Electronic and structural phase separation in strongly correlated sytems

We review recent work on frustrated electronic phase separation in strongly correlated systems and the connection between electronic phase separation at a mesoscopic scale and structural phase separation at larger scales associated with volume instabilities. The former is due to the competition between phase separation tendencies and the long-range Coulomb interaction and surface energy effects. Above a critical value of the Coulomb interaction electronic phase separation is not possible and a volume instability arises. The system shows the tendency to phase separate into two neutral phases with different unit cell volumes.