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The temperature and frequency dependencies of the dielectric susceptibility in relaxor electro-optical PLZT 8/65/35 modified with 3d transition-metal ions (Mn, Fe, Co, Ni) measured to study the aging and memory effects are reported. The studies of aging at room temperature show that 3d admixtures (Me) in PLZT 8/65/35 ceramics at small to medium concentration range (Me < 1.0 wt.%) change the depth of dispersion, the aging amplitude and the temperature range of the memory effect. At admixture concentrations Me →1.0 wt% the aging and memory effect are significantly reduced (or eliminated).The obtained results suggest that aging effects are determined by two substantial acceptor effects of the introduced ions: 1) formation of Me2+- VO (oxygen vacancy) dipoles and 2) Jahn-Teller effect.

The nature of intrinsic and impurity point defects in lead zirconate titanate (PZT) ceramics has been explored. Using electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS) methods, several impurity sites have been identified in the materials, including the Fe 3+ -oxygen vacancy (VO) complex and Pb ions. Both of these centers are incorporated into the PZT lattice. The Fe 3+ -V paramagnetic complex serves as a sensitive probe of the local crystal field in the ceramic; the symmetry of this defect roughly correlates with PZT phase diagram as the composition is varied from PbTiO 3 to PbZrO 3 . NMR spectra 207 Pb in PbTiO 3 , PbZrO 3 , and PZT with iron content from 0 to 0.4 wt% showed that increasing the iron concentration leads to a distortion of the crystal structure and to improvement of the electrophysical parameters of the piezoceramics. This is due to the formation of a phase which has a higher symmetry, but at high concentrations of iron (>0.4 wt%), it leads to sharp degradation of electrophysical parameters.

The short lived absorption induced by a pulsed electron beam in the led–lanthanum–zirconate–titanate (PLZT) optical ceramics was studied. The measured absorption spectrum covers 1.1–2.9 eV energy range and consists of several strongly overlapping peaks. The rise of the absorption is delayed with respect to the excitation pulse, due to charge carrier migration before trapping at centers responsible for the absorption. The formation rate of absorption centers and decay rate of absorption depend on the photon energy. The kinetics of short lived absorption varies over spectrum and can be approximated with a stretched exponent. The stretched exponent parameters indicate that the local disorder of a matrix is similar around all absorption centers.

A study of the effects of the 3d dopants Mn, Fe, Co, Ni, and Cu on relaxor behavior and other properties of the ferroelectric PLZT8/65/35(La8) ceramic compound by X-ray diffraction, electron microscopy and other techniques is reported. The complex dielectric permittivity ϵ* = ϵ′-iϵ′′ is measured in the 20–400°C range of temperature at frequencies within the range of 102 – 106 Hz. Essential changes caused by the admixtures in the behavior of dielectric permittivity with frequency and temperature are observed along with changes in the XRD SEM patterns are observed. The mechanisms of the phenomena are discussed.

Thermal lensing in relaxor type ferroelectrics as a function of temperature has been investigated by using pulse/probe method. Enhanced thermo-optical (TO) properties had been observed in 3d elements (Cu, Co) doped PLZT ceramics and in sodium-bismuth titanate single crystals near phase transitions (PT). Comparison of TO signals for several doped PLZT materials reveals that 0.5 wt.% Cu doping is responsible for improved thermal lensing parameters interpreted by optimal light absorption, heat transfer and possible PT adjustment. TO experiments in sodium-bismuth titanate single crystals ([001] cut) show enhancement of TO properties in the region of PT and coexisting phases (rhombohedral and tetragonal).

Thermo-optical phenomena in absorbing media containing nanosize ferromagnetic or ferroelectric particles in liquid or solid state matrix are investigated. Enhanced thermo-optical properties have been observed in lanthanum doped lead zirconate-titanate (PLZT) ceraMisc, sodium-bismuth titanate single crystals and ferrofluids near phase transitions.

The nature of intrinsic and impurity point defects in lead zirconate titanate (PZT) ceramics has been explored. Using electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) methods several impurity sites have been identified in the materials, including Fe3+-oxygen vacancy (VO) complex and Pb ions. Both of these centers are incorporated into the PZT lattice. The Fe3+-VO paramagnetic complex serves as a sensitive probe of the local crystalline field in the ceramic; the symmetry of this defect is roughly correlated with PZT phase diagram as composition is varied from PbTiO3 to PbZrO3. NMR spectra 207Pb in PbTiO3, PbZrO3 and PZT with iron content from 0 to 0.4 mol % showed that increasing the iron concentration leads to a distortion of the crystal structure and improve the electrophysical parameters of the piezoceramics. This is due to the formation of the phase, which has a higher symmetry, but at high concentrations of iron (> 0.4 mol. %) leads to sharp degradation of electrophysical parameters.

