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Supporting Information

Bright YAG:Ce nanorod phosphors prepared via a partial wet

chemical route and biolabeling applications

Daidong Guo,a Baojin Ma,

a Lili Zhao,

a Jichuan Qiu,

a Wei Liu,

a Yuanhua Sang,

a,* Jerome

Claverie,b Hong Liu

a,*

aState Key Laboratory of Crystal Materials, Shandong University, Jinan, Shandong 250100,

China

bNanoQAM Research Center, Department of Chemistry, University of Quebec at Montreal,

2101 rue Jeanne-Mance, CP 8888, Montreal, Quebec H3C3P8, Canada.

Corresponding authors: sangyh@sdu.edu.cn (Y. Sang); hongliu@sdu.edu.cn (H. Liu)

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S1. Evaluation process of yield

We used raw materials in stoichiometric to prepare the YAG:Ce precursor and phosphors.

Normally, the yield (η) can be calculated from the theoretical mass of product YAG:Ce and

experimental mass of YAG:Ce by the following equation (Eq. 1):

� ��

��

� 100%

Eq. 1

,where mo is represented as the theoretical mass of the product can be calculated from the

mass of raw materials, and m is the mass of final product, which was weighted from the

calcined nanoparticles.

S2. Phase of YAG:Ce phosphors

Fig. S1. XRD patterns of the phosphors (a) Granular YAG: 2 at % Ce3+

; (b) Granular YAG: 6

at % Ce3+

; (c) YAG: 2 at % Ce3+

nanorod; (d) YAG: 6 at % Ce3+

. Stars indicate Al2O3, and

dots indicate CeO2.

From Fig. S1, the diffraction peaks of both YAG: 2 at % Ce3+

phosphors can be identified as

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pure Y3Al5O12 (JCPDS card: no. 72-1315). No impurity or obvious shifting of the peaks can

be detected from their XRD patterns, which implies that the YAG:Ce-precursor has fully

transformed into YAG:Ce. Because of the difficulty in high Ce3+

doping concentration in

YAG: 6 at% Ce3+

phosphor, some very week diffractions peaks can be detected, which can be

ascribed to α-Al2O3 phase and CeO2 phase. The residual Al2O3 and CeO2 are of very small

amount.

S3. Synthesis of Al2O3 precursor nanorod

Fig. S2. Morphologies and XRD patterns of Al2O3 precursor at different time from

hydrothermal process. Al2O3 precursor after (a)1 h hydrothermal reaction; (b) 3 h

hydrothermal reaction; (c) 5 h hydrothermal reaction at 150 oC. Inset is the morphology of the

Al2O3 precursor nanorod tips.

The morphologies of Al2O3 precursor at different time from hydrothermal process were

characterized by SEM as shown in Fig. S2. At the first hour of the hydrothermal reaction,

Al-compounds primary particles, which are created by reaction between Al3+

and precipitant

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groups hydrolyzed from urea, aggregate together. During the last reaction hours, these

unstable particles assemble into rod-like Al2O3-precursor, which is identified as

NH4Al(OH)2CO3 (JCPDS card no. 42-0250). At the same time, the rod-like Al2O3-precursor

grow both in length and diameter, and the crystallinity get better and better.

The above results confirm the preparation process of the Al2O3 precursor nanorod.

S3. Synthesis of granular YAG:Ce phosphors

Fig. S3. Morphologies of (a) YAG:Ce granular precursor; (b) Core-shell structure of the

precursor; (c) YAG:Ce granular phosphors; and XRD patterns of (d)I YAG:Ce precursor;

(d)II YAG:Ce phosphors.

The morphologies of granular YAG:Ce samples were characterized by SEM and TEM as

shown in Fig. S3. The YAG:Ce granular precursor mainly consists of subsphaeroidal particles

with a size of around 200 nm and a rough surface. As the YAG:Ce precursor nanorod, the

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YAG:Ce granular precursor also exhibit a clear interface between the Al2O3 core and the

Y-compound shell. After calcination, the YAG:Ce granular phosphors is of similar with the

granular precursor. But the size of YAG:Ce granular phosphors (300-400 nm) is larger than

that of the granular precursor, which is due to the aggregation and agglomeration of the

nanoparticles.

As well as the XRD pattern of YAG:Ce nanorod samples, the phase of granular YAG:Ce

samples transform from the α-Al2O3 and amorphous Y-compounds to pure Y3Al5O12.

Therefore, the partial wet chemical route for granular YAG:Ce samples is the same as

YAG:Ce nanorod samples, but with different morphologies and microstructure.

S4. Properties of YAG:Ce phosphors

Table S1. Surface area of the YAG:Ce phosphors determined by BET method

BET surface area / m2 g

−1

Granular YAG: 2 at % Ce3+

15.42

Granular YAG: 6 at % Ce3+

14.90

YAG: 2 at % Ce3+

nanorod 8.89

YAG: 6 at % Ce3+

nanorod 9.58

The surface area of YAG:Ce3+

nanorod, which is below 10 m2 g

−1, is smaller than that of

granular YAG:Ce, which is around 15 m2 g

−1, determined by BET method. Meanwhile, the

size of YAG:Ce3+

nanorod is a length of around 3-5 µm and a diameter of about 200-500 nm,

and the size of granular YAG:Ce3+

phosphors is 300-400 nm. We can see that the surface area

of the samples increases when the size decreases.

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Average fluorescence lifetimes were calculated using follow equation (Eq. 2):1

�∑ �

�

∑ �

Eq. 2

And the results are shown in Table S2:

Table S2. Average fluorescence lifetimes of YAG:Ce nanorod phosphors

τi /ns Rel % τI /ns

YAG: 2 at % Ce3+

nanorod

28.39 28.38

66.85

72.79 71.62

YAG: 6 at % Ce3+

nanorod

31.06 25.14

70.09

75.48 74.86

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Fig. S4. Proliferation of BMMSC in the solution with different YAG: 6at%Ce nanorod

phosphors concentration after 12, 24, 48 hours.

YAG: 6at%Ce nanorod phosphors in the 50-100 µg ml−1

concentration range have no

significant toxic effect on BMMSC within 48 hours except higher phosphors concentration;

and in a certain concentration range of phosphors, which is below 100 µg ml−1

, the cell

compatibility of YAG: 6at%Ce nanorod is excellent and will not lead to hemolysis.

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Fig. S5. PL stability vs time (0, 12, 24, 48 h) of YAG:Ce nanorods when the material was

dispersed in aqueous solution and in PBS buffer and mixed with biological cells. (The values

of PL intensity were normalized. The PL intensity of nanorod phosphors in aqueous solution

at the beginning (at 0 h) was set as 1, which was the initial value.)

YAG: 6at%Ce nanorod phosphors with 100 µg ml−1

was dispersed in aqueous solution, in

PBS buffer with BMMSC and in PBS buffer. After incubating the cells with 12, 24 and 48 h,

the PL intensity of nanorod phosphors shows good stability. It means that luminescent

properties of YAG:Ce nanorod phosphors would not be influenced by PBS buffer and the

cells in application.

References

1. Fišerová, E.; Kubala, M., Mean Fluorescence Lifetime and Its Error. J. Lumin. 2012,

132 (8), 2059-2064.