Lanthanum titanate ceramics: Electrical characterizations in large temperature and frequency ranges

Abstract

Ceramics of the La 2 O 3 -TiO 2 system have very good dielectric properties, which make La 2 Ti 2 O 7 a good candidate for microwave applications. Using radio-frequency magnetron sputtering, we have deposited LaTiO x N y oxynitride thin films on (0 0 1) strontium titanate and glass substrates, starting from a homemade oxide target. The microwave dielectric properties of La 2 Ti 2 O 7 ceramic have been investigated in the 100 Hz to 10 GHz range in order to have a reference for further studies. The evolution of ε and ε shows a space charge domain with a critical frequency F c = 1 GHz. Measurements in the temperature range from 20 to 880 • C have been carried out to study phase transitions and conduction mechanisms.

Pure and Mn-doped La4SrTi5O17 layered perovskite as potential solid oxide fuel cell material: Structure and anodic performance

“…In air, the significant conductivity enhancement would tentatively correspond to a small polaron hopping mechanism associated to the presence of Mn 4þ /Mn 3þ pairs, as suggested by cell parameters refinement and in agreement with what occurs in Mn-doped cubiclike LSTs [19,51]. Such hypothesis could explain the marked difference of apparent activation energy with the non-doped compound, considering that in LST415 the conduction process is most probably ionic and poorly electronic with high activation energy [52]. In reducing conditions, the lower electrical conductivity and higher activation energy of LSTM415 compared to LST415 can be attributed to a decrease in the concentration of Ti 3þ , the n-type charge carriers, due to main Mn 4þ to Mn 3þ reduction process, as well as higher cell parameters, i.e.…”

Multiferroic properties of the layered perovskite-related oxide La6(Ti0.67Fe0.33)6O20

“…[11][12][13] The n = 4 type oxide, La 2 Ti 2 O 7 , is a high Curie temperature ferroelectric compound with T c = 1770 K, spontaneous polarization P s = 5 mC cm À2 and coercive field E c = 45 kV cm À1 at room temperature. 14,15 Recently, it was proposed that if a B-site cation was substituted by a magnetically active species, such as Fe or Mn, multiferroic compounds could be formed in the above-mentioned structure. 13 M. Scarrozza predicted the multiferroicity in V-doped La 2 Ti 2 O 7 by density functional calculations.…”

Preparation and Electrical Properties of La0.9Sr0.1TiO3+δ

“…In addition, in recent years, lanthanum-doped and strontium-doped ceramic composite material as a new kind of perovskite ceramic material has been widely researched and used as solid fuel cell anode material, microwave dielectric material and photo-dew-sensitive material, etc. [4,5,6,7,8]. Therefore, it could be supposed that La 1 − x Sr x TiO 3+δ (LST) may have better properties and potential applications.…”