COLOSSAL MAGNETORESISTANCE MANGANITE PEROVSKITES - RELATIONS BETWEEN CRYSTAL-CHEMISTRY AND PROPERTIES

Manganites with the perovskite structure represent a very important fa mily of oxides which are extensively studied for their colossal magnet oresistance (CMR) properties. In the present review we discuss the dif ferent factors which govern the magnetic and transport properties of t hese materials: carrier concentration, average size of the interpolate d cation, and mismatch effect on the A-site. Three types of oxides are mainly examined: (i) the hole doped manganites Ln(0.7)A(0.3)MnO(3) (A = Ca, Sr, Ba), (ii) the ''charge ordered'' Ln(0.5)A(0.5)MnO(3) mangan ites, and (iii) the electron doped manganites Ca(1-x)Ln(x)MnO(3) and C a1-xThxMnO3. The relationships between structural and magnetic transit ions are discussed, and particular attention is paid to charge orderin g phenomena. The doping of the Mn sites by various elements (Al, Ga, I n, Ti, Sn, Fe, Cr, Co, Ni) is systematically examined. The beneficial effect of ''Cr, Co, Ni'' elements, which induce CMR properties in thes e perovskites, is emphasized.