Phase transitions for flat anti-de Sitter black holes

We reexamine the thermodynamics of anti-de Sitter (adS) black holes with Ri cci flat horizons using the adS soliton as the thermal background. We find that there is a phase transition which is dependent not only on the tempera ture but also on the black hole area, which is an independent parameter. As in the spherical adS black hole, this phase transition is related via the adS/conformal-field-theory correspondence to a confinement-deconfinement tr ansition in the large-N gauge theory on the conformal boundary at infinity.