Structure and Properties of Novel Pb(B’1/2Nb1/2)O3-PbTiO3 Binary Systems with High Piezoelectric Coupling

2000

The (l-x)Pb(Lu1/2Nb1/2)O3-xPbTiO3 (PLuNT) and (l-x)Pb(Er1/2Nb1/2)O3-xPbTiO3 (PErNT) binary systems have been originally synthesized. Pure lutecium niobate (PLuN) (x = 0) has a pronounced long-range order in the B-sublattice and an antiferroelectric to paraelectric phase transition at ~258°C. The phase structure of the PLuNT system, at room temperature, changes from a pseudomonoclinic (psd-M, space group Bmm2) to tetragonal (T, space group P4mm). The pseudomonoclinic phase extends over the 0 ≤ x ≤ 0.38 interval within which the monoclinic angle β proceeds a minimum near to 90° at x≅0.2. The morphotropic region covers over the interval x = 0.38–0.49, the concentration ratio psd-M:T≅l (the mor…

X-ray Studies of Debye Temperature of Some ABO 3 Perovskites

2002

Debye temperatures T D of some perovskite compounds are determined by X-ray diffraction. Correlation between T D determined at T=180 °C, mean square displacements of atoms, quasi-elastic coupling, and melting temperature of the perovskite compounds is analysed.

Isomorphous ion substitutions and order-disorder phenomena in highly electrocaloric lead-scandium tantalate solid solutions

1996

Abstract The authors discuss the physical background of the electrocaloric effect in PST ceramics and its solid solutions. The most important contribution to the electrocaloric effect is due to field-induced Fm3m→R3m phase transition in the case of high long range ordering degree of B-ions in the perovskite structure ABO3.

Influence of Structure Ordering, Defects and External Conditions on Properties of Ferroelectric Perovskites

2000

Results of comprehensive studies of the (A’A“)(B’B”)O3-ferroelectric perovskites are reported. Examined compositions include Pb1-xLax(Zr0.65Ti0.35)1-x/4O3(PLZT), PbSc0.5Nb0.5O3(PSN), PbSc0.5Ta0.5O3(PST), and PMNT, PSNT and PLuNT pseudo-binary systems exhibiting pronounced dielectric, electrooptical, and electromechanical properties. Degree of ordering in the materials has been varied by chemical composition (modification, isomorphic ion substitution), by variation of technology (hot-pressing, specific thermal treatment, thin films), and by irradiation of different kind and intensity (γ-rays, electrons, neutrons).

Effects of structure ordering, structure defects and external conditions on properties of complex ferroelectric perovskites

1998

Abstract Structural rearrangements in lead-containing (A‘A’) (B’B“)O3 type perovskite compounds are caused by technological treatment, high-energy radiation and ambient conditions. Variation of structure ordering along with modification (substituted or defected solid solutions) may provide promising compositions for applications, e.g., cascade microcryogenic devices (PST solid solutions); efficient piezoelectric materials – here the new (1 – x)Pb(Lu1/2Nb1/2)O3 – xPbTiO3 system in the morphotropic region. The maximum values of the electromechanical coupling coefficients kp = 0·663, kt = 0·481, k 31 = 0·355 were attained in compositions PLuNT 59/41 (Tm = 353°C) near the morphotropic phase bou…

Uniaxial Pressure Effect on Electric Properties of PSN and 0.95PSN-0.05PLuN Ceramics

2006

The dielectric, pyroelectric and hysteresis loops measurements of PSN and 0.95PSN-0.05PLuN ceramics stress-free and under the stress (0–1.5 kbar) have been carried out. It was shown that axial pressure seems to change the partially ordered state to a disordered one, shifts the phase transformation and decreases the thermal hysteresis of the dielectric permittivity and the field-polarization hysteresis. These effects can be connected with change in domain structure, inter-ionic distances and defect density under the action of uniaxial pressure. The thermodynamic parameters of the phase transition were also determined.

X-ray diffraction study of crystallographic parameters and debye temperature of c60 single crystals

2002

Abstract The cubic lattice parameter value a =1.41568±0.00006  nm of large size C 60 single crystal has been measured and Debye temperature T D =53.9 K from the X-ray scattering spectrum at a fixed temperature was obtained. The microhardness and dislocation structure of the crystals was examined.

Heterovalent ion replacement in bi7Ti4NbO21: Some new compounds and phase transitions

1996

Abstract Simultaneous heterovalent substitutions at two cationic sites of the bismuth mixed-layered compound Bi7Ti4NbO21 have been made. Two new compounds: Bi2Pb⅓Ti(4/3)Mo⅓O7 and Bi(4/3)PbTiMo⅔O7, were obtained and identified by X-ray diffraction analysis. A model of possible mixed layer structure is discussed. Ferroelectric phase transitions at 510°C and 550°C have been studied by dielectric measurements.

