Improvement of Ferroelectric Properties in Mo-Substituted Bi_3.35La_0.75Ti₃O₁₂ Films by Optimization of Heating Rate

Abstract

The crystal structure of the U(Pd 1−x Fe x ) 2 Ge 2 compounds with Fe content x = 0-0.03 and the crystal and magnetic structure of U(Pd 0.98 Fe 0.02 ) 2 Ge 2 at high external pressures up to 4.5 GPa were studied by means of powder neutron diffraction in the temperature range 1.5-300 K. With increasing Fe content the values of the lattice parameters and interatomic distances change only slightly, but it is known from previous experiments that the magnetic structure changes drastically for x 0.015. In contrast to this, high external pressure modifies the crystal structure more significantly while the magnetic structure remains unchanged. The results obtained allow one to infer that drastic changes in the magnetic structure of the U(Pd 1−x Fe x ) 2 Ge 2 compounds with increasing Fe content are a consequence of modification of the RKKY-type (RKKY standing for Ruderman, Kittel, Kasuya and Yosida) indirect exchange interaction due to the variation of the number of conduction electrons per U atom rather than a result of lattice contraction.

Preparation, Microstructure, and Ferroelectric Properties of Bi3.25La0.75Ti3−xMxO12 (M = Mo, W, Nb, V) Ceramics

“…The increase of preferred c -orientation with donor substitution is in agreement with Chang et al’s observations in Bi 3.5 Nd 0.5 Ti 2.97 Nb x O 12 thin films . The decrease of preferred b -orientation at low substitution level is consistent with Hardy and Ohki et al’s results in Bi 3.5 La 0.5 Ti 2.97 M 0.03 O 12 (M = Nb, V, Mo, and W) and Bi 3.25 La 0.75 Ti 2.985 Mo 0.015 O 12 thin films, respectively. , However, in Hardys report, both an increase (M = Nb, Mo) and a decrease (M = V, W) of preferred b -orientation was observed in the Bi 3.5 La 0.8 Ti 2.97 M 0.03 O 12 thin films prepared at the same condition …”

“…and donor (Nb 5+ , V 5+ , Mo 6+ , W 6+ , etc.) cosubstituted Bi 4 Ti 3 O 12 films have been reported by Uchida et al ,− and other authors. − …”

“…Nd 3+ substitution has been reported to be more effective than La 3+ in improving the P r . , However, the BLTM x ceramics obtained from the citrate-gel method have larger P r than that of V 5+ cosubstituted (Bi,Nd) 4 Ti 3 O 12 , and Bi 3.25 La 0.75 Ti 3 O 12 ceramics prepared by solid-state reaction and Bi 4− y La y Ti 3 O 12 ( y = 0.5, 0.75) thin films ,, prepared by rf-sputter and chemical solution deposition methods. The maximum P r of BLTM x , about 16 μC/cm 2 at 300 kV/cm, is slightly smaller than that of BPTV ceramics (17 μC/cm 2 ) and BLTMo 0.005 thin films (18 μC/cm 2 ) prepared by sol−gel method and is about 30−40% of that of Bi 4 Ti 3 O 12 (50 μC/cm 2 ) and Bi 3.54 La 0.46 Ti 3 O 12 (36 μC/cm 2 ) single crystals along their polar axis. The former could be explained by larger structural distortion in Pr 3+ substitution than that of La 3+ substitution, because of the smaller effective radii of Pr 3+ (1.126 Å) than that of La 3+ (1.160) for a coordination number of 8 …”

Synthesis, Structure, and Properties of Bi3.25Pr0.75Ti2.97V0.03O12 Ferroelectric Ceramics

“…), ,,− B-site aliovalent substitution using high valence cations (as V 5+ , W 6+ , etc. ), , and cosubstitution of these A and B sites. ,,− …”

Recent progress in ferroelectirc memory technology

“…In this study, Mo-doped BLT was used as the ferroelectric film, since the film is known to exhibit a large remanent polarization even if the crystallization temperature is not very high [9]. The film was deposited using a sol-gel method and crystallized at 700 C for 30 min in O 2 atmosphere.…”