Showing papers by "L. E. Cross published in 1984"
TL;DR: In this paper, the dielectric properties of lead magnesium niobate (PbMg1/3Nb2/3/O3) ceramics were reported.
Abstract: Dielectric properties are reported for lead magnesium niobate (PbMg1/3Nb2/3/O3) ceramics which were prepared as single phase (i.e., without pyrochlore) with an improved technique. Dielectric constants of 18000 for pure PMN and 31000 for PMN with 10% PbTiO3 were achieved; these values are 50% larger than those reported in the literature. The dielectric constant of PMN ceramics was found to increase with both sintering temperature and excess MgO, and subsequent analysis of the microstructures confirmed that this was due to an increase in grain size. This grain-size dependence is explained as a consequence of low-permittivity grain boundaries.
495 citations
TL;DR: In this article, the internal stress model was used to calculate the dielectric constant for the whole ferroelectric temperature region, under various stress systems. But the model was not applied to polycrystalline BaTiO3.
Abstract: Grain size effects in polycrystalline BaTiO3 are reviewed in terms of the “internal stress model”. By considering polarization dependent terms in the Devonshire free energy expression, the dielectric constant may be calculated for the whole ferroelectric temperature region, under various stress systems. Encouraging comparisons with measured values may be made.
122 citations
TL;DR: The elastic Gibbs function for BaTiO3 introduced by Buessem, Goswami and Cross1 has been modified by including the last symmetry permitted sixth order term HP12P22P32 with a coefficient H = 4.91 × 109 Vm9 C-5.
Abstract: The elastic Gibbs function for BaTiO3 introduced by Buessem, Goswami and Cross1 has been modified by including the last symmetry permitted sixth order term HP12P22P32 with a coefficient H = 4.91 × 109 Vm9 C-5. The function predicts the correct high electric field behavior of the low temperature ferroelectric: ferroelectric phase changes in the single crystal and suggests an interesting change of sign of the pyroelectric effect at high field levels in the induced tetragonal ferroelectric phase.
119 citations
TL;DR: Grain-oriented glass-ceramics of Li2Si2o5, fresnoite (Ba2TiSi2O8), and its isomorphs, such as Ba2TiGe 2O8, were prepared by recrystallizing glasses in a temperature gradient as discussed by the authors.
Abstract: Grain-oriented glass-ceramics of Li2Si2o5, fresnoite (Ba2TiSi2O8), and its isomorphs Sr2TiSi2O8, and Ba2TiGe2O8, were prepared by recrystallizing glasses in a temperature gradient. Electromechanical and hydrostatic piezoelectric properties of these glass-ceramics were measured. Piezoelectric voltage coefficients g33 and hydrostatic voltage coefficient gh of these glass-ceramics are comparable to those of polyvinylidene fluoride and an order of magnitude higher than the corresponding values of lead zirconate-titanate. These glass-ceramics seem to be attractive candidate materials for hydrophones and several piezoelectric devices. Hydrostatic piezoelectric properties of Ba2TiSi2O8 and Ba2TiGe2O8 single crystals were also measured. The unusually high values of gh in fresnoite single crystals and glass-ceramics are supposed to be due to positive d31 in these materials. A composite model is proposed to explain the positive sign of d31 in fresnoite based on its crystal structure and internal Poisson's ratio stress.
85 citations
TL;DR: In this article, the dielectric, piezoelectric and electromechanical coupling coefficients are significantly large for tetragonal tungsten bronze (T.B.) single crystals, e.g., SBN, BSKNN, KLN, SKN and PBN.
Abstract: Ferroelectric tetragonal tungsten bronze (T.B.) family single crystals, e.g., SBN, BSKNN, KLN, SKN and PBN, have been grown and their ferroelectric properties have been investigated. The results show that the dielectric, piezoelectric, and electromechanical coupling coefficients are significantly large for these crystals; however, they are markedly different when going from smaller to bigger unit cell T.B. crystals. For example, e33 and d33 are substantially larger for the smaller unit cell T.B. crystals, e.g., SBN and SKN, while e11 and d15 are dominant for bigger unit cell bronzes. However, these differences do not have such a significant effect on the respective electro-optic and pyroelectric properties.
64 citations
TL;DR: In this article, the polarization and depolarization behavior of lead lanthanum zirconate titanate ceramics with Zirconia has been studied and shown to have a titania ratio 065/0 35 and La2O3 content from 007 to 0095.
Abstract: Studies have been made of the polarization and depolarization behavior for lead lanthanum zirconate titanate ceramics with zirconia: titania ratio 065/0 35 and La2O3 content from 007 to 0095 (7
48 citations
TL;DR: In this paper, single crystal lead scandium tantalate micro-domains with an ordered arrangement of Sc: Ta have been observed directly in transmission electron microscopy and the scale of the ordered structures in the size range 35 to 120 nm agrees well with earlier indirect measurements from X-ray superlattice line broadening.
38 citations
TL;DR: Several doping substitutions (Li+, Mn+, D+, P+5, As+5) in the TGS structure have been studied and the pyroelectric and dielectric properties measured.
Abstract: Several doping substitutions (Li+, Mn+, D+, P+5, As+5) in the TGS structure have been studied and the pyroelectric and dielectric properties measured. In the case of TGS single crystals modified by partial substitution of (P04 −3 and (As04)−3 groups for the (S04)−2. higher pyroelectric coefficients and an enhancement of the pyroelectric material figure of merit (p/K) > 2 x TGS have been observed.
26 citations
TL;DR: In this paper, the hydrostatic-pressure dependence of the refractive index and the low-frequency dielectric constant of a perovskite-type single crystal, KMg${\mathrm{F}}_{3}$, have been determined at room temperature.
