TUNING THE OPTICAL AND MECHANICAL PROPERTIES OF Y2O3 CERAMICS BY THE INCLUSION OF La3+ ION IN THE MATRIX FOR INFRARED TRANSPARENT WINDOW APPLICATIONS

Infrared transparent windows are generally used to protect highly delicate infrared sensor circuits from the harsh environments. In the present work a combustion technique was effectively used to incorporate La3+ ion in the yttria matrix. The crystallites were in the size limit of 20 nm. Powder characterization using X-ray diffraction, HRTEM and FTIR spectroscopy revealed that the La3+ ions were effectively replacing the Y3+ ion in the yttria matrix. There was a slight reduction in optical band gap with La3+ concentration. A novel sintering mechanism was used for sintering the samples by coupling definite proportions of resistive heating and microwave heating. The highly dense pellets showed better transmittance and hardness properties, which improved with La3+concentration. The present study authorises that combustion synthesis of the samples followed by resistive coupled microwave sintering can effectively be used to tune the optical and mechanical, properties of infrared transparent ceramics. Improving the transmittance properties without deteriorating the mechanical properties through the resistive coupled microwave sintering is the major highlight of this novel work.