Formation, photoluminescence and ferromagnetic characterization of Ce doped AlN hierarchical nanostructures

Accepted Manuscript Formation, photoluminescence and ferromagnetic characterization of Ce doped AlN hierarchical nanostructures Qiushi Wang, Wanze Wu, Jian Zhang, Ge Zhu, Ridong Cong PII:

S0925-8388(18)33782-4

DOI:

10.1016/j.jallcom.2018.10.110

Reference:

JALCOM 47928

To appear in:

Journal of Alloys and Compounds

Received Date: 17 July 2018 Revised Date:

3 October 2018

Accepted Date: 10 October 2018

Please cite this article as: Q. Wang, W. Wu, J. Zhang, G. Zhu, R. Cong, Formation, photoluminescence and ferromagnetic characterization of Ce doped AlN hierarchical nanostructures, Journal of Alloys and Compounds (2018), doi: https://doi.org/10.1016/j.jallcom.2018.10.110. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT

Formation, photoluminescence and ferromagnetic characterization of Ce doped AlN hierarchical nanostructures Qiushi Wanga,∗ Wanze Wua, Jian zhangc, Ge Zhua, Ridong Cong b,* a

RI PT

College of New Energy, Bohai University, Jinzhou 121013, People's Republic of China Hebei Key Laboratory of Optic-Electronic Information and Materials, College of Physics Science and Technology, Hebei University, Baoding 071002, People's Republic of China c College of Physics, Beihua University, Jilin 132000, People's Republic of China b

SC

Abstract

Cerium doped aluminum nitride (AlN:Ce) hierarchical nanostructures were fabricated

M AN U

by a direct reaction of Al and CeO2 mixed ingot with ammonia using modified arc discharge method. X-ray diffractometry, Raman spectrum and x-ray photoelectron spectroscopy analysis obviously indicated that Ce3+ ions incorporated inside the AlN nanostructures. The prepared AlN:Ce exhibited a strong red-orange emission at 600 nm and showed room temperature ferromagnetism. These results suggest that

TE D

AlN:Ce hierarchical nanostructures have potential as a light-emission nanodevice and diluted magnetic semiconductor.

EP

Keyword: AlN; Ce doped; ferromagnetic; photoluminescence

1. Introduction

As an important III-nitride semiconductor, aluminum nitride (AlN) possesses many

AC C

excellent properties such as high thermal conductivity, superior mechanical strength, excellent thermal and chemical stability and low dielectric constant [1]. These excellent properties make it promising for electronic, optoelectronic and field emission devices [2-4]. For enhancing the application of AlN, doping is regarded as an effective method. First of all, doping can improve electronic properties of AlN by increasing the number of carriers [5, 6]. Secondly, as the largest band gap (6.2 eV) semiconductors, AlN can be modified wide band from UV to infrared wavelengths ∗Corresponding author. E-mail addresses:[email protected](Q. Wang), [email protected](R. Cong)

ACCEPTED MANUSCRIPT through dopants [7-9]. Finally, the diluted magnetic semiconductors (DMS) can be produced by introducing appropriate dopants in AlN [10-13]. Therefore, it is important to synthesize AlN doped with transition metal or rare earth (RE) elements for their novel electronic, optical and magnetic properties, which are used as

RI PT

optoelectronic and spintronics devices. As an important RE metal dopant in semiconductors, Cerium (Ce) is the most commonly used activators, because its luminescence properties are attributed to fully permissible electric dipole 5d-4f transitions, which lead to a large absorption

SC

cross section in UV-visible range [14, 15]. Because Ce3+ ionic radius is significantly larger than the Al3+ ions, it has been difficult to stably dope Ce3+ ion into the AlN host

M AN U

lattice. Up to now, there are few reports about Ce doped AlN. For example, Si4+ and Ce3+ ions co-doped AlN polycrystalline powders which emit blue color have been produced through gas pressure sintering method [16]. Ce3+ doped single-crystal AlN bulk with intense pink-colored emission at 600 nm has been synthesized by an optimized high pressure and high temperature flux method [17]. The high quality

TE D

AlN:Ce ceramic with viable white emission has been produced by processing procedure based on current activated pressure assisted densification [18]. The AlN:Ce thin films with strong blue emission were synthesized using radio-frequency reactive sputtering [19]. All above reports are focused on AlN:Ce bulk materials or