Features of Phase Diagrams of Binary Pb(B<sub>1/2</sub>Nb<sub>1/2</sub>)O<sub>3</sub>-PbTiO<sub>3</sub&g…

2001

High Electromechanical Coupling in Relaxor Pb(Sc<sub>1/2</sub>Nb<sub>1/2</sub>) O<sub>3</sub> - PbTiO<sub>3…

1997

New ferroelectric materials on the basis of PbSc1/2Nb1/2O3–PbLu1/2Nb1/2O3 solid solutions

2004

Abstract Original binary solid solutions PbSc 1/2 Nb 1/2 O 3 –PbLu 1/2 Nb 1/2 O 3 (PSN-PLuN) have been produced. First of all nominally pure PSN and PLuN were synthesized by solid state reaction from oxides and carbonates. These compounds were mixed in different proportions to obtain (1− x )PSN− x PLuN solid solutions. Ceramic samples were hot-pressed at gradual change of the temperature. Solid solutions have the perovskite structure and are completely soluble in each other. Differential thermal analysis and X-ray diffraction were used to examine the synthesis and phase constitution. Dielectric properties—dielectric permittivity e and dielectric loss tan δ of ceramic samples of originally s…

Morphotropic ceramic solid solutions of the Pb(B3+½Nb½)O3- PbTiO3binary system

2000

Abstract The structure, dielectric, ferroelectric and electromechanical properties of lead lutecium niobate-titanate (PLuNT) and lead erbium niobate-titanate (PErNT) binary systems are reported. The data of phase diagram, crystallographic symmetry and morphotropic phase boundaries (MPB) are provided. High values of the electromechanical coupling coefficients kp = 0.66, kt = 0.48, k31 = 0.36 of (1−x)PLuN − xPT ceramics are attained in compositions near the MPB at x≈0.41.

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

1996

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.

New high piezoelectric coupling PLuNT binary system ceramics

1999

Abstract The new (1 − x)Pb( Lu 1 2 Nb 1 2 ) O 3 − x PbTiO 3 binary system ceramics in the interval 0 0.49). The morphotropic region extends over the interval x = 0.38–0.49, the concentration ratio M:T ≅ 1 corresponds to x = 0.41. The maximum values of the electromechanical coupling coefficients k p = 0.663, k t = 0.481, k 31 = 0.355 of (1 − x)PLuN-xPT ceramics were attained in compositions PLuNT 59/41 (T m = 353 °C) near the morphotropic phase boundary (MPB). The PLuNT system, having large values of electromechanical coupling and the highest T m (> 350 °C) among binary Pb(B′,B″)O 3 -PT perovskites may be favorable for piezoelectric sensors and actuators, and may have an interest as promisin…

The Effect of Technological Factors on the Synthesis of PbMg 1/3 Nb 2/3 O 3

2003

Conventional technique of solid phase reactions allows one to obtain PbMg 1/3 Nb 2/3 O 3 material with about 20 vol.% of the pyrochlore phase. The latter can be reduced to 5 vol.% by Swartz-Shrout two-stage solid state reaction via MgNb 2 O 6 having the columbite structure. A single-phase perovskite product can be obtained by by the two-stage columbite method from mixtures containing 0.2 mol. parts of overstoichiometric MgO. The best results are obtained by using magnesium carbonate hydroxide pentahydrate (MgCO 3 ) 4 ·Mg(OH) 2 ·5H 2 O as the magnesium source. The modified route yields stoichiometric single-phase PMN.

Ceramics and Thin Films of Some New Pb(B 3+ ,Nb)TiO 3 -PbTiO 3 Systems

2003

The structure, dielectric, and electromechanical properties of (1 m x )Pb(B 3+ ,Nb)TiO 3 - x PbTiO 3 binary systems (B = Lu, Er, Tb, Ho) are reported. The crystallographic features at the morphotropic phase boundary (MPB) between tetragonal P4mm and pseudo-monoclinic M phases are discussed with respect to electro-mechanical properties. Doping effect (with La 3+ ) on the properties of ceramic samples of pseudobinary Pb(Lu 1/2 Nb 1/2 )O 3 -PbTiO 3 (PLuNT) system has been investigated. Pb(Mg 1/3 Nb 2/3 )-PbTiO 3 (PT) solid solutions were studied under different processing conditions for obtaining ceramics of 100% perovskite structure with sufficient high j T EC ∼ 1 K near room temperature. The…

