Domain Structure Of Single Crystals Research Articles

The unexpected diffuse phase transition in relaxor-PbTiO3 ferroelectrics via acceptor modification

The diffuse phase transition (DPT) and domain structure are essential to the functional properties of relaxor ferroelectrics and are extremely sensitive to the ion doping. The utilization of acceptor doping has been observed to be an effective method in enhancing the high-power properties of relaxor ferroelectric materials. The present study aims to examine the acceptor-doped DPT and domain structure in single crystals of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3. An unexpected physical phenomenon was identified in which Mn-doping increased dielectric diffusion and lowered domain size while suppressing dielectric relaxation. Traceability investigations suggest that Mn-doping inhibited the growth of polar nanoregions by enhancing random electric fields, which increases dielectric diffusion while decreasing the domain size. Meanwhile, Mn doping redistributes the relaxation time function, which results in a reduction in dielectric relaxation. The current research deepens the understanding of the physical basis of DPT and can be applied to the development of high-performance piezoelectric materials.

Hierarchical domain structure of lead-free piezoelectric (Na1/2 Bi1/2)TiO3-(K1/2 Bi1/2)TiO3 single crystals

We report a unique hierarchical domain structure in single crystals of (Na1/2Bi1/2)TiO3-xat. %(K1/2Bi1/2)TiO3 for x = 5 and 8 by transmission electron microscopy (TEM). A high density of polar nano-domains with a lamellar morphology was found, which were self-assembled into a quadrant-like configuration, which then assembled into conventional ferroelectric macro-domains. Studies by high resolution TEM revealed that the polar lamellar regions contained a coexistence of in-phase and anti-phase oxygen octahedral tilt regions of a few nanometers in size. Domain frustration over multiple length scales may play an important role in the stabilization of the hierarchy, and in reducing the piezoelectric response of this Pb-free piezoelectric solid solution.

Formation of self-assembled domain structures in single crystals of lithium tantalate with artificial dielectric layer

ABSTRACTThe polarization reversal was studied in single crystals of lithium tantalate with intermediate deviation from stoichiometric composition (([Li]/([Li]+[Ta]) = 48.9%) with and without surface photoresist layer. The switching current was analyzed according to the stages of domain structure evolution revealed during in situ visualization of domain kinetics. The characteristic times of the switching process were extracted by fitting of the experimental data using modified Kolmogorov-Avrami model. The formation of the self-assembled domain chains was observed during polarization reversal with photoresist dielectric layer on one polar surface.

Piezoelectric and ferroelectric properties of organic single crystals and films derived from chiral 2-methoxy and 2-amino acids

ABSTRACTLocal piezoelectric and ferroelectric properties as well as morphology of single crystals and films of two novel chiral organic compounds derived from chiral 2-methoxy and 2-amino acids have been investigated. The crystals demonstrated piezoelectric response exceeding that of lithium niobate. The piezoelectric response was registered also in compound films. Piezoelectric properties and domain structure of single crystals and films have been studied by piezoresponse force microscopy.

Identification and mechanical control of ferroelastic domain structure in rhombohedralCaMn7O12

We report on observation of ferroelastic domain structure in single crystals of multiferroic ${\text{CaMn}}_{7}{\text{O}}_{12}$ at room temperature. Two types of ferroelastic domain wall are found, consistent with the material's rhombohedral symmetry that is reduced from cubic symmetry at higher temperatures. Using Raman spectroscopy along with other measurements, we develop a systematic method to determine the microscopic domain orientation. Moreover, we find a switching behavior of the domains, which allows us to detwin the crystals conveniently at room temperature using a moderate uniaxial compression. Our result paves the way for further spectroscopic study and domain engineering in ${\text{CaMn}}_{7}{\text{O}}_{12}$.

Temperature-induced martensite in magnetic shape memory Fe2MnGa observed by photoemission electron microscopy

The magnetic domain structure in single crystals of a Heusler shape memory compound near the composition Fe2MnGa was observed during phase transition by photoelectron emission microscopy at Beamline 11.0.1.1 of the Advanced Light Source. The behavior is comparable with recent observations of an adaptive martensite phase in prototype Ni2MnGa, although the pinning in the recent work is an epitaxial interface and in this work the effective pinning plane is a boundary between martensitic variants that transform in a self-accommodating way from the single crystal austenite phase present at high temperatures. Temperature dependent observations of the twinning structure give information as to the coupling behavior between the magnetism and the structural evolution.