EP

thin film and their optical properties. It is well known that hierarchical nanostructures with structural complexity and greater functionality have attracted

AC C

increasing interest for their application on nanodevices [20, 21]. To our knowledge, there is no report on AlN:Ce nanostructures. In addition, previous theoretical calculations predicted that Ce doping can induce the room temperature ferromagnetism in AlN using density functional theory [22, 23]. However, the experimental study of magnetic property of AlN:Ce has not yet to be reported. In this work, we present that AlN:Ce hierarchical nanostructures were synthesized using an improved direct current (DC) arc discharge method. Strong red-orange emission and ferromagnetism have been obtained from AlN:Ce hierarchical nanostructure. These results suggest AlN:Ce hierarchical nanostructures

ACCEPTED MANUSCRIPT have potential applications in light-emission and spintronic nanodevices. 2. Experimental The synthesis was carried out in a modified DC arc discharge apparatus described previously [24, 25]. A tungsten rod was used as the cathode. Al (purity: 99.999%) and

RI PT

CeO2 (purity: 99.99%) powders mixed with a molar ratio of 100:1 were pressed into ingot. The ingot was tightly inserted into the water-cooled graphite crucible serve as anode. When the plasma arc is kindled, the input current was set at 90 A and the voltage was a little higher than 40 V. The synthesis process was maintained for 30

SC

min in pure NH3 (purity: 99.999%) with a pressure of 30 kPa. Finally, the yellow products were collected at the water-cooled collecting wall, after passivation in Ar

M AN U

for 5 h.

The crystal structures of AlN:Ce were characterized by X-ray diffractometry (XRD, Rigaku D/Max γA, Cu-Kα target, λ=0.154178 nm). The morphology and chemical composition of these samples were characterized by field-emission scanning electron microscopy (SEM, FEI MAGELLAN-400) equipped with an energy dispersive

TE D

spectrometer (EDS). The bonding states of the elements were studied via X-ray photoelectron spectroscopy (XPS) on an EASY ESCA spectrometer (VG ESCA LAB MKII). Micro-Raman and photoluminescence (PL) spectra were obtained by JY-T800 Raman spectrometer excited with an Ar+ line at 514 nm and He-Cd line at 325 nm,

EP

respectively. The magnetic measurement was investigated using a vibrating sample magnetometer (VSM). All measurements were performed at room temperature.

AC C

3. Results and discussion The crystal structure of as-prepared sample was characterized by XRD, shown in Fig. 1a. All diffraction peaks can be assigned to pure wurtzite AlN structure with space group: P63mc (186) (DPF Card No. 08-0262). As show in Fig 1b, the (100), (002), and (101) peaks in AlN:Ce display an obvious shift to the lower angles compared with undoped AlN, indicating the expansion of lattice constants after doping is due to the substitution of larger Ce3+ (1.34 Å) for Al3+ (0.54 Å). This phenomenon agrees well with previous reports about Sc or Y doped AlN [11-13]. The Raman spectra of undoped and Ce doped AlN were used to further study the

ACCEPTED MANUSCRIPT crystal structure and the results are shown in Fig. 2. The spectrum of undoped AlN reveals the four Raman active modes around 247.3, 611.2, 655.9 and 668.2 cm-1, corresponding to vibrational modes of E2(low), A1(TO), E2(high) and E1(TO), respectively. The weak and broad peak at 904.2 cm−1 is indexed to the overlap of the

RI PT

modes A1(LO) and E1(LO) [26]. These locations display a wurtzite AlN structure. Compared with undoped sample, Raman peaks of A1(TO) and E2(high) in AlN:Ce broaden and shift to lower frequencies with increasing tensile strain, may be ascribe to the disorder of the crystals as a result of the substitutional doping of Ce ions in the

SC

AlN lattice. This result agrees well with the observed tensile strain in XRD. Similar phenomena were also observed in Sc, Mg and Co doped AlN [12, 27, 28].

