1. A dielectric composition comprising:particles having a perovskite crystal structure including at least Bi, Na, Sr and Ti; and
at least one element selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Ba, Ca, Mg and Zn,
wherein a content of the at least one element selected from the group consisting of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb, Ba, Ca, Mg and Zn is between 0.5 molar parts and 11.1 molar parts, taking a Ti content of the dielectric composition as 100 molar parts,
wherein 0.17???2.83, where ? is a molar ratio of Bi with respect to Sr in the dielectric composition,
wherein at least some of the particles include a high-Bi phase having a Bi concentration of at least 1.2 times a mean Bi concentration of the dielectric composition as a whole, and
wherein a total surface area of a high-Bi phase within the particles in a cross section of the dielectric composition is between 0.1% and 15% of a total surface area of the particles.