Upconversion Properties of Y 2 O 3 :Er 3+ , Yb 3+ Nanophosphors with Different Yb 3+ Concentrations

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Upconversion Properties of Y 2 O 3 :Er ³⁺ , Yb ³⁺ Nanophosphors with Different Yb ³⁺ Concentrations

Hyeon Mi Noh · Ju Hyun Oh · Jung Hyun Jeong ^∗

Department of Physics, Pukyong National University, Busan 608-737, Korea

Ha Ri Kang · Won Jong Kim · Chae Hyun Lee · Yong Rok Choi · Yong Dae Park

Haeundae High School, Busan 612-818, Korea

Jun Kyu Jang

Department of Ophthalmic Optics, Kaya University, Gimhae 621-748, Korea (Received 29 April 2015 : revised 1 June 2015 : accepted 1 June 2015)

Y

2

O

3

nanophosphors co-doped with 0.01 mol Er

³⁺

and various concentrations of Yb

³⁺

were synthesized by using the high-energy ball-milling method, and their upconversion properties were studied. The crystallinities and the surface morphologies of the nanophosphors that were investi- gated by using X-ray diffraction and scanning electron microscopy, respectively, and upconversion luminescence spectra were obtained by using a 975 nm laser diode (LD). According to the X- ray diffraction results, as the Yb

³⁺

concentration was increased, the crystallinity of the powder improved, and the powder tended to show a more cubic structure. The emission spectra of the Y

2

O

3

:Er

³⁺

, Yb

³⁺

nanophosphors showed green, red and blue UC emissions at 550, 660 and 410 nm, which could be assigned to the

²

H

11/2

,

⁴

S

3/2

→

⁵

I

15/2

,

⁴

F

9/2

→

⁵

I

15/2

and

⁴

G

11/2

→

⁵

I

15/2

of Er

³⁺

transitions, respectively. Also, their upconversion processes were explained by measuring the pump-power dependency of the upconversion luminescence spectra.

PACS numbers: 78.55.-m, 78.55.Hx, 78.66.Bf

Keywords: Upconversion, Y

2

O

3

:Er

³⁺

/Yb

³⁺

, Nanophosphors, Energy transfer

Yb ³⁺ Ò Þy ¢ ì Å× D; c Â \ ¥ Y ² O ₃ :Er ³⁺ , Yb ³⁺ x ¢] k ù° Ë Ñ= k8 ý V ê sU ê s ¹ Åò & ÿ ] k ù° Ë Ñ ¤V R Ë

{

¡g ` @Q · ¡® £g ` @ · + ä ^ ï Bg ` @ ^∗

Â

Ò â @ / < Æ § Ó ü t o < Æõ , Â Òí ß 608-737

~ ç

¡ P · » 4 w Hø ¶ B · T = g ` @ · L | ÷ 7 B ó i ; · ÷ 7 B6 0

K

î r @ / ¦1 p x < Æ §, Â Òí ß 612-818

ç

¡+ Ö <¦

@ / < Æ § î ß â F g < Æõ , ^ K 621-748

(2015¸ 4 Z 4 29{ 9 ~ Ã Î6 £ §, 2015¸ 6 Z 4 1{ 9 Ã º& ñ : r ~ Ã Î6 £ §, 2015¸ 6 Z 4 1{ 9 > F S X & ñ )

Er

³⁺

_ 0 l x ¸\ ¦ 0.01 mol Ð ¦& ñ ¦ Yb

³⁺

0 l x ¸\ ¦ or Y

2

O

3

:Er

³⁺

, Yb

³⁺

¸+ þ AF g ^ \ ¦ ¦

\

-t ^ ¦ x 9 a A ~ ½ ÓZ O ` ¦ s 6 x # ½ + Ë$ í ¦ © ~ ½ Ó ¨ 8 + þ AF g: £ ¤$ í ` ¦ ½ ¨ % i . X- r] X z ´+ « >, Å Ò

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.

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& ³p â ` ¦ s 6 x # ½ + Ë$ í ) a ì r ´ ú _ & ñ $ í x 9 ³ ð + þ A © ` ¦ ' a ¹ 1 Ï ¦, 975 nm Y Us $ s ¸× ¼ Ð # l

# © ~ ½ Ó ¨ 8 + þ AF g` ¦ % 3 % 3 . X- r] X 8 £ ¤& ñ ` ¦ : x K ½ + Ë$ í ) a ¸+ þ AF g ^ H { 9 ~ ½ Ó& ñ > (cubic) ½ ¨ ¸ e

` ¦ S X % i ¦, Yb

³⁺

_ 0 l x ¸ 7 £ x < Ê\ ì r ´ ú _ & ñ $ í s ¾ Ó © H d` ¦ · ú Ã º e % 3 . 975 nm Ð

#

l # % 3 É r Y

2

O

3

:Er

³⁺

, Yb

³⁺

¸+ þ AF g ^ _ µ 1 Ï F g Û ¼& 7 à Ô! 3 É r Yb

³⁺

_ 0 l x ¸ 7 £ x < Ê\ 550 nm Â Ò H _ y © ô Ç 0 l qÒ o + þ AF g õ 660 nm_ & h Ò o + þ AF g, Õ ªo ¦ ô Ç 410 nm_ ' õ AÒ o + þ AF g` ¦ Ð% i Ü ¼ 9 s

H y y Er

³⁺

s : r _

²

H

11/2

,

⁴

S

3/2

→

⁵

I

15/2

,

⁴

F

9/2

→

⁵

I

15/2

Õ ªo ¦

⁴

G

11/2

→

⁵

I

15/2

s \ l ô Ç

. ¢ ¸ô Ç © ~ ½ Ó ¨ 8 + þ AF g _ õ & ñ ` ¦ + þ AF g Û ¼& 7 à Ô! 3 õ * 3 á Ô F g _ > r ¸\ ¦ 8 £ ¤& ñ # [ O " î % i .