M AN U

XPS measurement is an effective tool to characterize electrical structure and composition. The survey scan XPS spectrum of AlN:Ce sample is shown in Fig. 3a. Besides the C 1s and O 1s peaks, the spectrum exhibits strong peaks for Al 2p, Al 2s and N 1s as expected. The Al 2p peak at 73.8 eV (Fig. 3b) is assigned to aluminum bound to nitrogen in wurtzite AlN, while the N 1s peak at 397.0 eV (Fig. 3c)

TE D

represents binding energy of nitrogen in AlN [29]. Complex XPS spectrum of Ce 3d is presented in Fig. 3d. Two obvious peaks at 885.6 eV and 904.5 eV, and two shoulder peak at 880.7 eV and 898.0 eV corresponding to two pairs of spin-orbit doublets is identified as trivalent Ce. The weak peak with a binding energy of 916.1 eV is

EP

attributed to the 3d3/24f0 component of Ce, indicating mixed valence of Ce. The XPS spectrum of Ce 3d matches with the previously reported value of Ce-N bonding in

AC C

CeN [30, 31]. On the basis of XPS analysis, it can be confirmed the successfully incorporation of Ce3+ ions into AlN lattice. The morphology of the AlN:Ce sample was examined by SEM. The

low-magnification SEM image in Fig. 4a shows the bulk densely packs with nanowires or nanobelts which constitute complex hierarchical nanostructures. Fig .4b and c are low- and high-magnification images of detailed fringe bulk, they display many branches irregular radiate from the main trunk of the crystals forming hierarchical nanostructures. The morphologies of branches are nanowires or nanobelts. The chemical composition of AlN:Ce hierarchical nanostructures was determined from

ACCEPTED MANUSCRIPT EDS spectrum (Fig. 4d). Quantitative analysis reveals that the dopants of Ce ions in AlN correspond to a concentration close to 1.09 %. The hierarchical nanostructures are easily formed under non-equilibrium and supersaturated growth condition. In previous studies, the AlN hierarchical

RI PT

nanostructures were also observed under high temperature and high N2 or NH3 pressure accompanied with non-equilibrium growth process [32, 33]. Arc discharge plasma with high energy supplies a sharp temperature gradient and heat convection in reaction chamber, which can effectively synthesize AlN:Ce hierarchical

SC

nanostructures. In addition, Ce ions incorporate into AlN lattice, leading to high concentration of Al and N vacancies. These imperfections can act as second new

M AN U

nucleation sites for growing branches. Therefore, AlN:Ce hierarchical nanostructures can be easily prepared through arc discharge method.

Fig. 5 (a) shows the room temperature PL spectrum of the AlN:Ce hierarchical nanostructures excited by 325 nm from He–Cd laser, demonstrating a broad emission ranging from 550 to 750 nm with a peak at about 600 nm (2.06 eV) in red-orange

TE D

light range. This red-orange emission can be clearly seen by the naked eye (Fig. 5 (c and d)). In previous studies, PL spectrum of AlN:Ce have a blue emission [16, 19] or red emission band [17]. It is well known that nephelauxetic effect and crystal-field splitting of the 5d states of luminescent ions influence final PL emission [34]. The

EP

blue emission is always observed in Ce doped AlN with oxygen impurities. However, our synthesis of AlN:Ce with ammonia can effectively reduce oxygen impurities.

AC C

Therefore, the emission peak shape and location are exactly the same as previously reported in AlN:Ce single crystals [17]. Ishikawa et al. reported aluminum vacancies (VAl) connecting with nearby CeAl (Ce substitutions on the Al site) can form complex and stable defect structure (CeAl-VAl) in AlN:Ce single crystals, and experimentally confirmed the luminescent center in AlN:Ce is neutral CeAl [17, 35]. As a result, the nonsymmetrical PL emission of AlN:Ce can be assigned to the 4f-5d electron transition of Ce3+ dopants in AlN. The reasonable studies on light-emitting properties of AlN:Ce are hot topics in literature but ferromagnetism is seldom explored. Recently, Dar et al. pointed out the

ACCEPTED MANUSCRIPT AlN:Ce has ferromagnetism for DMS applications through first principles calculations [22]. Later, Majid et al. predicted the favorable formation of CeAl–VN complex in AlN:Ce introduces ferromagnetism [23]. However, the experiment on the magnetic properties of AlN:Ce has not been reported. Fig. 6 shows typical magnetization

RI PT

curves of AlN:Ce hierarchical nanostructures versus field were measured with a VSM at room temperature. It is evident that AlN:Ce hierarchical nanostructures exhibit a well defined hysteresis loop and show ferromagnetic behavior at room temperature. The saturation magnetization and remanent magnetization of the AlN:Ce hierarchical

SC

nanostructures is 0.038 emu/g and 0.01 emu/g, respectively, while its coercive field is 284 Oe. The results from the XRD, Raman and XPS measurements in AlN:Ce samples

