Effects of LnAlO3 (Ln = La, Nd, Sm) additives on the properties of Ba4.2Nd9.2Ti18O54 ceramics

The effects of LnAlO3 (Ln = La, Nd, Sm) additives on the microstructure and the dielectric properties of Ba4.2Nd9.2Ti18O5 (BNT) materials have been investigated. The microstructure of BNT doped with NdAlO3 was analyzed using X-ray diffraction and scanning electron microscopy (SEM). Over 10 wt.% additions of NdAlO3 diminished grain growth and the densifications process. In addition, typical columnar grain morphology observed in BNT ceramics was transformed to quasi-rectangular shapes accompanied by increasing porosity. XRD analysis did not reveal any second phases or modification of the BNT crystal structure. The addition of small amounts of LnAlO3 (≤10 wt.%) increased the Q values remarkably and improved the TCf. The relative permittivity and the TCf values showed a linear decrease with increasing additions of LnAlO3. It was observed that near zero TCf values can be achieved with addition of LnAlO3 dopants to BNT ceramics. The Q values exhibited a non-linear behaviour with LnAlO3 additions with maxima attained at approximately 10 wt.% LnAlO3.