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1 Jurnal f the Krean Ceramic Sciety Vl. 45, N. 5, pp. 263~267, Piezelectric Prperties and Phase Transitin behavirs f (Bi 1/2 ) 1 x Ca x Ceramics Yng-Hyun Lee*, **, Jeng-H Ch**, Byung-Ik Kim**, and Duck-Kyun Chi* *Department Ceramic Engineering, Hanyang University, Seul , Krea **Department f Ceramic Building Materials Research, Krea Institute f Ceramic Engineering and Technlgy, Seul , Krea (Received April 3, 2008; Accepted May 13, 2008) (Bi 1/2 ) 1 x Ca x p x*, ** Á y**á½ **Á ³* *w w œw ** ( )» ( ; ) ABSTRACT (Bi 1/2 -based ceramics have been intensively studied as lead-free piezelectric ceramics. In this study, the piezelectric prperties and phase transitin behavirs f BNT based slid slutin (Bi 0.5 Na 0.5 ) 1 x Ca x (X = 0.01 ~ 0.25) were investigated. The mrphtrpic phase bundary(mpb) zne which BNT is transfrmed frm rhmbhedral t cubic structure was appeared by adding Ca with 0.12 ml by the measurement f permittivity and X-ray diffractin. The behavir which ferrelectric BNT with adding Ca was changed t antiferrelectric and paraelectric state was cnfirmed by the measurement f hysterisis lp and deplarizatin temperature as a functin f temperature. As Ca cncentratin was increased, the phase transitin temperature was decreased. The piezelectric prperties were highest at 0.01 ml f Ca cncentratin. The electrmechanical cupling factr(k t ) and mechanical quality factr(q m ) were 42% and 254, respectively. Key wrds : Lead Free, Piezelectric, (Bi 1/2, Phase transitin, Ferrelectric 1. ey w ƒ ³ w ƒ š, q j w û w w y w v j y š. p, x w t Pb(Zr,Ti)O 3 ( w PZT)» w» wz y w Lead Free š. Bi 1,2) Lead Free pervskite, illmenite, layer-structure, tungsten-brnz-type w ƒ š, ƒ y ƒ w š pervskite layer-structure(d ). Pervskite cercive fieldƒ f pling, layer-structure j» ht-frging ù templated grain grwth (TGG) z œ v w. 3-11) Crrespnding authr : Yng-Hyun Lee amclab@kicet.re.kr Tel : Fax : Bi pervskite t (Bi 1/2 ( w BNT) cercive fieldƒ 7.3 kv/mm p (lattice distrtin) 0.4 (α =89 36' ± 3') š, rhmbhedral ƒ pervskite yw w k š š š. w, curie temperature(tc) 320 C š, ë 200 C p (lattice distrtin) ù ƒ r e p yw ùkü ) BNT w T. Takenaka 3) w ù A, B site ey» p w. Lead Free Bi (Bi 1/2 Ca š k w š y X- z y l w. w Ca š š ùkù deplarizatin y P-E š (plarizatin-electric field hysteresis curve) wš w (anti-ferrelectric) p e w w. 263

2 264 xá yá½ Á ³ 2. x (Bi 1/2 (x = 0 ~ 0.25 ml) yw y yw (Mixed Oxide Prcess) w. Bi 2 O 3 (Junsei, 99%), Na 2 CO 3 (High Purity, 99%), CaCO 3 (High Purity, 99%), TiO 2 (High Purity, 99.9%) w. yw yw w» w w 10 g¾ 4 s w k g w Ì high density plyethylene(hdpe)» w z 24 yw, wš w z w w. w (Calcinatin) ù ƒ 800 C 2 w š X- z»(enraf-nnius C.) mw pervskite w y z 5 wt% plyvinyl alchl (PVA) 5wt% ƒw #100 w z, 10φ disk mld š 2 1 tn/cm w xw. x r 600 C 5 w w w z w C 2 5 C/min w. óù r» w ̃ 1mmƒ z r p(sung Jee Tech. c., SJT ) swš 600 C 10 w x w. x r w w» w 50 ~ 100 C g 4kV/mm 30 ƒ w w z 24 w z r p d w. LF v» (HP4192A) w 1kHz C d w w. ε r A = C d ε 0 p Electrnic Material Manufacture Assciatin Standard-6003 (EMAS-6003) w œ - œ w Netwrk Analyzer(Agilent Technlgies., HP5100A) LF v» w»-» w (electrmechanical cupling factr, k t )» t (quality factr, Q m ) w. k t = π f -- r π ( f a f r ) tan f a f a 1 Q m 2πf r Z r C f 2 2 a f r = f a, C R ƒƒ 1kHz œ w. y y LF v» š (Deata Design Inc., DELTA9023) w Fig. 1. XRD patterns f (Bi 1/2 ) 1 x Ca x ceramics sintered at 1150 C. (x = 0.05 ~ 0.25) d w, deplarizatin Netwrk Analyzer š w d w. P-E š d»(radiant Technlgies, Inc., RT66A) š s» (Radiant Technlgies, Inc., RT6000 HVA) w d w. 3. š Fig C w (Bi 1/2 š x y X z ql ùkü. Ca ƒ 0.10 ml¾ pervskite z peak peak w ù, 0.15 ml l Ca 2 peakƒ ùkùš. 2+ Ca BNT ü š ƒ 0.15 ml ƒ š wš Ca 2 j». w» w (Bi 1/2 (x=0.11~0.13) (111) z š w X z»(hrxrd) w lw scanw Fig. 1 ü w ùkü. CaCO 3 ƒ 0.11 ml¾ (rhmbhedral structure) e w (111) ( 111) peak ƒ ùù 0.13 ml l wù w w. rhmbhedral BNT Caƒ š cubic structure (phase transitin)w q Ca š 0.12 ml rhmbhedralcubic phase 7) bundary, T.Takenaka š ew. Fig. 2 r ƒw» d w. Ca š k ƒw w wz