M AN U

demonstrated that the Ce3+ ion was incorporated into the host lattice without changing its structure. The ferromagnetism of AlN:Ce hierarchical nanostructures should be intrinsic and come from Ce doped AlN lattice. According to bound magnetic polaron model, the magnetic behavior in AlN:Ce is sensitive to defects, such as anion or cation vacancies and interstitials. The stable CeAl-VAl complex has

TE D

been confirmed by experiment and theoretical calculation [17, 35]. Wu et al. found that Al vacancies in AlN can introduce spin polarization to N atoms around the defect site resulting in ferromagnetism [36]. Lei et al. reported introduction of rare-earth element Y into AlN leads to high Al vacancies responsible for the ferromagnetism [11].

EP

Given the above, the observation of ferromagnetism in AlN:Ce nanostructures may be attribute to Al vacancies which are introduced by incorporating of Ce3+ ions into

AC C

AlN lattice.

4. Conclusions

Through a simple arc discharge method, AlN:Ce hierarchical nanostructures have

been successfully fabricated. The synthesis approach provides an opportunity for doping large size rare-earth elements into AlN materials. AlN:Ce hierarchical nanostructures exhibit strong red-orange emission and room temperature ferromagnetism, which have applications in optoelectronic and spintronic nanodevices.

ACCEPTED MANUSCRIPT Acknowledgements This study was supported financially by the National Natural Science Foundation of

RI PT

China (grant no. 11504028, 61504036 and 11747117).

References

[1] Y. Taniyasu, M. Kasu, T. Makimoto, An aluminium nitride light-emitting diode with a wavelength of 210 nanometres, Nature, 441 (2006) 325-328.

SC

[2] J. Zheng, Y. Yang, B. Yu, X.B. Song, X.G. Li, 0001 oriented aluminum nitride one-dimensional nanostructures: Synthesis, structure evolution, and electrical

M AN U

properties, ACS Nano, 2 (2008) 134-142.

[3] J.H. He, R.S. Yang, Y.L. Chueh, L.J. Chou, L.J. Chen, Z.L. Wang, Aligned AlN nanorods

with

multi-tipped

surfaces-Growth,

field-emission,

and

cathodoluminescence properties, Adv. Mater., 18 (2006) 650-654. [4] Y. Taniyasu, M. Kasu, T. Makimoto, Field emission properties of heavily Si-doped

TE D

AlN in triode-type display structure, Appl. Phys. Lett., 84 (2004) 2115-2117. [5] Y.B. Tang, X.H. Bo, J. Xu, Y.L. Cao, Z.H. Chen, H.S. Song, C.P. Liu, T.F. Hung, W.J. Zhang, H.M. Cheng, I. Bello, S.T. Lee, C.S. Lee, Tunable p-Type Conductivity and

3591-3598.

EP

Transport Properties of AlN Nanowires via Mg Doping, ACS Nano, 5 (2011)

[6] Q. Wu, N. Liu, Y.L. Zhang, W.J. Qian, X.Z. Wang, Z. Hu, Tuning the field emission

AC C

properties of AlN nanocones by doping, J. Mater. Chem. C, 3 (2015) 1113-1117. [7] K. Inoue, N. Hirosaki, R.J. Xie, T. Takeda, Highly Efficient and Thermally Stable Blue-Emitting AlN:Eu2+ Phosphor for Ultraviolet White Light-Emitting Diodes, J. Phys. Chem. C, 113 (2009) 9392-9397. [8] K.B. Nam, M.L. Nakarmi, J. Li, J.Y. Lin, H.X. Jiang, Mg acceptor level in AlN probed by deep ultraviolet photoluminescence, Appl. Phys. Lett., 83 (2003) 878-880. [9] W.M. Jadwisienczak, H.J. Lozykowski, I. Berishev, A. Bensaoula, I.G. Brown, Visible emission from AlN doped with Eu and Tb ions, J. Appl. Phys., 89 (2001) 4384-4390. [10] X.H. Ji, S.P. Lau, S.F. Yu, H.Y. Yang, T.S. Herng, J.S. Chen, Ferromagnetic Cu-doped

ACCEPTED MANUSCRIPT AlN nanorods, Nanotechnology, 18 (2007) 105601. [11] W.W. Lei, D. Liu, X. Chen, P.W. Zhu, Q.L. Cui, G.T. Zou, Ferromagnetic Properties of Y-Doped AlN Nanorods, J. Phys. Chem. C, 114 (2010) 15574-15577. [12] W.W. Lei, D. Liu, P.W. Zhu, X.H. Chen, Q. Zhao, G.H. Wen, Q.L. Cui, G.T. Zou,

RI PT

Ferromagnetic Sc-doped AlN sixfold-symmetrical hierarchical nanostructures, Appl. Phys. Lett., 95 (2009) 162501.