PACS numbers: 78.55.-m, 78.55.Hx, 78.66.Bf

Keywords: © ~ ½ Ó ¨ 8 + þ AF g, Y

2

O

3

:Er

³⁺

/Yb

³⁺

, ¸+ þ AF g ^ , \ -t ² ú

I. " e Â ] Ø

s

: r s { © I \ " f F g \ -t \ ¦ f ¨ Ã º # r {

© I Ð [ t t \ ¢ ¸ É r F g \ -t \ ¦ f ¨ Ã º # Z }

É

r \ -t © I Ð s H õ & ñ ` ¦ © ~ ½ Ó ¨ 8 (upconver- sion) õ & ñ s ¦ ô Ç . H& h ü @ % ò % i _ µ 1 Ï © ` ¦ ° ú

H Y Us $ s ¸× ¼\ ¦ B ÐÀ Ó " é ¶ è ' ) a & ñ s Ä

»o \ e# r F g % ò % i _ + þ AF g` ¦ ~ ½ ÓØ ¦ H © ~ ½ Ó

¨ 8

+ þ AF g \ @ /ô Ç ½ ¨ H ª > s À Ò# Q4 R M ® o Ü ¼ 9 [1–3], (

Qn Û ¼e ¦ Y Us , F g 7 £ x; ¤ © u , F g: x , Ò q tÓ ü t _ < Æ é ß , I

ª t _ ´ òÖ ¦ ¾ Ó © 1 p x \ ´ ú § É r 6 £ x6 x 0 p x$ í ` ¦ t ¦ e

[4–6]. Õ ªo ¦ B ÐÀ Ó s : r` ¦ ' ô Ç & ñ s Ä »o \

"

f { 9 # Q H © ~ ½ Ó ¨ 8 & ³ © É r & h ü @ 8 £ ¤& ñ © u , © ~ ½ Ó

¨ 8

Y Us $ ü < _ « Ñ6 x é ß © u 1 p x _ ª ô Ç 6 £ x6 x 0 p x$ í

`

¦ t ¦ e # Q" f Ë ¨ï r ô Ç ½ ¨ s À Ò# Q4 R M ® o .

Er ³⁺ s : r É r ü @ Ü ¼ ÐÂ Ò' r F g , & h ü @ % ò % i

\

s Ø Ôl t ´ ú § É r \ -t ï r 0 A\ ¦ t ¦ e ¦, / B N" î

<

Ê É r ï r / B N" î ¸| ` ¦ ë ß 7 á ¤ r v H ï r 0 A_ © [ þ t s e # Q" f

ª ô Ç \ -t ² ú õ & ñ õ © ~ ½ Ó ¨ 8 + þ AF g s { 9 # Q± ú Ã º e

H ¸| ` ¦ ° ú Æ Ò ¦ e . ¢ ¸ô Ç Yb ³⁺ s : r É r \ -t ï r 0

A é ß ¿ º > h Ð l $ © I ² F _7/2 ï r 0 Aü < # l © I

2 F _5/2 ï r 0 Aë ß t ¦ e # Q % 3 ! s sà Ô s : r Ü ¼ Ð ´ ú §s 6 x

÷

& 9, É r B ÐÀ Ó " é ¶ èü < < Êa ' # ª ô Ç ½ ¨

s

À Ò# Q4 R M ® o . Yb ³⁺ s : r _ [ þ t H © I ü < { © I _ \

-t s \ @ /6 £ x H \ -t ï r 0 A\ ¦ Eu ³⁺ , Tb ³⁺ , Er ³⁺ , Pr ³⁺ , Tm ³⁺ s : r 1 p x s Yb ³⁺ s : r õ < Êa ' ÷ &

H s : r[ þ t s 9, s [ þ t s \ { 9 # Q H \ -t ² ú Ð ô

Ç + þ AF g : £ ¤$ í ½ ¨ ´ ú §s s À Ò# Qt ¦ e ¦ [7–11], þ j H

\

H © ~ ½ Ó ¨ 8 ´ òÖ ¦` ¦ Z } s l 0 A # ± ú É r í 7 H \ -t

\

¦ t H Ó ü t| 9 \ " f upconversion : £ ¤$ í s ½ ¨ ) a e

[12–14]. Õ ª × æ Y 2 O ₃ H q §& h ± ú É r þ j@ / F g < Æ í 7 H \

-t (597 cm ⁻¹ )\ ¦ t ¦ e ¦, Ó ü t o & h s o < Æ& h Ü ¼

∗

E-mail: [email protected]

Ð î ß & ñ 9 1 l q$ í s \ O H Ó ü t| 9 Ð ñÛ ¼à Ô Ð" f & h ½ + Ëô Ç Ó ü t

| 9

s .

