Publications
441 results found
Karpinsky DV, Selezneva EK, Bdikin K, et al., 2009, Development of novel multiferroic composites based on BaTiO<inf>3</inf> and hexagonal ferrites, Pages: 13-18, ISSN: 0272-9172
New multiferroic composite ceramics with the general formula (x)Ba(Sr)Fe12O19-(1-x)BaTiO3 (x=0.1, 0.5) were synthesized via a simple solid-state reaction technique. Crystal structure analysis performed for such materials revealed the presence of two crystalline phases pertinent to the initial composite components. X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to assess the crystallinity, microstructure, and local magnetoelectric interactions between ferroelectric and ferromagnetic grains. Magnetic measurements revealed that the saturation magnetization is proportional to the volume fraction of ferrite phase. Dielectric studies demonstrated strong frequency relaxation due to space charge polarization and high conductivity loss making macroscopic magnetoelectric measurements difficult. Novel nanoscale magnetoelectric effect observed by AFM is discussed. © 2009 Materials Research Society.
Axelsson A-K, Pan Y, Valant M, et al., 2009, Synthesis, Sintering, and Microwave Dielectric Properties of KTaO<sub>3</sub> Ceramics, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Vol: 92, Pages: 1773-1778, ISSN: 0002-7820
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- Citations: 31
Kozyrev A, Gaidukov M, Gagarin A, et al., 2009, Evaluation of the space charge trap energy levels in the ferroelectric films, JOURNAL OF APPLIED PHYSICS, Vol: 106, ISSN: 0021-8979
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- Citations: 7
Rawal R, McQueen AJ, Gillie LJ, et al., 2009, Influence of octahedral tilting on the microwave dielectric properties of A<sub>3</sub>LaNb<sub>3</sub>O<sub>12</sub> hexagonal perovskites (A=Ba, Sr), APPLIED PHYSICS LETTERS, Vol: 94, ISSN: 0003-6951
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- Citations: 16
Axelsson A-K, Valant M, Fenner L, et al., 2009, Chemistry of post-annealing of epitaxial CoFe<sub>2</sub>O<sub>4</sub> thin films, THIN SOLID FILMS, Vol: 517, Pages: 3742-3747, ISSN: 0040-6090
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- Citations: 23
Breeze JD, Perkins JM, McComb DW, et al., 2009, Do Grain Boundaries Affect Microwave Dielectric Loss in Oxides?, JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Vol: 92, Pages: 671-674, ISSN: 0002-7820
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- Citations: 120
Breeze J, Krupka J, Centeno A, et al., 2009, Temperature-stable and high Q-factor TiO<sub>2</sub> Bragg reflector resonator, APPLIED PHYSICS LETTERS, Vol: 94, ISSN: 0003-6951
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- Citations: 4
Pullar RC, Zhang Y, Chen L, et al., 2009, Dielectric measurements on a novel Ba<sub>1-<i>x</i></sub>Ca<sub><i>x</i></sub>TiO<sub>3</sub> (BCT) bulk ceramic combinatorial library, International Conference on Electroceramics, Publisher: SPRINGER, Pages: 245-251, ISSN: 1385-3449
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- Citations: 47
Pullar RC, Penn SJ, Wang X, et al., 2009, Dielectric loss caused by oxygen vacancies in titania ceramics, JOURNAL OF THE EUROPEAN CERAMIC SOCIETY, Vol: 29, Pages: 419-424, ISSN: 0955-2219
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- Citations: 150
Karpinsky DV, Selezneva EK, Bdikin IK, et al., 2009, Development of novel multiferroic composites based on BaTiO<inf>3</inf> and hexagonal ferrites, Pages: 7-12, ISSN: 0272-9172
New multiferroic composite ceramics with the general formula (x)Ba(Sr)Fe12O19-(l-x)BaTiO3 (x=O. 1, 0.5) were synthesized via a simple solid-state reaction technique. Crystal structure analysis performed for such materials revealed the presence of two crystalline phases pertinent to the initi2l composite components. X-ray diffraction (XRD), scanning electron microscopy (SEM) nd atomic force microscopy (AFM) were used to assess the crystallinity, microstructure, and local magnetoelectric interactions between ferroelectric and ferromagnetic grains. Magnetic measurements revealed that the saturation magnetization is proportional to the volume fraction of ferrite phase. Dielectric studies demonstrated strong frequency relaxation due to space charge polarization and high conductivity loss making macroscopic magnetoelectric measurements difficult. Novel nanoscale magnetoelectric effect observed by AFM is discussed. © 2009 Materials Research Society.