[13] W.W. Lei, D. Liu, Y.M. Ma, X. Chen, F.B. Tian, P.W. Zhu, X.H. Chen, Q.L. Cui, G.T. Zou, Scandium-Doped AlN 1D Hexagonal Nanoprisms: A Class of Room-Temperature

SC

Ferromagnetic Materials, Angew. Chem.-Int. Edit., 49 (2010) 173-176.

[14] Y.Q. Li, N. Hirosaki, R.J. Xie, T. Takeda, M. Mitomo, Yellow-Orange-Emitting

M AN U

CaAlSiN3:Ce3+ Phosphor: Structure, Photoluminescence, and Application in White LEDs, Chem. Mat., 20 (2008) 6704-6714.

[15] P. Dorenbos, Ce3+ 5d-centroid shift and vacuum referred 4f-electron binding energies of all lanthanide impurities in 150 different compounds, J. Lumines., 135 (2013) 93-104.

TE D

[16] T.C. Liu, H. Kominami, H.F. Greer, W.Z. Zhou, Y. Nakanishi, R.S. Liu, Blue Emission by Interstitial Site Occupation of Ce3+ in AlN, Chem. Mat., 24 (2012) 3486-3492. [17] R. Ishikawa, A.R. Lupini, F. Oba, S.D. Findlay, N. Shibata, T. Taniguchi, K. Watanabe, H. Hayashi, T. Sakai, I. Tanaka, Y. Ikuhara, S.J. Pennycook, Atomic Structure

(2014) 3778.

EP

of Luminescent Centers in High-Efficiency Ce-doped w-AlN Single Crystal, Sci Rep, 4

AC C

[18] A.T. Wieg, E.H. Penilla, C.L. Hardin, Y. Kodera, J.E. Garay, Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting, APL Mater., 4 (2016) 126105. [19] A.E. Giba, P. Pigeat, S. Bruyere, H. Rinnert, F. Soldera, F. Mucklich, R. Gago, D. Horwat, Strong Room Temperature Blue Emission from Rapid Thermal Annealed Cerium-Doped Aluminum (Oxy)Nitride Thin Films, ACS Photonics, 4 (2017) 1945-1953. [20] K. Biswas, J.Q. He, I.D. Blum, C.I. Wu, T.P. Hogan, D.N. Seidman, V.P. Dravid, M.G. Kanatzidis, High-performance bulk thermoelectrics with all-scale hierarchical

ACCEPTED MANUSCRIPT architectures, Nature, 489 (2012) 414-418. [21] G.B. Sun, B.X. Dong, M.H. Cao, B.Q. Wei, C.W. Hu, Hierarchical Dendrite-Like Magnetic Materials of Fe3O4, gamma-Fe2O3, and Fe with High Performance of Microwave Absorption, Chem. Mat., 23 (2011) 1587-1593.

RI PT

[22] A. Dar, A. Majid, DFT study of cerium doped aluminum nitride, Eur. Phys. J.-Appl. Phys, 71 (2015) 10101.

[23] A. Majid, F. Asghar, U.A. Rana, S.U.D. Khan, M. Yoshiya, F. Hussain, I. Ahmad, Role of nitrogen vacancies in cerium doped aluminum nitride, J. Magn. Magn. Mater., 412

SC

(2016) 49-54.

[24] Q.S. Wang, Y.H. Xie, J. Zhang, R.D. Cong, Synthesis, photoluminescence and

M AN U

ferromagnetic properties of pencil-like Y doped AlN microrods, Ceram. Int., 43 (2017) 3319-3323.

[25] X.Y. Liu, J.S. Mi, B. Zhang, J. Zhang, Q.S. Wang, R.D. Cong, Dopant concentration dependent magnetism of Sc-doped AlN nanowires, J. Alloy. Compd., 731 (2018) 1037-1043.

