Patents

Gel is considered as semisolid rich in solvent. It consists of 5-10% solid material in the form of a three dimensional cross-linked network filled with the solvent. In general terminology, alcohol filled gel network is known as alcogel. Whereas an aerogel is a specific class of light weight porous solid material having air or gas in its pores instead of solvent, which is made possible using supercritical drying of alcogel. In the similar way, phosphor aerogel is a special class of luminescent material having narrow particle size distribution with remarkable luminescent properties useful for several strategic applications such as display, lightning, insulating, catalytic and sensing devices. Synthesis of phosphor aerogel with controlled particle sizes, monolithic, crack-free and near uniform luminescent properties is a challenging.and tough task. Yet no one has reported preparation process for the same. The formation of cracks takes place during gel settling time and difficult to form monolithic gel. In the proposed process we have developed a simple and versatile process for the formation of monolithic gel, at room temperature, which on further drying at supercritical temperature and pressures result in a dry aerogel. Further annealing under mild reduced atmosphere around 1000-1400°C not only retains the porous network with uniform size particles but also crystallizes to form a phosphor aerogel having brightest luminescence with bulk density as low as 100 kg m-3, and strong enough to support a weight much higher than its own weight. The proposed process can be used for the bulk synthesis of phosphor aerogel with uniform size distribution and could be extended to many other hosts that include oxide, sulfide and phosphate systems.