X-ray diffraction and dielectric studies were performed on synthesized ceramic samples of the section (1–x) (0.8PbMg[Formula: see text]Nb[Formula: see text]O[Formula: see text]BiScO 3 )⋅ x(0.8PbTiO[Formula: see text]BiScO 3 ) with [Formula: see text]–1 of the ternary BiScO 3 –PbTiO 3 –PbMg[Formula: see text]Nb[Formula: see text]O 3 (BS–PT–PMN) system, including the temperature dependence of thermally stimulated depolarization currents (TSDC). It was found that the samples are solid solutions with a perovskite structure, which have cubic symmetry in the range of x = 0–0.587 and tetragonal symmetry in the range of x = 0.680–1. In the intermediate composition range of x = 0.587–0.680 (morphotropic region — MR), the samples consist of a mixture of solid solutions of different symmetries. Data on the change in dielectric properties and TSDC(T) dependencies of solid solutions with a change in their composition were obtained. It was found that samples of compositions x =0–0.625 and 0.6875–1 exhibit relaxor-ferroelectric and conventional ferroelectric properties, respectively, while samples of compositions x = 0.625–0.6875 combine ferroelectric and relaxor-ferroelectric properties.

Ceramic samples of the ([Formula: see text])BaTiO3⋅xPbFe[Formula: see text]W[Formula: see text]O3, [Formula: see text] (([Formula: see text])BT⋅xPFW) system were synthesized by solid-state reactions method. The samples were characterized by X-ray diffraction (XRD) and dielectric studies, as well as by the measurements of the thermally stimulated depolarization currents (TSDC). It was found that the predominant phase in the samples is presented by the (Ba[Formula: see text]Pbx)(Ti[Formula: see text]Fe[Formula: see text]W[Formula: see text])O3 solid solutions with a perovskite structure, herewith the samples with [Formula: see text] are practically single-phase, and with [Formula: see text] contain the impurity phase BaWO4 (up to 15 mass.% at [Formula: see text]–0.90). Information has been obtained about the changes in the structural and dielectric characteristics of the solid solutions with the change of their composition. It is established that the solid solutions crystal lattice symmetry at 296 K changes from tetragonal at [Formula: see text] to cubic at [Formula: see text]. An increase in the PFW content in solid solutions causes a gradual change in their properties from ferroelectric at [Formula: see text] to relaxor ferroelectric at [Formula: see text], and then to properties similar to those of the dipole glass with weak or zero correlation between dipoles at [Formula: see text]. The addition of BT to PFW leads to rather quick degradation of the relaxor ferroelectric properties of PFW in the region [Formula: see text]–1.0.

Single-crystal samples of the 3R-CuCrO2 phase (R3m, a = 2.9613(2) Å, c = 17.098(2) Å) with a delafossite structure were grown by the flux method. Structural parameters were refined by X-ray structural analysis. The elemental composition of the grown crystals was confirmed by Auger electron spectroscopy. A threshold electric field switching effect from a high-resistance to a low-resistance state was discovered. The effect is characterized by a jump in electrical resistance (up to 5 orders of magnitude at E = 4.7 kV/cm, T = 120 K) and S-shaped current–voltage characteristics with a region of negative differential resistance. The temperature dependences of dielectric permittivity and dielectric loss tangent exhibit a Debye-type relaxation process with an activation energy of 0.51(3) eV. The observed features of dc conductivity, current–voltage characteristics, and dielectric properties interpreted on the basis of the existence of charge carriers in a small polaron state and the destruction of this state by the electric field.

LiCu3O3 is a novel two-dimensional S = 1/2 antiferromagnet with randomly depleted square lattice. The crystal structure contains two types of square planes with different Cu2+-> Li+ substitution rates (20% and 40%). 7Li NMR and magnetization measurements performed on single crystals of LiCu3O3 revealed the occurrence of magnetic order at Tc1 = 123 K and the change of the magnetic state at Tc2 approximate to 30 K. The high-temperature transition can be attributed to establishment of magnetic order in planes with higher concentration of magnetic ions and the low-temperature transition to the magnetic ordering in planes with lower concentration of magnetic ions. Broad continuous NMR spectra below Tc1 reflect a continuous distribution of values or directions of magnetic moments in LiCu3O3 typical for spiral, spin-modulated magnetic structures or structures with frozen disorder. Magnetization measurements revealed a spin-flop transition which indicates weak uniaxial anisotropy of the spin structure. The relatively small magnetic susceptibility at all orientations of applied magnetic field shows that the magnetic structure is rigid since the estimated value of saturation field derived from differential susceptibility measured at mu 0H = 5 T is mu 0Hsat approximate to 200 T.

