Piezoelectric properties of Sr2-XCaXNaNb5O15 (SCNN) ceramics (0.05<X<0.35) for a smart patch

The study investigating the electrical properties of dense lead-free piezoelectric ceramics in the (1-x)Sr 2 NaNb 5 O 15 -xCa2NaNb5O15 (SCNN) system with x ranging from 0.05 to 0.35 is reported here. Materials were produced with Spark Plasma Sintering (SPS) method. X-Ray diffraction patterns all showed a single tetragonal tungsten bronze phase, peak broadening being seen on increasing the Ca content. The lattice constant calculation indicated distortion and shrinkage of the crystal structure with Ca substitution. Ferroelectric and piezoelectric properties of SCNN greatly depended on the Ca content. The composition with x =0.15 exhibited the greatest polarization with Pr =3.0 μ C cm -2 and piezoelectric constant of d 33 =96 pC/ N, whereas the compositions with x =0.30 and 0.35 almost lost their ferroelectricity and piezoelectricity. Not only investigation of materials properties but also application possibility as a sensor is surveyed. The ultrasonic waves generated by SCNN material as a sensor are much clearer that that by commercially available PZT materials. This study apparently indicates that lead-free SCNN piezoelectric ceramics have potential for electromechanical application.