Structure and Dielectric Properties of (Ca_1-xNd_2x/3)TiO₃

Abstract

(Ca1- x Nd2 x /3)TiO3 sintered samples are fabricated with 0≦x≦1 and the crystal structure and dielectric properties are investigated. It is shown that (Ca1- x Nd2 x /3)TiO3 has an orthorhombic GdFeO3-type structure for 0≦x≦0.69 and an La2/3TiO3-type double-layered perovskite structure for 0.78≦x≦0.93. High ε and high f Q values are obtained for the GdFeO3 phase of (Ca1- x Nd2 x /3)TiO3, e.g., ε=108 and f Q=17200 GHz for x=0.39. On the other hand, for the La2/3TiO3 phase, ε is between 80 and 100 and f Q is below 1000 GHz.

Microwave dielectric properties of aluminum substituted Ca_0.61Nd_0.26TiO₃ ceramics

“…2),5)8), 12) The EDS data in Table 1 confirmed this mechanism derivation. Because of the growing Q©f value in 0¯x¯0.1 with declined grain size, for the declination of the Q©f value of 0.15¯x¯0.2, high tangent loss secondary phase probably played a key role.…”

Microstructure and microwave dielectric properties of (1 − x)Ca(Mg1/3Nb2/3)O3/xCa0.61Nd0.26TiO3 complex perovskite ceramics

“…The difference of ionic radius and electronegativity between the Mg 2+ and Nb 5+ in B-site originates the 1:2 ordering structure in Ca(Mg 1/3 Nb 2/3 )O 3 [12]. On the other hand, Masashi et al have suggested that Ca 1−x Nd 2x/3 TiO 3 (x≦0.69) could be refined as orthorhombic structure with space group Pnma(62) [9]. peaks are displaced to higher 2θ angles with increasing Ca 0.61 Nd 0.26 TiO 3 content.…”

“…Several studies on such solid solution systems have been reported [3][4][5][6][7], where the microwave dielectric characteristics were discussed together with crystal structures and phase transitions. On the other hand, the A-site deficient perovskites Ca 1−x Ln 2x/3 TiO 3 (Ln = La, Nd and Sm) have much higher Q value and smaller t f than those of CaTiO 3 [8][9][10]. Therefore, one can expect to obtain the temperature stable microwave dielectric ceramics combined with a higher dielectric constant and a higher Q value in the systems of Ca(B,B″)O 3 -Ca 1−x Ln 2x/3 TiO 3 .…”

“…It was refined in P2 1 /c (14), resulting from b − b − c + titling system, and 1:2 long-range ordering of B-site ions was observed [12]. On the other hand, Ca 1−x Nd 2x/3 TiO 3 ceramics indicate the best combination of microwave dielectric characteristics at x=0.39: ɛ=108, Qf=17,200 GHz, t f =+270 ppm/°C [9]. It should be an interesting issue to investigate the possible solid solution in Ca(Mg 1/3 Nb 2/3 )O 3 -Ca 0.61 Nd 0.26 TiO 3 (CMN-CNT) system, and a moderate dielectric constant combined with the nearzero temperature coefficient of resonant frequency and high Q value are expected.…”

Crystal structure and microwave dielectric properties of Ba4Nd9.33Ti18O54 ceramics with Ca0.61Nd0.26TiO3 addition

“…The phase variation was similar to Casubstituted Ba6-3xSm8+2xTi18O54 ceramics. 9) Because the diffraction peaks of perovskites phase might overlap with those of the tungsten bronze type phase, the perovskites phase was identified from the change of relative intensitis of diffraction peaks until the x was beyond 0.8.…”