Strain-induced diffuse dielectric anomaly and critical point in perovskite ferroelectric thin films

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Halide perovskites deposited by physical or chemical vapour deposition techniques are significantly less explored than their solution-processed counterparts. In this talk I will cover our contributions to understanding the hybrid vapour-vapour deposition approach, where one first needs to understand the caveats of the first step (i.e., strong vacuum ~10-6 mbar PVD of the inorganic template), before studying the transformation of the inorganic template into a 3D perovskite upon exposure to organohalide vapou

We introduce a minimal model describing the physics of classical two-dimensional (2D) frustrated Heisenberg systems, where spins order in a nonplanar way at T=0. This model, consisting of coupled trihedra (or Ising-RP3 model), encompasses Ising (chiral) degrees of freedom, spin-wave excitations, and Z2 vortices. Extensive Monte Carlo simulations show that the T=0 chiral order disappears at finite temperature in a continuous phase transition in the 2D Ising universality class, despite misleading intermediate

Systems with a ferroelectric to paraelectric transition in the vicinity of room temperature are useful for devices. Adjusting the ferroelectric transition temperature (T-c) is traditionally accomplished by chemical substitution - as in BaxSr1-xTiO3, the material widely investigated for microwave devices in which the dielectric constant (epsilon(r)) at GHz frequencies is tuned by applying a quasi-static electric field(1,2). Heterogeneity associated with chemical substitution in such films, however, can broad

Deposition of a hydrothermal method has a number of advantages; low deposition temperature, high-purity, deposition on a three-dimensional structure, and a large thickness. The present paper investigates the improvement of an epitaxial lead zirconate titanate (PZT) thin film deposited via hydrothermal synthesis. The critical parameter contributing to the film morphology was revealed to be the holding position of the reaction solution during deposition. In addition to this improvement, the SrRuO3 bottom elec

Urotropin (U) and azelaic acid (AA) form 1:1 co-crystals (UA) that give rise to a rather complex diffraction pattern, the main features of which are diffuse rods and bands in addition to the Bragg reflections. UA is characterized by solvent inclusions, parasite phases, and high vacancy and dislocation densities. These defects compounded with the pronounced tendency of U to escape from the crystal edifice lead to at least seven exotic phase transitions (many of which barely manifest themselves in a different

PZT (PbZrx Ti1-xO3) thin films have been locally grown by means of sol-gel deposition and local annealing on microhotplates. The microhotplates were based on a stress compensated Si3N4 /SiO2 membranes as structural elements and contained tantalum silicide filaments (Ta5Si3) for resistive heating. Above the filaments, a passivation layer of SiO2, an adhesion layer of Ti/TiO2 and a bottom electrode of Pt were deposited. Due to the low heat conductivity of the membrane, crystallization of the PZT film occurs e

Pb(Zr,Ti)O-3 (PZT) and Pb(Zr,Ti,Nb)O-3 (PNZT) thin films were grown on platinized silicon substrates by r.f. magnetron sputtering followed by a post-annealing treatment. The Niobium, Nb, concentration varied from 1 to 7 at.% by increment of 1 at.%. The effects of the Nb introduction on the PZT electrical properties, i.e, dielectric, ferroelectric and piezoelectric ones were investigated. The relative dielectric constant (epsilon (T)) was very sensitive to the Nb introduction; epsilon (T) reaches 1100 for a

Electromechanical properties of a number of ferroelectric films including PbZrxTi1-xO3(PZT), 0.9PbMg(1/3)Nb(2/3)O(3)-0.1PbTiO(3)(PMN-PT), and SrBi2Ta2O9(SBT) are investigated using laser interferometry combined with conventional dielectric measurements. Effective electrostriction coefficients of the films, Q(eff), are determined using a linearized electrostriction equation that couples longitudinal piezoelectric coefficient, d(33), with the polarization and dielectric constant. It is shown that, in PZT film

Diverse device applications for lead zirconate titanate (PZT) ceramics in thick-film form are currently in active development. In the present study, the particle dispersion properties of thick-film ink formulations containing PZT powder have been determined using rheological measurements. Although all of the eight commercially available dispersants tested are more effective than the terpineol solvent alone in decreasing attractive interparticle forces in suspensions, the best dispersant identified for hard

