High-temperature X-ray analysis and magnetoresistance method allow us to reveal the anomalous behaviour of crystalline-lattice parameter of La₀,6A₀,2Mn₁,2O_3delta (A²⁺: Ca²⁺, Sr²⁺, Pb²⁺) near the temperatures of transitions - T_c, T_m (colossal magnetoresistance), and T_p. The sample consists of a single phase. The La₀,6A₀,2Mn₁,2O_3delta (A²⁺: Sr²⁺, Pb²⁺) - structure is rhombohedral (R3c) and includes the plane clusters of gamma-Mn₂O₃ or Mn₃O₄ types [1]. The clusters are dissolved in the matrix structure, when the temperature is increased and the matrix structure is transformed into the cubic one at the temperatures within the range 1070-1100 K (Pm3m). Structure La₀,6Ca₀,2Mn₁,2O_3delta is cubic (Pm3m), but also consist the plane clusters of gamma-Mn₂O₃ or Mn₃O₄ types [2].
The linear relationship is determined between the width of NMR spectrum from octahedral manganese ions taking place in a high-frequency electronic exchange and the tolerance factor calculated for defect structure accounting the infringement of a co-ordination number, giving rise to distortions of polyhedrons owing to anionic vacancies.
The broad asymmetric NMR spectra suggest that there is a high-frequency electron exchange between Mn3+ and Mn4+ and that the environment of Mn³⁺, Mn⁴⁺ and La³⁺ is nonequivalent because of the vacancies and clusters and different valence of the ions.
Probably, the origin of the structural anomaly is Mn²⁺+Mn⁴⁺2Mn³⁺ transformation or transition of Mn³⁺ ions from low-spin state into high-spin one.

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