  The model discussion focused on links between the unique properties of
relaxor ceramics and the basics of critical phenomena physics and glass
transition physics. It indicates the significance of uniaxiality for appearing
mean-field features near paraelectric_ferroelectric transition. Pretransitional
fluctuations, increasing up to grain size and leading to inter-grain, random,
local electric fields, are indicated to be responsible for relaxor ceramics
characteristics. Their impacts yield the pseudo spinodal behavior associated
with weakly discontinuous local phase transitions. The emerging model redefines
the meaning of the Burns temperature and polar nanoregions PNRs. It explains
coherently dielectric constant changes with the diffused maximum near
paraelectric_ferroelectric transition, the sensitivity even to moderate
electric fields, tunability, and the glassy dynamics. These considerations are
confronted with experimental results for the complex dielectric permittivity
studies in relaxor ceramic, covering the 200K range, from the paraelectric to
the deep ferroelectric phase. The distortions-sensitive and derivative-based
analysis revealed the preference for the exponential scaling pattern in the
paraelectric phase and the surroundings of the paraelectric-ferroelectric
transition. It may suggest the Griffith phase behavior associated with the
mean-field criticality disturbed by random local impacts. The discussion of
experimental results is supplemented by relaxation times changes and the
coupled energy losses analysis. The studies also led to the description of
tunability temperature changes with scaling relations.