TE D

[26] W.W. Lei, D. Liu, J. Zhang, P.W. Zhu, Q.L. Cui, G.T. Zou, Direct Synthesis, Growth Mechanism, and Optical Properties of 3D AlN Nanostructures with Urchin Shapes, Cryst. Growth Des., 9 (2009) 1489-1493.

[27] Y.S. Xu, B.B. Yao, D. Liu, W.W. Lei, P.W. Zhu, Q.L. Cui, G.T. Zou, Room temperature

EP

ferromagnetism in new diluted magnetic semiconductor AlN:Mg nanowires, Crystengcomm, 15 (2013) 3271-3274.

AC C

[28] Y.S. Xu, B.B. Yao, Q.L. Cui, Co-doped AlN nanowires with high aspect ratio and high crystal quality, RSC Adv., 6 (2016) 113204-113208. [29] L. Rosenberger, R. Baird, E. McCullen, G. Auner, G. Shreve, XPS analysis of aluminum nitride films deposited by plasma source molecular beam epitaxy, Surf. Interface Anal., 40 (2008) 1254-1261. [30] W.D. Xiao, Q.L. Guo, E.G. Wang, Synthesis and oxidation of CeN film: an in situ investigation by electron spectroscopies, J. Phys. Chem. B, 109 (2005) 4953-4958. [31] W.D. Xiao, Q.L. Guo, E.G. Wang, Thickness dependent valence fluctuation of CeN film, Surf. Sci., 572 (2004) 296-300.

ACCEPTED MANUSCRIPT [32] W.W. Lei, D. Liu, P.W. Zhu, X.H. Chen, J. Hao, Q.S. Wang, Q.L. Cui, G.T. Zou, One-step synthesis of AlN branched nanostructures by an improved DC arc discharge plasma method, Crystengcomm, 12 (2010) 511-516. [33] W.W. Lei, D. Liu, P.W. Zhu, Q.S. Wang, G. Liang, J. Hao, X.H. Chen, Q.L. Cui, G.T.

RI PT

Zou, One-step synthesis of the pine-shaped nanostructure of aluminum nitride and its photoluminescence properties, J. Phys. Chem. C, 112 (2008) 13353-13358.

[34] L. Gan, Z.Y. Mao, Y.Q. Zhang, F.F. Xu, Y.C. Zhu, X.J. Liu, Effect of composition variation on phases and photoluminescence properties of beta-SiAlON:Ce3+ phosphor,

SC

Ceram. Int., 39 (2013) 4633-4637.

[35] R. Ishikawa, N. Shibata, F. Oba, T. Taniguchi, S.D. Findlay, I. Tanaka, Y. Ikuhara,

Rev. Lett., 110 (2013) 065504.

M AN U

Functional Complex Point-Defect Structure in a Huge-Size-Mismatch System, Phys.

[36] R.Q. Wu, G.W. Peng, L. Liu, Y.P. Feng, Z.G. Huang, Q.Y. Wu, Ferromagnetism in

AC C

EP

TE D

Mg-doped AlN from ab initio study, Appl. Phys. Lett., 89 (2006) 142501.

ACCEPTED MANUSCRIPT Fig. 1. (a) XRD patterns of AlN and AlN:Ce hierarchical nanostructures. (b) The enlarged (100), (002), and (101) peaks. Fig. 2. typical Raman spectra of AlN and AlN:Ce hierarchical nanostructures. Fig. 3. XPS spectra of AlN:Ce hierarchical nanostructures: (a) survey scan, (b) Al 2p, (c)

RI PT

N 1s, and (d) Ce 3d core levels, respectively. Fig. 4. (a) and (b) Low- and (c) high-magnification SEM image and (d) EDS spectrum of the AlN:Ce hierarchical nanostructures.

Fig. 5. (a) The PL spectrum of AlN:Ce hierarchical nanostructures, (b) photographs of

and 380 nm UV lamp box, respectively.

SC

AlN:Ce sample, (c) and (d) photographs of AlN:Ce sample irradiated under 254 nm

AC C

EP

TE D

measured at room temperature

M AN U

Fig. 6. Magnetization hysteresis loops of AlN:Ce hierarchical nanostructures

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT Ce was incorporated in AlN forming hierarchical nanostructures.




The Ce doped AlN exhibited an intensive PL emission band at 600 nm.




The AlN:Ce nanostructures exhibited room ferromagnetism.

AC C

EP

TE D

M AN U

SC

RI PT