For hexagonal structures RMnO3, where R - rare earth ions are Er, Tm, Yb, Lu, and Y entered anisotropic relative tolerance factor tx / tz. A correlation tx / tz with changes spontaneous polarization (strain) on the temperature and pressure, with a lattice parameter changes from the radii R ion concentration and changes in the structural parameters of R1-xAxMnO3 (A - Ca, La) solid solutions. It is shown that an increase in the Neel temperature TN corresponds to a decrease in tx / tz, with an increase tx / tz external pressure - increased temperature phase transitions in structures RMnO3 and concentration phase transitions Y1-xAxMnO3 (A - Ca, La) correspond to abrupt changes in tx / tz.

Keywords: tolerance factor, hexagonal ABO3 structure, chemical composition, temperature, pressure, solid solution

"This review covers various methods of synthesis LaMnO3 ferroics. The general analysis of the solid-phase synthesis reactions methods and wet methods (sol-gel, sorption, co-precipitation) are carred out. The original results of LaMnO3 syntheses from various precursors by means of the in situ method are showned. The advantages and disadvantages of different methods of synthesis are determined. The analysis of synthesis LaMnO3 ferroics published data is shown:
- the structure formation of LaMnO3 in perovskite-type phases occurs at different temperatures, depending on precursors states;
- LaMnO3 perovskite phases differ in symmetry and unit cells parameters at room temperature, depending on the preparation conditions;
- the highest synthesis temperature of LaMnO3 are typical for solid phase reactions method (950-1050 ° C), the lowest - for wet synthesis methods (500-700 ° C);
 - the synthesis conditions effect the stoichiometry of LaMnO3 for oxygen content.
Our studies of structure formation processes of LaMnO3 by in situ method are allowed to define the role of precursors states at synthesis of solid phase reactions methods, adsorption, co-precipitation and sol-gel mixtures.
It is determined that in samples prepared by wet chemical methods, the formation processes of  LaMnO3 perovskite phases occur at lower temperatures than by solid phase reaction (sol-gel precursor - 500 <T <600 ° C; precursors obtained by coprecipitation and sorption methods - at 600 <T <700 ° C and 700 <T <800 ° C, respectively).  

Keywords: ferroics, LaMnO3, X-ray diffraction, solid-phase synthesis, sol-gel synthesis, sorption, co-precipitation