A method comprising: placing electrically conductive particles between and in contact with a first electrode and a second electrode , the particles providing a conductive path between the first electrode and the second electrode , the first electrode exhibiting a first Seebeck coefficient, the second electrode exhibiting a second Seebeck coefficient greater than the first Seebeck coefficient, and the particles exhibiting a third Seebeck coefficient between the first and the second Seebeck coefficient; compressing the particles while heating the particles to a higher temperature above a temperature for a heating phase transition from a lower-temperature solid phase to a higher-temperature solid phase, the heating including applying an electric current from the second electrode through the particles to the first electrode and thus generating heat due to the Peltier effect at a junction between the first electrode and the particles and at a junction between the second electrode and the particles; as a result of the heating, phase transitioning the particles from the lower-temperature solid phase to the higher-temperature solid phase; after the heating phase transition of the particles, compressing the particles while cooling the particles to a lower temperature below a temperature for a cooling phase transition from the higher-temperature solid phase to the lower-temperature solid phase, the cooling including applying an electric current from the first electrode through the particles to the second electrode and thus removing heat due to the Peltier effect at the junction between the first electrode and the particles and at the junction between the second electrode and the particles; as a result of the cooling, phase transitioning the particles from the higher-temperature solid phase to the lower-temperature solid phase; and densifying the particles due to the heating and cooling phase transitions while compressing the particles. placing electrically conductive particles between and in contact with a first electrode and a second electrode , the particles providing a conductive path between the first electrode and the second electrode , the first electrode exhibiting a first Seebeck coefficient, the second electrode exhibiting a second Seebeck coefficient greater than the first Seebeck coefficient, and the particles exhibiting a third Seebeck coefficient between the first and the second Seebeck coefficient; compressing the particles while heating the particles to a higher temperature above a temperature for a heating phase transition from a lower-temperature solid phase to a higher-temperature solid phase, the heating including applying an electric current from the second electrode through the particles to the first electrode and thus generating heat due to the Peltier effect at a junction between the first electrode and the particles and at a junction between the second electrode and the particles; as a result of the heating, phase transitioning the particles from the lower-temperature solid phase to the higher-temperature solid phase; after the heating phase transition of the particles, compressing the particles while cooling the particles to a lower temperature below a temperature for a cooling phase transition from the higher-temperature solid phase to the lower-temperature solid phase, the cooling including applying an electric current from the first electrode through the particles to the second electrode and thus removing heat due to the Peltier effect at the junction between the first electrode and the particles and at the junction between the second electrode and the particles; as a result of the cooling, phase transitioning the particles from the higher-temperature solid phase to the lower-temperature solid phase; and densifying the particles due to the heating and cooling phase transitions while compressing the particles. <EOS>