scholarly journals Dielectric studies of cerium doped barium titanate at different frequencies

1970 ◽  
Vol 32 (1) ◽  
pp. 79-85
Author(s):  
SN Rahman ◽  
N Khatun ◽  
Md Tofazzal Hossain ◽  
AH Khan
Keyword(s):  
Barium Titanate ◽  
Room Temperature ◽  
Dielectric Constants ◽  
Relaxation Phenomena ◽  
Dielectric Studies ◽  
Frequency Range ◽  
Ceramic Method ◽  
Dipole Oscillator ◽  
Doped Barium Titanate ◽  
Academy Of Sciences

Cerium doped barium titanate is prepared by conventional ceramic method. The dielectric studies of Ba1-x Cex TiO3 have been accomplished at room temperature over a frequency range 75 KHz to 30 MHz for x = 0.1 to 0.4 with pure BaTiO3. The measurements of the real and imaginary part of dielectric constants show strong frequency dependence. The relaxation phenomena that take place cane be attributable to the damping of dipole oscillator due to the application of external field. In the present experiment relaxation occurs at the frequency of about - 1MHZ. doi: 10.3329/jbas.v32i1.2445 Journal of Bangladesh Academy of Sciences, Vol. 32, No. 1, 79-85, 2008

scholarly journals Structural, Dielectric and Electrical Properties of Zirconium Doped Barium Titanate Perovskite

1970 ◽  
Vol 32 (2) ◽  
Author(s):  
Shamima Choudhury ◽  
Shurayya Akter ◽  
MJ Rahman ◽  
AH Bhuiyan ◽  
SN Rahman ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Barium Titanate ◽  
Loss Factor ◽  
Room Temperature ◽  
Sintering Temperature ◽  
Small Addition ◽  
Dielectric Study ◽  
Frequency Range ◽  
Doped Barium Titanate ◽  
Academy Of Sciences

The microstructural and electrical properties of pure and Zirconium (Zr) doped Barium titanate (BT) samples with general formula Ba(Ti1-xZrx)O3 (where x=0.0, 0.1, 0.2 and 0.3), prepared by high temperature solid state reaction at a sintering temperature of 1250° C, were investigated. Dielectric and structural properties of BT ceramics is influenced significantly by small addition of ZrO2. Scanning Electron Microscope (SEM) observations revealed enhanced microstructural uniformity and retarded grain growth with increasing Zr content. The dielectric study with frequency at room temperature in the frequency range 75 kHz to 30 MHz shows that dielectric constant decreases with increasing frequency. The resistivity of the samples shows asymptotic behavior with the variation of frequency and was found to be of the order of ~103 Ω-m. Loss factor of the grown materials decreased with increasing frequency but it became independent at higher frequency range. doi: 10.3329/jbas.v32i2.2434 Journal of Bangladesh Academy of Sciences Vol.32(2) 2008 151-159

Dielectric Studies of a Series of Liquid Crystalline Pyridine Derivates

1996 ◽  
Vol 51 (9) ◽  
pp. 1019-1026 ◽  
Author(s):  
S. Heinemann ◽  
H. Kresse ◽  
S. Saito ◽  
D. Demus
Keyword(s):  
Frequency Dependence ◽  
Crystalline State ◽  
Liquid Crystalline ◽  
Structural Changes ◽  
Alkoxy Group ◽  
Dielectric Constants ◽  
Dielectric Studies ◽  
Frequency Range ◽  
Liquid Crystalline Phases ◽  
Static Dielectric Constants

Abstract Measurements of the temperature and frequency dependence of dielectric constants have been performed for five homologues in the range 100 Hz -10 MHz. These substances exhibit a negative anisotropy of the dielectric constants and two relaxation regions (rotation of the molecules around the short resp. long axis) in the investigated frequency range. Even in the crystalline state dipolar reorientations are possible which have been interpreted as rotations of the alkoxy group. Changes of the static dielectric constants, relaxation frequencies and transition entropies are discussed as a measure of structural changes passing the several liquid crystalline phases.

Defect controlled room temperature ferromagnetism in Co-doped barium titanate nanocrystals

2011 ◽  
Vol 23 (2) ◽  
pp. 025702 ◽  
Author(s):  
Sugata Ray ◽  
Yury V Kolen’ko ◽  
Kirill A Kovnir ◽  
Oleg I Lebedev ◽  
Stuart Turner ◽  
...  
Keyword(s):  
Barium Titanate ◽  
Room Temperature ◽  
Room Temperature Ferromagnetism ◽  
Doped Barium Titanate ◽  
Co Doped

Up-Conversion Luminescence in Thulium Doped Barium Titanate Inverted Opal

2007 ◽  
Vol 336-338 ◽  
pp. 561-563
Author(s):  
Jing Cao ◽  
Ji Zhou ◽  
Bo Li ◽  
Ming Fu ◽  
Rui Long Zong
Keyword(s):  
Barium Titanate ◽  
Room Temperature ◽  
Photonic Band Gap ◽  
Reference Sample ◽  
Laser Source ◽  
Luminescence Spectroscopy ◽  
Temperature Changes ◽  
Light Inhibition ◽  
Doped Barium Titanate ◽  
Photonic Band

The synthesis, infiltration into a polystyrene opal and luminescence spectroscopy of BaTiO3: Tm3+ were reported in this paper. A photonic band gap and blue up-conversion photoluminescence were achieved in the synthesized inverted opal, respectively demonstrated by reflection spectrum and emission spectrum excited by 650nm laser source at room temperature. Changes of the emission spectroscopy compared with the thulium doped barium titanate reference sample were observed and thus provided evidence for the light inhibition effect of the photonic structure.