Ferroelectric and Structural Antiphase Domains in Hexagonal RMnO3

ABSTRACTWe have investigated characteristic ferroelectric and structural antiphase domain structures in single crystals of hexagonal RMnO3 (R=Y, Ho, Lu, and Yb) by obtaining various electron diffraction patterns, dark-filed images and high-resolution lattice images. In the ferroelectric phase of RMnO3 characteristic domain structures consisting of six ferroelectric and structural antiphase domains, which can be identified as the “cloverleaf” pattern, is found in the (110) plane, in addition to the (001) plane, and are inherent to the ferroelectric phase of hexagonal RMnO3. In domain configuration with the cloverleaf pattern in the (110) plane, the structural antiphase boundaries are inclined to be parallel to the [001] direction.

Domain Wall Dynamics Near the Phase Transition in PZN-9%PT

To investigate the paraelectric–ferroelectric phase transition in relaxor Pb(Zn1/3Nb2/3)O3-9% PbTiO3, correlations and scaling relations were measured from the domain structure of single crystals near the Curie temperature using a multifractal analysis. The dynamics of the domain walls were observed in (100) platelets using polarized light microscopy. The complexity of the domain wall distribution was evaluated by means of its fractal dimension and singularity spectrum. The changes in the energy state of the samples are assessed by measuring changes of the spatial distribution of the walls as a function of temperature; this can be used to estimate the specific heat.

Ferroelectric properties of ruthenium-doped lead zinc niobate-lead titanate single crystal

Using atomic force microscopy and piezoresponse force microscopy (PFM), as well as complementary dielectric measurements, the ferroelectric domain structure of single crystals of pure and ruthenium (Ru)-doped 0.9Pb(Zn1/3Nb2/3)O3 (PZN)-0.1PbTiO3 (PT), and Ru/(Zn+Nb+Ti)∼0.002 was analyzed. The coexistence of tetragonal and nontetragonal ferroelectric domains in PZN-PT near the morphotropic phase boundary (MPB) was directly observed via PFM imaging. The incorporation of Ru in the perovskite structure substantially decreases the ferroelectric domain size, thus reducing the polar fraction distributed in the pseudocubic matrix. The polarization and strain hysteresis loops show that Ru doping leads to significant ferroelectric hardening, which is attractive for high-power applications. The local structure and valent state of the incorporated Ru cations were additionally analyzed by electron paramagnetic resonance spectroscopy. Our results demonstrate that doping of tetragonal PZN-PT near MPB is a promising route to design advanced multifunctional single-crystal materials.

Kinetics of ferroelectric domain structure: Retardation effects

We review the experimental and theoretical investigations of the kinetics of ferroelectric domain structure in single crystals and thin films. The significant influence of the retardation of screening process on the evolution of the domain structure is pointed out and is demonstrated in various experimental situations.

Fourier analysis of a space-periodic magnetic configuration using resonance depolarization of polarized neutrons

It is experimentally proved that, from the wavelength dependence of the spin-reverse probability of a polarized neutron moving through a macroscopic space-periodic magnetic field, it is possible to determine the coefficients of the Fourier expansion of the spatially dependent magnetic configuration under study. The possibility of applying the method for studying 90° domain structures in single crystals is pointed out.

Domain structure studies of the single crystal magnetic oxide Ba 3Co 2Fe 24O 41 (Co 2Z)

The domain structure of single crystals of the hexagonal ferrite Co 2Z (Ba 3Co 2F 24O 41) with an easy plane of magnetization has been studied with the Bitter technique. The results are consistent with the existence of large area 180° domain walls lying in the easy basal plane. No domain structure is visible on polished basal surfaces. The magnetization process in applied dc fields is dominated by the nucleation of reverse domains and the subsequent displacement of 180° walls. Both the remanence and coercivity are low. During the magnetization cycle domain contrast is observed which indicates the presence of a surface charge.