{ 9

ì ø Í& h Ü ¼ Ð © ~ ½ Ó ¨ 8 + þ AF g É r @ /Â Òì r # l © I f ¨ Ã º (excited state absorption, ESA) õ & ñ õ H] X ô Ç s : r s

\

{ 9 # Q H \ -t ² ú © ~ ½ Ó ¨ 8 (energy transfer up- conversion, ETU) õ & ñ Ü ¼ Ð µ 1 ÏÒ q t ¦, # l F g õ Ö ¸$ í ^ s

: r _ 0 l x ¸ Õ ªo ¦ ¸^ _ $ í | 9 \ % ò ¾ Ó` ¦ ~ Ã Î H . B Ð À

Ó s : r É r & ñ © _ % ò ¾ Ó` ¦ > ~ Ã Ît ë ß , ï r / B N" î ¸| \ Â

Ò½ + Ë H ï r 0 A © s _ \ -t s ç ß ë ß ² ú t

8 ¸ ETU o ß ¼> { 9 # Q 9 - í 7 H © ñ 6 x Ü

¼ Ð ETU\ Ã Ð# H ï r 0 A_ Ã º" î \ o { 9 # Q± ú Ã º e

. " f ¸^ _ 7 á x À Ó\ Er ³⁺ s : r _ © ~ ½ Ó

¨ 8

+ þ AF g _ [ jl ´ ú §s ² ú . ¢ ¸ô Ç - í 7 H © ñ 6

x Ü ¼ Ð Ã ºÑ þ cm ⁻¹ \ -t s H ï r 0 A[ þ t s \ H

× æ í 7 H q ~ ½ Ó õ & ñ s { 9 # Qè ß . s Qô Ç כ ¹ [ þ t õ < Ê a

# l © , power density, Ô ¦í HÓ ü t 0 l x ¸, # l © I \ " f Er ³⁺ _ + þ AF g Ã º" î 1 p x _ ´ ú § É r כ ¹ [ þ t s Er ³⁺ s : r s '

)

a Z O ß ¼ & ñ [15–17] x 9 ¸ & ñ [18, 19]\ " f © ~ ½ Ó ¨ 8 + þ

AF g _ ª ô Ç B j m 7 £ § \ % ò ¾ Ó` ¦ p 2 ; .

: r ½ ¨\ " f H ¦\ -t ^ ¦ x 9 a A ~ ½ ÓZ O Ü ¼ Ð 0.01 mol_ Er ³⁺ s : r õ 0 l x ¸\ ¦ or Yb ³⁺ s : r s 4 ¤ ½ + Ë' ) a Y 2 O 3 ¸+ þ AF g ^ \ ¦ ½ + Ë$ í ¦ 975 nm Y Us $ s ¸× ¼

Ð # l # © ~ ½ Ó ¨ 8 + þ AF g: £ ¤$ í ` ¦ ¸ % i . + þ AF g ^ _

& ñ ½ ¨ ¸ü < { 9 _ & ñ $ í ` ¦ ¸ l 0 A # X-

r] X z ´+ « >` ¦ s 6 x % i ¦, { 9 _ + þ A © õ ç H{ 9 $ í ` ¦ ¸

l 0 AK ³ ð p [ j½ ¨ ¸\ ¦ ì r$ 3 % i . ¢ ¸ô Ç s + þ AF g ^

\

@ /ô Ç © ~ ½ Ó ¨ 8 + þ AF g Û ¼& 7 à Ô! 3 ` ¦ 8 £ ¤& ñ ¦, * 3 á Ô F g [ j l

\ @ /ô Ç © ~ ½ Ó ¨ 8 + þ AF g [ jl o\ ¦ 8 £ ¤& ñ # © ~ ½ Ó

¨ 8

+ þ AF g _ B j& m 7 £ §` ¦ ½ ¨ % i .

II. ÷ m Ç] M ö U ê s0 n É

Er ³⁺ s : r _ 0 l x ¸ H 0.01 mol Ð ¦& ñ ¦ Yb ³⁺ s

: r _ 0 l x ¸\ ¦ ª > or Y ₂ O 3 ¸+ þ AF g ^ \ ¦

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Fig. 1. (Color online) XRD patterns of Y ₂ O ₃ :Er ³⁺ , Yb ³⁺

nanophosphors with various sintering temperatures.

¦\ -t ^ ¦ x 9 a A ~ ½ ÓZ O Ü ¼ Ð ½ + Ë$ í % i . Ø ¦ µ 1 ÏÓ ü t| 9 Ð H Y 2 O 3 (99.9%, Aldrich), Er 2 O 3 (99.99%, Aldrich), Yb 2 O 3

(99.99%, Aldrich)\ ¦ s 6 x % i ¦ ¸ H r « Ñ\ ¦ o < Æ ª : r Ü

¼ Ð > í ß % i . o < Æ ª : r Ü ¼ Ð > | ¾ Ó ) a Ø ¦ µ 1 ÏÓ ü t| 9 ` ¦ ^ ¦ x 9

a A (ball milling)` ¦ l 0 AK e ¦ Û ¼h Ë : ÐÖ ¦ (bowl) \ ï

r q ô Ç r « Ñü < 10 mm ß ¼l _ ZrO ^ ¦` ¦ ° ú s V , # Q 350 rpm _ r 5 Å q ¸ Ð 50ì r 1 l x î ß D ¥ ½ + Ëô Ç Ê ê 10ì r 1 l x î ß

@

/l r ç ß ` ¦ ° ú H כ ` ¦ 10 r ì ø Í4 ¤ # D ¥ ½ + Ë·ì r W # ï r q

% i ¦, Õ ª Ê ê 1100 ^◦ C _ : r ¸\ " f 4r ç ß 1 l x î ß \ P % o

% i .

