Parameters determining the phase transformation in the Gadolinium-doped Yttrium iron garnet

This study aims to evaluate the phase transformation in the Gd-YIG sintering reaction. Based on the shrinking core model (SCM), the Fe2O3 compound reacts with Y2O3 to form the YIP intermediate product. Then YIP reacted further with Fe2O3 to form YIG. The phase change process is largely influenced by parameters simultaneously including sintering temperature, sintering duration, sintering atmosphere, powder size, compressive force on the pellets and doping material. The ideal operating conditions for YIG Gd-doped sintering are carried out at 1450 °C within 5 hours in an inert atmosphere. The powder size less than 5 µm and applied compressive force at about 800 MPa will improve densification value. The presence of internediate product takes place in the first hour of sintering, and then undergoes further reaction to form a Gd-doped YIG. The experimental results are in accordance with literature data that the Gd-doped YIG sintering reaction takes place in two steps, so that the SCM accordingly describes the actual conditions of the sintering reaction.