Growth of Lithium Niobate Single Crystals from Granulated Charge

Comparative studies of different techniques and the synthesis of single-phase granulated mixtures of high density essentially improving technical and economical parameters of lithium niobate single crystal technology are reported. Efficiency of using granulated mixtures of high density in growing lithium niobate single crystals is discussed.

Broadband Dielectric Investigation of Sodium Potassium Niobate Ceramic Doped 8% of Antimony

In this work we present dielectric permittivity measurement results of KNN ceramic doped antimony (K0.5Na0.5)(Nb0.92Sb0.08)O3 with sintering aid MnO2 (0.5 mol% MnO2) (KNNSbx + 0.5Mn). Its dielectric properties were investigated in broad frequency (from 20 Hz to 32 GHz) and temperature (from 26 K to 780K) ranges. Above room temperature obtained results show two diffused phase transitions. Below room temperature investigation revealed dielectric permittivity dispersion similar to the relaxor one. The obtained mean relaxation times fulfills Arrhenius relationship with dipole activation energy Ea/kB = 2282 K.

<title>Dielectric response to low and infra-low frequency in layered ferroelectrics</title>

Features of dielectric response to frequencies in the 0.25.1000 Hz range in ceramic samples of BaBi2Nb2O9, Na0,5Bi8.5Ti2Nb4O27, Na0,5Bi8.5Ti2Ta4O27, and K0,5Bi8.5Ti2Nb4O27 compounds are reported. Considerable relaxation of e'(T) and e"(T) maximums has been observed at all frequencies in BaBi2Nb2O9. Na0,5Bi8.5Ti2Nb4O27 and Na0,5Bi8.5Ti2Ta4O27 are characterised by broad maximums on e'(T) at frequencies below 100 Hz and a weak anomaly in K0,5Bi8.5Ti2Nb4O27 at temperatures well below the paraelectric phase transition. Increasing values of e' are observed at low temperatures in compounds containing sodium. The observed features of dielectric response are explained by largescale charge fluctuatio…

Relaxor ferroelectric PbSc1/2Nb1/2O3—PbZn1/3Nb2/3O3— PbMg1/3Nb2/3O3ceramics

Abstract Original ternary solid solutions PbSc1/2Nb1/2O3 — PbZn1/3Nb2/3O3-PbMg1/3Nb2/3O3 (PSN-PZN-PMN) have been synthesized by solid state reaction from oxides. Ceramic samples have been obtained by both conventional and hot pressing techniques. The density of the obtained hot pressed ceramics reaches 98% of the value calculated from X-ray data. Dense, high quality samples of pure PZN and compositions containing over 0.8 molar parts of PZN could not be obtained — porosity was up to 10% and they were mainly comprised of the cubic pyrochlore phase. Density, porosity, water absorbtivity, and dielectric permittivity and dissipation factor of the ceramic samples have been measured. Data of diff…

Radio and Microwave Spectroscopy of 0.2PMN-0.4PSN-0.4PZN Relaxor Ceramics

Dielectric spectroscopy results of 0.2PbMg 1/3 Nb 2/3 O 3 -0.4PbSc 1/2 Nb 1/2 O 3 -0.4PbZn 1/3 Nb 2/3 O 3 ceramics are reported for 200 < T < 450 K and 20 Hz < v < 11 GHz. Dielectric constant is very high (more than 12000) in the vicinity of the peak. Anomalous broad dielectric relaxation has been observed near and below the temperature of the maximum permittivity, T m (at 1 kHz). The distribution of relaxation times have been calculated directly from the dielectric spectra. At higher temperatures than the maximum permittivity, T m the distribution of the relaxation times is symmetrically shaped (Cole-Cole function satisfactory describes the dielectric response). At lower temperatures, the …

Effect of Zr4+Doping on the Electrical Properties of BaTiO3Ceramics

The BaZrxTi1-xO3 for 0⩽x⩽15 ceramics were prepared by a conventional solid state reaction method and were determined by an X-ray diffraction (XRD) and scanning electron microscopy (SEM) for crystallographic, surface morphological and compositional studies. A single phase with perovskite structure was identified in the samples at room temperature. No significant impurities were detected in an EDS spectrum and the samples are in good stoichiometric ratio. The temperature dependence of electric conductivity was evaluated in the temperature range from 300 to 550 K for a selected frequency by a HP4284 LCR meter. The activation energy was calculated from the Arrhenius plots.

Low temperature measurements by infrared spectroscopy in $CoFe_2O_4$ ceramic

In this paper results of new far-infrared and middle-infrared measurements (wavenumber range of 4000cm-1 - 100cm-1) in the range of the temperature from 300K to 8K of the CoFe2O4 ceramic are presented. The bands positions and their shapes are the same in the wide temperature range. The quality of the sample was investigated by X-ray, EDS and EPMA studies. The CoFe2O4 reveals the cubic structure (Fd-3m) in the temperature range from 85K to 360 K without any traces of distortion. On the current level of knowledge the polycrystalline CoFe2O4 does not exhibit phase transition in the temperature range from 8 K to 300 K.

