Influence of Sintering Temperature of Kaolin, Slag, and Fly Ash Geopolymers on the Microstructure, Phase Analysis, and Electrical Conductivity oleh Nur Nadiah Izzati Zulkifli, Mohd Mustafa Al Bakri Abdullah, Anna Przybył, Paweł Pietrusiewicz, Mohd Arif Anuar Mohd Salleh, Ikmal Hakem Aziz, Dariusz Kwiatkowski, Marcin Gacek, Marek Gucwa, Jitrin Chaiprapa