Study of magnetic properties of materials using Moessbauer spectroscopy. Currently studying organo-metallic layered compounds which undergo both magnetic and structural phase transitions. The magnetic interactions between the Fe ions can be varied by diluting the Fe with Zn and by changing the organic radical. The magnetic phase transitions are related to commensurate-incommensurate transitions. Study of lattice defects in metals by quenching and irradiation. Use of slow-quenching technique in high-quality single crystals. Also studying recovery processes of excess vacancy concentration at low temperatures.