Domain wall contributions in Pb(Zr,Ti)O3 ceramics at morphotropic phase boundary: A study of dielectric dispersion

Abstract

The dielectric properties of undoped, Nb-, and Fe-doped Pb͑Zr, Ti͒O 3 ceramics with composition near morphotropic phase boundary were investigated in the frequency range from 1 MHz to 20.2 GHz at room temperature. Temperature dependences of dielectric permittivity Ј and loss Љ are measured at 100 kHz from 50 to 300 K and around 13.4 GHz from 100 to 300 K. These measurements permit estimation of the upper limit of the intrinsic permittivity and lower limit of the extrinsic contributions to the permittivity as a function of temperature. The extrinsic contributions account for more than 50% of the quasistatic dielectric permittivity in studied samples. © 2010 American Institute of Physics. ͓doi:10.1063/1.3455328͔Ferroelectric ceramics are the most widely used piezoelectric materials. The best properties are found in solid solutions exhibiting the morphotropic phase boundary ͑MPB͒. 1 The processes leading to the enhanced properties in the MPB region are of considerable technological and scientific interest. It is well known that in ferroelectric materials the motion of domain walls accounts for a large part of the experimentally observed piezoelectric and dielectric response. [2][3][4][5][6] In practice, the domain wall contributions are most often controlled by dopants, leading to electromechanically hard or soft materials. 1 In addition to dopants, domain wall contributions are dependent on microstructure and crystal structure of ceramics and, in general, it is found that the density of domain walls, domain structure, domain wall mobility, and the ceramics grain size are inter-related, and all depend on dopant concentration. 7-9 Within such a complex relationship among many parameters that influence properties, it is difficult to separate effects due to individual factors. It is advantageous when intrinsic properties are known either from a theory or direct measurements. This is unfortunately not the case for the most widely used piezoelectric material, Pb͑Zr, Ti͒O 3 ͑PZT͒, where single crystal data are not available and for which intrinsic ͑lattice͒ properties can be obtained only indirectly from the phenomenological LandauGinzburg-Devonshire ͑LGD͒ theory. One approach in separating lattice and domain wall contributions has been to measure properties of ceramics as a function of temperature and compare them with those obtained from the LGD theory. 10 The difference between thus obtained values is taken as an estimate of domain wall contributions. A good agreement between the dielectric properties measured in ceramics at low temperatures where domain walls are assumed to be frozen and values predicted from the LGD theory were taken as an indication that this method works well. 11 However, the recent discovery of a monoclinic phase in the MPB region of PZT ͑Ref. 12͒ has put some doubts in estimates derived from LGD approach based only on tetragonal and rhombohedral phases.Another approach to estimate domain wall and lattice contributions is to examine properties of ferroelectric ceramics as a function of frequenc...

Estimation of intrinsic contribution to dielectric response of Pb0.92La0.08Zr0.52Ti0.48O3 thin films at low frequencies using high bias fields

“…The threshold bias field required to suppress complete domain wall motion in PLZT 8/52/48 thin films was $20-25 MV/m, and the intrinsic permittivity measured at those fields was $300-350, agreeing well with that reported for PZT (52/48) bulk ceramics and thin films measured at low temperatures and high frequencies ($350). 5,6,8,[10][11][12][13][14] The intrinsic contribution to the measured dielectric permittivity response at room temperature was $29%-34%, agreeing well with the literature values. …”

“…6,[8][9][10] Second is by determining the permittivity dispersion characteristics in the gigahertz region, where the domain wall motions are too large to follow the oscillation frequency, thus not contributing to the measured permittivity. [11][12][13][14] Models based on Landau-Ginzburg-Devonshire theory have also been developed to predict and corroborate these experimental results. 14 Major drawbacks of these two methods are that (1) costs are high for associated cryogenic equipments, and (2) permittivity is difficult to evaluate at such high frequencies.…”

“…[11][12][13][14] We believe the weak dispersion (gradual decrease) in permittivity at frequencies below the relaxation frequency is also caused by domain wall motion. Figure 3 (left) shows the frequency dependence of permittivity under different bias fields.…”

Enhanced direct flexoelectricity in paraelectric phase of Ba(Ti0.87Sn0.13)O3 ceramics

“…The grain size can also be decreased by introducing dopant into the lattice. [29][30][31] If we can broaden the ferroelectric-paraelectric peak of BTS ceramics through such a grain size effect, a large flexoelectric response with good temperature stability may be expected.…”

Cryogenic motion performances of a piezoelectric single crystal micromotor

“…[4][5][6] Conventional piezoelectric lead zirconate titanate (PZT) ceramics at room temperature have shown a strong resonance electromechanical coupling ability; but at cryogenic temperature, the dielectric and piezoelectric properties decreased severely, especially for a soft PZT ceramic. [7][8][9] When temperature is close to absolute zero ($0 K), the piezoelectric and dielectric constants, d 33 , d 31 , e T , of PZT ceramics would converge. 9 However, piezoelectric single crystals are much different from PZT ceramics.…”