Junbao Li

Formation of GaN nanorods by a sublimation method

Abstract GaN nanorods with diameters of 10–45xa0nm were formed through a simple sublimation method. They were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). SEM images showed that the nanorods were straight. XRD, SAED and HRTEM indicated that the nanorods were wurtzite GaN single crystals.

Growth and electrical properties of large size Pb(In1∕2Nb1∕2)O3–Pb(Mg1∕3Nb2∕3)O3–PbTiO3 crystals prepared by the vertical Bridgman technique

Relaxor-based ferroelectric single crystals Pb(In1∕2Nb1∕2)O3–Pb(Mg1∕3Nb2∕3)O3–PbTiO3 (PIMNT) have been grown directly from their melt using the vertical Bridgman method, and their boules have reached the size of ϕ45×80mm. The as-grown PIMNT28/40/32 crystals on the (001) cuts exhibit a dielectric constant e∼5200, dielectric loss tanδ∼0.50%, piezoelectric strain constant d33∼1700–2200pC∕N, electromechanical coupling factors kt∼0.61 and k33∼0.92, coercive field Ec∼10.88kV∕cm, remanent polarization Pr∼46μC∕cm2, Curie temperature TC∼192°C, and rhombohedral to tetragonal phase transition temperature Trt∼119°C. Moreover, their piezoelectric properties show good thermal stability under the heat treatment at 105°C.

Dielectric and piezoelectric properties of lead-free 0.95(K0.5Na0.5)NbO3–0.05LiNbO3 crystals grown by the Bridgman method

Lead-free potassium sodium niobate piezoelectric single crystals substituted with lithium 0.95(K0.5Na0.5)NbO3–0.05LiNbO3 have been grown by Bridgman method and their dielectric and piezoelectric properties were studied. The orthorhombic-tetragonal and tetragonal-cubic phase transition temperatures of the single crystal appear at 192 and 426°C according to the dielectric constant versus temperature loops, respectively, and the (001) plates show good piezoelectric properties with piezoelectric constant d33 as high as 405pC∕N, large thickness electromechanical coupling factor kt=61%, and low dielectric constant of 185 at room temperature. These excellent properties show that the 0.95(K0.5Na0.5)NbO3–0.05LiNbO3 single crystal is a good lead-free piezoelectric material.

Enhanced superconductivity by strain and carrier-doping in borophene: A first principles prediction

By first principles calculations, we predict that the recently prepared borophene is a pristine two-dimensional monolayer superconductor in which the superconductivity can be significantly enhanced by strain and charge carrier doping. The intrinsic metallic ground state with high density of states at Fermi energy and strong Fermi surface nesting lead to sizeable electron-phonon coupling, making the freestanding borophene superconduct with Tc close to 19.0u2009K. The tensile strain can increase the Tc to 27.4u2009K, while the hole doping can notably increase Tc to 34.8u2009K. The results indicate that the borophene grown on substrates with large lattice parameters or under photoexcitation can show enhanced superconductivity with Tc far above the liquid hydrogen temperature of 20.3u2009K, which will largely broaden the applications of such promising material.

Manipulating charge density waves in 1 T − TaS 2 by charge-carrier doping: A first-principles investigation

The transition-metal dichalcogenide

Manipulation of type-I and type-II Dirac points in PdTe2 superconductor by external pressure

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5B-2 Growth and Properties of Some Relaxor-Based Ferroelectric Single Crystals with High Curie Temperature by the Solution Bridgman and Modified Bridgman Techniques

exhibits a rich set of charge-density-wave (CDW) orders. Recent investigations suggested that using light or an electric field can manipulate the commensurate CDW (CCDW) ground state. Such manipulations are considered to be determined by charge-carrier doping. Here we use first-principles calculations to simulate the carrier-doping effect on the CCDW in

A new model of magnetostrictive ‘‘jumps’’ in twinned Terfenol‐D (abstract)

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A new method for synthesis of amorphous carbon nitride powders

. We investigate the charge-doping effects on the electronic structures and phonon instabilities of the

Tuning the electronic and magnetic properties of borophene by 3d transition-metal atom adsorption

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