INFLUENCE OF MnO₂ ADDITIONS TO BaNd₂Ti₄O₁₂ MICROWAVE CERAMICS ON SINTERING BEHAVIOR AND DIELECTRIC PROPERTIES

The sintering behaviors and microwave dielectric properties of BaNd 2 Ti 4 O 12 (BNT4) ceramics with x wt. % MnO 2 dopants (x = 0, 1, 2, 3 and 4) were investigated in this paper. The tungsten-bronze type BaNd 2 Ti 4 O 12 accompanied with a certain amount of Ba 2 Ti 9 O 20 secondary phase was observed for all Mn doped compositions when samples were sintered at 1300C. Manganese substitution for Ti caused a decrease of the lattice parameters, and the addition of MnO 2 effectively improved the densification and lowered the sintering temperature of ceramics, which was closely related to the liquid phase sintering mechanism. The microstructure was homogeneous fine grained when x equaled to 3. At last, the BaNd 2 Ti 4 O 12 with 3.0 wt. % MnO 2 dopants well-sintered at 1300C for 1 h had good microwave dielectric properties of r = 90.2, Q f = 5225 GHz and f = 9.7 ppmC -1 .