Formation of Crystal Structure in Dielectric BaAl2Si2O8BaAl_2Si_2O_8-Based Materials Depending on Preparation Conditions

Crystal structure formation of $BaAl_2Si_2O_8$ known as polymorphic compound is investigated in present work depending on conditions of preparation. Characteristics of ceramics have been studied for different modifications of crystal structure. Additional technologic operations (grinding with following heat treatment) have been found to result in polymorphic transformation. Dielectric properties of $BaAl_2Si_2O_8$ ceramics have been studied for hexagonal, monoclinic crystal structure modifications as well as for that based on phase mixture. It has been shown that the sintering of ceramic material based on the monoclinic crystal structure modification of $BaAl_2Si_2O_8$ takes place in temperature diapason of 1300-1350°C. Sintering of material with the hexagonal crystal structure modification occurs in temperature diapason of 1450-1500°C. Ceramics materials based on compound $BaAl_2Si_2O_8$ are found to have low porosity, high Q-factor and dielectric characteristics, allowing use of these ceramic materials for production of resonators and other microwave equipments