The paper reports a non-Pb piezoelectric ceramic system, Ba(T$_{0.8}$Zr$_{0.2}$)O$_3$-(Ba$_{0.7}$Ca$_{0.3}$)TiO$_3$, which exhibits a high piezoelectric coefficient of $d_{33} \sim 620$ pC/N at an optimal composition. The phase diagram of this system features a morphotropic phase boundary (MPB) starting from a tricritical triple point (TCP) of a cubic paraelectric, ferroelectric rhombohedral, and tetragonal phases. The high piezoelectricity at the MPB compositions is attributed to the vanishing polarization anisotropy, facilitating easy polarization rotation between the $\langle 001\rangle T$ and $\langle 111\rangle R$ states. The authors predict that the single-crystal form of the MPB composition may achieve a giant $d_{33} = 1500$–2000 pC/N. This work suggests that non-Pb piezoelectric materials can compete with Pb-based systems by designing compositions that approach a TCP-type MPB, potentially offering superior piezoelectric properties.The paper reports a non-Pb piezoelectric ceramic system, Ba(T$_{0.8}$Zr$_{0.2}$)O$_3$-(Ba$_{0.7}$Ca$_{0.3}$)TiO$_3$, which exhibits a high piezoelectric coefficient of $d_{33} \sim 620$ pC/N at an optimal composition. The phase diagram of this system features a morphotropic phase boundary (MPB) starting from a tricritical triple point (TCP) of a cubic paraelectric, ferroelectric rhombohedral, and tetragonal phases. The high piezoelectricity at the MPB compositions is attributed to the vanishing polarization anisotropy, facilitating easy polarization rotation between the $\langle 001\rangle T$ and $\langle 111\rangle R$ states. The authors predict that the single-crystal form of the MPB composition may achieve a giant $d_{33} = 1500$–2000 pC/N. This work suggests that non-Pb piezoelectric materials can compete with Pb-based systems by designing compositions that approach a TCP-type MPB, potentially offering superior piezoelectric properties.