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Microwave Dielectric Loss of Titanium Oxide
Author(s) -
Templeton Alan,
Wang Xiaoru,
Penn Stuart J.,
Webb Stephen J.,
Cohen Lesley F.,
Alford Neil McN.
Publication year - 2000
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.1151-2916.2000.tb01154.x
Subject(s) - crystallite , ionic radius , materials science , analytical chemistry (journal) , doping , dielectric loss , dielectric , titanium , titanium oxide , atmospheric temperature range , oxide , titanium dioxide , mineralogy , ion , inorganic chemistry , chemistry , metallurgy , optoelectronics , physics , organic chemistry , chromatography , meteorology
The dielectric loss (tan δ) of titanium dioxide (TiO 2 ) disks has been measured at a frequency of 3 GHz. High‐purity TiO 2 sintered to almost‐full density exhibits a very high tan δ, which is interpreted to be due to oxygen deficiency. To counter this, doping with stable divalent and trivalent cations, such as Mg and Al, leads to a low tan δ, probably by preventing Ti 4+ reduction. The tan δ of polycrystalline TiO 2 doped with divalent and trivalent ions with ionic radii in the range of 0.5–0.95 Å at 3 GHz can be very low: 6 × 10 −5 ( Q ∼ 17 000) at a temperature of 300 K. The tan δ of undoped pure TiO 2 disks increases when the disks are cooled from 300 K to ∼100 K. At temperatures <100 K, the tan δ decreases rapidly, which is interpreted as carrier freeze‐out. The tan δ for all the high‐ Q doped TiO 2 polycrystalline samples smoothly decrease to ∼5 × 10 −6 ( Q ∼ 200 000) at 15 K, comparable to that of single crystals.