The effects of donor (Nb, Ta) and acceptor (Na, Mg, Fe) dopants on the crystallization mechanism of PZT thin films were investigated. The parameters which control microstructure development were found to be different for donors and accepters. Lead stoichiometry was found to be the critical parameter for donor doped films. Donor substitutions in the perovskite lattice ABO(3), require a compensation by creation of A-site vacancies, Pb1-x/2(Zr,Ti)(1-x) NbxO3, in order to maintain electroneutrality. In the pyro

Electrode stability, interdiffusion, phase purity and deviation from stoichiometry at the PZT-electrode interface are key issues in PZT thin film integration. This article highlights the use of transmission electron imaging combined with energy dispersive spectroscopy (EDS) for the investigation of these phenomena. The accuracy of the EDS analysis is discussed. It will be shown that using a standard PZT sample and controlled conditions, reliable analysis can be performed. Diffusion mechanisms have been stud

The weak-field dielectric properties of ordered, disordered, and lead-deficient disordered Pb(Sc0.5Ta0.5)O-3 (PST) ceramics (PST-O, PST-D, and PST-DV, respectively) were investigated under various de-bias conditions. The de-bias field influences the paraelectric-to-ferroelectric transition in PST-O and the relaxor-to-normal-ferroelectric transition in disordered PST-D, Phase diagrams, with respect to de bias and temperature, were proposed for ordered and disordered PST materials. A field-induced ferroelectr

The effects of niobium doping on the hysteresis parameters of sol-gel Pb-1.1-x/2(Zr0.53Ti0.47)(1-x)NbxO3 (0 < x < 0.05) have been reported fbr two sets of films with analogous grain size and degree of (111) texture but with different surface microstructures. For both sets, a strong continuous decay of the remnant and maximum polarizations and slope of the hysteresis loop at the coercive field was observed with increasing niobium concentration. The held dependence of the remnant polarization for any given ni

We report on in-plane paraconductivity measurements in thin YBa2Cu3O6.9 films. Our analysis of the data shows that the temperature dependence of paraconductivity is affected by lattice disorder and deviates at all temperatures from the universal power laws predicted by both scaling and mean-field theories. This gives evidence for the absence of critical fluctuations and for the failure of the Aslamazov-Larkin universal relation between critical exponent and dimensionality of the spectrum of Gaussian fluctua

The in-situ growth of PbZrxTi1-xO3 (PZT) and PbTiO3 (PT) thin films by reactive sputter deposition has been investigated for applications with silicon substrates. In-situ deposition from three simultaneously operating magnetron sources was applied. At the selected growth temperature range (550-600 degrees C), self-stabilisation of lead composition by a lar ge desorption rate of Pb on stoichiometric PZT surfaces has been observed. Interlayer mixing was found to be limited to a few monolayers. Both Pt and RuO

A zero-field spontaneous relaxor-ferroelectric transition is reported in Pb(Sc0.5Ta0.5)O3 (PST). This behavior is different from that of other relaxors, where such transitions occur only under the field. A highly disordered PST that has the wide relaxation spectrum typical of relaxors is shown to transform spontaneously into a macroscopic ferroelectric state. Introduction of defects (lead vacancies) into the material impedes the transition resulting in the usual relaxor behavior. Dielectric properties of PS

Strain-induced diffuse dielectric anomaly and critical point in perovskite ferroelectric thin films

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Different facets of hybrid vapour-vapour deposited halide perovskites

Thermal destruction of chiral order in a two-dimensional model of coupled trihedra

Room-temperature ferroelectricity in strained SrTiO3

Ferroelectric properties of an epitaxial lead zirconate titanate thin film deposited by a hydrothermal method below the Curie temperature

Urotropin azelate: a rather unwilling co-crystal

Local growth of sol-gel films by means of microhotplates

Ferroelectric and piezoelectric properties of Nb doped PZT films

Characterization of the effective electrostriction coefficients in ferroelectric thin films

Lead zirconate titanate particle dispersion in thick-film ink formulations

Effect of dopants on the crystallization mechanism of PZT thin films

Stoichiometry and interdiffusion in PZT thin films studied by transmission electron microscopy

Dielectric properties of complex perovskite lead scandium tantalate under dc bias

Use of ferroelectric hysteresis parameters for evaluation of niobium effects in lead zirconate titanate thin films

Evidence for nonuniversal behavior of paraconductivity caused by predominant short-wavelength Gaussian fluctuations in YBa2Cu3O6.9

In-situ sputter deposition of PT and PZT films on platinum and RuO2 electrodes

The Spontaneous Relaxor-Ferroelectric Transition of Pb(Sc0.5ta0.5)O3