significant crystal growth occurs and under conditions to achieve substantially total evaporation the resulting intermediate product may desirably be an amorphous solid formed as a thin film and may have a spherical shape or a shape as part of a sphere the intermediate product may then be calcined in any suitable calcination apparatus 230 by raising the temperature to a temperature between about 400 u00b0 c to about 800 u00b0 c for a period of time from about 2 to about 24 h and then cooled to room temperature the cooled product may be washed 240 by immersing it in water or dilute acid to remove any water soluble phase that may still be present after the calcination step the temperature and the length of time of the calcination process may be varied to adjust the particle size and the reactivity of the product the particles resulting from the calcination generally have a size between 1 and 1000 u03bcm the calcined particles consist of individual crystals bound together in a structure with good physical strength and a porous structure the individual crystals generally have a size between 20 nm and 10 u03bcm the products made by methods shown in fig1 2 and 3 comprise ceramic particles with a porous.