Details

Autor(en) / Beteiligte

• Surendran, K P
• Varma, M R
• Mohanan, P
• Sebastian, M T

Titel

Microwave Dielectric Properties of RE sub 1-xRE'dxTiNbOd6 [RE = Pr, Nd, Sm; RE' = Gd, Dy, Y] Ceramics

Ist Teil von

• Journal of the American Ceramic Society, 2003-10, Vol.86 (10), p.1695-1699

Erscheinungsjahr

2003

Link zum Volltext

Quelle

Wiley Online Library - AutoHoldings Journals

Beschreibungen/Notizen

• The microwave dielectric properties of rare-earth titanium niobates can be tailored by preparing solid-solution phases between RETiNbOd6 [RE = Pr, Nd, Sm] and RE'TiNbOd6 [RE' = Gd, Dy, Y] microwave dielectric ceramics. Dielectric ceramics based on solid-solution phases RE sub 1-xRE'dxTiNbOd6 are prepared by the conventional solid-state ceramic route for different values of x. The ceramic samples are characterized by XRD, SEM, and microwave methods. Ceramics based on RETiNbOd6 belonging to aeschynite group show a positive value of tau df, and those based on RE'TiNbOd6 belonging to the euxenite group have a negative value of tau df. The solid-solution phases between aeschynites and euxenites show intermediate dielectric constant and tau df values. The results indicate the possibility of tailoring the microwave dielectric properties by varying the composition of solid-solution phases. The range of solid solubility of euxenites in aeschynites and aeschynites in euxenites are different for different rare-earth ions. The ceramics have low sinterability and a high dielectric loss factor near the vicinity of aeschynite to euxenite transition. The value of dielectric constant changes abruptly close to the transition point. The abrupt variation in microwave dielectric properties indicate a first-order phase transition at ix = 0.86 in Pr sub 1-xGddxTiNbOd6, x = 0.48 in Nd sub 1-xDydxTiNbOd6 and ix = 0.27 in Sm sub 1-xYdxTiNbOd6 ceramics. The dielectric constant and the sign of tau df of the solid-solution phases are found to depend on the average ionic radius of the rare-earth ions in RE sub 1-xRE'dxTiNbOd6. The euxenite to aeschynite phase transition occurs at an average ionic radius of 0.945 AA in all three systems of solid-solution phases.