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The Influence of ZnNb 2 O 6 on the Microwave Dielectric Properties of ZrTi 2 O 6 Ceramics
Author(s) -
RiaziKhoei Parinaz,
Azough Feridoon,
Freer Robert
Publication year - 2006
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2005.00705.x
Subject(s) - columbite , analytical chemistry (journal) , rutile , phase (matter) , materials science , ceramic , dielectric , diffraction , microwave , mineralogy , chemistry , optics , physics , metallurgy , organic chemistry , chromatography , quantum mechanics , optoelectronics
Ceramics in the system (1− x )ZrTi 2 O 6 – x ZnNb 2 O 6 (for 0.1≤ x ≤0.85) have been prepared by the mixed oxide route; specimens fired in oxygen at 1260°–1300°C achieved 97% theoretical density for most compositions. X‐ray diffraction analysis confirmed the co‐existence of a disordered α‐PbO 2 ‐type structured phase and a rutile‐structured second phase for 0.1≤ x ≤0.25, a single phase having a disordered α‐PbO 2 ‐type structure for 0.3≤ x ≤0.7, and a columbite‐type structured phase for x ≥0.85. Wavelength dispersive spectroscopy (WDS) revealed that the TiO 2 ‐rich second phase contained significant amounts of ZrO 2 , Nb 2 O 5 , and ZnO. In the two‐phase region relative permittivities (ɛ r ) are predominantly in the range 39–47 (with a peak at x =0.24), quality factor ( Q × f ) values peak at 34 000 GHz, and temperature coefficient of resonant frequency (τ f ) decreases with increase in ZnNb 2 O 6 content and tune through zero at x =0.24. In the single‐phase α‐PbO 2 region ɛ r decreases, Q × f increases to 49 000 GHz and τ f decreases to −58 ppm/°C with increasing ZnNb 2 O 6 . In the ordered columbite structure region ( x ≥0.85) the ɛ r falls to 28, Q × f increases to 59 000 GHz and τ f is more positive (−20 ppm/°C). Ceramics with x =0.24 exhibited an excellent combination of properties: ɛ r =47, Q × f =34 000 GHz, and τ f ∼0 ppm/°C.