Nadir toprak elementli bileşiklerin manyetik, yapısal ve termal karakterizasyonu

Bu tez calismasinda bilesigine ait kristal yapi ve manyetik ozellikleri, x-isini toz kirinim ve AC alinganlik olcumleri ile incelenmistir. Bu bilesik, bilesigi olusturan saf elementlerin argon atmosferi altinda su sogutmali bakir pota icinde eritilmesi ile elde edilmistir. X-isini toz kirinim olcumleri, Bruker D8 Advance x-isini toz difraktometresi ile yapilmistir. xx1?X-isini toz kirinim calismalari, I4/mmm uzay grubuna sahip tetragonal CeFeSi-tipi kristal yapiyi ve bazi bilesiklerde az miktarda yabanci fazlari ortaya cikarmistir. Bu kristal yapi, atomik tabakalarin c-ekseni boyunca R?X-T2-X-R seklinde siralanmasiyla olusur. Artan x degerleri ile birim hucre parametleri ve birim hucre hacmi, Vegard yasasina uygun olarak azalmislardir.AC manyetik alinganlik sicakligin fonksiyonu olarak Lake Shore 7130 AC alinganlik olcer ile 15-325 K sicaklik araliginda frekansi 111 Hz olan 80 A/m manyetik alanda olculmustur. Curie Sicakligi TC(Mn), artan Gd orani x ile azalmaktadir.AbstractIn this thesis, the crystal structure and magnetic properties of compounds has been investigated by means of x-ray diffraction and AC magnetic susceptibility measurements. These samples have been prepared by induction melting constituent elements under Ar atmosphere in a water-cooled copper boat. X-ray powder diffraction studies have been carried out by using Bruker D8 Advance x-ray powder diffractometer. xx1?X-ray powder difraction studies have revealed the existence of a tetragonal main phase having CeFeSi-type structure with the space group I4/mmm and small amounts of foreign phases appearing in some compounds. This structure comprises the atomic layers stacked along the c-axis direction in the sequence R?X-T-X-R. With increasing x, lattice parameters and the unit cell volume have decreased linearly, obeying the Vegard?s law. 2The AC magnetic susceptibility as a function of temperature was measured by means of a Lake Shore 7130 AC Susceptometer in the temperature range 15?325K in a magnetic field of 80 A/m and 111 Hz frequency. The Curie temperature TC(Mn) decreases with increasing Gd content x.