Evidence of polar nanoregions in quantum paraelectric KTaO3

Coexistence of the relaxor-like and ferroelectric behavior in K1-xLixTaO3

“…We have detected additional relaxation at low temperatures below 30 K (Figure 3). Most probably, the origin of this relaxation in the nominally pure KTaO 3 crystal, [31] as proposed by Bidault et al [37] and Levstik et al [38] and observed by us, lies in the localization of polarons on defects. Figure 4 shows the temperature dependences of the of the linear, x 0 1 , (Figure 4(a)) and the nonlinear,x 0 2 , (Figure 4(b)), x 0 3 , (Figure 4(c)), electric susceptibility and the scaled non-linear susceptibility, a 3 , (Figure 4(d)), for the four frequencies of the ac probing electric field: 37, 111, 317 and 1000 Hz at ZFH after ZFC regime.…”

“…The motions of the Ta ions are correlated and form the PNRs as precursors of ferroelectric domains. [31,48,49] In the KTaO 3 crystal, the effective local restoring force, the depolarization field, [44] associated with displacements of Ta ions, is large enough and thus the ferroelectric phase transition is restricted. The local strain field around the Li C ion induces a random electric field and the effective local restoring forces decrease.…”

Electric field‐revealed precursor ferroelectric properties of low lithium ion‐doped KTaO3

“…The linear electric susceptibility below the freezing temperature is independent of the frequency of the ac electric field, and increases from the value of to the value of at 4.2 K, owing to a net polarization. Comparing the value of at 4.2 K with that of KTaO 3 () , one estimates the net polarization volume to consist of 48% of the total volume of the sample. The nonlinear and electric susceptibilities are hardly detectable below T g at moderate driving fields.…”

“…KT crystal has a highly polarizable lattice, and is very sensitive to even small amounts of defects, impurities, and application of electric and elastic field . Recently, evidence of polar nanoregions (PNRs) in nominally pure KT crystals , SrTiO 3 , and a strain‐induced ferroelectric order in epitaxial thin films of KT have been reported. Particularly large interest was attracted by the solid solution: lithium‐doped potassium tantalate K 1– x Li x TaO 3 (KLT‐ x %Li for short), a very complex polar system .…”

Low temperature Raman scattering study of barium doped lead ytterbium tantalate ceramics

“…[1][2][3][4][5][6][7][8][9] The characteristic properties of RFEs include (i) high dielectric constant, (ii) strong dielectric dispersion around T m , the temperature corresponding to the dielectric constant maximum, (iii) diffused phase transition around T m and (iv) absence of macroscopic polarization far below T m . The polar nanoregions (PNRs) exhibited in RFEs are believed to be responsible for the multi-scale dynamics and spatial in-homogeneity that leads to the above peculiar properties.…”