&lt;title&gt;Dielectric polarization in &lt;emph type="1"&gt;x&lt;/emph&gt;PbZn&lt;formula&gt;&lt;inf&gt;&lt;roman&gt;1/3&lt;/roman&gt;&lt;/inf&gt;&lt;/formula&gt;Nb&lt;formula&gt;&lt;inf&gt;&lt;roman&gt;2/3&lt;/roman&gt;&lt;/inf&gt;&lt;/formula&gt;O&lt;formula&gt;&lt;inf&gt;&lt;roman&gt;3&lt;/roman&gt;&lt;/inf&gt;&lt;/formula&gt;-(1-&lt;emph type="1"&gt;x&lt;/emph&gt;)PbSc&lt;formula&gt;&lt;inf&gt;&lt;roman&gt;1/2&lt;/roman&gt;&lt;/inf&gt;&lt;/formula&gt;Nb&lt;formula&gt;&lt;inf&gt;&lt;roman&gt;1/2&lt;/roman&gt;&lt;/inf&gt;&lt;/formula&gt;0&lt;formula&gt;&lt;inf&gt;&lt;roman&gt;3&lt;/roman&gt;&lt;/inf&gt;&lt;/formula&gt; ferroelectric solid solutions&lt;/title&gt;

Manifestation of relaxor properties in the x PbZn1/3Nb2/3O3-(1-x )PbSc1/2Nb1/203 ceramic solid solution system, similar to those observed in lead magnesium niobates, are reported. Dependence of the effective dielectric permittivity and dielectric loss on the temperature at frequencies of 0.1-10 Hz and different measuring field amplitudes E 0 are examined ceramic samples of 0.05PbZn1/3Nb2/3O3-0.95PbSc1/2Nb1/203. It is demonstrated that the temperature at which the dielectric permittivity has a maximum, T m, decreases with the increase of E 0. The dependence of T m on the frequency in both strong and weak fields is shown to follow the Vogel-Fulcher law, with Voger-Fulcher temperature decreasi…

Chemical strain effects and changed lattice dynamic in (Sr1-1.5xBix)TiO3ceramics (x ≤ 0.15)

ABSTRACTIn this work lattice strain (induced by chemical Bi substitution on A-site) effects on the lattice dynamic of SrTiO3 ceramics were investigated by broadband dielectric spectroscopy in the very broad frequency range from 10 mHz up to 30 GHz and temperatures from 30 K to 500 K. Obtained results confirmed predicted induce of the ferroelectricity and suppression of the structural phase transition due to substitution of A-site ions – chemical straining of the lattice, both happening at the local scale but evident in macroscopic dielectric spectroscopy measurements. Calculated relaxation time distribution function broadens towards the longest relaxation times with temperature decrease and…

Broad Distribution of Relaxation Times in 0.6PMN-0.4PZN Relaxor Ceramics

In this paper dielectric spectra of 0.6PMN-0.4PZN ceramic obtained from broadband dielectric spectroscopy is presented. Measurements revealed an unusual relaxor like nature. Two different processes in the dielectric spectra have been observed. High frequency, or short relaxation times, behaviour is typical for ferroelectric crystals. Longest relaxation times do not follow Vogel—Fulcher dependence, which is unusual for relaxors.

Dipolar Glass-Like Perovskite Sr0.8Bi0.2TiO3Ceramic

In this work lead-free Sr0.8Bi0.2TiO3 ceramic have been investigated in the frequency range from 20 Hz to 36 GHz. The obtained results show pronounced dispersion below room temperature. It looks more similar to the one observed in dipolar glasses as in relaxors. Calculated relaxation time distribution function broadens towards longest relaxation times with decreasing temperature. The obtained most probable relaxation time fulfills Vogel-Fulcher relationship with the following parameters: dipole activation energy EA/kB = 1718 K, freezing temperature T0 = 65 K, attempt relaxation time, referring to dipole relaxation at very high temperatures, τ0 = 5.5·10−14 s.

Anomalous Broad Distribution of Relaxation Times in Mixed PMN-PSN Ceramics

Dielectric permittivity of 0.8PMN-0.2PSN ceramic was measured in the frequency range from 20 Hz to 3 GHz. The typical ferroelectrics relaxor dielectric dispersion was observed. From the frequency dependence of complex dielectric permittivity, the distribution of relaxation times was calculated. The low frequency limit of the distribution of relaxation times diverges according to the Vogel–Fulcher law with the freezing temperature T f = 226 K which is lower than in PMN ceramics, obtained previously. The comparison of distributions of relaxation times between 0.8PMN-0.2PSN and pure PMN tends to the conclusion about smaller polar nano regions in 0.8PMN-0.2PSN ceramic.