¸+ þ AF g ^ _ & ñ ½ ¨ ¸ ì r$ 3 ` ¦ 0 AK X- r] X (X- ray diffraction, XRD, Philips, X’Pert)` ¦ 8 £ ¤& ñ % i Ü ¼ 9, X- _ í ß ê ø Íy (2Θ) É r 10 ^◦ ∼ 70 ^◦ % ò % i \ " f ì r { © 0.02 ^◦ _ Û

¼ ± p5 Å q ¸ Ð 8 £ ¤& ñ % i . Õ ªo ¦ Field Emission Scanning Electron Microscopy (FE-SEM, JSM-6700F, JEOL)` ¦ s 6

x # r « Ñ_ ³ ð ½ ¨ ¸ x 9 + þ A © ` ¦ ì r$ 3 % i . © ~ ½ Ó

¨ 8

+ þ AF g` ¦ 8 £ ¤& ñ l 0 AK þ j@ / F gØ ¦§ 4 1 W 975 nm Y U s

$ s ¸× ¼\ ¦ # l F g Ü ¼ Ð 6 x % i Ü ¼ 9 + þ AF g ñ H é

ß Ò oF g © u \ ¦ : x õ r & F g 7 £ x C l Ð Ø ¦ % i .

III. ÷ m Ç] M ö+ s ÇÊ Ý õ m Í w ² o

Fig. 1 É r ¦\ -t ^ ¦ x 9 a A ~ ½ ÓZ O Ü ¼ Ð ½ + Ë$ í ô Ç Y ₂ O ₃ :Er ³⁺ , Yb ³⁺ ¸+ þ AF g ^ _ ½ + Ë$ í : r ¸\ É r X-

r] X © s . 8 £ ¤& ñ ) a X- r] X © É r ½ + Ë$ í : r ¸ 7 £ x < Ê

\

É r Ô ¦í HÓ ü t x ß ¼ \ O s { 9 ~ ½ Ó& ñ > (cubic) ½ ¨ ¸

Ð ¸¿ º ° ú É r õ \ ¦ Ð# Å Ò ¦ e ¦, s \ ¦ JCPDS

×

¼ (88-1040) õ ü < ¸ ú { 9 u < Ê` ¦ S X % i . Õ ªo ¦ ½ + Ë

$ í

: r ¸ 7 £ x ½ + ÉÃ º2 ¤ r] X x ß ¼_ [ jl 7 £ x ¦ Å Ò

Fig. 2. FE-SEM images of Y 2 O 3 :Er ³⁺ , Yb ³⁺ nanophos- phors sintered at (a) 800, (b) 900, (c) 1000 and (d) 1100

◦ C.

Fig. 3. FE-SEM images of Y 2 O 3 :Er ³⁺ , Yb ³⁺ nanophos- phors at (a) 0 mol and (b) 0.05 mol Yb ³⁺ sintered at 1100 ^◦ C.

x

ß ¼_ ì ø Íu ; ¤ (full with at half maximum, FWHM) É r Yb ³⁺ _ 0 l x ¸ 0\ " f 0.07 mol Ð 7 £ x < Ê\ 0.226\

"

f 0.180Ü ¼ Ð y è # & ñ $ í s ¾ Ó © ÷ &% 3 6 £ §` ¦ · ú Ã º e

.

Fig. 2 H \ P % o : r ¸ (a) 800, (b) 900, (c) 1000 Õ ªo

¦ (d) 1100 ^◦ C{ 9 M :_ FE-SEM s . \ P % o : r ¸

7 £

x ½ + ÉÃ º2 ¤ { 9 [ þ t _ ß ¼l & t ¦ 8¹ ¡ ¤ ç H{ 9 > + þ A

$ í

÷ &# Q { 9 [ þ t _ ì ø Í6 £ x s Ö ¸ µ 1 Ïy { 9 # Qz ¤6 £ §` ¦ · ú Ã º e .

& ñ { 9 [ þ t s & f Ü ¼ Ð" f Õ ªY U [ þ t _ â > x 9 ¸ H × ¦ # Q [

þ

t > ÷ &# Q + þ AF g _ < Hz ´s × ¦ # Q[ þ t כ e ` ¦ \ V © ½ + É Ã º e .

{ 9

[ þ t s ç H{ 9 > ì r í÷ &# Q e H 1100 ^◦ C \ " f Yb ³⁺ _ 0

l

x ¸\ É r FE-SEM ` ¦ Fig. 3 \ ? /% 3 . Yb ³⁺

s

: r` ¦ ' t · ú § ¤` ¦ M : H 2 ; ³ ð _ { 9 [ þ t s é

#

Qo Ð Ó ü æ 5 ge H ¸_ þ v` ¦ Ð% i ¦ 0.05 mol Yb ³⁺ s : r _

â

Ä º 90 nm_ ½ ¨+ þ A\ î r ¸ ß ¼l _ { 9 [ þ t s ¦ Ø

Ô> ì r í ¦ e 6 £ §` ¦ S X % i . Yb ³⁺ _ < Ê| ¾ Ós 0.05 mol ì r ´ ú _ â Ä º { 9 [ þ t s 8¹ ¡ ¤ ç H{ 9 > ÷ & ¦ { 9 [

þ

t _ ì ø Í6 £ x s Ö ¸ µ 1 Ïy { 9 # Qz ¤6 £ §` ¦ · ú Ã º e .

0.01 mol Er ³⁺ s : r õ 0 l x ¸\ ¦ ² ú o ô Ç Yb ³⁺ s : r` ¦ < Ê a

4 ¤ ½ + Ë' ô Ç Y ₂ O 3 :Er ³⁺ , Yb ³⁺ ¸+ þ AF g ^ _ Yb ³⁺ 0 l x

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Fig. 4. (Color online) (a) Upconversion emission spectra of Y 2 O 3 :Er ³⁺ , Yb ³⁺ and (b) comparing the upconver- sion emission intensity with different Yb ³⁺ concentra- tions under 975 nm excitation.