The magnetic domain structure of monocrystalline Co/sub 2/Y

The domain structure of single crystals of the hexagonal ferrite Co/sub 2/Y (Ba/sub 2/Co/sub 2/Fe/sub 12/O/sub 22/) with planar anisotropy has been studied with the Bitter technique. The results are consistent with the existence of large area domain walls parallel to the easy plane. The domain spacing accords with a previous theoretical model. No domain structure is visible on the basal plane. The authors have followed the magnetization process from studies on axial samples. On reducing from saturation 360 degrees walls are first nucleated; these then split into reversed domains with 180 degrees walls which move independently. A converse behavior is observed as the field is reversed and increased to saturation in the opposite sense.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Analytical Electron Microscopy of Ferroelectric BaTiO3

Ferroelectric BaTiO3 has been the subject of TEM investigations since the early 1960’s(1,2). However most attention has been focussed on the ferroelectric domain structure in single crystals. This current work involves the analysis of polycrystalline, ferroelectric BaTiO3 from various commercial sources. This material is used for high capacitance capacitors because of its high dielectric constant. Various dopants (Zr and Bi oxides predominantly) must be added to stabilize the high dielectric constant over a range of temperatures(3). Impurities such as Al2O3 and SiO2 can also be present due to ceramic processing procedures. An analysis of this material was performed using TEM and energy dispersive analysis of x-rays (EDAX) in order to understand better the effects of these dopants and impurities on the structure and chemical composition of BaTiO3.

The temperature dependence of the domain structure of uniaxial single crystals with high-anisotropy field

The temperature dependence of the domain structure of single crystals of uniaxial ferrimagnetic oxides with high-anisotropy field in the SrO( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6 - x</tex> )Fe <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</tex> Al <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> O <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> compositional series, with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x = 1.8</tex> and 2.4, was investigated. The domain configurations of thermally and/or ac field demagnetized states and the changes in dc and ac fields were observed by means of the colloid technique using a suspension in paraffine oil. The temperature dependence of the wall energy density between room temperature and the Curie point (270°C) of the compound with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x = 1.8</tex> was computed using the temperature dependence of the saturation magnetization and the domain width for the Kittel-like domain structure. It has been found that the room temperature domain structure of the compound with <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x = 2.4</tex> depends upon the mode of demagnetization, i.e., thermally or in the ac field. The ac demagnetized states are more stable than the thermally demagnetized ones. The samples exhibit a room temperature memory of the previous magnetization, which decreases with rising temperature. This memory is completely lost after heating at 400°C. The peculiarities of the temperature dependence of the domain structure and magnetic behavior on thermal cycling are explained by considering the existence of magnetic inhomogeneities within the crystal.

The domain structure of alloys YuNDK24, YuNDK35T5, and YuNDK40T7 in the high-coercivity condition

1. After optimal TMT, domains of magnetic interaction appear in the form of a band system only in single crystals of the YuNDK24 alloy. 2. Rearrangement of the domain structure in single crystals of alloy YuNDK24 is observed in fields corresponding to the steep sections of the hysteresis loop. 3. The domain structure depends on the magnitude and the uniformity of the demagnetizing field; the more intense and the less uniform the field, the more distinct the domain structure.

Microscopic and X-Ray Studies on Tungsten Oxide (WO3)

The domain structure of single crystals of tungsten oxide was observed between -130°C and 1200°C. An abrupt change of domain structure was observed at -50°C on cooling and it varied only gradually on heating, as reported (previously). No change was observed at. the 910°C transition. The crystal structure was investigated in detail near 910°C. and 1230°C respectively. No change of crystal symmetry except for only slight anomalies of lattice constants was observed at these two transitions. Ferroelectricity or antiferroelectricity and bond structure of this substance were discussed using the result of observations, and it was stressed that these would be in an intimate relation with each other.

A Quantitative Study of the Domain Structure of Single Crystals of Silicon-Iron by the Powder Pattern Technique

A quantitative study of the domain structure of single crystals of silicon-iron has been made by the powder pattern method, special examination being made of the patterns formed on a strip specimen whose surface was approximately a (100) plane with a [011] direction parallel to the long edge of the strip. For Mode III magnetization, which occurs when a field acts inside the specimen parallel to the [011] direction, the line deposits formed at right angles thereto were on the average spaced in good accord with N?el's theory in the case of wide strips, but in less good accord for narrow strips. Qualitative results of other measurements on strip and disc specimens are reported and interpreted.