“…For example, alumina ceramics are prepared by synthesizing alumina powders by non-combustion methods, by reducing the sintering temperature, by ice template method, or by doping ceramic composites to reduce the sintering temperature of alumina ceramics [ 4 , 5 , 6 , 7 ]. Other methods include ball milling to refine powders [ 8 , 9 ], microwave and plasma sintering [ 10 ], 3-D printing [ 11 , 12 , 13 , 14 ], etc. These methods indicate a trend towards increasing energy efficiency in production.…”