Microwave property improvement of Ca[(Li1/3Nb2/3)0.95Zr0.15]O3+δ perovskite by A-site substitution

Abstract

The crystal structure and microwave dielectric properties of Ca[(Li[Formula: see text]Nb[Formula: see text])[Formula: see text]Zr[Formula: see text]]O[Formula: see text] ceramic (CLNZ) are tuned by A-site substitution of Sr[Formula: see text] and Ba[Formula: see text] ions in the present paper. The tuning effect on the crystal structure is investigated by the X-ray diffraction (XRD) pattern and it illustrates that single phase of orthorhombic perovskite structure is formed, however, minor amount of BaNb2O6-type second phase is also detected in (Ca[Formula: see text]Ba[Formula: see text])[(Li[Formula: see text]Nb[Formula: see text])[Formula: see text]Zr[Formula: see text]]O[Formula: see text] ceramics (CBLNZ) in the range of [Formula: see text], while pure perovskite phase is obtained in (Ca[Formula: see text]Sr[Formula: see text][(Li[Formula: see text]Nb[Formula: see text])[Formula: see text]Zr[Formula: see text]]O[Formula: see text] ceramics (CSLNZ) in the whole investigation range of [Formula: see text]. With the increase of [Formula: see text] value, the unit cell volumes of both CBLNZ and CSLNZ perovskites gradually expand, which results in the degradation of the vibration bond strength between the B-site ions and oxygen in the perovskites. The microscopic structure related thermal parameters in CSLNZ and CBLNZ perovskites are analyzed in terms of Clausius–Mossotti equation to reveal the original contributors in the temperature coefficients. The results show that both Sr[Formula: see text] and Ba[Formula: see text] substitution can effectively improve the permittivity and [Formula: see text] value, especially, improve the temperature coefficient of CLNZ ceramic in a certain range.