  Recently new incipient ferroelectrics with off-center ions SrTiO3 with Mn2+
substituted for Sr2+ was revealed (Tkach et. al PRB 73, 104113 (2006).
Experimental investigation of Sr1-xMnxTiO3 properties, namely temperature,
frequency and external electric field dependence of dielectric permittivity at
different concentrations gave evidence about phase transitions induced by the
impurities. However their nature was not found out up to now because of the
absence of the theoretical analysis of the results. In this paper we performed
such analysis by the theoretical description of the temperature of dielectric
permittivity maxima dependence on Mn2+ concentration, the change of residual
polarization with temperature, frequency and temperature dependence of the
permittivity with Arrhenius and Vogel-Fulcher law at smaller and larger
concentration respectively. The obtained results had shown that at x less than
0,03 and x between 0,15 and 0,03 the considered system Sr1-xMnxTiO3 is in
dipole glass state and mixed ferroglass phase respectively.