Abstract: The hydrostatic-pressure dependence of the refractive index and the low-frequency dielectric constant of a perovskite-type single crystal, KMg${\mathrm{F}}_{3}$, have been determined at room temperature. The refractive index $n$ for $\ensuremath{\lambda}=589.3$ nm increases monotonously in proportion to pressure $p$ with a slope of $\frac{\ensuremath{\partial}n}{\ensuremath{\partial}p}=2.46\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}{\mathrm{kbar}}^{\ensuremath{-}1}$. On the other hand, the dielectric constant at 10 kHz decreases with increasing pressure, from which the electric-displacement-related electrostrictive coefficient ${Q}_{h}$ ($={Q}_{11}+{2Q}_{12}$) is calculated as 0.24 ${\mathrm{m}}^{4}$ ${\mathrm{C}}^{\ensuremath{-}2}$. These data are compared with the $\frac{\ensuremath{\partial}n}{\ensuremath{\partial}p}$ values and the ${Q}_{h}$ coefficients of various alkali fluorides and perovskite oxides.
23 citations
TL;DR: In this article, high frequency resonance characteristics of piezoelectric PZT rod-polymer composites with 1-3 connectivity were investigated using a laser probe dilatometry to interpret the vibration pattern of resonant modes.
Abstract: High frequency resonance characteristics of piezoelectric PZT rod-polymer composites with 1–3 connectivity have been investigated. Electrical admittance plots and laser probe dilatometry of the dynamic displacement on the composite as a function of frequency are used to interpret the vibration pattern of resonant modes.
22 citations
01 Jan 1984
TL;DR: In this paper, the effect of temperature on the electromechanical properties of piezoelectric composite materials composed of PZT rods arranged in a periodic square lattice in a polymer matrix was investigated.
Abstract: The objective of the present work was to gain a deeper understanding of the vibration behavior of piezoelectric composite materials composed of PZT rods arranged in a periodic square lattice in a polymer matrix. Electrical admittance measurements and lalet probe dilatometry of the dynamic displacement on the composite surface were used to investigate t he vibration pattern of resonant modes. The effect of temperature on the electromechanical properties of the composite has also been studied as a function of frequency. The implication of these results for the design optimization of ultrasonic transducers are discussed.
01 Jan 1984
TL;DR: In this article, the ultrasonic properties relevant to transducer applications are reported for PZT rodpolymer composites, including the coustic impedance, free-field transmitting and receiving voltage responses.
Abstract: The ultrasonic p roperties relevant to transducer applications are reported for PZT rodpolymer composites, including the a coustic impedance, free-f ield transmitting and receiving voltage responses. When compared to a standard PZT transdncer, the composite materials were found to be three times more sensitive, both in the receiving and transmitting mode. An additional 50 percent i ncrease in sensitivity of the composite transducer was obtained using a quarter wavelength matching layer of Incite. These composite materials can be molded into curved shapes by simple t hermal process to fabricate focused transducers.
TL;DR: Using the piezoelectric effect, the variation of coercive stress with temperature for ferrobielastic switching in synthetic quartz crystals has been measured under unaxial load applied in a direction favoring Dauphine twinning as mentioned in this paper.
TL;DR: In this article, the dielectric, piezoelectric and pyroelectric properties of tetragonal:orthorhombic morphotropic phase boundary were determined.
Abstract: Tungsten bronze single crystals in the Pb1−xBaxNb2O6 system were grown from a melt using the Czochralski technique. The dielectric, piezoelectric and pyroelectric properties were determined. The dielectric constant Ka and piezoelectric coefficient dI5 showed a strong enhancement upon approaching the tetragonal:orthorhombic morphotropic phase boundary as predicted by thermodynamic phenomenology. It is clear that crystals with a composition in the tetragonal phase field near this boundary will be of major interest for various piezoelectric device applications.
Patent•
30 May 1984
TL;DR: In this article, pyroelectric crystals having relatively high figures of merit (p/K) of the order of 1.8 or more are provided. They are preferably prepared by doping alanine substituted triglycine sulfate crystals with phosphorous and/or arsenic.
Abstract: Pyroelectric crystals having relatively high figures of merit (p/K) of the order of 1.8 or more are provided. They are preferably prepared by doping alanine substituted triglycine sulfate crystals with phosphorous and/or arsenic.
TL;DR: In this paper, the separated electrostriction tensor components for alkaline-earth fluoride single crystals have been measured by the converse method using the uniaxial stress dependence of the dielectric permittivity.
TL;DR: Grain-oriented glass-ceramics of Li2Si2o5, fresnoite (Ba2TiSi2O8), and its isomorphs, such as Ba2TiGe 2O8, were prepared by recrystallizing glasses in a temperature gradient.
Abstract: Grain-oriented glass-ceramics of Li2Si2o5, fresnoite (Ba2TiSi2O8), and its isomorphs Sr2TiSi2O8, and Ba2TiGe2O8, were prepared by recrystallizing glasses in a temperature gradient. Electromechanical and hydrostatic piezoelectric properties of these glass-ceramics were measured. Piezoelectric voltage coefficients g33 and hydrostatic voltage coefficient gh of these glass-ceramics are comparable to those of polyvinylidene fluoride and an order of magnitude higher than the corresponding values of lead zirconate-titanate. These glass-ceramics seem to be attractive candidate materials for hydrophones and several piezoelectric devices. Hydrostatic piezoelectric properties of Ba2TiSi2O8 and Ba2TiGe2O8 single crystals were also measured. The unusually high values of gh in fresnoite single crystals and glass-ceramics are supposed to be due to positive d31 in these materials. A composite model is proposed to explain the positive sign of d31 in fresnoite based on its crystal structure and internal Poisson's ratio stress.