We present neutron diffraction, dielectric permittivity and photoconductivity
measurements, evidencing that lead-magnesium niobate experiences a diffuse
phase transformation between the spherical glass and quadrupole glass phases,
in the temperature interval between 400 K and 500 K, with the quadrupole phase
possessing extremely high magnitudes of dielectric permittivity. Our analysis
shows that the integral diffuse scattering intensity may serve as an order
parameter for this transformation. Our experimental dielectric permittivity
data support this choice. These data are important for the aplications desiring
giant dielectric responses, in a wide temperature intervals and not related to
electron's excitations.Comment: 6 figure
