Structural and Magnetic Characteristics of Zn

Vol. 65, No. 11, November 2015, pp. 1049∼1052

New Physics: Sae Mulli, DOI: 10.3938/NPSM.65.1049

Structural and Magnetic Characteristics of Zn

Co

Al

O:H Powders

Dooyong Lee · YunHee Cho · Ji Woong Kim · Hyegyeong Kim · Dongjin Kim · Sungkyun Park

Department of Physics, Pusan National University, Busan 46241, Korea (Received 15 September 2015 : revised 6 October 2015 : accepted 12 October 2015)

Al-doped Zn0.95−xCo0.05AlxO (x = 0, 0.03, 0.05) powders were synthesized by using a solid-state reaction method and were annealed in hydrogen environments for 3 hours. The Al-content depen- dent structural and magnetic properties were examined for the as-prepared and the post-annealed powders. A Rietveld analysis revealed that most of the powders had a wurtzite structure with small amounts (∼ 3%) of the Co3O4 phase. With increased Al content, the powders experienced com- pression (increased 2θ) due to the discrepancy in the ionic radius of Al with degraded crystallinity.

On the other hand, the magnetic characteristics, such as the saturation magnetization, remnant magnetization and coercivity, improved with increased Al content.

PACS numbers: 61.05.cp, 61.72.sd, 75.50.Pp

Keywords: Zn0.95−xCo0.05AlxO, Dilute magnetic semiconductor, Rietveld analysis, Room-temperature fer- romagnetism

Al Y 8 ÈS ë s; c  Â \ ¥ Zn

Co

Al

O:H Ä Z Ø­  o8 ý  Œ ºX ì Ä,  M X Ä ì — ¤V R Ë Ž ì ŏ Œ

T

¨ £ ÷ 7 B · ‚ Ð* × <r ) ·  ™ »U ] ï B ·  ™ »A j# Ü  ·  ™ » ò 6 B > . · ƒ ‘ š) ç # Ò

Â

Òíߖ@/†<Ɠ§ Ótüo†<Æõ, ÂÒíߖ 46241

(2015¸ 9Z4 15{9 ~ÃÎ6§, 2015¸£  10Z4 6{9 ú&ñ‘:r~ÃÎ6£§, 2015¸ 104 12{Z 9 >FSX‰&ñ)

Ã

º™è ÅÒ{9)a Zn0.95−xCo0.05AlxO ìr˜_ú´ Al (x = 0, 0.03, 0.05) '‘|¾Ó\ Ér ½¨›¸&h, l

&

h

 :£¤$í`¦ ƒ½¨ l 0A #Œ “¦©œìøÍ6£xZOܼ–Ð r«Ñ\¦ ½+Ë$í ôÇ Êê ú™è ìr0Al\"f Êê\P%ƒo %i.

Rietveld ìr$3 õ, ½+Ë$í)a rì´ú˜“ÉrÊê\P%ƒo õ&ñ\ ©œ›'a\Os wurtzite ½¨›¸\¦°úH כ `¦ SX‰“ %i



. Êê\P%ƒo ôÇ ìr˜\ú´ @/K"f Al '‘|¾Ós 7£x½+Éú2Ÿ¤ unit cell_ ÂÒx x9 &ñwn_ ß¼l yŒ™™è†<Ê

`

¦½¨›¸ ìr$3`¦ :ŸxK"f ·ú˜ ú e”%3. tëߖ, l&h :£¤$í“Ér Al '‘|¾Ós 7x£½+Éú2Ÿ¤ Ÿío l°úכ, ï

ߖÀÓ o°úכ, ˜Ð§4, yŒ•+þAq 7£x H 1pxy©œ$í :£¤$ís †¾Ó©œ÷&Hכ `¦SX‰“ ½+É Ãº e”%3.

