Relaxor ferroelectrics and related superglasses (original) (raw)

Mesoscopic ferroic glasses such as martensitic strain glass Ti 50Àx Ni 50þx , magnetic cluster glass La 0.7 Ca 0.3 Mn 0.7 Cd 0.3 O 3 , and superdipolar relaxor PbMg 1/3 Nb 2/3 O 3 (PMN) undergo glass transitions preceded by mesoscopic precursor patternselastic or magnetic tweed or polar nanoregions (PNR), respectively. In PMN the PNR glass transition at T g % 240 K reveals glassy dynamic criticality and non-ergodicity of the field-induced low-T phase similar to that of a superspin glass of fixed magnetic nanoparticles in a diamagnetic environment. A final ferroelectric domain state is reached at T p % 213 K via PNR percolation, which is absent in weak relaxors like BaTi 0.65 Zr 0.35 O 3 (BTZ35).