%

3 . 550 nm Â Ò H _ y © ô Ç 0 l qÒ o + þ AF g ( ² H _11/2 , ⁴ S _3/2 → ⁵ I 15/2 ) õ 660 nm Â Ò H _ & h Ò o + þ AF g ( ⁴ F 9/2 → ⁵ I 15/2 ), Õ ª o

¦ 410 nm Â Ò H _ ô Ç ' õ AÒ o + þ AF g ( ⁴ G _11/2 → ⁵ I _15/2 ) s

'

a ¹ 1 Ï÷ &% 3 . Yb ³⁺ 0 l x ¸ 7 £ x < Ê\ + þ AF g _ [ jl

7 £

. Yb ³⁺ s : r _ 0 l x ¸_ o\ É r + þ AF g [ jl o\ ¦ Fig. 4(b) \ Õ ªA á Ô Ð ? /% 3 .

AF g _ õ & ñ ` ¦ [ O " î l 0 Aô Ç \ -t ï r 0 A³ ðs . 975 nm _ # l F g É r Er ³⁺ s : r _ ⁴ I _15/2 \ " f ⁴ I _11/2 ï r 0 A Ð_

s ü < Yb ³⁺ s : r _ ² F _7/2 \ ² F _5/2 ï r 0 A Ð_ s \ K {

\ -t H @ /Â Òì r Yb ³⁺ s : r \ " f f ¨ Ã º÷ & ¦ Er ³⁺ s : r

É r Yb ³⁺ \ " f Er ³⁺ s : r Ü ¼ Ð_ \ -t ² ú õ & ñ \ _ K

#

l ) a . 0 l qÒ o + þ AF g É r Er ³⁺ s : r \ " f_ # l ï r 0 Af ¨ Ã º õ

& ñ (ESA : ⁴ I _15/2 → ⁴ I _11/2 → ⁴ F _7/2 ) õ \ -t ² ú

Fig. 5. (Color online) Energy level diagram of Er ³⁺ and Yb ³⁺ ions under 975 nm excitation.

F _7/2 (Er ³⁺ )) \ _ K µ 1 ÏÒ q t 9, & h Ò o + þ AF g É r 0 l qÒ oï r 0 A

2 H _11/2 < Ê É r ⁴ S _3/2 ï r 0 A\ " f ⁴ F _9/2 Ð q ~ ½ Ó s # µ 1 Ï Ò q

tô Ç . s M : ¸^ r « Ñ t H í 7 H \ -t _ ß ¼l

q

ø Í& h Ü ¼ Ð B ÐÀ ÓF K5 Å q \ " f { 9 # Q H q ~ ½ Ó s S X Ò ¦ É r

\

-t Ì s Z O g Ë :` ¦ ë ß 7 á ¤ ô Ç . ¸^ _ þ j@ / F g < Æ í 7 H \ - t

÷

& q ~ ½ Ó s { 9 # Q± ú S X Ò ¦ É r B Ä º . Y ² O 3 _ þ

j@ / F g < Æ í 7 H \ -t H 597 cm ⁻¹ s ¦, ⁴ S _3/2 ü < ⁴ F _9/2 ï r 0

A ç ß \ -t H 3140 cm ⁻¹ s Ù ¼ Ð \ -t s 5.3 s . " f q ~ ½ Ó s õ & ñ Ü ¼ Ð ⁴ F _9/2 ï r 0 A G 0

>| 9 S X Ò ¦ É r B Ä º ± ú & h Ò o + þ AF g É r É r B j m 7 £ §` ¦ : x K

& t ² H _11/2 → ⁴ I _15/2 : ⁴ I _9/2 → ⁴ I _13/2 _ § s

¢ -

a (cross relaxation, CR) õ & ñ Ü ¼ Ð ⁴ I _13/2 ï r 0 A G 0 >| 9 Ã

º e ¦ ⁴ I _13/2 ï r 0 A_ [ þ t s Yb ³⁺ s : r Ü ¼ ÐÂ Ò' \

-t \ ¦ ² ú ~ Ã Î ⁴ I 13/2 → ⁴ F 9/2 _ ETU õ & ñ s { 9 # Q

& h Ò o + þ AF g s > ) a . ¢ ¸ô Ç 0 l qÒ o + þ AF g _ [ jl

& 4 R ⁴ F _9/2 ï r 0 A_ x 9 ¸ Z } t Yb ³⁺ s : r \

"

f_ \ -t ² ú õ & ñ ( ⁴ F _9/2 → ⁴ G _11/2 → ⁴ I _15/2 ) \ _ K

⁴ F 9/2 ï r 0 A\ " f ⁴ G 11/2 ï r 0 A Ð # l 0 p x K t ¦ ' õ A Ò

o + þ AF g s ± ú Ã º e .

s

*

&

ñ % i . { 9 ì ø Í& h Ü ¼ Ð * 3 á Ô F g _ [ jl (P ) Õ ªo ß ¼t

· ú

§` ¦ M : + þ AF g _ [ jl H P ⁿ \ q Y V ¦ n É r + þ AF g \ ' a

#

ô Ç # l F g _ > hÃ ºs 9, * 3 á Ô F g \ @ /ô Ç + þ AF g [ jl _

log-log Õ ªA á Ô_ l Ö ¦ l ÐÂ Ò' ½ ¨½ + É Ã º e . Fig. 6 É r

0.01 mol Er ³⁺ s : r õ 0.05 mol Yb ³⁺ s : r s 4 ¤ ½ + Ë' ) a

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Fig. 6. (Color online) Pump power dependence of green, red and blue upconversion emission.