PACS numbers: 61.05.cp, 61.72.sd, 75.50.Pp

Keywords: Zn0.95−xCo0.05AlxO, ӄ“üÉr$íìø͕¸^‰, Rietveld ìr$3, ©œ“:ry©œ$í^‰

∗E-mail: [email protected]

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

1050 New Physics: Sae Mulli, Vol. 65, No. 11, November 2015

I. " e  ] Ø

Ó ü

„“Ér $íìø͕¸^‰ (diluted magnetic semiconductor, DMS)H éߖ{9 Óüt|9s ìø͕¸^‰ „½¨›¸\¦ °úH 1lxr\ y

©œ$ís µ1ω&³÷&H Óüt|9–Ð, lFg†<Æ (magneto-optics),



„l (magnetoelectrics) 1px 4Ÿ¤½+Ël0px$í Û¼—2;àԖÐ_”Û¼

™

è–Ð_ 6£x6 x 0px$íܼ–Ð “K ´§“úÉr›'ad”`¦~ÃÎM®o [1–3]. ÕªQ
 {9ìøÍ&h“ DMSH“ú±Ér Ç©o “:r•¸ M:ëH\ z

´]j–Ð 6£x6 x l\ H]j€•s e” [4]. ZnO\¦lìøÍܼ

–

Ð ôÇ DMSH Z}“Ér Ç©o “:r¸ x• 9 l s“:r[þt_ Z}“Ér 6

xK•¸ 1px_ $í|9–Ð “K Û¼—2;àԖÐ_”Û¼ ™è–Ð_ 6£x6 x

0px$ís Z} Ö¸µ1Ïy ƒ½¨ ”'Ÿ ÷&%3 [5–7]. :£¤y CoH ZnO\ @/ôÇ Z}“Ér 6 x•K¸–Ð “K €ªœôÇ qÖ¦–Ð Zn1−xCoxO½+ËFK`¦ ëߖ[tþ ú e”l M:ëH\, Co '‘)a ZnO r¼#\ @/ôÇ ƒ½¨ ´ú§s ”'Ÿ÷&%3 [8]. þjHú

™

è\¦ Zn0.9Co0.1Or¼#\ ÅÒ{9 € y©œ$í ‰&³©œs †¾Ó©œ

÷

&H כ s s:r x9 z´+«>&hܼ–Л'a¹1Ï÷&%3 [9,10]. ú™è ì

r0Al\"f \P%ƒo ½+É âĺ, yœ©$í :£¤$ís †¾Ó©œ÷&HX<

s

H ZnO\¦lìøÍܼ–Ð ôÇ DMS Óüt|9 ?/\"f l |9"f•¸

 ~1> &ñ§>=÷&l M:ëHs [11–13]. ¢¸ôÇ Zn_1−xCo_xO\



Ér "鶙è\¦ '‘ #Œ y©œ$ :í £¤$í`¦ Ó¾†©œrvl•¸ ôÇ



. Zn o\ Als u¨8Š|¨cÄâº, ·û “Ér•¸- YU6\š (shal- low donor level)`¦ëߖ[þt#Q Ho#Q 0lx•¸\¦ 7£xr& r«Ñ _

 $í:£¤$í`¦†¾Ó©œrvH כ ܼ–Ð ·ú˜94R M®o [14,15].

Õ

ªQ
 f”t Als '‘a) Zn1−xCoxO ©œ“:r\"f y

©œ$í :£¤$`í¦
?/H "¶é“s &ñSX‰y ½©"î÷&t ·ú§“¦ e”

. ‘:rƒ½¨\"fHº™Ãè ÅÒ{9)aZn0.95−xCo0.05AlxO ì

r´ú˜_ Al '‘|¾Ó (x = 0, 0.03, 0.05)\ @/ôÇ ´òõ\¦ƒ

½

¨ %i. X-‚ r]X`¦s6x  #Œ Al '‘|¾Ó\ Ér½¨›¸

&

h“ :£¤$í`¦›¸ HôǼ#, l s§4 /BG‚`¦ :ŸxK"f  l

&h :£¤$í`¦ƒ½¨ %i.