Dielectric nonlinearity of the PBB′B″O3 ferroelectric solid solutions

Abstract Obtaining of novel thin film materials for electrically tuneable capacities is one of the current problems of ferroelectric material application. Suitable ferroelectric compounds exhibiting broad phase transitions and small dielectric loss in the paraelectric phase have been searched for the purpose. Lead-containing niobates PbMg1/3Nb2/3O3 (PMN), PbNi1/3Nb2/3O3 (PNN) and PbZn1/3Nb2/3O3 (PZN) and their solid solutions have been found as most appropriate. Materials have been synthesized by solid phase reactions from the relevant oxides; ceramic samples were obtained by conventional ceramic technology. Results of the studies of thermal dependence of dielectric permeability and loss fa…

Broadband Dielectric Spectroscopy of PSN-Rich PMN-PSN Ceramics

The broadband dielectric permittivity of ordered 0.1PMN-0.9PSN and disordered 0.2PMN-0.8PSN ceramics was investigated. The anomaly of dielectric permittivity is clearly seen in the region of 370 K for 0.1 PMN-0.9 PSN at all frequencies. 0.2 PMN-0.8 PSN shows relaxor behaviour with huge frequency dispersion below 350 K. Calculated distribution of relaxation times shows noticeable influence of polar nano regions to the total dielectric spectrum below 320 K with the longest relaxation times edge diverging according to the Vogel-Fulcher law. In 0.1 PMN-0.9 PSN two a little overlapped peaks present in the distribution of relaxation times, influenced by displacive lead motions at high frequencies…

Far-infrared and THz spectroscopy of 0.4PMN–0.3PSN–0.3PZN relaxor ferroelectric ceramics

Abstract Temperature dependence of the optic phonons in 0.4PbMg 1/3 Nb 2/3 O 3 –0.3PbSc 1/2 Nb 1/2 O 3 –0.3PbZn 1/3 Nb 2/3 O 3 (0.4PMN–0.3PSN–0.3PZN) ceramics were studied by means of FTIR reflection and THz transmission spectroscopy in the temperature range of −253.15 to 226.85 °C. On heating from low temperatures, the A 1 component of the strongly split TO 1 mode softens towards the Burns temperature, but the softening ceases near 126.85 °C which could be a signature of polar cluster percolation temperature. Surprisingly, the TO 2 mode also softens on heating and follows the Cochran law with extrapolated critical temperature close to the melting point.

Storage of information in lithium niobate single crystals

Reported studies of recording information were made with a number of LiNbO 3 compositions: stoichiometric and congruent single crystals. The present study shows that recording is possible in pure LiNbO 3 single crystals and in single crystals containing inactive cation dopants. Recording in stoichiometric crystals is likely possible because of a considerable amount of electrons localised in shallow traps. Absence of recorded information in pure congruent crystals were observed.

Modified YBCO superconductor-ferroelectric composites: Bulk materials and thick films

Bulk samples and 50–125 μm thick films of (1-x)YBa2Cu3O7−δ-xBaTiO3 (0⩽x⩽0.12 by weight) composites have been synthesized, the films being obtained by Stokes sedimentation on SrTiO3 ceramic plates and firing in oxygen by Melt Textured Growth techniques. The phase composition and texture have been studied by X-ray diffraction and microstructure. Resistance and magnetic susceptibility of prepared samples have been measured.

Dielectric and acoustic properties of modified barium titanate ceramics

This work was supported in part by the Ministry of Education and Science of the Russian Federation.

Anomalous Broad Dielectric Dispersion of 0.4PZN-0.3PSN-0.3PZN Relaxor Ceramics at Lower Temperatures

Dielectric properties of 0.4PbZn1/3Nb2/3O3-0.3PbSc1/2Nb1/2O3-0.3PbMg1/3Nb2/3O3- (0.4PZN- 0.3PSN-0.3PMN) ceramics are presented for 200 &lt; T &lt; 500 K and 20 Hz &lt; ν &lt; 1 MHz. Dielectric constant is very high (more 14000) in the vicinity of the peak. Anomalous broad dielectric relaxation have been observed near the temperature of the maximum permittivity, Tm (at 1 kHz). External bias field considerably lowers the value of dielectric losses at low frequencies due to decrease of polar nano regions contribution to the dielectric permittivity.

Microscopic studies of surface morphology of high temperature superconductor thick layers

Abstract The surface morphology and structure of the YBa2Cu3O7−δ superconductor ayers prepared on passive ceramic and single crystal substrates is studied by electron microscopy. The layers reveal features of structure formation.