Ó

ü t| 9 \ " f { 9 F g [ jl \ É r © ~ ½ Ó ¨ 8 + þ AF g _ [ jl \ ¦ log-log Õ ªA á Ô Ð · p כ s . 0 l qÒ o + þ AF g _ l Ö ¦ l H 1.903 Ü ¼ Ð 2\ î r ° ú כ` ¦ Ð% i ¦ s H 0 l qÒ o + þ AF g s ¿ º

>

õ & ñ (two-photon process)\ _ ô Ç כ e ` ¦ · p כ s

. & h Ò o + þ AF g _ â Ä º l Ö ¦ l 1.585 Ð { 9 F g õ & ñ (one-photon process) Ü ¼ Ð H X < s H § s ¢ - a & ³

1\ 0 >t l M :ë H s . s Qô Ç õ H · ú ¡" f \ - t

< Ê` ¦ · ú Ã º e . ¢ ¸ô Ç ' õ AÒ o + þ AF g _ l Ö ¦ l H 2.603 Ü ¼

Ð ⁴ F _9/2 → ⁴ G _11/2 → ⁴ I _15/2 s \ É r F g õ & ñ (three-photon process) Ü ¼ Ð z ¤ .

IV. + s Ç Â ] Ø

: r ½ ¨\ " f H ¦\ -t ^ ¦ x 9 a A ~ ½ ÓZ O ` ¦ s 6 x # Y ₂ O ₃ :Er ³⁺ , Yb ³⁺ ¸+ þ AF g ^ \ ¦ ½ + Ë$ í ¦ © ~ ½ Ó ¨ 8 + þ A F

g: £ ¤$ í ` ¦ ½ ¨ % i . XRD 8 £ ¤& ñ õ ¸ + þ AF g ^ H

Yb ³⁺ _ 0 l x ¸ 7 £ x ü < ' a > \ O s { 9 ~ ½ Ó& ñ > (cubic) ½ ¨ ¸ Ð

z ¤ ¦ Yb ³⁺ _ 0 l x ¸ 7 £ x ½ + ÉÃ º2 ¤ Å Ò x ß ¼_ [ jl

&

º e % 3 . 975nm Y Us $ s ¸× ¼ Ð # l # 550 nm Â

Ò H _ y © ô Ç 0 l qÒ o + þ AF g ( ² H _11/2 , ⁴ S _3/2 → ⁵ I _15/2 ) õ 660 nm Â Ò H _ & h Ò o + þ AF g ( ⁴ F _9/2 → ⁵ I _15/2 ), Õ ªo ¦ 410 nm Â

Ò H _ ô Ç ' õ AÒ o + þ AF g ( ⁴ G _11/2 → ⁵ I _15/2 ) s ' a ¹ 1 Ï÷ &% 3 .

Yb ³⁺ s : r _ 0 l x ¸ 7 £ x < Ê\ 0 l qÒ o + þ AF g É r Er ³⁺ s

: r \ " f_ ESA õ & ñ ( ⁴ I _15/2 → ⁴ I _11/2 → ⁴ F _7/2 ) õ ETU õ

&

ñ ( ² F _5/2 → ² F _7/2 (Yb ³⁺ ): ⁴ I _11/2 → ⁴ F _7/2 (Er ³⁺ )) \ l

9 & h Ò o + þ AF g É r ² H _11/2 → ⁴ I _15/2 : ⁴ I _9/2 → ⁴ I _13/2 _ CR \ _ ô Ç ETU õ & ñ , Õ ªo ¦ ' õ AÒ o + þ AF g É r ⁴ G _11/2 → ⁵ I _15/2 s \ l ô Ç . s © _ : r É r * 3 á Ô F g _ > r ¸\ ¦ :

£ ¤& ñ ô Ç õ \ " f ¸ S X % i H X < 0 l qÒ o + þ AF g É r l Ö ¦ l

1.903 s F g õ & ñ s 9 & h Ò o + þ AF g É r l Ö ¦ l 1.585 { 9

F g õ & ñ , Õ ªo ¦ ' õ AÒ o + þ AF g É r l Ö ¦ l 2.603 F

g õ & ñ Ü ¼ Ð [ O " î ½ + É Ã º e .

P

c p 8 ý ò k >

: r ½ ¨ H Â Ò â @ / < Æ §ü < K î r @ / ¦1 p x < Æ §_ R&E á Ô Ð Õ

ªÏ þ t " é ¶ Ü ¼ Ð s À Ò# Q& _ þ v m . Y ² O 3 :Er ³⁺ , Yb ³⁺ ¸ + þ

AF g ^ H Â Ò â @ / < Æ § + þ AF g èF É r' _ èF t " é ¶ \ O ` ¦ :

x K Ã º' ÷ &% 3 _ þ v m .

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Upconversion Properties of Y 2 O 3 :Er 3+ , Yb 3+ Nanophosphors with Different Yb 3+ Concentrations

Upconversion Properties of Y 2 O 3 :Er 3+ , Yb 3+ Nanophosphors with Different Yb 3+ Concentrations

Hyeon Mi Noh · Ju Hyun Oh · Jung Hyun Jeong ∗

Department of Physics, Pukyong National University, Busan 608-737, Korea

Ha Ri Kang · Won Jong Kim · Chae Hyun Lee · Yong Rok Choi · Yong Dae Park

Haeundae High School, Busan 612-818, Korea

Jun Kyu Jang

Department of Ophthalmic Optics, Kaya University, Gimhae 621-748, Korea (Received 29 April 2015 : revised 1 June 2015 : accepted 1 June 2015)

Y

O

nanophosphors co-doped with 0.01 mol Er

and various concentrations of Yb

concentration was increased, the crystallinity of the powder improved, and the powder tended to show a more cubic structure. The emission spectra of the Y

O

:Er

, Yb

nanophosphors showed green, red and blue UC emissions at 550, 660 and 410 nm, which could be assigned to the

H

,

S

→

I

,

F

→

I

and

G

→

I

of Er

transitions, respectively. Also, their upconversion processes were explained by measuring the pump-power dependency of the upconversion luminescence spectra.

