Dielectric properties of Y and Nb co-doped TiO2 ceramics

Abstract

In this work, the (Y0.5Nb0.5)xTi1−xO2 (x = 0.001, 0.01, 0.02, 0.04, 0.06 and 0.1) ceramics (as called YNTO) were fabricated by synthesized through a standard solid-state reaction. As revealed by the X-ray diffraction (XRD) spectra, the YNTOs exhibit tetragonal rutile structure. Meanwhile, the grain size of YNTO ceramics increased and then decreased with the increase of x value, and the largest value reached when x = 0.02. All the YNTO samples display colossal permittivity (~102–105) over a wide temperature and frequency range. Moreover, the optimal ceramic, (Y0.5Nb0.5)0.02Ti0.98O2, exhibits high performance over a broad temperature range from 20 °C to 180 °C; specifically, at 1 kHz, the dielectric constant and dielectric loss are 6.55 × 104 and 0.22 at room temperature, and they are 1.03 × 105 and 0.11 at 180 °C, respectively.

Topological invariants for Floquet-Bloch systems with chiral, time-reversal, or particle-hole symmetry

“…These phases cannot be characterized by static invariants, such as the Chern numbers of the Floquet bands, but only through invariants that depend on the entire dynamical evolution of the system 11 . Irradiated solid state systems [13][14][15] and photonic crystals [16][17][18][19] , where the third spatial dimension represents the time axis, are promising candidates for the realization of these new topological phases.…”

Influence of Zr dopant on polarization in rutile (In0.5Nb0.5)0.005(Ti1‐xZrx)0.995O2 ceramics

“…6,7 This CP phenomenon could be attributed to electron-pinned defect-dipoles (EPDD) polarization, but the concept remains controversial. [8][9][10][11] Other mechanisms in the CP co-doped TiO 2 are also presented, such as Maxwell-Wagner polarization, which stems from the spatial heterogeneity of conductivity at the grain boundary (GBLC), interface (IBLC) and resistive outer surface (SBLC), and polaronic polarization caused by microscopic heterogeneities have been observed. 8,[11][12][13][14] These mechanisms coexist and are consistent with the defect-cluster model in co-doped TiO 2 .…”

Dual‐Responsive Carbon Dot for pH/Redox‐Triggered Fluorescence Imaging with Controllable Photothermal Ablation Therapy of Cancer

“…FRET can be accurately used to monitor the delivery of nanoparticles in living cells through the fluorescence on/off system by the application of hydrophobic organic dyes. Previous studies have successfully demonstrated the use of near‐infrared (NIR)‐induced photothermal dyes such as indocyanine green (ICG), IR780, and heptamethine dyes (IR825) . For theranostics, photothermal therapy (PTT) dyes tagged to fluorescent particles that overlap fluorescence excitation and/or emission spectra can be used to turn off fluorescence during the FRET process.…”