Fradkin L, Mishakin V, Alford N, et al., 2009, Perturbing paths of slow cracks in PMMA by local heating, Pages: 37-47, ISSN: 1875-3507
Real-time control of the direction of a propagating crack is little explored area of management of structural integrity. We have examined it with experiments on quasi-static (slow) cracks in PMMA (Polymethyl-Methacrylate). We have observed that in PMMA when the mean crack speeds are low (between 0.1 and 0.4mms-1) secondary thermal sources of relatively low power (of the order of 2W) can be used to achieve a significant crack redirection. In this interval the micro-photographs of cracks present a fishbone structure, and we argue that the side lobes are micro-cracks which appear inside shear bands. The respective fracture surfaces look rippled (hackled). We have observed a clear reverse correlation between the crack speed and the angle of redirection. When the mean crack speed exceeds 0.4mms-1 and the fracture surface is mirror smooth no trajectory redirection is achieved. It appears the micro-cracks act as notches and alleviate crack redirection. Therefore, one of our conclusions is that it might be possible to use relatively weak sources to redirect fast cracks that propagate with a super-critical speed. This hypothesis is advanced because fast cracks are also known to possess a fishbone structure and hackled fracture surface. © 2009 Springer Science+Business Media B.V.
Shimada T, Ichikawa K, Minemura T, et al., 2009, Intrinsic Microwave Dielectric Loss of Lanthanum Aluminate, Joint Meeting of 12th International Meeting on Ferroelectricity/18th IEEE International Symposium on Applications of Ferroelectrics (IMF-ISAF-2009), Publisher: IEEE, Pages: 250-+, ISSN: 1099-4734
Fradkin L, Mishakin V, Alford N, et al., 2009, Perturbing Paths of Slow Cracks in PMMA by Local Heating, IUTAM Symposium on Scaling in Solid Mechanics, Publisher: SPRINGER, Pages: 37-+
Buslov OY, Keys VN, Kozyrev AB, et al., 2008, Band-pass tunable filter based on planar dielectric resonators, Pages: 513-514
An X-band 2-pole filter based on uniplanar dielectric resonators (PDR) with ferroelectric tuning was designed and fabricated. PDR's were chosen because of their high Q-factor and the rarefied spectrum of resonance mode frequencies. At frequency ~10.5GHz the filter displayed insertion losses not more than S 21=-3dB in the bandwidth Δf=110MHz. The frequency of tuning was ΔF=420MHz. © 2008: CriMiCo'2008 Organizing Committee.
Alford NMN, Buslov OY, Keis VN, et al., 2008, Band-pass tunable ferroelectric filter based on uniplanar dielectric resonators, Pages: 1703-1706
An X-band 2-pole filter based on uniplanar dielectric resonators (UPDR) with ferroelectric tuning was designed and fabricated. UPDRs were chosen because of their high Q-factor, the rarefied spectrum of resonance mode frequencies, simplicity of manufacture and the convenience for integrating a ferroelectric tuning varactor. The analytical description of the filter response is presented and good agreement between simulated and measured experimental data is demonstrated. At a frequency of ∼ 10.5 GHz the filter displayed insertion losses not more than S21 = -3.5 dB in the bandwidth Δf ∼ 110 MHz. The frequency of tuning was ΔF ∼ 420 MHz. © 2008 EuMA.
Kimber DP, Pullar RC, Alford NM, 2008, The effects of dielectric loss and tip resistance on resonator <i>Q</i> of the scanning evanescent microwave microscopy (SEMM) probe, MEASUREMENT SCIENCE AND TECHNOLOGY, Vol: 19, ISSN: 0957-0233
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- Citations: 5
Dunne LJ, Valant M, Manos G, et al., 2008, Microscopic theory of the electrocaloric effect in the paraelectric phase of potassium dihydrogen phosphate, APPLIED PHYSICS LETTERS, Vol: 93, ISSN: 0003-6951
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- Citations: 20
Salak AN, Ferreira VM, Ribeiro JL, et al., 2008, Bismuth-induced dielectric relaxation in the (1-<i>x</i>)La(Mg<sub>1/2</sub>Ti<sub>1/2</sub>)O<sub>3</sub>-<i>x</i>Bi(Mg<sub>1/2</sub>Ti<sub>1/2</sub>)O<sub>3</sub> perovskite system, JOURNAL OF APPLIED PHYSICS, Vol: 104, ISSN: 0021-8979
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- Citations: 9
Centeno A, Breeze JD, Alford NMN, et al., 2008, Measurement of high loss dielectric materials using a resonant technique
This paper will report on a technique that has been developed for the measurement of the dielectric loss of materials which have a relatively high loss tangent. The method used employs a composite resonator that consists of the material under test being placed in the centre of a low loss ceramic ring resonator. The important feature of this configuration is that the electric energy filling factor in the sample is significantly lowered. This has the desirable effect of reducing the contribution to the resonator Q-factor of the sample material which has a high loss compared to the ceramic ring resonator. This enables the measurement of dielectric loss tangents which are significantly larger than those that can be measured using a conventional technique, such as making a cylindrical dielectric resonator of the sample material. In this technique the choice of resonant mode is very important. The electrical energy filling factor must low enough to ensure a measurable Q factor but at the same time high enough to measure a detectable perturbation of the resonance. It is also important