For over a century, materials science has been focused on comparing magnetism and ferroelectricity, revealing similarities in order types, domains, hysteresis, and responses to external stimuli. The exceptional physical properties of magnets often originate from frustration, which can result from site disorder and lattice geometry. While disordered relaxor ferroelectrics exhibit ultra-high dielectric and piezoelectric properties and fingerprinted behavior similar to spin glasses, ferroelectric-like materials with clear geometrically frustrated states have not been previously identified. Here we introduce a new type of relaxor material, a geometrically frustrated relaxor, exemplified by a Bi2Ti2O7 single crystal with a compositionally ordered pyrochlore structure. Our findings demonstrate canonical relaxor behavior, including dielectric anomalies, dipole freezing, non-ergodicity and a lack of spontaneous phase transitions. Furthermore, we show the emergence of a unique dipole ice state upon cooling, arising from conflicting order parameters related to two mutually exclusive rigid unit modes of Bi4O' tetrahedral rotations. The coexistence of these rotations does not satisfy symmetry constraints, causing geometrical frustration and suppressing the long-range order. The results provide the structural mechanism of geometrical frustration manifestation in Bi-containing pyrochlores, opening up avenues for exploring exotic ground states and advanced functionalities in dielectric materials.

Samples of the CuCr1-xAlxO2 system with x = 0, 0.25, 0.5, 0.75, 1 were synthesized using conventional ceramic technology. X-ray diffraction phase analysis data indicate the formation of an unlimited solid solution in the system with the delafossite crystal structure (a = 2.97–2.95 Å, c = 17.1–16.9 Å, sp. gr. R-3 m). Scanning electron microscopy data show that in samples with x = 0.25, 0.5, 0.75, particles of large and small sizes are embedded into each other. The calculated average grain sizes of the samples vary from 1.2 to 7.5 µm. The temperature dependencies of the electrical resistance of the samples under direct current were studied in the temperature range from 77 to 300 K with electric field strengths of 0.001, 0.94, 1.27, and 1.5 kV/cm. The current–voltage characteristics of the samples were studied in the range of electric field strengths up to 4.5 kV/cm at temperatures of 120, 175, and 220 K. It was established that the application of a constant electric field of 0.94, 1.27, and 1.5 kV/cm leads to switching from a high resistance state to a low resistance state. This switching is manifested in the form of giant resistance jumps (up to six orders of magnitude) in the temperature range of 90–200 K, as well as in the form of S-shaped volt-ampere characteristics containing a region of negative differential resistance. An interpretation of the observed switching effect is provided based on the polaron mechanism of conductivity.

The effect of doping on the chemical and physical properties of semiconductors, alloys, ferroelectrics, glasses, and other substances has been a classic topic in materials science for centuries. Strontium titanate, SrTiO3, is an archetypal perovskite of interest for both fundamental science as quantum paraelectric and numerous outstanding physical properties and applications, including dielectrics, tunable microwave and photovoltaic devices, superconductors, thermoelectrics, potential multiferroics. Its chemical doping with transition metals leads to new functionalities, but intrinsic mechanisms of structural responses, activated by impurities, have not been systematically investigated. Herein, we present the results of a comparative study of the crystal structure, vibrational spectra, and dielectric properties of SrTiO3:M (M = Mn, Ni, and Fe, 2 at%) single crystals. It is shown that impurities constitute a different tendency to off-centering and the formation of dipoles: Mn and Fe atoms are shifted from the center of the oxygen octahedron, while Ni atoms remain on-centered. As a result, small chemical doping has a dramatic effect on the dielectric response through various structural mechanisms, including the pseudo Jahn-Teller effect, the first-order Jahn-Teller effect, and defect-induced distortion. These findings open up fundamentally new possibilities for the practical solution of a difficult problem: controlling the dielectric responses of quantum paraelectrics by choosing the type of chemical additive.