Dielectric properties of potassium–sodium niobate ceramics at low frequencies

ABSTRACTA study of the effects of ageing history on the electrical properties of lead-free ferroelectric ceramics of (K0.5Na0.5)(Nb1−xSbx)O3 + 0.5 mol% MnO2 and (K0.5Na0.5)(Nb1−xTax)O3 + 0.5 mol%MnO2 for x = 0.05 is reported. The samples after storage at a constant temperature have been subject to infra-low-frequency electric field and radiation. Differences of the photoelectric response between the two examined compounds were found and the restoration of polarisation in the aged ceramic materials by cycles of applied field is discussed.

Behaviour of thermal expansion of (1-x)Pb(Ni1/3Nb2/3)O3–xPbTiO3 solid solutions

The publication costs of this article were covered by the Estonian Academy of Sciences and the University of Tartu.

Dielectric investigation of lead‐free perovskite strontium titanate with 25% bismuth ceramics

In this work lead-free 0.75SrTiO3-0.25BiTiO3 ceramics have been investigated in broad frequency range. Obtained results showed pronounced dispersion below room temperature typical for the dipolar glasses. The calculated relaxation time distribution function broadens toward longest relaxation times part on cooling. The obtained most probable relaxation time diverges according to the Vogel-Fulcher relationship with the following parameters: dipole activation energy EA=2123 K, glassy state temperature T0=52.7 K, shortest relaxation time, referring to dipole relaxations at very high temperatures, τ0=2.1·10–14 s. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Infrared and broadband dielectric spectroscopy of PZN-PMN-PSN relaxor ferroelectrics: Origin of two-component relaxation

Dielectric spectra of several solid solutions of $\mathrm{Pb}{\mathrm{Mg}}_{1∕3}{\mathrm{Nb}}_{2∕3}{\mathrm{O}}_{3}\text{\ensuremath{-}}\mathrm{Pb}{\mathrm{Sc}}_{1∕2}{\mathrm{Nb}}_{1∕2}{\mathrm{O}}_{3}\text{\ensuremath{-}}\mathrm{Pb}{\mathrm{Zn}}_{1∕3}{\mathrm{Nb}}_{2∕3}{\mathrm{O}}_{3}$ (PMN-PSN-PZN) relaxor ferroelectrics were investigated in a broad frequency range from $20\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}$ up to $100\phantom{\rule{0.3em}{0ex}}\mathrm{THz}$ by a combination of dielectric spectroscopy $(20\phantom{\rule{0.3em}{0ex}}\mathrm{Hz}\char21{}53\phantom{\rule{0.3em}{0ex}}\mathrm{GHz})$, time-domain terahertz spectroscopy $(0.1\char21{}0.9\phantom{\rule{0.3em}{0ex}}\mathrm{TH…

Dielectric investigation of sodium potassium niobate ceramic doped 7% of antimony

Abstract Electric properties of sodium potassium niobate ceramic doped antimony (Na0.5K0.5)(Nb0.93Sb0.07)O3 with sintering aid MnO2 (0.5 mol% MnO2) (KNNSbx + 0.5Mn) were investigated in a broad frequency (from 1 Hz to 54 GHz) and temperature (from 110 K to 800 K) ranges. The mean relaxation times calculated from the dielectric permittivity measurements fulfill Arrhenius relationship with dipole activation energy EA = 3409 K (EA/kB = 0.29 eV). The DC conductivity has been extracted from experimental results and the activation energy was calculated EA = 11733.78 K (EA/kB = 1.011 eV).

High Temperature Dielectric Properties of PMN‐PSN‐PZN Relaxors

Terahertz Spectroscopy of Ordered PbSc1/2Nb1/2O3Ceramics

Polar phonons in relaxor ferroelectric 0.2PSN-0.4PMN-0.4PZN

Relaxor ferroelectrics 0-2PbSc(1/2)Nb(1/2)O(3) - 0.4PbMg(1/3)Nb(2/3)O(3)-0.4PbZn(1/3)Nb(2/3)O(3) ceramics were studied by means of the Fourier transform infrared reflection and THz transmission spectroscopy in the temperature range of 20-500 K. On heating from low temperatures, the A(1) component of the strongly split TO1 mode softens towards the Burns temperature, but the softening ceases near 400 K, which could be a signature of polar cluster percolation temperature.

Dynamics of Polar Clusters in PMN Ceramics: Comparison with PMN Single Crystal

The dielectric permittivity of PMN ceramics was measured in the frequency range from 20 Hz to 37 GHz. From the frequency dependence of the real and imaginary parts of dielectric permittivity, the distribution of relaxation times f(τ) was calculated. The f(τ) function broadens significantly, and the second maximum appears below the 270 K temperature. The dielectric response and also relaxation time distribution of PMN ceramics was compared with the previous results of PMN single crystal. The results showed that dynamics of polar nano regions in PMN ceramics is suppressed due to the small size of grains in the ceramics.