Piezoelectric Properties of <TEX>$(Pb, La)(Ti,Mn)O_3$</TEX> Ceramics at VHF Band

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J. Korean Ceram. Soc. > Volume 36(11); 1999 > Article

Journal of the Korean Ceramic Society 1999;36(11): 1183.

$(Pb, La)(Ti,Mn)O_3$ 세라믹의 VHF 대역 압전특성

김명수, 안병기, 문남칠¹, 박상준², 양성석³, 이재신

울산대학교 재료금속공학부
¹울산대학교 재료금속공학
²(주)코아텍 개발팀
³(주) 코아텍 개발팀

Piezoelectric Properties of $(Pb, La)(Ti,Mn)O_3$ Ceramics at VHF Band

ABSTRACT

Piezoelectric properties of (Pb1-5xLax)(Ti0.98Mn0.02)O3(PLT) ceramics at VHF band were studied to examine their applicability as ceramic resonators. With the amount of La substitution in the range of x=0.05 to 0.25 the concentration of Pb-vacancies in the ceramics was gradually increased resulting in improved sinterability and decreased lattice anisotropy. Thickness-longitudinal vibration mode resonators fabricated with 0.3mm thick PLT ceramics showed better piezoelectric characteristics at the 3rd overtone resonant frequency(fr3) of about 24MHz than at the fundamental resonant frequency(fr0) of about 8MHz. When x=0.15 the values of elastic stiffness coefficient(c33) and electromechanical quality factor(Qm) reached maximum values of 2.1$times$1011 N/m2 and 3400 respectively while the 3rd harmonic piezoelectric coupling factor(kt) showed a minimum value of 11% Very low temperature coefficients of fr3(<10ppm/$^{circ}C$) were obtained with the PLT ceramic resonators when x=0.1~0.15

Key words: Piezoelectric ceramics, lead titanate, Ceramic resonators, VHF components