Optical spectra and dielectric parameters are used to study PLZT X/65/35 (X=4.5−11 at.% La) and PSN ceramics subject to gamma- electron-, and neutron irradiation. In neutron-irradiated ceramics stable defects, maintained at annealing up to 700 °C are manifested by a gradual shift of extinction edge near the fundamental absorption to longer wavelengths and by reduced polarization values. The thermal dependence of the extinction edge in reference samples of PLZT and PSN has been determined to be ca. 0.10 nm/deg (0.9 meV/deg) and 0.125 nm/deg, respectively in the range 20-500°C. In PLZT 6.5-8/65/35 ceramics a defect enforced phase transformation from the initial rhombohedral structure to “quasicubic” with essential broadening of the phase transition takes place.

The results of the first observation of 207 Pb NMR spectra both in pure PLZT and doped by chromium are reported. The observed NMR spectra peculiarities were shown to be dependent on lanthanum and chromium content, and connected with a distribution of chemical shift tensor values and their principal axis directions. The ESR spectra were measured in PLZT with Cr for the first time. The spectra were shown to be those of Cr 3+ , Cr 5+ and Ti 3+ their intensities being dependent on the La content. It was shown that with increasing La concentration the reduction of Cr 5+ to Cr 3+ and disappearance of Ti 3+ took place. The relative intensity of Cr 3+ and Cr 5+ in the ESR spectra was supposed to be proportional to the volume of PZT regions in PLZT samples. It follows both from ESR and NMR measurements that for lanthanum concentrations higher than 4.5% there are no local PZT regions in PLZT. The role of the obtained data for the appearance of dipole glass state is discussed.

X-band EPR spectra of PLZT 1/65/35 and PLZT 8/65/35 doped with 1% FE3+ were recorded at temperature range −175°C to 200°C. Three types of paramagnetic centers were found. Two of them are in strong axial and rhombic crystal field due to neighboring oxygen and lead vacancies. The other center has symmetry determined by polarization and oxygen octahedra tilt. EPR spectra of PLZT 8/65/35 are in agreement with its glassy behavior.

EPR spectra of PMN ceramics doped with 0.1 mol% Fe2O3 were recorded at T=100 K and T=475 K and were attributed to Fe3+ ions in positions with different local symmetries. Three types of Fe3+ paramagnetic centres of rhombic, axial and cubic symmetry in average and individual low-symmetry fluctuations were described by spin Hamiltonians with distributed constants. The other type of centre at T=100 K was found to retain the pure cubic symmetry of ideal homogeneous regions. The superhyperfine interaction between Fe3+ and neighbouring 207Pb nuclei is 4 mT. The mechanisms by which the paramagnetic centre symmetry is decreased involves a contribution from the cation disorder in B sites and a temperature dependent contribution of lattice distortions in polar regions. The oxygen sublattice shift was estimated.

This is the first presentation of optical absorption and luminescence emission and excitation spectra of transparent Plzt 10/65/35 (Pb0.9La0.1Zr0.65Ti0.35O3) and Plzt 8/65/35 (Pb0.92La0.08Zr0.65Ti0.35O3) ferroelectric ceramics, both undoped and doped with Cr2O3. Undoped samples exhibit a band gap absorption at 77 K near 365 nm and broad-band luminescence peaked at 610 nm, which is attributed to self-trapped exciton emission of Ti3+ Ox oxygen deficient complexes. The newly arising absorption, excitation and emission spectra of Cr2O3-doped PLZT are ascribed to transitions of Cr3+ and Cr5+ in octahedral positions. The temperature dependence of the inhomogeneously broadened R line luminescence of Cr3+ (2Eg 4A2g), peaked at ≈ 13610 cm−1 at 77 K in Plzt 8/65/35, reveals a line split in the vicinity of 183 K. This is tentatively attributed to an unknown low-temperature lattice reconstruction or to a phase transition. Die optischen Absorptions-, Emission- und Anregungs-Spektren der Lumineszenz von transparen-ten, undotierten und mil Cr2O3 dotierten Plzt 10/65/35 (Pb0.9La.0.1Zr0.65Tio.35O3) und 8/65/35 (Pb0.92La0.08Zr0.65Ti0.35O3) ferroelektrischen Keramiken wird erstmals prasentiert. Die undotierten Proben zeigen bei 77 K. Bandkantenabsorption in der Nahe von 365 nm und Breitband-Lumineszenz mit einem Maximum bei 610 nm, fur welche die, „self-trapped” Exzitonencmission der Sauerstoffdefizit-Komplexe Ti3+ Ox verantwortlich ist. Die zusatzlichen Absorptions-, Anregungs- und Emission-Banden im mit Cr2O3 dotierten PLZT gehoren zu Ubergangen der Cr3+ - und Cr5+-Ioncn in oktaederischen Positionen. Die Temperaturabhangigkeit der inhomogen verbreiterten R-Linien-Lumineszenz des Cr3+ (2Eg 4A2g) mit Maximum 13610 cm−1 bei 77 K im Plzt 8/65/35 zeigt eine Linienaufspaltung in der Nahe von 183 K. Dieser Effekt wird vorlaufig einer unbekannten Tieftcmperatur-Gitterrekonstruk-tion beziehungsweise einem Phasenubergang zugeschrieben.