II. ÷ m Ç] M ö U ê s0 n É

Ã

º™è ÅÒ{9)aZn0.95−xCo0.05AlxO (x = 0, 0.03, 0.05) ì

r´ú˜`¦ëߖ[þtl 0A #Œ {9ìøÍ&h“ “¦©œìøÍ6£xZOܼ–Ð ëߖ[þt#Q

”

 r¼#`¦Ãº™è ìrAl0\"f Êê\P%ƒo %i. ZnO, CoO ì

r´ú˜`¦rŒ• Óüt|9–Ð #Œ Al2O<sub>3</sub>ìr´ú˜_ '|‘ ¾Ó`¦²ú˜o 

€

"f Zn^0.95−xCo0.05AlxO (x = 0, 0.03, 0.05) ìr´ú˜`¦½+Ë

$í

%i. ìr˜[ú´þts çH{9 > [O{9 ú e”•¸2Ÿ¤, 1rçߖ 1lx î

ߖ x9aA ôÇ Êê, „l–Ð\¦s6 x #Œ 750^◦C\"f 1 , 800

◦C\"f 2  ™è`¦ %i. Êê\P%ƒoHú™èìr0Al\"f 3rçߖ 1lxîߖ 800^◦C\"f ”'Ÿ %i. éߖҐoFg(λ = 1.5406

˚A) X-‚ r]X ©œu (X’Pert³ Powder, PANalytical)\¦s

Fig. 1. (Color online) X-ray powder diffraction pattern and Rietveld refinement result of the Zn_0.95Co_0.05O pow- der sintered at 800 ^◦C. The inset shows the wurtzite structure of the Zn_0.95Co_0.05O powder.

6  

x #Œ Al '‘|¾Ó\ Ér Zn0.95−xCo_0.05Al_xO:H ìr´ú˜_

½

¨›¸&h :£¤$í`¦ 8£¤&ñ %i. X-‚ r]X8£¤&ñ“Ér 2θ = 20<sup>◦</sup>- 80<sup>◦</sup> #30A ?/\"f 0.0263<sup>◦</sup>–ßçܼ–Ð 2θ − θ scan`¦ z´r÷&

%

3. 8£¤&ñ)a X-‚ r]XJ‡Ü¼–ÐÂÒ' ìr˜ rú´«Ñ_ &ñ

½

¨›¸ x9 &ñ$í`¦ ìr$ 3l 0AK Rietveld ìr$3ZO`¦ s 6

x %i [17]. ¢¸ôÇ r «Ñ\¦ ½¨$í H ™D¥½+ËÓüt_ qÖ¦“Ér Rietveld ìr$3_ þj&ho–ÐÂÒ' ·ú˜ ú e” [18]. r«Ñ_



l&h :£¤$í“Ér ©œ“:r"\f œí„•¸€ªœçߖ[O©œu (MPMS- 7, Quantum Design)–Ð 8£¤&ñ #Œ ƒ½¨ %i. sM: r¼#

\

 “ôÇ þj@/ l©œ“Ér Hmax = ± 10,000 Oe%i.

III. + s ÇÊ Ý õ m Í ‚ º8 ý

í

HúôÇ Zn_0.95Co_0.05O ìr´ú˜s ]j@/–Ð ½+Ë$ís ÷&%3Ht

\

¦SX‰“ l 0A #Œ, ú™è ìr0Al\"f \P%ƒo l „_ r

¼#\ @/K"f X-‚ r]X 8¤&£ñ`¦ %i. Fig. 1“Ér 800^◦C

\

"f ™è)aZn_0.95Co_0.05O ìr˜_ú´ X-‚ r]X 8£¤&ñ õ ü

< Rietveld ìr$3 õ (R-profile = 1.60)s. ½+Ë$í)ar

«

эH > 97%_ Zn0.95Co_0.05O (wurtzite½¨›¸, P63mc)ü<

< 3%_ Co3O₄(ICSD#69365)–Ð sÀÒ#Qf”`¦·ú˜ ú e”%3



. ¢¸ôÇ r¼#_  ©œÃºH a = b = 3.250 ˚A, c = 5.204 ˚A Ü

¼–Ð ·ú˜9” Zn_0.95Co_0.05O ìr´ú˜ (ICSD #165018)_ 



©œÃº(a = b = 3.253 ˚A, c = 5.208 ˚A)ü< Ä»†<Ê`¦ ·ú˜ Ã

º e”. Fig. 1\ ¶úš{9)a ªaÕË>“Ér wurtzite ½¨›¸\¦ ” Zn0.95Co0.05Os.

