Disk-type piezoelectric transformer of a Na_(0.5)K_(0.5)NbO_3-CuNb_2O_6 lead-free ceramic for driving T5 fluorescent lamp

摘要

Lead-free (Na_(0.5)K_(0.5))NbO_3 (NKN) ceramics doped with 1 mol% CuNb_2O_6 (CN) ceramics were prepared using the conventional mixed oxide method, with a sintering temperature of 1075 °C. Microstructural analyses of the NKN-OICN ceramics were carried out and compared, using X-ray diffraction (XRD). NKN-01CN ceramics sintered at 1075°C not only exhibited excellent 'hard' piezoelectric properties of k_p=40%, k_t = 45%, k_(33) = 57%, a ferroelectric property of E_c = 23 kV/cm, and an extraordinarily high mechanical quality factor (Q_m) of 1933 but also showed excellent stability with temperature (TCF=-154 ppm/°C). The piezoelectric transformer was simplified, using an equivalent circuit, and analyzed, using MATLAB; the simulation data agreed well with the experimental results. An efficiency of 95.7% was achieved for the NKN-01 CN piezoelectric transformer with load resistance of 20 kΩ. An 8 W T5 fluorescent lamp was successfully driven by the NKN-01CN piezoelectric transformer.