Improved room temperature dielectric properties of Gd3+ and Nb5+ co-doped Barium Titanate ceramics

2021 ◽  
pp. 160836
Author(s):  
Khalid Mujasam Batoo ◽  
Ritesh Verma ◽  
Ankush Chauhan ◽  
Rajesh Kumar ◽  
Muhammad Hadi ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Barium Titanate ◽  
Room Temperature ◽  
Doped Barium Titanate ◽  
Titanate Ceramics ◽  
Co Doped

Dielectric and impedance spectroscopy of K+-doped MgAl2O4 nanoparticles

2018 ◽  
Vol 32 (15) ◽  
pp. 1850189
Author(s):  
Javed Ahmad ◽  
S. H. Bukhari ◽  
M. Qadeer Awan ◽  
M. Ehsan Mazhar ◽  
A. R. Makhdoom
Keyword(s):  
Dielectric Constant ◽  
Impedance Spectroscopy ◽  
High Frequency ◽  
Dielectric Response ◽  
Room Temperature ◽  
Parent Compound ◽  
Low Frequency ◽  
Space Charge Polarization ◽  
Relaxation Phenomena ◽  
Frequency Range

In this study, the dielectric response of Potassium (K[Formula: see text])-doped magnesium aluminates nanoparticles (Mg[Formula: see text]K[Formula: see text]Al2O4, x = 0.0, 0.25, 0.5, 0.75, 1.0) have been investigated as a function of frequency (20 Hz to 2 MHz) at room-temperature. Interestingly, the behavior of dielectric constant indicated the ionic or space charge polarization in the low-frequency range and it remains almost constant at high frequency. However, the value of conductivity increases at higher frequencies which is consistent with the previously reported results for the parent compound MgAl2O4. Moreover, the Cole–Cole plots represent various relaxation phenomena reflecting the existence of grain (boundaries) resistance effects.

scholarly journals Effects of Ca substitution on room temperature resistivity of donor-doped barium titanate based PTCR ceramics

2014 ◽  
Vol 122 (1426) ◽  
pp. 402-405 ◽  
Author(s):  
Kohei MATSUURA ◽  
Takuya HOSHINA ◽  
Hiroaki TAKEDA ◽  
Yukio SAKABE ◽  
Takaaki TSURUMI
Keyword(s):  
Barium Titanate ◽  
Room Temperature ◽  
Room Temperature Resistivity ◽  
Ca Substitution ◽  
Doped Barium Titanate ◽  
Temperature Resistivity

scholarly journals Photothermal, Photoelectric, and Photothermoelectric Effects in Bi-Sb Thin Films in the Terahertz Frequency Range at Room Temperature

Photonics ◽  
2021 ◽  
Vol 8 (3) ◽  
pp. 76
Author(s):  
Mikhail K. Khodzitsky ◽  
Petr S. Demchenko ◽  
Dmitry V. Zykov ◽  
Anton D. Zaitsev ◽  
Elena S. Makarova ◽  
...  
Keyword(s):  
Thin Films ◽  
Terahertz Radiation ◽  
Room Temperature ◽  
Voltage Drop ◽  
Radiation Detection ◽  
Radiation Detectors ◽  
Thz Radiation ◽  
Terahertz Frequency ◽  
Frequency Range ◽  
Terahertz Frequency Range

The terahertz frequency range is promising for solving various practically important problems. However, for the terahertz technology development, there is still a problem with the lack of affordable and effective terahertz devices. One of the main tasks is to search for new materials with high sensitivity to terahertz radiation at room temperature. Bi1−xSbx thin films with various Sb concentrations seem to be suitable for such conditions. In this paper, the terahertz radiation influence onto the properties of thermoelectric Bi1−xSbx 200 nm films was investigated for the first time. The films were obtained by means of thermal evaporation in vacuum. They were affected by terahertz radiation at the frequency of 0.14 terahertz (THz) in the presence of thermal gradient, electric field or without these influences. The temporal dependencies of photoconductivity, temperature difference and voltage drop were measured. The obtained data demonstrate the possibility for practical use of Bi1−xSbx thin films for THz radiation detection. The results of our work promote the usage of these thermoelectric materials, as well as THz radiation detectors based on them, in various areas of modern THz photonics.

scholarly journals A hybrid broadband metalens operating at ultraviolet frequencies

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Farhan Ali ◽  
Serap Aksu
Keyword(s):  
Dielectric Material ◽  
Berry Phase ◽  
Uv Light ◽  
Fdtd Method ◽  
Numerical Aperture ◽  
Limited Range ◽  
Unit Cell ◽  
Dielectric Constants ◽  
Phase Method ◽  
Frequency Range

AbstractThe investigation on metalenses have been rapidly developing, aiming to bring compact optical devices with superior properties to the market. Realizing miniature optics at the UV frequency range in particular has been challenging as the available transparent materials have limited range of dielectric constants. In this work we introduce a low absorption loss and low refractive index dielectric material magnesium oxide, MgO, as an ideal candidate for metalenses operating at UV frequencies. We theoretically investigate metalens designs capable of efficient focusing over a broad UV frequency range (200–400 nm). The presented metalenses are composed of sub-wavelength MgO nanoblocks, and characterized according to the geometric Pancharatnam–Berry phase method using FDTD method. The presented broadband metalenses can focus the incident UV light on tight focal spots (182 nm) with high numerical aperture ($$\hbox {NA}\approx 0.8$$ NA ≈ 0.8 ). The polarization conversion efficiency of the metalens unit cell and focusing efficiency of the total metalens are calculated to be as high as 94%, the best value reported in UV range so far. In addition, the metalens unit cell can be hybridized to enable lensing at multiple polarization states. The presented highly efficient MgO metalenses can play a vital role in the development of UV nanophotonic systems and could pave the way towards the world of miniaturization.

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