Ceramic samples of the ([Formula: see text])BaTiO 3 ⋅xPbFe[Formula: see text]W[Formula: see text]O 3 , [Formula: see text] (([Formula: see text])BT⋅xPFW) system were synthesized by solid-state reactions method. The samples were characterized by X-ray diffraction (XRD) and dielectric studies, as well as by the measurements of the thermally stimulated depolarization currents (TSDC). It was found that the predominant phase in the samples is presented by the (Ba[Formula: see text]Pb x )(Ti[Formula: see text]Fe[Formula: see text]W[Formula: see text])O 3 solid solutions with a perovskite structure, herewith the samples with [Formula: see text] are practically single-phase, and with [Formula: see text] contain the impurity phase BaWO 4 (up to 15 mass.% at [Formula: see text]–0.90). Information has been obtained about the changes in the structural and dielectric characteristics of the solid solutions with the change of their composition. It is established that the solid solutions crystal lattice symmetry at 296 K changes from tetragonal at [Formula: see text] to cubic at [Formula: see text]. An increase in the PFW content in solid solutions causes a gradual change in their properties from ferroelectric at [Formula: see text] to relaxor ferroelectric at [Formula: see text], and then to properties similar to those of the dipole glass with weak or zero correlation between dipoles at [Formula: see text]. The addition of BT to PFW leads to rather quick degradation of the relaxor ferroelectric properties of PFW in the region [Formula: see text]–1.0.

Ceramic samples with compositions along the (1 – 2 x )BiScO 3 ·(2 – y ) x PbTiO 3 ∙ yx PbMg 1/3 Nb 2/3 O 3 ( y = 1.2, 1.0, 0.9, 0.5) sections in the BiScO 3 –PbTiO 3 –PbMg 1/3 Nb 2/3 O 3 (BS–PT–PMN) system have been characterized by X-ray diffraction and dielectric, piezoelectric, and thermally stimulated depolarization current measurements. The materials with 1 – x ≲ 0.5 have been shown to consist of perovskite solid solutions. With increasing BS content, the symmetry of the solid solutions rises from tetragonal to cubic. In the intermediate composition region (morphotropic region (MR)), the samples consist of a mixture of solid solutions differing in symmetry. We have located the MR boundaries and examined the effect of composition on the dielectric and piezoelectric properties of the solid solutions.

Systematic study of the terahertz soft -mode in SrTiO3: M thin (150 nm) films doped (2 at%) with transition metals M = Mn, Fe, Ni, Co is performed at frequencies 7-1000 cm(-1) and temperatures 5-300 K. The soft mode dielectric strength and frequency follow the Barrett -like temperature behaviours with unusually high quantum temperatures and large in magnitude negative Curie temperatures, indicating strong destabilization of the ferroelectric state due to a combined effect of quantum fluctuations, dead layers at the boundaries of crystallites, misfit strains within crystallites and disorder induced by doping. Dopant-dependent variation in the asymmetry of the Fano resonance describing coupling of the TO2 phonon and continuum states of polarization fluctuations is observed suggesting presence of polar nanoregions in the films. Clear correlation between the asymmetry parameter and the Barrett quantum temperature is observed that highlights the complex character of the local structure -dielectric properties relationships in the films.

Single crystal X-ray diffraction (XRD), thermogravimetric, and dielectric studies are performed for single and polycrystalline samples of [(1–x)PbO + xWO3], 0≤ x ≤0.20, synthesized by solid phase reactions and crystallization of melts. The formation of previously unknown solid solutions based on the tetragonal form of lead oxide (α-PbO) – Pb1–2xWxO1+x, x ≈ 0.05 is observed. Single crystals of solid solutions are analyzed by XRD at 100 K and 293 K. It is found that their crystal structure isotypical to α-PbO is characterized by the orthorhombic space group Cmma with unit cell parameters (293 K) a = 5.510 Å, b = 5.570 Å, c = 5.301 Å. The main structural characteristics of solid solutions are determined. A structural model of the formation of solid solutions is established, according to which partial W substitution for Pb in α-PbO is accompanied by the inclusion of additional oxygen atoms to the location of lone pairs of substituted Pb2+ and the formation of vacancies in this cation sublattice. Temperature dependences of the permittivity and losses of solid solution crystals studied in the temperature range T = 80-570 K and at frequencies f = 1-1000 kHz do not have features characteristic of phase transitions.