PACS numbers: 78.55.-m, 78.55.Hx, 78.66.Bf

Keywords: Upconversion, Y

O

:Er

/Yb

, Nanophosphors, Energy transfer

Yb 3+  Ò Þy ¢ ì Å× D; c  Â \ ¥ Y 2 O 3 :Er 3+ , Yb 3+ x ¢] k ù° Ë Ñ= k8 ý V ê sU ê s ¹ Åò & ÿ ] k ù° Ë Ñ ¤V R Ë

{

¡g ` @Q  ·  ¡® £g ` @ · + ä ^ ï Bg ` @ ∗

Â

Ò â @ / < Æ § Ó ü t o  < Æõ , Â Òí ß  608-737

~ ç

¡ P  ·  » 4 w Hø ¶ B · T = g ` @ · L | ÷ 7 B ó i ; ·    ÷ 7 B6 0

K

î  r @ / ¦1 p x  < Æ §, Â Òí ß  612-818

 ç

¡+ Ö <¦ 

 @ / < Æ § î ß  â F g  < Æõ , ^  K  621-748

(2015¸  4 Z 4 29{ 9  ~ Ã Î6 £ §, 2015¸  6 Z 4 1{ 9  Ã º& ñ  : r ~ Ã Î6 £ §, 2015¸  6 Z 4 1{ 9  > F  S X & ñ )

Er

_  0 l x  ¸\  ¦ 0.01 mol  Ð  ¦& ñ  ¦ Yb

0 l x  ¸\  ¦   or   Y

O

:Er

, Yb

 ¸+ þ AF g ^ \  ¦  ¦

\

 -t  ^  ¦ x 9 a A ~ ½ ÓZ O `  ¦ s 6 x #  ½ + Ë$ í  ¦  © ~ ½ Ó  ¨ 8  + þ AF g: £ ¤$ í `  ¦   ½ ¨ % i  . X-  r] X z ´+ « >, Å Ò  

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.



 & ³p  â `  ¦ s 6 x #  ½ + Ë$ í  ) a ì  r ´ ú _    & ñ $ í x 9 ³ ð  + þ A © `  ¦  ' a ¹ 1 Ï  ¦, 975 nm Y Us $  s  ¸× ¼ Ð #  l

 #   © ~ ½ Ó  ¨ 8  + þ AF g`  ¦ % 3 % 3  . X-  r] X 8 £ ¤& ñ `  ¦ :  x K  ½ + Ë$ í  ) a  ¸+ þ AF g ^   H { 9 ~ ½ Ó& ñ >  (cubic) ½ ¨ ¸ e 

`  ¦ S X    % i  ¦, Yb

_  0 l x  ¸ 7 £ x  < Ê\     ì  r ´ ú _    & ñ $ í s   ¾ Ó ©  H  d`  ¦ · ú  Ã º e  % 3  . 975 nm Ð

#

l  #  % 3  É r Y

O

:Er

, Yb

 ¸+ þ AF g ^ _  µ 1 Ï F g Û ¼& 7 à Ô! 3  É r Yb

_  0 l x  ¸ 7 £ x  < Ê\     550 nm Â Ò   H _  y © ô  Ç 0 l qÒ  o + þ AF g õ  660 nm_  & h Ò  o + þ AF g, Õ ªo  ¦   ô  Ç 410 nm_  ' õ AÒ  o + þ AF g`  ¦  Ð% i Ü ¼ 9 s 



 H y  y   Er

s  : r _ 

H

,

Upconversion Properties of Y 2 O 3 :Er ³⁺ , Yb ³⁺ Nanophosphors with Different Yb ³⁺ Concentrations

Hyeon Mi Noh · Ju Hyun Oh · Jung Hyun Jeong ^∗

Yb ³⁺ Ò Þy ¢ ì Å× D; c Â \ ¥ Y ² O ₃ :Er ³⁺ , Yb ³⁺ x ¢] k ù° Ë Ñ= k8 ý V ê sU ê s ¹ Åò & ÿ ] k ù° Ë Ñ ¤V R Ë

¡g ` @Q · ¡® £g ` @ · + ä ^ ï Bg ` @ ^∗

Ò â @ / < Æ § Ó ü t o < Æõ , Â Òí ß 608-737

¡ P · » 4 w Hø ¶ B · T = g ` @ · L | ÷ 7 B ó i ; · ÷ 7 B6 0

î r @ / ¦1 p x < Æ §, Â Òí ß 612-818

ç

¡+ Ö <¦

@ / < Æ § î ß â F g < Æõ , ^ K 621-748

(2015¸ 4 Z 4 29{ 9 ~ Ã Î6 £ §, 2015¸ 6 Z 4 1{ 9 Ã º& ñ : r ~ Ã Î6 £ §, 2015¸ 6 Z 4 1{ 9 > F S X & ñ )

_ 0 l x ¸\ ¦ 0.01 mol Ð ¦& ñ ¦ Yb

0 l x ¸\ ¦ or Y

¸+ þ AF g ^ \ ¦ ¦

-t ^ ¦ x 9 a A ~ ½ ÓZ O ` ¦ s 6 x # ½ + Ë$ í ¦ © ~ ½ Ó ¨ 8 + þ AF g: £ ¤$ í ` ¦ ½ ¨ % i . X- r] X z ´+ « >, Å Ò