to know the electrical filling factor of the ring resonator, which is made of a well characterised ceramic material, and the Q-factor contribution of any conducting surfaces in the resonant structure such as cavity walls. The choice of resonant mode and the effects of the other components in the resonator are obtained by using Finite Difference Time Domain (FDTD) and Mode Matching modelling tools. Measurement of the loss tangent of high resistivity Silicon over temperature has already been carried out with this technique by employing a BZT ring resonator resonating at around 5GHz in the TE01? mode. The results are very promising with loss tangents being measured that are an order of magnitude higher than could be measurable using a more conventional resonant technique. The current focus of this work is the measurement of liquids at microwave and millimetre wavelengths using Alumina resonators
Scott DJ, Manos S, Coveney PV, et al., 2008, Functional ceramic materials database: An online resource for materials research, JOURNAL OF CHEMICAL INFORMATION AND MODELING, Vol: 48, Pages: 449-455, ISSN: 1549-9596
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- Citations: 8
Centeno A, Breeze JD, Alford NMN, et al., 2008, Measurement of high loss dielectric materials using a resonant technique
This paper will report on a technique that has been developed for the measurement of the dielectric loss of materials which have a relatively high loss tangent. The method used employs a composite resonator that consists of the material under test being placed in the centre of a low loss ceramic ring resonator. The important feature of this configuration is that the electric energy filling factor in the sample is significantly lowered. This has the desirable effect of reducing the contribution to the resonator Q-factor of the sample material which has a high loss compared to the ceramic ring resonator. This enables the measurement of dielectric loss tangents which are significantly larger than those that can be measured using a conventional technique, such as making a cylindrical dielectric resonator of the sample material. In this technique the choice of resonant mode is very important. The electrical energy filling factor must low enough to ensure a measurable Q factor but at the same time high enough to measure a detectable perturbation of the resonance. It is also important to know the electrical filling factor of the ring resonator, which is made of a well characterised ceramic material, and the Q-factor contribution of any conducting surfaces in the resonant structure such as cavity walls. The choice of resonant mode and the effects of the other components in the resonator are obtained by using Finite Difference Time Domain (FDTD) and Mode Matching modelling tools. Measurement of the loss tangent of high resistivity Silicon over temperature has already been carried out with this technique by employing a BZT ring resonator resonating at around 5GHz in the TE01? mode. The results are very promising with loss tangents being measured that are an order of magnitude higher than could be measurable using a more conventional resonant technique. The current focus of this work is the measurement of liquids at microwave and millimetre wavelengths using Alumina resonators
Alford NM, 2008, A(B′<sub>1/2</sub>B"<sub>1/2</sub>)O<sub>3</sub> [A = A<SUP>2+</SUP> OR A<SUP>3+</SUP>; B′ = B<SUP>2+</SUP>,B<SUP>3+</SUP>; B" = B<SUP>4+</SUP>,B<SUP>5+</SUP>,B<SUP>6+</SUP>] COMPLEX PEROVSKITES, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION, Publisher: ELSEVIER SCIENCE BV, Pages: 205-260, ISBN: 978-0-08-045330-9
Alford NM, 2008, MICROWAVE DIELECTRIC MATERIALS IN THE BaO-TiO<sub>2</sub> SYSTEM, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION, Publisher: ELSEVIER SCIENCE BV, Pages: 49-82, ISBN: 978-0-08-045330-9
Alford NM, 2008, ZIRCONIUM TIN TITANATE, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION, Publisher: ELSEVIER SCIENCE BV, Pages: 83-108, ISBN: 978-0-08-045330-9
Alford NM, 2008, CATION-DEFICIENT PEROVSKITES, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION, Publisher: ELSEVIER SCIENCE BV, Pages: 335-360, ISBN: 978-0-08-045330-9
Alford NM, 2008, MEASUREMENT OF MICROWAVE DIELECTRIC PROPERTIES AND FACTORS AFFECTING THEM, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION, Publisher: ELSEVIER SCIENCE BV, Pages: 11-47, ISBN: 978-0-08-045330-9
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- Citations: 14
Alford NM, 2008, TAILORING THE PROPERTIES OF LOW-LOSS DIELECTRICS, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION, Publisher: ELSEVIER SCIENCE BV, Pages: 513-523, ISBN: 978-0-08-045330-9
Alford NM, 2008, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION CONCLUSION, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION, Publisher: ELSEVIER SCIENCE BV, Pages: 525-530, ISBN: 978-0-08-045330-9
Alford NM, 2008, Ca(Ca<sub>1/4</sub>B<sub>2/4</sub>Ti<sub>1/4</sub>)O<sub>3</sub> (B = Nb, Ta) COMPLEX PEROVSKITES, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION, Publisher: ELSEVIER SCIENCE BV, Pages: 361-377, ISBN: 978-0-08-045330-9
Alford NM, 2008, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION INTRODUCTION, DIELECTRIC MATERIALS FOR WIRELESS COMMUNICATION, Publisher: ELSEVIER SCIENCE BV, Pages: 1-10, ISBN: 978-0-08-045330-9
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