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Applied Physics Reviews — 2012

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High performance ferroelectric relaxor-PbTiO3 single crystals: Status and perspective

Shujun Zhang and Fei Li

J. Appl. Phys. 111, 031301 (2012); http://dx.doi.org/10.1063/1.3679521 (50 pages)

Online Publication Date: 7 February 2012

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Ferroelectrics are essential components in a wide range of applications, including ultrasonic transducers, sensors, and actuators. In the single crystal form, relaxor-PbTiO3 (PT) piezoelectric materials have been extensively studied due to their ultrahigh piezoelectric and electromechanical properties. In this article, a perspective and future development of relaxor-PT crystals are given. Initially, various techniques for the growth of relaxor-PT crystals are reviewed, with crystals up to 100 mm in diameter and 200 mm in length being readily achievable using the Bridgman technique. Second, the characterizations of dielectric and electromechanical properties are surveyed. Boundary conditions, including temperature, electric field, and stress, are discussed in relation to device limitations. Third, the physical origins of the high piezoelectric properties and unique loss characteristics in relaxor-PT crystals are discussed with respect to their crystal structure, phase, engineered domain configuration, macrosymmetry, and domain size. Finally, relaxor-PT single crystals are reviewed with respect to specific applications and contrasted to conventional piezoelectric ceramics.
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77.65.-j Piezoelectricity and electromechanical effects
77.80.Dj Domain structure; hysteresis
81.10.Fq Growth from melts; zone melting and refining
77.80.Jk Relaxor ferroelectrics
61.66.Fn Inorganic compounds
77.22.Gm Dielectric loss and relaxation

A review and analysis of microwave absorption in polymer composites filled with carbonaceous particles

F. Qin and C. Brosseau

J. Appl. Phys. 111, 061301 (2012); http://dx.doi.org/10.1063/1.3688435 (24 pages)

Online Publication Date: 16 March 2012

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Carbon (C) is a crucial material for many branches of modern technology. A growing number of demanding applications in electronics and telecommunications rely on the unique properties of C allotropes. The need for microwave absorbers and radar-absorbing materials is ever growing in military applications (reduction of radar signature of aircraft, ships, tanks, and targets) as well as in civilian applications (reduction of electromagnetic interference among components and circuits, reduction of the back-radiation of microstrip radiators). Whatever the application for which the absorber is intended, weight reduction and optimization of the operating bandwidth are two important issues. A composite absorber that uses carbonaceous particles in combination with a polymer matrix offers a large flexibility for design and properties control, as the composite can be tuned and optimized via changes in both the carbonaceous inclusions (C black, C nanotube, C fiber, graphene) and the embedding matrix (rubber, thermoplastic). This paper offers a perspective on the experimental efforts toward the development of microwave absorbers composed of carbonaceous inclusions in a polymer matrix. The absorption properties of such composites can be tailored through changes in geometry, composition, morphology, and volume fraction of the filler particles. Polymer composites filled with carbonaceous particles provide a versatile system to probe physical properties at the nanoscale of fundamental interest and of relevance to a wide range of potential applications that span radar absorption, electromagnetic protection from natural phenomena (lightning), shielding for particle accelerators in nuclear physics, nuclear electromagnetic pulse protection, electromagnetic compatibility for electronic devices, high-intensity radiated field protection, anechoic chambers, and human exposure mitigation. Carbonaceous particles are also relevant to future applications that require environmentally benign and mechanically flexible materials.
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78.70.Gq Microwave and radio-frequency interactions
81.05.Qk Reinforced polymers and polymer-based composites

Smart textiles: Challenges and opportunities

Kunigunde Cherenack and Liesbeth van Pieterson

J. Appl. Phys. 112, 091301 (2012); http://dx.doi.org/10.1063/1.4742728 (14 pages)

Online Publication Date: 7 November 2012

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Smart textiles research represents a new model for generating creative and novel solutions for integrating electronics into unusual environments and will result in new discoveries that push the boundaries of science forward. A key driver for smart textiles research is the fact that both textile and electronics fabrication processes are capable of functionalizing large-area surfaces at very high speeds. In this article we review the history of smart textiles development, introducing the main trends and technological challenges faced in this field. Then, we identify key challenges that are the focus of ongoing research. We then proceed to discuss fundamentals of smart textiles: textile fabrication methods and textile interconnect lines, textile sensor, and output device components and integration of commercial components into textile architectures. Next we discuss representative smart textile systems and finally provide our outlook over the field and a prediction for the future.
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89.20.Kk Engineering
89.20.Bb Industrial and technological research and development

Thermal fluctuations of magnetic nanoparticles: Fifty years after Brown

William T. Coffey and Yuri P. Kalmykov

J. Appl. Phys. 112, 121301 (2012); http://dx.doi.org/10.1063/1.4754272 (47 pages)

Online Publication Date: 17 December 2012

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The reversal time, superparamagnetic relaxation time, of the magnetization of fine single domain ferromagnetic nanoparticles owing to thermal fluctuations plays a fundamental role in information storage, paleomagnetism, biotechnology, etc. Here a comprehensive tutorial-style review of the achievements of fifty years of development and generalizations of the seminal work of Brown [Phys. Rev. 130, 1677 (1963)] on thermal fluctuations of magnetic nanoparticles is presented. Analytical as well as numerical approaches to the estimation of the damping and temperature dependence of the reversal time based on Brown's Fokker-Planck equation for the evolution of the magnetic moment orientations on the surface of the unit sphere are critically discussed while the most promising directions for future research are emphasized.
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75.75.-c Magnetic properties of nanostructures
62.40.+i Anelasticity, internal friction, stress relaxation, and mechanical resonances
75.30.Cr Saturation moments and magnetic susceptibilities
75.50.Tt Fine-particle systems; nanocrystalline materials
75.60.Jk Magnetization reversal mechanisms
75.70.Rf Surface magnetism
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