Relaxors, spin-, Stoner- and cluster-glasses

It is argued that the main characteristic features of displacive relaxor ferrolectrics of the form ${\mathrm{A}(\mathrm{B},{\mathrm{B}}^{\mathrm{\prime }})\mathrm{O}}_3$ with isovalent $\mathrm{B},{\mathrm{B}}^{\mathrm{\prime }}$ can be explained and understood in terms of a soft-pseudospin analogue of conventional spin glasses as extended to itinerant magnet systems. The emphasis is on conceptual comprehension and on stimulating new perspectives with respect to previous and future studies. Some suggestions are made for further studies both on actual real systems and on test model systems to probe further. The case of heterovalent systems is also considered briefly.