APL Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Flickr Twitter iResearch App Facebook

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

18 Jun 2001

Volume 78, Issue 25, pp. 3927-4046

Return to All Sections
back to top
RSS Feeds

Emission from ferroelectric cathodes versus temperature and the relevant physics

I. Boscolo and S. Cialdi

Appl. Phys. Lett. 78, 4013 (2001); http://dx.doi.org/10.1063/1.1371249 (3 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We show that electron emission from a relaxor ferroelectric cathode varies with the temperature as the dielectric constant. Consequently, there is no variation when the material makes the antiferroparaelectric phase transition. In addition, we have found that the emission increases with the polarizability of the material. The emission is originated by an induced change of the normal and/or spontaneous polarization. The maximum efficiency of the process, that is the ratio between the emitted charge of energetic electrons and the charge supplied to the sample by the excitation pulse, resulted in about 20%. The good emission of energetic electrons from a ceramic cathode at few hundred degrees temperature, makes this kind of cathode a proper electron injector for ion sources. © 2001 American Institute of Physics.
Show PACS
79.70.+q Field emission, ionization, evaporation, and desorption
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.22.Ch Permittivity (dielectric function)
77.22.Ej Polarization and depolarization

Coulomb glass origin of defect-induced dielectric loss in thin-film oxides

R. M. Fleming, C. M. Varma, D. V. Lang, C. D. W. Jones, M. L. Steigerwald, and G. R. Kowach

Appl. Phys. Lett. 78, 4016 (2001); http://dx.doi.org/10.1063/1.1379984 (3 pages) | Cited 1 time

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The dielectric loss in amorphous, thin-film oxide insulators produces a real part of the ac conductivity σ′(ω) that scales as ωs with s ∼ 1. Conventional models explain this frequency dependence by hopping or tunneling of charge between neighboring defect sites. These models fail at low temperatures since they predict that σ′ should vanish at T = 0. We observe that the ac conductivity of Ta2O5, ZnO, and SiO2 has a nonzero extrapolated value at T = 0. We propose that this behavior is consistent with the predictions of a Coulomb glass, an insulator with a random distribution of charged defects. © 2001 American Institute of Physics.
Show PACS
77.55.-g Dielectric thin films
73.61.Ng Insulators
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
72.30.+q High-frequency effects; plasma effects
77.22.Gm Dielectric loss and relaxation
73.50.Mx High-frequency effects; plasma effects

Nonlinear-optic and ferroelectric behavior of lithium borate–strontium bismuth tantalate glass–ceramic composite

G. Senthil Murugan, K. B. R. Varma, Yoshihiro Takahashi, and Takayuki Komatsu

Appl. Phys. Lett. 78, 4019 (2001); http://dx.doi.org/10.1063/1.1380237 (3 pages) | Cited 39 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Transparent glasses in the system (100–x) Li2B4O7–xSrBi2Ta2O9 (0 ⩽ x ⩽ 20) were fabricated via a splat-quenching technique. The glassy nature of the as-quenched samples was established by differential thermal analyses. X-ray powder diffraction and transmission electron microscopic studies confirmed the amorphous nature of the as-quenched and crystallinity (40 nm) in the heat-treated (glass–ceramic) samples. The dielectric constant (ϵr) of the glass–ceramic composite (x = 20, heat treated at 773 K/8 h) was in between that of the parent host glass (Li2B4O7) and strontium bismuth tantalate ceramics in the frequency range 100 Hz–40 MHz at 300 K. These exhibited intense second-harmonic generation and a ferroelectric hysteritic behavior (P vs E loops) at 300 K. The coercive field (Ec) and the remnant polarization (Pr) were 1053 V/cm and 0.483 μC/cm2, respectively. © 2001 American Institute of Physics.
Show PACS
42.70.Nq Other nonlinear optical materials; photorefractive and semiconductor materials
81.05.Pj Glass-based composites, vitroceramics
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
77.80.Dj Domain structure; hysteresis
42.70.Ce Glasses, quartz
81.40.Gh Other heat and thermomechanical treatments
81.40.Tv Optical and dielectric properties related to treatment conditions
61.43.Fs Glasses
42.65.Ky Frequency conversion; harmonic generation, including higher-order harmonic generation
77.22.Ch Permittivity (dielectric function)
Return to All Sections
Close

Google Calendar

ADVERTISEMENT

Go to AIP Home   © AIP Publishing LLC
close