& ³p â ` ¦ s 6 x # ½ + Ë$ í ) a ì r ´ ú _ & ñ $ í x 9 ³ ð + þ A © ` ¦ ' a ¹ 1 Ï ¦, 975 nm Y Us $ s ¸× ¼ Ð # l

# © ~ ½ Ó ¨ 8 + þ AF g` ¦ % 3 % 3 . X- r] X 8 £ ¤& ñ ` ¦ : x K ½ + Ë$ í ) a ¸+ þ AF g ^ H { 9 ~ ½ Ó& ñ > (cubic) ½ ¨ ¸ e

` ¦ S X % i ¦, Yb

_ 0 l x ¸ 7 £ x < Ê\ ì r ´ ú _ & ñ $ í s ¾ Ó © H d` ¦ · ú Ã º e % 3 . 975 nm Ð

l # % 3 É r Y

¸+ þ AF g ^ _ µ 1 Ï F g Û ¼& 7 à Ô! 3 É r Yb

_ 0 l x ¸ 7 £ x < Ê\ 550 nm Â Ò H _ y © ô Ç 0 l qÒ o + þ AF g õ 660 nm_ & h Ò o + þ AF g, Õ ªo ¦ ô Ç 410 nm_ ' õ AÒ o + þ AF g` ¦ Ð% i Ü ¼ 9 s

H y y Er

s : r _

Õ ªo ¦

s \ l ô Ç

. ¢ ¸ô Ç © ~ ½ Ó ¨ 8 + þ AF g _ õ & ñ ` ¦ + þ AF g Û ¼& 7 à Ô! 3 õ * 3 á Ô F g _ > r ¸\ ¦ 8 £ ¤& ñ # [ O " î % i .

Keywords: © ~ ½ Ó ¨ 8 + þ AF g, Y

, ¸+ þ AF g ^ , \ -t ² ú

: r s { © I \ " f F g \ -t \ ¦ f ¨ Ã º # r {

© I Ð [ t t \ ¢ ¸ É r F g \ -t \ ¦ f ¨ Ã º # Z }

É

r \ -t © I Ð s H õ & ñ ` ¦ © ~ ½ Ó ¨ 8 (upconver- sion) õ & ñ s ¦ ô Ç . H& h ü @ % ò % i _ µ 1 Ï © ` ¦ ° ú

H Y Us $ s ¸× ¼\ ¦ B ÐÀ Ó " é ¶ è ' ) a & ñ s Ä

»o \ e# r F g % ò % i _ + þ AF g` ¦ ~ ½ ÓØ ¦ H © ~ ½ Ó

+ þ AF g \ @ /ô Ç ½ ¨ H ª > s À Ò# Q4 R M ® o Ü ¼ 9 [1–3], (

Qn Û ¼e ¦ Y Us , F g 7 £ x; ¤ © u , F g: x , Ò q tÓ ü t _ < Æ é ß , I

ª t _ ´ òÖ ¦ ¾ Ó © 1 p x \ ´ ú § É r 6 £ x6 x 0 p x$ í ` ¦ t ¦ e

[4–6]. Õ ªo ¦ B ÐÀ Ó s : r` ¦ ' ô Ç & ñ s Ä »o \

f { 9 # Q H © ~ ½ Ó ¨ 8 & ³ © É r & h ü @ 8 £ ¤& ñ © u , © ~ ½ Ó

Y Us $ ü < _ « Ñ6 x é ß © u 1 p x _ ª ô Ç 6 £ x6 x 0 p x$ í

¦ t ¦ e # Q" f Ë ¨ï r ô Ç ½ ¨ s À Ò# Q4 R M ® o .

Er ³⁺ s : r É r ü @ Ü ¼ ÐÂ Ò' r F g , & h ü @ % ò % i

s Ø Ôl t ´ ú § É r \ -t ï r 0 A\ ¦ t ¦ e ¦, / B N" î

Ê É r ï r / B N" î ¸| ` ¦ ë ß 7 á ¤ r v H ï r 0 A_ © [ þ t s e # Q" f

ª ô Ç \ -t ² ú õ & ñ õ © ~ ½ Ó ¨ 8 + þ AF g s { 9 # Q± ú Ã º e

H ¸| ` ¦ ° ú Æ Ò ¦ e . ¢ ¸ô Ç Yb ³⁺ s : r É r \ -t ï r 0

A é ß ¿ º > h Ð l $ © I ² F _7/2 ï r 0 Aü < # l © I

2 F _5/2 ï r 0 Aë ß t ¦ e # Q % 3 ! s sà Ô s : r Ü ¼ Ð ´ ú §s 6 x

& 9, É r B ÐÀ Ó " é ¶ èü < < Êa ' # ª ô Ç ½ ¨

À Ò# Q4 R M ® o . Yb ³⁺ s : r _ [ þ t H © I ü < { © I _ \

-t s \ @ /6 £ x H \ -t ï r 0 A\ ¦ Eu ³⁺ , Tb ³⁺ , Er ³⁺ , Pr ³⁺ , Tm ³⁺ s : r 1 p x s Yb ³⁺ s : r õ < Êa ' ÷ &

H s : r[ þ t s 9, s [ þ t s \ { 9 # Q H \ -t ² ú Ð ô

Ç + þ AF g : £ ¤$ í ½ ¨ ´ ú §s s À Ò# Qt ¦ e ¦ [7–11], þ j H

H © ~ ½ Ó ¨ 8 ´ òÖ ¦` ¦ Z } s l 0 A # ± ú É r í 7 H \ -t

¦ t H Ó ü t| 9 \ " f upconversion : £ ¤$ í s ½ ¨ ) a e

[12–14]. Õ ª × æ Y 2 O ₃ H q §& h ± ú É r þ j@ / F g < Æ í 7 H \