CeIrGaHy system: hydrogen induced structural and valence change

CeIrGa is shown to be a mixed-valent compound with very high Kondo temperat ure (approximate to 1000 K). From the hydriding studies on CeIrGa. it is fo und that (i) only single hydride phase with hydrogen to metal ratio congrue nt to 1.7 is stabilized, which involves change of crystalline structure fro m orthorhombic (epsilon -TiNiSi type, space group Pnma) to hexagonal (B8(2) type, space group P6(3)/mmc) and (ii) charge state of cerium changes from mixed-valent to Ce+3 state, though no magnetic ordering is observed down to 2 K. (C) 2001 Elsevier Science Ltd. All rights reserved.