The work is devoted to the fabrication and study of electret material based on cellulose diacetate polymer film with an intercalated active component, polar macromolecules Zn{(NH 2 ) 2 CO} 2 Br 2 . The introduction of macromolecules into the film was carried out during its formation from solutions of various concentrations of cellulose diacetate and Zn{(NH 2 ) 2 CO} 2 Br 2 in tetrahydrofuran with ethyl alcohol under the action of a constant electric field of 2–4 kV cm –1 . The temperature curves of the dielectric constant ε, the dielectric loss tangent tan δ, as well as the thermally stimulated depolarization currents j of the resulting films were determined. It was established that modification leads to the appearance of additional maxima in the ε( T ), tan δ( T ), and j ( T ) curves caused by the active component embedded in the film. Modification of a cellulose diacetate film causes an increase in the value of j and the surface charge density found from the j ( T ) curve by more than two orders of magnitude. The results obtained indicate the possibility of application of the method under consideration to fabricate electret films.

Путем медленного охлаждения расплавов получены монокристаллы (Pb0.86Sr0.14)5Ge3O11. Изучено влияние облучения высокоэнергетическими электронами флюенсами до 6.2×1018э/cм2 на структурные и диэлектрические свойства этих кристаллов. Изучена зависимость параметров кристаллической структуры от величины флюенсов, установлен структурный механизм избирательного замещения Pb на Sr. Найдено, что позиции свинца с неподеленной парой электронов остаются свободными от замещения катионами стронция. Вплоть до флюэнса 6.2×1018э/cм2 структура (Pb0.86Sr0.14)5Ge3O11 сохраняет совершенство. Показано, что облучение данными флюенсами сохраняет параэлектрическую структуру при 293К (пр. гр. P) и приводит лишь к незначительным изменениям атомных смещений. Характер температурных зависимостей диэлектрических проницаемости и потерь (в интервалах 5-300 K и 1-1000 кГц) указывает, что облучение сопровождается как смещением ТС от 158 K до 145 K, так и усилением размытия сегнетоэлектрического фазового перехода.

Ceramic samples with compositions along the (1 – 2x)BiScO3·(2 – y)xPbTiO3∙yxPbMg1/3Nb2/3O3 (y = 1.2, 1.0, 0.9, 0.5) sections in the BiScO3–PbTiO3–PbMg1/3Nb2/3O3 (BS–PT–PMN) system have been characterized by X-ray diffraction and dielectric, piezoelectric, and thermally stimulated depolarization current measurements. The materials with 1 – x ≲ 0.5 have been shown to consist of perovskite solid solutions. With increasing BS content, the symmetry of the solid solutions rises from tetragonal to cubic. In the intermediate composition region (morphotropic region (MR)), the samples consist of a mixture of solid solutions differing in symmetry. We have located the MR boundaries and examined the effect of composition on the dielectric and piezoelectric properties of the solid solutions.

Dielectric spectra of SrTiO 3 and SrTiO 3 :Mn single crystals have been studied in the frequency range of 10‒3000 cm –1 and in the temperature range of 5–297 K using time-domain terahertz spectroscopy and Fourier-transform infrared spectroscopy. A comparative analysis of the experimental results made it possible to detect a significant broadening of the absorption lines corresponding to the Slater and Last phonon modes, while the parameters of the Axe mode when replacing Ti with Mn (2 at %) stay invariant. This effect is associated with an enhance in structural disorder in the cation subsystem (B-sublattice) of the SrTiO 3 crystal. It has been established that doping with Mn ions reduces the antiferrodistortive phase transition temperature by about 20 K, but hardly affects the character of the temperature dependence of the parameters of a ferroelectric soft mode at temperatures of about 60–297 K. It has been found that an additional excitation with the frequency below the frequency of the ferroelectric soft mode should be taken into account for an appropriate model description of the dispersion of the permittivity of SrTiO 3 :Mn in the terahertz frequency range. The results obtained in this work indicate that dielectric relaxation in the SrTiO 3 :Mn crystal is due to thermally activated hops of Mn atoms between displaced (noncentral) crystallographic sites; i.e., the mechanism of radiofrequency relaxation in SrTiO 3 :Mn is hopping rather than polaronic, which is also actively discussed in the literature.