Fig. 2H ú™è ìr0Al\"f Êê\P%ƒo ôÇ Zn0.95−xCo0.05AlxO ìr´ú˜_ X-‚ r]X 8£¤&ñ õs

Structural and Magnetic Characteristics of Zn0.95−xCo0.05AlxO:H Powders – Dooyong Lee et al. 1051

Table 1. Rietveld refinements result of Al-doped Zn0.95−xCo0.05−xO:H powder.

Sample a (˚A) c (˚A) Volume (˚A³) Crystallite size (nm) Quantification of Co3O4 (%) R-profile

Zn0.95Co0.05O:H 3.250 5.204 47.600 195.19 1.2 2.34

Zn0.92Co0.05Al0.03O:H 3.249 5.200 47.537 183.67 2.9 2.88 Zn0.90Co0.05Al0.05O:H 3.247 5.199 47.470 122.01 2.1 2.94

Table 2. Magnetic characteristics of Al-doped Zn0.95−xCo0.05−xO:H powder.

Sample Ms (emu/g) Mr (emu/g) Hc(Oe) Mr/Ms (%)

Zn0.95Co0.05O:H 4.75 0.12 53.47 2.53

Zn0.92Co0.05Al0.03O:H 5.18 0.30 137.23 5.79

Zn0.90Co0.05Al0.05O:H 6.22 0.60 264.30 9.65

Fig. 2. (Color online) X-ray powder diffraction patterns of Zn0.95−xCo0.05AlxO:H powders with different Al con- centrations.



. X-‚ r]X 8£¤&ñ õ\¦ :ŸxK ú™è ìr0Al\"f \P%ƒ o

 „_ r¼#õ °ú “Ér½¨›¸\¦t“¦ e”6£§`¦ Rietveld ìr

$ 3

`¦ :ŸxK"f ·ú˜ ú e”%3“¦, #Œ„y ∼3% &ñ•¸_ Co³O4

½

¨›¸ s ©œÜ¼–Ð ”>rF %i. ú™è ìr0Al\"f_ Êê

\P

%ƒo #ŒÂÒü< Al '‘|¾Ó_ 7x£\•¸ s ©œ_ ©œ@/

&

h“ q ot ·ú§H Üכ¼–ÐÂÒ' Co³O4_ s ©œ“Ér 800 ^◦C_ ™è õ&ñ\"f Òt|q כ ܼ–Ð ^¦Ãº e”. Wang et al. [19]\ _ €, ½+Ë$í“:r¸ Z• }“Érâĺ\ Co3O₄_ s

 ©œs Òqt|H˜Ð“¦•¸ e”. Table 1“Ér Rietveld ìr

$ 3

 õ\¦
?/“¦ e”. r¼#_ Rietveld ìr$3 õ\¦

˜

Ѐ, ú™è ìr0Al\"f Zn0.95Co_0.05O ìr´ú˜`¦ Êê\P%ƒo

\

¦ €  ©œÃº 7£x H כ s SX‰÷“&%3. sH H s“:rõ Co s“:rs †Êa< '‘|¨c âĺ, Co dimer ½¨›¸

×

æçߖ\ H s“:rs 0Au > ÷&#Q l”>r_ Co dimer ½¨

›

¸˜Ð 8 &&’l M:ëHs [20]. Al '‘|¾Ós 7£x½+É Ã

º2Ÿ¤ X-‚ r]X J‡s Z}“rÉ yŒ••¸\"f

HX<, s

Fig. 3. (Color online) Room temperature magnetic hys- teresis loops of Zn_0.95−xCo_0.05Al_xO:H powders with dif- ferent Al concentrations. The inset shows the magnetic hysteresis loops in enlarged range.



H Al³⁺ (0.39 ˚A)s“:rs Zn²⁺ (0.60 ˚A) s“:ro\ u

¨8

Š÷&#Q unit cells Œ•&’l M:ëHs [21, 22]. Õª õ Table 1\"f  ©œÃºü< ÂÒx_ y™™Œè\¦ SX‰“½+É Ãº e”



. ¢¸ôÇ Al '‘|¾Ós 7£x½ÉÃ+º2Ÿ¤ X-‚ r]X_ [jl %i r

 yŒ™™è H< sXHr¼#_ &ñwn ß¼l y™™Œèü< &ñ$í s


&’l M:ëHs [4].