3 (Bi 1/2 ) 1 x Ca x p 265 Fig. 2. Variatin f dielectric cnstant as a functin f Ca cncentratin at rm temperature ml ƒ 1366 e ùkü, š ƒw w w ùkü. (Bi 1/2 ) Ca TiO 1 x x 3 y Fig. 3 ùkü. Ca 0.01 ml ƒw r Curie (T c ) 290 C Ca š ƒw ƒwù š T c w. (Bi 1/2 ) Ca TiO 1 x x 3 š d BNT Ca š k Ca T c shift w depressr w w q. Fig. 4 (Bi 1/2 y q p (frequency sweep/10 C)»» w (K p ) ùkü. Fig. 4. Impedance characterizatin and electrmechanical cupling factrs(k p ) f (Bi 1/2 ceramics as a functin f temperature. ƒ»» w (K p )ƒ w.»» w (K p ) d w (deplarizatin temperature) 190 C ùkû. Fig. 5 (Bi 1/2 y P-E š ùkü. (remanent plarizatin, P r ) w (cercive electric field, E c ) ƒƒ µc/cm 46.5 kv/cm. 150 C ¾ P-E š x (ferrelectric) š ùküš 200 C l K. Sakata 15,16) w duble hysteresis lp (antiferrelectric) š p ùküš. deplarizatin ew ùkû Curie (T c ), Fig. 3. Dielectric cnstant change f (Bi 1/2 ) 1 x Ca x ceramics (x = 0.01 ~ 0.15) as a functin f temperature. Fig. 5. P-E hysterisis lps f (Bi 1/2 ceramics as a functin f temperature. 45«5y(2008)

4 266 xá yá½ Á ³ Fig. 6. Phase transitin f (Bi 1/2 ) 1-x Ca x ceramics as functins f temperature and Ca cncentratin. deplarizatin d P-E š d kƒ ù diffuse p y w. (Bi 1/2 ) 1 x Ca x Ca š Curie (T c ), deplarizatin d P-E š d Fig. 6 k ùký. (Bi 1/2 ) 1-x Ca x Ca š (ferrelectric) (antiferrelectric) (paraelectric) j, š ƒ ƒ ù w w w ùkü. Fig. 7 (Bi 1/2 ) 1 x Ca x Ca š»-» w (electrmechanical cupling factr, k t )» t (quality factr, Q m ) Fig. 7. Electrmechanical cupling factrs and quality factrs f (Bi 1/2 ceramics (x = 0 ~ 0.05) as a functin f Ca cncentratin. ùkü. Ca š»» w (K t ) 0.01 ml ƒ 42% ƒ ùkû š ƒw w w ùkü.» t (Q m ) Ca š ƒw w. 4. (Bi 1/2 ) 1 x Ca x Ca š 0.13 ml w 1366 ùkû. Ca š ƒ y (ferrelectric) (antiferrelectric) (paraelectric) j, (antiferrelectric). Ca š ƒw ƒ ù w w ùkþ. (Bi 1/2 ) 1 x Ca x Ca š Curie (T c ), deplarizatin temperature d P-E š d (Bi 1/2 ) 1 x Ca x k ùký. (Bi 1/2 ) 1 x Ca x CaTiO3 š p 0.01 ml ƒ j ùkû, (remanent plarizatin, P r ), w (cercive electric field, E c ),»-» w (electrmechanical cupling factr, k t )» t (quality factr, Q m ) ƒƒ 36.9 µc/cm 2, 46.5 kv/cm, 42%, 254 ùkû. REFERENCES 1. Y. Jyun and Y. Tmikawa, Applicatin f Multilayered Ceramic Capacitr t Pb-Free Electrmechanical Transducer, Jpn. J. Appl. Phys., (2000). 2. A. Kerfah, K. Taibi, A. Guehria-Laidudi, A. Simn, and J. Ravez, New Oxyfluride Lead-Free Ferrelectric Relaxrs in the Ba -BaZrO 3 -BaLiF 3 System, Mater. Lett., (2000). 3. T. Takenaka, T. Okuda, and K. Takegahara, Lead-Free Piezelectric Ceramics Based n (Bi 1/2 - NaNbO 3, Ferrelectrics, (1997). 4. J. Ravez and A. Simn, Relaxr Ferrelectricity in Ceramics with Cmpsitin Ba 1 xk x (Ti 1 xnb x )O 3, Mater. Lett., (1998). 5. T. Takenaka, Piezelectric Prperties f Sme Lead-Free Ferrelectric Ceramics, Ferrelectrics, (1999). 6. M. Kimura, T. Minamikawa, A. And, and Y. Sakabe, Temperature Characteristics f (Ba 1 xsr x ) 2 NaNb 5 O 15 Ceramics, Jpn. J. Appl. Phys., (1997). 7. T. Takenaka, K. Sakata, and K. Tda, Acustic Wave Characteristics f Lead-Free (Bi 1/2 Piezelectric Ceramic, Jpn. J. Appl. Phys., 28 Suppl (1989). 8. T. Takenaka. K. Marnyama, and K. Sakata, (Bi 1/2 - Ba System fr Lead-Free Piezelectric Ceramics, Jpn. w wz

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