Published online by Cambridge University Press: 11 February 2011
The orthorhombic clathrate compound Eu4Ga8Ge16 orders antiferromagnetically at about 8 K. The magnetic structure is established by neutron powder diffraction while the thermal expansion and atomic displacement parameters are studied by synchrotron powder diffraction. The Eu spins align along the a-axis and achieve a zero-temperature magnetic moment equivalent to that of the free Eu2+ ion. The thermal expansion is largest along the a-axis while the expansion along c has almost the same magnitude as that along b. The Eu displacement parameters display significant residual values at 0 K, largest in the c direction.