To further balance the relationship between piezoelectricity and temperature stability, the (0.975 - y)NaNbO3-yBaTiO(3)-0.025BaZrO(3) (y = 0-0.20) ceramics are developed by constructing a wide tetragonal phase region. Effects of BaTiO3 on the relationships among phase structure, electrical properties, and temperature dependence are investigated. With increasing BaTiO3 contents, the ceramics endure the structural evolutions from orthorhombic phase to tetragonal phase, and then to relaxor cubic phase. A wide tetragonal phase zone of 24-180 degrees C can be realized in the ceramics with y = 0.08, together with an enhanced piezoelectric coefficient d(33) = 215 pC/N. Intriguingly, excellent temperature stability unipolar strain (S-uni) and piezoelectric coefficient (d(33)) are observed in the ceramics with y = 0.08 within 20-180 degrees C. This work provides an alternative way to enhance piezoelectricity and temperature stability in lead-free piezoceramics.