This paper presents the results of a systematic study aimed at searching for organometallic molecules with a large dipole moment in order to create new film electret materials. A number of porphyrin complexes of transition metals, titanium, and vanadium and also complexes with bismuth( iii ) iodide with an axial metal—oxygen bond were synthesized. The obtained compounds were identified by physicochemical methods (IR spectroscopy and X-ray photoelectron spectroscopy). The optimized geometry of the complexes, their vibrational spectra, dipole moments, and charge density distributions were evaluated by quantum chemical calculations. The Mulliken population analysis was performed. The maximum dipole moments were found for BiI etioporphyrin II (6.47 D) and BiI 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (3.87 D). The metal ion acts as a transmitter of electron density from nitrogen atoms to the counterion, resulting in an increase in the dipole moment of the molecule as a whole compared to the starting porphyrin ligands. The inclusion of porphyrin complexes under the action of an electric field resulted in the formation of polyvinyl acetate films. Copper layers 100 nm thick were deposited by magnetron sputtering onto both sides of these films. The dielectric properties and the temperature dependences of thermally stimulated depolarization currents of the obtained samples were studied. All samples were found to have a pronounced electret effect.

Single crystals of (Pb0.86Sr0.14)5Ge3O11 are prepared by a slow melt cooling. The effect of high-energy electron irradiation with fluences up to 6.2·1018 e/cm2 on the structural and dielectric properties of these crystals is studied; the dependence of crystal structure parameters on the fluences is considered; the structural mechanism of selective substitution of Pb by Sr is established. It is determined that the sites occupied by lead with a lone pair are not substituted by strontium cations. Up to the fluences of 6.2·1018 e/cm2, the (Pb0.86Sr0.14)5Ge3O11 structure remains perfect. It is shown that the irradiation with these fluences preserves the paraelectric structure at 293 K ( $$P\bar{6}$$ space group) and causes only minor atomic displacements. The temperature dependences of the dielectric permittivity and the dielectric loss (in the ranges of 5-300 K and 1-1000 kHz) show that the irradiation shifts TC from 158 K to 145 K and increases the diffusion of the ferroelectric phase transition.

The work is devoted to the fabrication and study of electret material based on cellulose diacetate polymer film with an intercalated active component, polar macromolecules Zn{(NH2)(2)CO}(2)Br-2. The introduction of macromolecules into the film was carried out during its formation from solutions of various concentrations of cellulose diacetate and Zn{(NH2)(2)CO}(2)Br-2 in tetrahydrofuran with ethyl alcohol under the action of a constant electric field of 2-4 kV cm(-1). The temperature curves of the dielectric constant epsilon, the dielectric loss tangent tan delta, as well as the thermally stimulated depolarization currents j of the resulting films were determined. It was established that modification leads to the appearance of additional maxima in the epsilon(T), tan delta(T), and j(T) curves caused by the active component embedded in the film. Modification of a cellulose diacetate film causes an increase in the value of j and the surface charge density found from the j(T) curve by more than two orders of magnitude. The results obtained indicate the possibility of application of the method under consideration to fabricate electret films.

Stoichiometric single crystals of Pb 5 (Ge 1– х Si x ) 3 O 11 solid solutions (0 ≤ x ≤ 0.55) are obtained by slow cooling of 5PbO·3(1– y )GeO 2 ·3 y SiO 2 melts. The chemical analysis confirms their cation and anion stoichiometry. The effect of their high-energy (10 MeV) electron irradiation with fluences from 0.1·10 18 e/cm 2 to 4.39·10 18 e/cm 2 on the structural, ferroelectric, and nonlinear optical characteristics of the crystals is studied for the first time. The dependence of crystals on concentrations and fluences is detected. According to the date of dielectric spectroscopy and second harmonic generation of laser radiation, the doping with Si causes a systematic shift of T c to low temperatures, a decrease in the peak value of the dielectric permittivity, and a noticeable phase transition smearing with transforming to the zelaxor ferrollectric state of x = 0.35. According to the structural studies of initial and irradiared, Pb 5 (Ge 1– x Si x ) 3 O 11 crystals, they retain the structural perfectness without any signs of amorphization. Structural distortions of Pb 5 (Ge 1– x Si x ) 3 O 11 do not significantly depend on the fluence.