Influence of synthesis procedure on the YIG formation

The influence of synthesis procedure on the yttrium iron garnet (YIG; Y 3Fe 5O 12) formation has been investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Mössbauer and magnetization measurements. The samples were prepared by coprecipitation or ceramic processing using the starting molar ratio Y 2O 3/Fe 2O 3=3:5. The fractions of Y 2O 3, α-Fe 2O 3, YFeO 3 and YIG present in the samples depended on the method of materials processing and the calcination temperature. XRD of the thermally treated hydroxide coprecipitate at 1173 K showed the formation of YIG as a dominant phase, and YFeO 3 and Y 2O 3 as associated phases, whereas upon heating at 1473 K, YIG and a small amount of YFeO 3 were found. The samples produced by combining ball-milling of the starting powder and ceramic processing at 1573 K contained YIG and a smaller amount of YFeO 3, as found by XRD. It was shown that high-energy ball-milling with stainless steel can be substituted by milling with agate bowl and balls, thus decreasing the contamination of the oxide system due to wear. FT-IR and 57Fe Mössbauer spectroscopic measurements were in agreement with XRD; however, the smaller amount of YFeO 3 produced at 1573 K could not be detected with certainty by means of FT-IR and 57Fe Mössbauer spectroscopies. The magnetization values of end-products measured at 5 K were in agreement with their phase composition.