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Modification of ZnAl 2 O 4 ‐Based Low‐Permittivity Microwave Dielectric Ceramics by Adding 2MO–TiO 2 (M=Co, Mg, and Mn)
Author(s) -
Lei Wen,
Lu WenZhong,
Zhu JianHua,
Liang Fei,
Liu Dan
Publication year - 2008
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.1551-2916.2007.02233.x
Subject(s) - ceramic , materials science , rutile , analytical chemistry (journal) , dielectric , mineralogy , microstructure , phase (matter) , metallurgy , chemical engineering , chemistry , chromatography , organic chemistry , optoelectronics , engineering
ZnAl 2 O 4 ‐based microwave dielectric ceramics with added 2MO–TiO 2 (M=Co, Mg, and Mn) were synthesized using the solid‐state reaction. The effects of 2MO–TiO 2 additions on the microstructures, phase compositions, and microwave dielectric properties of the 0.79ZnAl 2 O 4 –0.21M 2 TiO 4 ceramics has been investigated. It can be observed from X‐ray diffraction results that the single‐phase solid solution in the 0.79ZnAl 2 O 4 –0.21Co 2 TiO 4 ceramics, and second‐phase rutile, MgTi 2 O 5 , and ZnMn 3 O 7 in the 0.79ZnAl 2 O 4 –0.21TiO 2 , 0.79ZnAl 2 O 4 –0.21Mg 2 TiO 4 , and 0.79ZnAl 2 O 4 –0.21Mn 2 TiO 4 ceramics, respectively, appear. The ɛ r and τ f values of the 0.79ZnAl 2 O 4 –0.21M 2 TiO 4 ceramics are weakly dependent on the M element (Co, Mg, and Mn). The ɛ r values of the 0.79ZnAl 2 O 4 –0.21M 2 TiO 4 ceramics (about 9.7) are lower than that of the 0.79ZnAl 2 O 4 –0.21TiO 2 ceramics (ɛ r =11.6), whereas the τ f values of the former (about −65 ppm/°C) are higher than those of the latter (τ f =−0.4 ppm/°C). However, in contrast to the Q × f value of the 0.79ZnAl 2 O 4 –0.21TiO 2 ceramics ( Q × f =74 000 GHz), the magnitude of the 0.79ZnAl 2 O 4 –0.21Co 2 TiO 4 ceramics increases to 94 000 GHz and that of the 0.79ZnAl 2 O 4 –0.21Mg 2 TiO 4 ceramics improves more than twice, whereas the value of the 0.79ZnAl 2 O 4 –0.21Mn 2 TiO 4 ceramics undergoes a sharp decline and reaches a minimum of 23 530 GHz at about 6.5 GHz.