Results of Mn, Fe, Co, and Cu admixture EPR spectra studies in PLZT and PMN ceramics are discussed. The spectra of Mn, Fe, and Co ions with dominating absorption at geff = 2.0 and 4.3 are proposed due to d5 (S = 5/2) configurations (Mn2+, Fe3+, Co4+). The latter can be used as probes disclosing specific features (glass-like behaviour) of the structures. The Jahn-Teller ions (Mn3+, Fe4+, Co5+, Cu2+) are responsible for the dopant effect, e.g., the shift of the e(T) maximum to higher temperatures. The microscopic nature of differences of the dopant effect in PLZT and PMN materials and in the Mn Fe Co sequence is analyzed. [Russian Text Ignored].

The present paper deals with X-ray studies, dielectric measurements, linear expansion and Raman scattering in PLZT 1/65/35 ceramics doped with Mn and Fe. Admixture of Mn and Fe is found to increase the phase transition temperature and to appear in the tetragonal structure.

Data on chemical composition and spatial fluctuations thereof as well as fracture mode behaviour of pure and doped PLZT ceramics have been obtained.

Dielectric memory effects—effect of thermal memory (ETM) and effect of electric field memory (EFM) have been studied in (Mn, Fe, Co, Cu, Eu) doped PLZT ceramics. The obtained results have been discussed on the assumption that the ETM and EFM depends on relaxation of domain and interphase (polar and nonpolar) boundaries influenced by changes of defects conditions at doping.

This paper deals with Raman scattering room temperature spectra in a) PLZT X/65/35 (X = 0; 2; 8; 13 at.%); b) PLZT 8/65/35 with a different degree of deficiency of O2 and Pb; c) PLZT 8/65/35 and PMN ceramics doped with 3d elements (Cr, Mn, Fe, Co, Ni, Cu).

The authors discuss the physical background of the possible diversity of modified lead-containing perovskite ceramic compositions with field-induced first order and diffused phase transitions, a number of particular model devices being considered. Specific changes of structure and properties of the PLZT (La-doped lead titanium zirconate) ceramics doped with 3D-elements and with radiation effects in some of the compositions are examined. In the applications considered the modified lead-containing perovskite compounds are used in the form of plates (thick films) about 0.3-mm thick cut from bulk ceramic bulbs. >

Pulsed electron irradiation of ferroelectric PLZT ceramics or single-crystal SrTiO3 induces a short-lived optical absorption ΔD(t). The dependences of the kinetics of transient absorption on temperature and/or photon energy has been investigated. The transient absorption in the region hν > 2.0 eV is probably due to the creation of oxygen vacancies under electron irradiation, while the absorption in the region hν < 2.4 eV is due to the redistribution of defects in the cation sublattice. Dependences ΔD(hν), ΔD(t), and ΔD(t) for SrTiO3 and PLZT are similar. It is suggested that the quantitative differences between them are caused by the relatively higher mobility of the defects in SrTiO3.

The optical transmitance, crystallographic structure and dielectric properties for PLZT 8/65/35 samples either containing a number of various dopands (Mn, Fe, Co, Eu), or subject to neutron or electron irradiation have been studied.

Results of light absorption, x-ray diffraction and dielectric studies of Mn, Fe, Co and Eu-doped PLZT ceramics are reported. Most of them are qualitatively explained by dopant-induced change of vacancy concentration in sublattice A (and/or B) as well as in the oxygen sublattice. Possible use of the ideas of on-off effects of B(A) ions are discussed to explain relaxor properties and some other features of the PLZT ceramics.

Spectra, kinetics and thermal behavior of photoluminescence in PLZT X/65/35 ceramics have been studied with respect to different concentrations of different sorts of defects (inherent: lead and oxygen vacancies and dopant-induced by Mn, Fe, Co, Ni). The features observed are shown to be related to disordering of the material.

