Defect of Structure, Magnetic and Transport Properties of Ceramic of Manganite-Lanthanum Perovskites La1-xMex2+MnO3± (Me2+ = Ca2+ (sic)Sr2+)

The investigation of ceramic magnetoresistive manganite-lanthanum perovskites La1-xMex2+MnO3 +/-delta, (Me2+ = Ca2+ (sic) Sr2+; x = 0-0,3) was performed by x-ray, magnetic, NMR Mn-55 and resistance methods. It was found the increase of concentration Me2+ ions brings to decrease of rhombohedric distortion and volume of crystal lattice and specific resistance of ceramic. The differences of phase transition temperatures 'conduction-semiconduction' and 'ferromagnetic-paramagnetic' and an activation energy of lanthanum-calcium and lanthanum-strontium manganites have explained by their difference of defect structure. It was shown the conditions of electro-neutrality perform not only through transition Mn3+-> Mn4+ but also formation of anion vacancies. A magnetic phase diagrams describe the influence of composition to ferro, antiferro- and paramagnetic rectangular components. The broad asymmetric Mn-55 NMR spectrum confirms the existence of a high-frequency electron-hole exchange between Mn3+<-> Mn4+ and heterogeneity of their surroundings by other ions and vacancies.