The doping of the divalent elements in La_(1-x)A_xMnO_3(A=Ca, Sr, Ba or Ph) produces a mixture of Mn~(3+) and Mn~(4+) inos which improve the conductivity of the oxides, and the CMR effect appears as a result.

• 在La_(1-x)A_xMnO_3(其中A=Ca、Sr、Ba或Pb)中,当阳离子La被二价的A离子部分替代时,部分Mn~(3+)转变为Mn~(4+)离子,形成Mn~(3+)/Mn~(4+)混合价态,改善了材料的电导,并由此而产生了CMR效应。