Microwave Dielectric Properties of ( Pb 0.2 Ca 0.8   )[ (Ca 1/3 Nb 2/3 ) 1?x Ti x   O 3   세라믹스의 마이크로파 유전특성

김응수; 김용현; 김준철; 방규석; Eung Soo Kim; Yong Hyun Kim; Jun Chul Kim; Kyu Seok Bang

Korean Journal of Materials Research, Vol.11, No.8, 708-712, August, 2001

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Microwave Dielectric Properties of ( Pb 0.2 Ca 0.8 )[ (Ca 1/3 Nb 2/3 ) 1?x Ti x O 3 세라믹스의 마이크로파 유전특성

Microwave Dielectric Properties of ( Pb 0.2 Ca 0.8 )[ (Ca 1/3 Nb 2/3 ) 1?x Ti x ] O 3 Ceramics

김응수 , 김용현, 김준철¹, 방규석¹

경기대학교 재료공학과
¹고주파재료 연구센터 전자부품 연구원

Eung Soo Kim , Yong Hyun Kim, Jun Chul Kim¹, and Kyu Seok Bang¹

Department of Materials Engineering, Kyonggi University, Suwon 442-760, Korea
¹High Frequency Materials Research Center, KETI, Pyungtaek 451-865, Korea

초록

( Pb 0.2 Ca 0.8 )[( Ca 1 3 Nb 2 3/) 1?x Ti x ]O 3 세라믹스의 4+ 치환량 변화에 따른 마이크로파 유전특성을 고찰하였다. Ti 4+ 치환량이 증가함에 따라 x=0.05부터 x=0.15까지의 조성범위에서는 단일상의 페롭스카이트상을 얻을 수 있었으며, x=0.2이상에서는 Ti 2 와 CaNb 2 O 6 가 제 2상으로 존재하였고, 결정구조는 x=0.05에서 사방정(orthorhombic) 구조가 x=0.35에서 이방정(cubic) 구조로 전이하였다. 유전상수(K)는 Ti 4+ 치환량의 증가에 따라 rattling 효과의 증가로 인하여 증가되었으며, B-자리 양이온의 평균이온반겨의 세제곱의 반비례하였다. 그러나 결정립 크기의 감소와 제 2상의 존재로 인하여 Qf값은 감소하였다. Ti 4+ 치환량이 증가됨에 따리 tolerance factor(t)와 B-자리 결합원자가의 영향으로 공진주파수의 온도계수(TCF)는 -27.36ppm/ ? C 값으로부터 +18ppm/ ? C r값으로 조절되었다. 1350 ? C d서 3시간 소결한 ( Pb 0.2 Ca 0.8 )[(Ca 1 3 Nb 2 3) 1?x / Ti x ] O 3 시편에서 K=51.67, Qf=7268(GHz), TCF=0 ppm/ ? C 의 우수한 특성을 얻을 수 있었다.

Microwave dielectric properties of (Pb 0.2 Ca 0.8 )[(Ca 1/3 Nb2/3) 1?x Ti x ]O 3 ceramics were investigated as a function of Ti 4+ content (0.05 ≤ x ≤ 0.35). A single perovskite phase was obtained from x=0.05 to x=0.15, and TiO 2 and CaNb 2 O 6 were detected as a secondary phase beyond x=0.2. The structure was changed from orthorhombic at x=0.05 to cubic at x=0.35. Dielectric constant(K) was increased with increase of Ti 4+ content due to increase of rattling effect, and was inversely proportional to the cube of the average radius of B-site cation, however, Qf value was decreased, which was due to the decrease of grain size and the secondary phase. With the increase of Ti 4+ content, the temperature coefficient of resonant frequency(TCF) was controlled from -27.36 ppm/ ? C value to +18.4 ppm/ ? C value, which was caused by the influence of tolerance factor(t) and the bond valence of B-site. Typically, K of 51.67, Qf of 7268(GHz), TCF of 0 ppm/ ? C were obtained in the (Pb 0.2 Ca 0.8 )[(Ca 1/3 Nb 2/3 ) 0.8 Ti 0 .2]O 3 sintered at 13 50 ? C for 3h.

Keywords:(Pb 0.2 Ca 0.8 )[(Ca 1/3 Nb 2/3 ) 1?x Ti x ]O 3 secondary phase;rattling effect;tolreance factor(t);bond valence of B-site

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[1] Kato J, Kagata H, Nishimoto K, Jpn. J. Appl. Phys., 30(9B), 2343 (1991)

[2] Kato J, Kagata H, Nishimoto K, Jpn. J. Appl. Phys., 31, 3144 (1992)

[3] Kagata H, Kato J, Nishimoto K, Inoue T, Jpn. J. Appl. Phys., 32, 4332 (1993)

[4] Park HS, Yoon KH, Kim ES, J. Am. Ceram. Soc., 84, 199 (2001)

[5] Reaney IM, Colla EL, Setter N, Jpn. J. Appl. Phys., 33(7A), 3984 (1994)

[6] Shannon RD, Acta Cryst A., 32, 751 (1976)

[7] Swartz SL, Shrout TR, Mater Res. Bull., 17, 1245 (1982)

[8] Akabas MA, Davis PK, J. Mater. Res., 12, 102617 (1997)

[9] Cohen MU, Rev. Sci. Instrum., 6, 68 (1935)

[10] ASSTM C373-72. 313 (1982) (1982)

[11] Hakki BW, Coleman PD, IRE Trans. Microwave Theory Tech., 8, 402 (1960)

[12] Nishikawa T, Wakino K, Tanaka H, Ishikawa Y, IEEE MTT-S Digest, 277 (1987)

[13] Kay HF, Bailey PC, Acta Cryst., 10, 219 (1957)

[14] Kim WS, Kim ES, Yoon KH, J. Am. Ceram. Soc., 82(8), 2111 (1999)

[15] Shannon RD, J. Appl. Phys., 73(1), 348 (1993)