MAGNETIC AND STRUCTURAL-PROPERTIES OF IRON-BASED OXIDE GLASSES, FE2O3-BAO-B2O3, FROM FE-57 MOSSBAUER-SPECTROSCOPY

**5**7FE MOSSBAUER SPECTROSCOPY HAS BEEN COMBINED WITH BULKRESULTS TO DETERMINE THE ELECTRONIC CONFIGURATION OF IRON, THE SHORT-RANGE STRUCTURAL ORDER AND THE MAGNETIC PROPERTIESOF GLASSES IN THE SYSTEM (FE//2O//3)//X(BAO)//Y(B//2O//3)//Z. THE AVERAGE COORDINATION OF THE IRON ATOMS IS DETERMINED BY THE FE/O ATOMIC RATIO WHILE THE VALENCE STATE OF FE SEEMSTO BE AFFECTED ESSENTIALLY BY THE PREPARATION CONDITIONS. STRUCTURAL SHORT-RANGE ORDER AROUND FE ATOMS IS CONCLUDED TO BE VERY STRONG, WITH RANDOM BONDING ANGLE AND DISTANCE FLUCTUATIONS. AT LOW FE//2O//3 CONTENT, THE GLASS IS PARAMAGNETICDOWN TO 1. 5K. LOCAL MOMENT MEASUREMENTS REVEAL THE COEXISTENCE OF ISOLATED FE IONS AND OF ATOMIC SCALE CLUSTERS. AT INTERMEDIATE FE//2O//3 CONCENTRATION (APPROXIMATELY 25P), THE GLASS PRESENTS A MICTOMAGNETIC TRANSITION. AT LARGE FE//2O//3 CONTENT (APPROXIMATELY 50P), THE GLASS BEHAVES LIKE A SUPERPARAMAGNET, INDICATING INHOMOGENEOUS DISTRIBUTION OF THE FEATOMS IN THE SOLID. MOSSBAUER SPECTROSCOPY IS ALSO APPLIED TO THE INVESTIGATION OF THE CRYSTALLIZATION OF A GLASS WITH INTERMEDIATE FE//2O//3 CONCENTRATION.