A novel high-k ‘Y5V’ barium titanate ceramics co-doped with lanthanum and cerium

Effect of uniform and periodic doping by Ce on the properties of barium strontium titanate thin films

“…It is further reported that this decrease takes place when Ce 3+ replaces Ba 2+ and does not occur if Ce 4+ replaces Ti 4+ [11]. A broadening of the phase transition and a lowering of the dielectric constant of BaTiO 3 by doping with Ce has also been reported [12]. Similar effects have been observed on doping of Ba 0.5 Sr 0.5 TiO 3 films by Ce [13].…”

“…[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26]. Ce can exist as Ce 3+ or Ce 4+ depending on the precursor used and the processing temperature.…”

Structural and optical properties of rare earth–doped (Ba0.77Ca0.23)1−x(Sm, Nd, Pr, Yb)xTiO3

“…Therefore, it is unlikely that the described axially symmetric signal in our samples is due to F þ centers. Previous studies 34,36,37 have attributed the axially symmetric signal near g ¼ 2.004 to singly ionized Ti vacancies in BaTiO 3 . The presence of charge-compensating Ti vacancies is consistent with Raman spectroscopy data, which show a narrow peak originating from the Ti-vacant octahedron.…”

“…The signal is consistent with an axially symmetric signal near g ¼ 2.004 seen in previous studies. 34,36,37 In order to satisfactorily fit the RE-doped BCT samples using the XSophe simulation program, a hyperfine coupling with a Ba nucleus of 11 to 15 G had to be included in the simulation of this axially symmetric signal. An obvious choice for the origin of this signal would be an electron trapped at an oxygen vacancy (a F þ center), as the g value is near the free electron value; the signal shows hyperfine coupling to a Ba nucleus, which would be the nearest neighbor to an oxygen vacancy in the BCT structure, and F þ centers could be the charge compensation mechanism for the incorporation of RE ions.…”

“…An obvious choice for the origin of this signal would be an electron trapped at an oxygen vacancy (a F þ center), as the g value is near the free electron value; the signal shows hyperfine coupling to a Ba nucleus, which would be the nearest neighbor to an oxygen vacancy in the BCT structure, and F þ centers could be the charge compensation mechanism for the incorporation of RE ions. However, Lu et al 36 ruled out the possibility of oxygen vacancies (V O ) in a BaTiO 3 structure due to the presence of oxygen during the sintering process, the absence of conductivity from oxygen vacancies, and the absence of complexes upon intentional doping with Fe 3þ . We did not intentionally dope our samples with Fe 3þ , but we did use a similar sintering procedure, and the RE-doped BCT samples did not show an increase in conductivity.…”