A novel aluminosilicate geopolymer material with low dielectric loss

Geopolymers are generally formed by chemosynthetic aluminosilicate powders with an alkaline silicate solution under approximately ambient conditions. Free Na, water molecules, and hydroxyl ions are the major components determining the dielectric loss in these alkaline geopolymer materials at various radio frequencies. Therefore, it is difficult to decrease the dielectric losses resulting from ion transfer. Previously, we prepared a novel geopolymer material from chemosynthetic Al2O3–2SiO2 powders and phosphoric acid. In comparing phosphate geopolymers with alkaline geopolymers, it can be shown that the dielectric loss of the 2.4H3PO4–Al2O3–2SiO2 geopolymer resulting from ion transfer is reduced due to the lack of free alkali cations (such as Na+ or K+) within these polymers. Therefore, by also decreasing or eliminating the water within the phosphate-based geopolymers through heat treatment, the order of magnitude of its dielectric loss can be reduced from 10−2 to 10−3.

• This paper presents a novel material that is fabricated by chemosynthetic Al2O3–2SiO2 powders and phosphoric acid at room temperature, which can be applied in high-temperature packaging or encapsulating materials. The results showed the dielectric loss of the 2.4H3PO4–Al2O3–2SiO2 geopolymer that is lower than alkali-activated geopolymer materials. By decreasing or eliminating the water within the phosphate-based geopolymers through heat treatment, the orders of magnitude of its dielectric loss must be reduced from 10−2 to 10−3.