Neutron irradiation effects in chemical-vapor-deposited diamond

The structural disorder, heat capacity, resistivity, Hall effect, and magnetic susceptibility of polycrystalline chemical-vapor-deposited diamond irradiated with fast neutrons at temperature of (325{+-}10) K at high fluences {phi}=(1-5)x10{sup 20} cm{sup -2} were investigated. Despite a significant increase in unit-cell volume ({approx}4.5%), the crystalline structure remains stable in this fluence range. The irradiation results in a paramagnetic contribution to magnetic susceptibility and to a strong (by 4 orders of magnitude) increase in heat capacity at low temperatures (T<20 K) due to electron contribution with a T dependence characteristic of multilevel electron systems (the Schottky anomaly)