PLZT and PSN ceramics have been exposed to γ-radiation (energy ≈ 1.15 MeV, dose up to 3 · 109 rad), electron flux (≈4.5 MeV, dose up to 3.1018 electr./cm2) and fast neutrons (≥ 0.1 MeV, dose up to 1018 n/cm2). The irradiated material was used to study radiation effects on dielectric parameters (e and tgδ were measured at frequencies from 1 kHz to 5 MHz), polarization (dielectric hysteresis quasistatic loops) and non-linear optical properties (I2w). The measurements were made in the region of phase transition as well as to examine annealing of radiation-induced defects. As compared to PLZT the PSN ceramics is more resistant to radiation, the most sensitive PLZT compounds being with 7 ≤ × ≤ 9.5 at .% of La. Obtained results are explained by the change of ion charge, redistribution of vacancies in A and B sublattices of PLZT and by possible ion ordering in sublattice B of PSN with account for intrinsic fields in the relevant compounds.

1. The relationships between the change of critical parameters and the critical detonation velocities and the charge density, porosity, grain size, and quality of explosives have been studied in systems containing an explosive substance and an inert filler. A sharp difference is observed in the values of the critical detonation velocities in the case of monocrystalline grains of hexogen and industrial powders. 2. For a monocrystalline grain of hexogen with a filler (paraffin), a constant critical detonation velocity is characteristic (Dcr≃5300 m/sec). The latter is independent of the grain size (within the limits 0.1 to 0.85 mm studied) and also of the content of filler. Moreover, there is a proportionality between the grain size and the chemical-reaction time. The latter can be considered as confirmation for the layered combustion scheme of a grain. 3. With small contents of filler (porosity>20%) for charges of industrial grians of hexogen and trotyl, Dcr is constant. Subsequent increase of the degree of filling of the free space in the charge (up to complete filling) with an inert substance is accompanied by an increase of Dcr (with industrial hexogen from 5300 to 7300 m/sec and with trotyl from 4500 to 6300 m/sec) which, obviously, is due to reactions in the irregularities (micropores, dislocations) which are present in the charges. 4. The experimental data obtained agree poorly with the conclusions of [2, 5, 6] advancing crushing of the grains as a reason for explaining the disagreement between the reaction time in the detonation wave and the grain size of the explosive.

This work has been supported by Latvian state research program IMIS2 ., A series of PLZT (8/65/35) ceramics with different Mn2O3 concentration (0.01, 0.1, 0.3, 1.0, and 3.0% by weight) have been synthesized to figure out its influence on their dielectric properties. The complex dielectric permittivity ε* = ε′−iε″ as function of frequency and temperature as well as polarisation loops P(E) have been studied as a function of Mn concentration. It was found that Mn doping is restrained the Vogel-Fulcher law held in the unmodified PLZT compound producing essential change of the dependence of ε* on temperature and frequency and of the shape of P(E). The observed effects are explained by gradual involvement of Debye and Maxwell-Wagner polarisation mechanisms in relaxation processes with the growth of the concentration of Mn concentration admixture. A decrease of the ε'(T) maximum value and shift of the maximum to higher temperatures is observed. The observed effects are attributed to impacts of Mn2+ and Mn3+ ions: formation of oxygen vacancies paired with Mn2+ as dipoles and Jahn-Teller distortion prompted by Mn3+ ions., IMIS2; Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART²

i. A. V. Obmenin, V. A. Balykov, A. I. Korotkov, et al., Fiz. Goreniya Vzryva, ~, No. 4, 571 (1970). 2. A. A. Sulimov, A. V. Obmenin, A. I. Korotkov, et al., in: Combustion and Explosion [in Russian], Nauka, Moscow (1972). 3. D. Stirpe, J. O. Johnson, and J. Wackerly, J. Appl. Phys., 41, No. 9, 3884 (1970). 4. A. F. Belyaev, V. K. Bobolev, A. I. Korotkov, et al., The Transition from Combustion in a Condensed System to Explosion [in Russian], Nauka, Moscow (1973). 5. A. V. Dubovik and V. K. Bobolev, Blasting [in Russian], No. 63/20, Nedra, Moscow (1967). 6. K. K. Shvedov, S. A. Koldunov, and A. N. Dremin, Fiz. Goreniya Vzryva, 2, No. 3, 424 (1973). 7. A. N. Dremin and S. A. Koldunov, Blasting [in Russian], No. 63/20, Nedra, Moscow (1967).