Fig. 3“Ér ©œ“:r\"f 8£¤&ñ)a Al '‘|¾Ó\ Ér Zn_0.95−xCo_0.05Al_xO ìr´ú˜_ l s§4 /BG‚ ÕªAáÔs.

Ê

ê\P%ƒo ôÇ [j r¼# —¸¿º ©œ“r:\"f y©œ$ :í £¤$í`¦
 

·p. ¢¸ôÇ, ·ú˜9” \ _ € Zn0.95Co0.05O“Ér©œ

$í

:£¤$í`¦
?/“¦, s\¦Ãº™è ìr0Al\"f Êê\P%ƒo 

€

 y©œ$í :£¤$í`¦
·p [14]. Zn^0.95Co0.05O:H\"f

•

¸ y©œ$í :£¤$`í¦ SX‰“½+É Ãº e”. sH º™Ãè s“:rs '‘

 |¨c âĺ, Co-H-Co ½¨›¸\¦ ëߖ[tþ#Q y©œ$í :£¤$í`¦
 


> l M:ëHs [20]. ¢¸ôÇ Êê\P%ƒo Êê, Al '‘

1052 New Physics: Sae Mulli, Vol. 65, No. 11, November 2015

|

¾Ós 7£x½+Éú2Ÿ¤y©œ$í :£¤$sí †¾Ó©œ÷&H `כ¦·ú˜ ú e”



. Fig. 3\ ¶úš{9)aÕªAáԍH^„‰ #30A_ l s§4 /BG

‚

s. Table 2Hl s§4 /G‚Bܼ–ÐÂÒ' ½¨K” Ÿío



l°úכ (Ms), ïߖÀÓ o°úכ (Mr), ˜Ð§4 (H_c), yŒ•+þAq (M_r/M_s)s. Al '‘|¾Ós 7£x½+Éú2Ÿ¤ Als Zn o\ u

¨8Š÷&#Q · “ûÉr•¸- YU6\š`¦+þA$í “¦, Õª õ Ho#Q 0lx

•

¸ 7£xôÇ. s–ÐÂÒ' Co²⁺s“:r[þts_ y©œ$í 

½

+Ës 7£x #Œ, r«Ñ_ Ÿío l°úכ, ïߖÀÓ o°úכ, ˜Ð

§

4, yŒ•+þAq 7£xôÇ [1,4,5,23–28].

IV. + s Ç Â ] Ø

‘

:rƒ½¨\"fH Al '‘|¾Ó\ Ér Zn0.95−xCo0.05AlxO ì

r´ú˜`¦º™Ãè ìr0Al\"f \P%ƒoôÇ Êê ½¨›¸&h, l&h :£¤

$í

o\¦ƒ½¨ %i. X-‚ r]X 8£¤&ñõ Rietveld ìr$3



õ, Als '‘|¨cú2Ÿ¤ ìr˜ rú´«Ñ_ &$ñís
&’“¦,



©œÃº %ir Œ•” כ `¦ ˜ ÷ú º e”. ¢¸ôÇ ©œ“:r\"f 8

£¤&ñ)a l s§4 /BG‚`¦ :xŸK Als '‘|¨cú2Ÿ¤y©œ$í :

£¤$ís †¾Ó©œ÷&Hכ `¦‰XS“ %i. sH Al_ '‘|¾Ós 7

£

x½+Éú2Ÿ¤Ho#Q 0lx¸\•¦ 7£x “¦, s\  Co²⁺_ y

©œ$í ½+Ë`¦ 7£x l M:ëHs.

P

c p 8 ý ò k >

s

 õ]jH ÂÒíߖ@/†<Ɠ§ “§Ãº²DGü@©œl|t"é¶q (2013)\ _ #Œ ƒ½¨÷&%3_þvm.

REFERENCES

[1] X. C. Liu, E. W. Shi, Z. Z. Chen, H. W. Zhang and B. Xiao et al., Appl. Phys. Lett. 88, 252503 (2006).

