The system Nd
2O
3–Y
2O
3 contains solid‐solution phases with several different structures. Single‐phase B‐type (Nd
1−xY
x)
2O
3 solid solutions in the range of
were formed at 1873 K and retained on cooling to ambient temperature. They showed a linear composition dependence of lattice parameters, enabling extrapolation to
x = 0 and 1 for comparison with the structures of the stable...