangli Gao,1 Hairong Zheng,1,a) Xiangyu Zhang,2 Zhenxing Fu,1 Zhenglong Zhang,1
Yu Tian,1 and Min Cui1
1College
2College
of Physics and information technology, Shaanxi Normal University, Xi’an 710062, Shaanxi, China
of Physics and Electronic Information Engineering, Qinghai Nationalities University, Xining 810007,
Qinghai, China
Reagents: La(NO3)3.6H2O, Eu2O3, Tm2O3, Yb2O3, Tb2O3, Gd2O3 and Pr6O11 (purity ≥99.99%)
were purchased from Shanghai Chemical Reagent Company. NaF and HNO3 were supplied by Xian
Chemical Reagent
Company.
All
chemicals
were
of
analytical
grade
and
used
without further purification. Deionized water was used as a reactive solvent.
Synthesis of the nanocrystals(NCs): To synthesize lanthanide-doped LaF3 NCs, 1.2 mL of 0.5 mol/L
RE(NO3)3 (RE = La, Eu, Tm. Yb, Gd, Tb or Pr) was dropped into 30 mL deionized water under stirring,
followed by addition of 2.4 mL of sodium fluoride solution (NaF, 1.0 mol/L) and thorough stirring.
Once a colloidal solution was obtained, it was transferred to a 40 mL Teflon-lined autoclave and heated
at 200°C for 16 h. Ln3+ doped LaF3 nanoparticles were collected by centrifuging and washing the final
product with water and ethanol. The collected LaF3 NCs were dried at 60 C for 12 h. Ln3+ doped LaOF
NCs were produced by thermally treating Ln3+:LaF3 NCs at 800 C for several hours.
Characterization: XRD analysis was performed on a D/Max2550VB+/PC X-ray diffraction meter
with Cu Ka (40 kV, 40mA) irradiation (  =0.15406 nm). TEM measurements were made with a JEM
2100 transmission electron microscope operating at an acceleration voltage of 200 kV. A YAG:
Nd3+(Quanta Ray Lab-170) and a He-Cd(MMF-12B24DH-F00) continuum laser were employed as
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excitation sources for the spectroscopic investigation. Resonant excitation was performed by a pulsed
dye laser (Sirah) equipped with a second harmonic generation crystal. The laser dye was LDS 698. A
Xenon lamp(LHX 150) was employed for the measurements of broadband excitation and transmission.
A SP 2750i monochromator equipped with a CCD system (ACTON, PIXIS 100) was used for signal
collection and detection. The sample was mounted in an ARS DE-202NI optical cryostat that has a
temperature range from 6.8 K to 450 K. A Tektronix TDS 5000B digital oscilloscope was employed to
conduct fluorescence lifetime measurements.
FIG. S1. XRD patterns and corresponding TEM images of the hexagonal phase LaF3 (a) and tetragonal
phase LaOF (b) NCs doped with 1.0 mol % Eu3+ ions.
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FIG. S2. Temporal decay of the fluorescence emission from LaOF: Eu3+(1.0 mol %) NCs at 549 nm (a)
and 609 nm (b). The solid lines are numerical fits to the experimental observations.
Fig. S2 (a) shows that the decay curve of fluorescence at 549 nm has a very sharp rising feature,
indicating the emission is from 5D1 level through direct excitation. The immediate rise in the intensity
decay of fluorescence at 609 nm indicates that the emission is from 5D0 level, which is populated
through relaxation from the 5D1 level.
FIG. S3. XRD spectra of LaOF NCs doped with (a) Eu3+ (1.0 mol %), (b) Eu3+ (1.0 mol %)/Tm3+ (0.5
mol %), and (c) Eu3+ (1.0 mol %)/Yb3+(1.0 mol %). Inset: some enlarged spectra.
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All of the detected XRD peaks are in good agreement with tetragonal crystal phase of LaOF(LaOF:
JCPDS card No. 05-0470). It can be seen that the XRD peaks shift to larger angles with Tm3+ or Yb3+
as codpants to Eu3+:LaOF NCs.
FIG. S4. Decay profiles of the fluorescence at 624 nm from Eu3+ and at 453 nm from Tm3+ in LaOF
NCs. (a) 1.0 mol % Eu3+:LaOF; (b) 1.0 mol % Tm3+/1.0 mol % Eu3+:LaOF; (c) 1.0 mol % Pr3+/1.0
mol % Eu3+: LaOF; (d) 1.0 mol % Tm3+:LaOF, and (e) 1.0 mol % Tm3+/1.0 mol % Eu3+:LaOF.
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