Radiation effects in transparent ferroelectric ceramics

1997

Radiation of different types ((gamma) -rays, electrons, neutrons) and fluence has been used to study the defect processes as well as the change of physical parameters in PLZT X/65/35 (X equals 4.5 - 11 at.%) and PbSc 0.5 Nb 0.5 O 3 (PSN) ceramics and to evaluate critical irradiation conditions. Effects on optical (extinction) spectra and dielectric characteristics (polarization, thermal and frequency dependences of dielectric permittivity (epsilon) and losses), dependent on composition and state of phase and polarization have been analyzed by means of annealing in isochronic and prolonged time regimes. A gradual shift of extinction edge to longer wavelengths, reduction of polarization and (…

Structure and properties of high piezoelectric coupling Pb(B′½Nb½)O3-PbTiO3binary systems

1999

Abstract The (1-x)Pb(Lu½ Nb½)O3-xPbTiO3 and (1-x)Pb(Er½ Nb½)O3-xPbTiO3 binary systems have been obtained, the structure and properties of which are studied. The unit cell of erbium niobate (PErN) is described as pseudomonoclinic of orthorhombic Bmm2 symmetry: a=c=4.2161 A b=4.0869 A β=90.55° and composition is characterized with antiferroelectric phase transition at 305°C. The PErNT system has the morphotropic phase region extending over the x=0.4–0.6 interval. In PLuNT ceramics system the pseudomonoclinic phase structure Bmm2 extending over the 0≤x ≤0.38 interval becomes pseudocubic at x≈ 0.2. The morphotropic region is spread over 0.38< × < 0.49; at higher PT concentrations (1.0 ≥ × ≥ 0.4…

Phase transitions and properties of perovskite ferroelectric ceramics and films for certain applications

1999

Abstract The structure-properties relationships and phase transitions in perovskite ceramics, and films of PLZT, PLZST, PST, PSN, PMNT compounds are discussed with regard to ordering, relaxor behaviour, pronounced ferroelectric, electromechanical and electrocaloric properties. The theoretical approach is extended to the time dependent Ginsburg-Landau model. The evolution of dielectric properties in relaxors after the change of temperature and electric field creating an increase of dielectric permittivity is found to follow a logarithmic law of decay. A strong electromechanical response is observed in a number of thin films of different compositions.

Some New Ceramics and Thin Films of Pb(B 3+ ,Nb)TiO 3 -PbTiO 3 System

2002

The structure, dielectric, and electromechanical properties of (1-x)Pb(B 3+ ,Nb)TiO 3 -xPbTiO 3 binary systems (B=Lu,Er,To,Ho) are reported. High values of the electromechanical coupling coefficien...

Influence of Axial Pressure on Electric Properties of PLuN and 0.6PLuN–0.4PSN Ceramics

2005

The dielectric, pyroelectric and hysteresis loops measurements of PLuN and 0.6PLuN–0.4PSN ceramics, stress-free or under the stress (0–1.5 kbar), have been carried out. It is shown that uniaxial pressure shifts the phase transformation and decreases the thermal hysteresis of the electric permittivity and the field-polarization hysteresis. These changes of properties could be connected with domain wall motion and with switching of the polarization under uniaxial pressure.

CO2 laser-induced structure changes in lead zirconate titanate Pb(Zr0.58Ti0.42)O3 sol–gel films

2003

Based on absorption spectra of lanthanum modified lead zirconate titanate Pb0.9La0.1(Zr0.65Ti0.35)O3 (PLZT10/65/35) ferroelectric ceramics an idea of local and selective treatment of lead zirconite titanate Pb(ZrXTi1−X)O3 (PZT) sol–gel film in the multi-layer structure by CO2 laser radiation was formulated. The possibility to obtain PZT perovskite film on the SiO2/Si substrate by irradiation with CO2 laser was shown experimentally. X-ray studies revealed the PZT perovskite structure ratio growth at the expenses of pirochlore structure with an increased power density of laser radiation.

Phase State and Structure of Ferroelectric Ceramics under Irradiation

1997

Thermodynamic properties at the phase transition of Pb(Zr, Sn, Ti)O3solid solutions

2000

Abstract Field induced deformation and electrocaloric effect are investigated in the vicinity of phase transition at 163°C. The sharp increase of electrostriction below Tc is explained by the field induced ferroelectric to antiferroelectric phase transition. The antiferroelectric phase appears and remains stable below Tc in the absence of field. Elastic compliance and thermal expansion as functions of temperature are studied.