Influence of Rare Earth Ions on BaO-TiO₂-Rare Earth Oxide Ceramics for Microwave Applications

Abstract

The dielectric ceramic materials, 0.143BaO-0.714TiO2-0.143 rare earth oxides (REO x ), have unique dielectric properties at microwave frequencies, which depend on the rare earth element (RE=Pr, Nd, Sm). In order to study the effect of the rare earth ions on dielectric properties, infrared reflection spectra of these ceramics were measured from 50 to 4000 cm-1 at room temperature. These data were analyzed according to the model proposed by Gervais and Piriou. Also, the fourth-order dielectric constants of these materials were estimated for the purpose of investigating the relationship between the dielectric loss and the anharmonic terms in the potential energy.

Pseudo-Tungsten Bronze-Type Dielectric Materials

“…Several authors studied [3,5,10,11,13,16,19,21,29,41,57,56,[66][67][68][69][70][71][72][73][74][75][76][77][78][79][80][81][82][83][84] the dielectric properties of Ba 6-3x Ln 8 þ 2x Ti 18 O 54 ceramics for different values of x and Ln = La, Pr, Sm, Nd, Eu, Gd and are given in Table 5.3. A study of Table 5.3 shows that the ceramics based on Eu, Sm and Nd have high quality factors (Qf) up to 14 000 GHz.…”

“…Figure 5.1 shows the phase diagram for the ternary BaO-RE 2 O 3 -TiO 2 system. Kolar et al [4], Polyakov et al [9] and Fukuda et al [10] all assigned the 1:1:5 compound for BaNd 2 Ti 5 O 14 with orthorhombic lattice parameters practically coinciding with those of Gens et al [7] for the 1:1:4 [BaNd 2 Ti 4 O 12 ], a stoichiometry first suggested by Razgon et al [6]. In 1986, Jaakola et al [11] reported that the true stoichiometry for the 1:1:4 and 1:1:5 phase must be closer to 15:19:72 (Ba 3.75 Nd 9.5 Ti 18 O 54 ).…”

“…Matveeva et al [14] proposed the composition Ba 3.75 Pr 9.5 Ti 18 O 54 . However, many workers [10,[15][16][17][18][19][20][21] represented the composition as 1:1:5. Several authors [4,11,14, investigated the crystal structure of BaO-Ln 2 O 3 -TiO 2 tungsten bronze-type dielectrics.…”

“…13 The effect of rare earth substitution on the infrared spectra (a) BaOPr 6 O 11 TiO 2 (b) BaONd 2 O 3 TiO 2 (c) BaOSm 2 O 3 TiO 2 (after Ref [10]…”

Microwave characteristics of BaPr2Ti4O12 and BaPr2Ti5O14 ceramics

“…% Ba4.05Pr9.3Ti 18 6.9 vol. Based on the results of XRD, XMA, and, the dielectric properties of Bae-xPrs+MTiisC^ system, it was suggested that BaPr 2 Ti 5 0i 4 ceramics are composed of mixed phases, approximately, 85.0 vol.…”