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Zn Al 2 O 4 and (0.79) Zn Al 2 O 4 –(0.21) Mn 2 TiO 4 Microwave Dielectric Ceramics Prepared by Hot Pressing and Spark Plasma Sintering
Author(s) -
Lorite Israel,
Rodriguez Miguel Angel,
Azough Feridoon,
Freer Robert,
Fernandez Jose Francisco
Publication year - 2012
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.1551-2916.2011.04907.x
Subject(s) - spark plasma sintering , materials science , ceramic , sintering , dielectric , hot pressing , analytical chemistry (journal) , microwave , phase (matter) , grain size , composite material , chemistry , optoelectronics , physics , organic chemistry , chromatography , quantum mechanics
Ceramics of Zn Al 2 O 4 ( ZA ) and 0.79 Zn Al 2 O 4 –0.21 Mn 2 TiO 4 ( ZAMT ) were prepared by the mixed oxide route using hot pressing and spark plasma sintering ( SPS ) techniques. Sintering temperatures were 1300°C in all cases; hot‐pressed samples were held at peak temperature for 1 h, the SPS samples for 5 min. Sintered densities were at least 98% theoretical for the SPS samples. Zn Al 2 O 4 prepared by SPS was single phase; all other samples contained minor amounts of second phase. Grain sizes for Zn Al 2 O 4 were typically 200–500 nm, but 2–5 μm for ZAMT . FTIR spectra for all the samples include Al–O bend mode band at ~450 cm −1 . The microwave dielectric properties of the ZA ‐ SPS (ε r = 8.7; Qxf = 57 000 GHz) were comparable with conventionally produced samples; the dielectric properties of the ZAMT ‐ SPS (ε r = 9.6; Qxf = 30 630 GHz) were superior to conventionally produced ceramics. The SPS approach yielded high density, high quality dielectric ceramics at lower sintering temperatures and much reduced processing times.