[2] J. K. Park, K. W. Lee, S. J. Noh, H. S. Kim and C.

E. Lee, Curr. Appl. Phys. 14, 206 (2014).

[3] K. S. Park, Y. G. Joh, D. H. Kim and E. C. Kim, Sae Mulli 58, 273 (2008).

[4] P. Cao, Y. Bai, D. X. Zhao and D. Z. Shen, Mater.

Sci. Semicond. Process 14, 73 (2011).

[5] Y. Belghazi, D. Stoeffler, S. Colis, G. Schmerber and C. Ulhaq-Bouillet et al., J. Appl. Phys. 105, 113904 (2009).

[6] Z. H. Wang, D. Y. Geng, S. Guo, W. J. Hu and Z.

D. Zhang, Appl. Phys. Lett. 92, 242505 (2008).

[7] K. -C. Kim, Y. -H. Kang and Y. -S. Kim, Curr.

Appl. Phys. 8, 755 (2008).

[8] V. Jayaram, J. Rajkumar and B. S. Rani, J. Am.

Ceram. Soc. 82, 473 (1999).

[9] Y. C. Cho, S. Lee, H. H. Nahm, S. J. Kim and C. H.

Park et al., Appl. Phys. Lett. 100, 112403 (2012).

[10] H. Lee, J. M. Shin, Y. C. Cho, S. Lee and C. H.

Park et al., J. Phys.: Condens. Matter 26, 255501 (2014)

[11] L. Li, Y. Cuo, X. Y. Cui, R. Zheng and K. Ohtani et al., Phys. Rev. B 85, 174430 (2012).

[12] M. Khalid and P. Esquinazi, Phys. Rev. B 85, 134424 (2012).

[13] M. Khalid, P. Esquinazi, D. Spemann, W. Anwand and G. Brauer, New J. Phys. 13, 063017 (2011).

[14] H. -J. Lee, C. H. Park, S. -Y. Jeong, K. -J. Yee and C. R. Cho et al., Appl. Phys. Lett. 88, 062504 (2006).

[15] P. Sagar, M. Kumar and R. M. Mehra, Thin Solid Films 489, 94 (2005).

[16] J. Alaria, H. Bieber, S. Colis, G. Schmerber and A.

Dinia, Appl. Phys. Lett. 88, 112503 (2006).

[17] H. M. Rietveld, Acta Crystallogr. 22, 151 (1967).

[18] R. J. Hill and C. J. Howard, J. Appl. Crystallogr.

20, 467 (1987).

[19] Y. Wang, L. Sun, L.-G. Kong, J. -F. Kang, X. Zhang and R. -Q. Han, J. Alloys Compd. 423, 256 (2006).

[20] C. H. Park and D. J. Chadi, Phys. Rev. Lett. 94, 127204 (2005).

[21] R. D. Shannon and C. T. Prewitt, Acta Crystallogr.

Sect. B: Struct. Crystallogr. Cryst. Chem. 25, 925 (1969).

[22] W. Prellier, A. Fouchet and B. Mercey, J. Phys.:

Condens. Matter 15, R1583 (2003).

[23] X. J. Liu, C. Song, F. Zeng and F. Pan, J. Phys.:

Condens. Matter 19, 296208 (2007).

[24] X. C. Liu, E. W. Shi, Z. Z. Chen, H. W. Zhang and B. Y. Chen et al., J. Cryst. Growth 307, 14 (2007).

[25] H. -T. Lin, T. S. Chin, J. C. Shih, S. -H. Lin and T.

-M. Hong et al., Appl. Phys. Lett. 85, 621 (2004).

[26] C. H. Park, D. J. Chadi, Sato and H. K. Yoshida, Jpn. J. Appl. Phys. Part 2 39, L555 (2000).

[27] J. H. Kim, H. Kim, D. Kim and Y. E. Ihm, J. Appl.

Phys. 92, 6066 (2002).

[28] S. A. Wolf, D. D. Awschalom, R. A. Buhrman, J.

M. Daughton and S. V. Molnar et al., Science 294, 1488 (2001).