The defect structure, sintering behavior, and dielectric responses of Cr2O3-doped Sr0.5Ba0.5Nb2O6

Abstract

Phase structure, dielectric properties, and relaxor behavior of ( K 0.5 Na 0.5 ) NbO 3 -( Ba 0.5 Sr 0.5 ) TiO 3 lead-free solid solution for high temperature applications Effect of sintering temperature on the phase transition and dielectrical response in the relaxor-ferroelectricsystem 0.5PZN-0.5PZT Sr 0.5 Ba 0.5 Nb 2 O 6 ͑SBN50͒ with and without Cr 2 O 3 dopant had been prepared by the solid-state reaction. The structural variations of undoped and Cr 2 O 3 -doped SBN were examined by the x-ray diffractometer. As the Cr 2 O 3 content increases, the lattice parameters remain almost unchanged initially but become greatly changed revealing the increase in a axis and the decrease in c axis when the Cr 2 O 3 content is Ͼ1 mol %, which was mainly influenced by the created oxygen vacancies. Isothermal sintering behavior of undoped and Cr 2 O 3 -doped SBN50 has been investigated. It was found that the creation of the charge-compensated oxygen vacancies and the accompanied structural change had a significant influence on the sintering behavior. The direct jumping path through vacant O sites ͑path 2 in Fig. 9͒ was further considered as the main reason for the enhancement of the densification rate and slight increase of the activation energy when the Cr 2 O 3 content is Ϲ1 mol % and the decrease of the densification rate but great increase of the activation energy when the Cr 2 O 3 content is Ͼ1 mol %. T max ͓temperature at the maximum dielectric constant ͑ max ͔͒ decreased with the increase of Cr doping and is essentially determined by the structural change of the NbO 6 units in SBN. max is suggested to be determined by the competition between the reduction of the polarization due to the substitution of Cr for Nb and the enhancement of the polar moment arising from the weakening of Nb-O bonds due to the creation of the oxygen vacancies.

Diffuse ferroelectric phase transition in Na2Pb2Nd2W2Ti4Nb4O30 ceramic

“…Tri or pentavalent cations are substituted at octahedral sites B1 and B2 [4] and C site (smallest interstice) is generally empty. Detailed literature survey reveals that a lot of work has been carried out on TB structure ferroelectric niobates in binary, ternary and quaternary systems [5][6][7][8][9][10][11][12]. Neurgaonkar et al [13] have reported the synthesis, structure and ferroelectric properties of M 6 2+ M 2 4+ Nb 8 O 30 where M 2+ = Ba, Sr or Ca and M 4+ = Ti, Sn or Zn.…”

Defects, Structure Changes, and the Effect of Random Fields on the Displacement of Off‐Center Ions in Sr0.5Ba0.5Nb2O6 Doped with Combinations of Ce and Cr

“…The defect reactions of undoped and Cr‐doped SBN50 had been determined via the study of the sintering behavior 34,35 . However, the conclusion drawn previously concerning the charge‐compensating defect of Ce‐doped SBN50 36 was misinterpreted and needs to be reassessed.…”

“…It clearly shows that the densification rate of SBN50 increases with the doping content for Ce dopant. Moreover, there are interesting results occurring in (Ce,Cr)‐doped SBN50: While the densification rate is not significantly changed with the doping content for the Ce/Cr ratio of 2, it is for Ce/Cr of 1, behaving like Cr‐doped SBN50 35 . Ce had been proved to be mainly in the valence state of 3+ 37 and suggested 38 to substitute Sr.…”

Dielectric and impedance properties of Ba2Sr3DyTi3V7O30 ceramics

“…The TB structured compounds of a type (A 1 ) 5 (A 2 )(B 1 ) 3 (B 2 ) 7 O 30 and (A 1 ) 4 (A 2 ) 2 (B 1 ) 4 (B 2 ) 6 O 30 form a typical tetragonal filled tungsten-bronze structures whereas with formula (A 1 ) 2 (A 2 ) 4 C 4 (B 1 ) 2 (B 2 ) 8 O 30 belongs to fully filled tungsten-bronze structure. Detailed literature survey on TB structure compounds reveals that a lot of work has been carried out on structural and dielectric property of TB structure niobates and tantalates binary, ternary and quaternary systems [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Detailed studies of structural and electrical property especially impedance and conductivity of some members of this family is still lacking.…”