Effect of structural changes in complex perovskites on the temperature coefficient of the relative permittivity

1993 ◽  
Vol 74 (5) ◽  
pp. 3414-3425 ◽  
Author(s):  
E. L. Colla ◽  
I. M. Reaney ◽  
N. Setter
Keyword(s):  
Temperature Coefficient ◽  
Relative Permittivity ◽  
Structural Changes ◽  
Complex Perovskites

Human Orosomucoid: Dissociation of Tyrosines in the Systems Water-Low Aliphatic Alcohol

1997 ◽  
Vol 62 (10) ◽  
pp. 1533-1543
Author(s):  
Vladimír Karpenko ◽  
Jana Horálková ◽  
Milan Kodíček
Keyword(s):  
Human Serum ◽  
Systems Analysis ◽  
Titration Curve ◽  
Relative Permittivity ◽  
Structural Changes ◽  
Aliphatic Alcohol ◽  
Mixed Media ◽  
Spectrophotometric Titration ◽  
Electrostatic Effects

The influence of methanol, ethanol, propan-1-ol, and propan-2-ol on the dissociation of tyrosines of human serum orosomucoid (acid α1-glycoprotein) was studied. The content of alcohols was chosen so that their solutions had the same value of the relative permittivity. Then, the contribution of electrostatic effects was equal in all cases and the observed differences between aqueous and alcoholic solutions reflected other, nonelectrostatic effects in the studied systems. Analysis of the spectrophotometric titration curve revealed three kinds of tyrosine groups (n1, n2, n3), but only the values pK1 and pK2 could be calculated. The observed differences of pK values in aqueous and mixed media are discussed and compared with the structural changes of the orosomucoid molecule.

scholarly journals Potato tuber permittivity during deformation in compression

2008 ◽  
Vol 53 (No. 3) ◽  
pp. 79-84 ◽  
Author(s):  
J. Blahovec ◽  
J. Sobotka
Keyword(s):  
Potato Tuber ◽  
Complex Permittivity ◽  
Relative Permittivity ◽  
Structural Changes ◽  
Potato Tissue ◽  
Compression Loading ◽  
Permittivity Measurements ◽  
Permittivity Spectrum

Potato tuber specimens of two varieties (Nicola and Saturna) were deformed in a compression loading/unloading test. The tuber complex permittivity spectrum at frequencies 0.1–500 kHz was measured repeatedly during the deformation. The results show that both parts of relative permittivity (real and imaginary) decrease with increasing deformation and vice versa. The same trend was observed at all studied frequencies even if it was not equally strong in all cases. The permittivity plots versus frequency were similar in both the tested varieties and in different stages of deformation. The influence of tuber deformation on the permittivity values as well as the reversibility of the permittivity changes during the deformation are changed substantially at strains about 20% in comparison to strains up to 10%. The obtained results support the hypothesis that permittivity measurements can serve as an alternative indication of the internal structural changes in potato tissue during its loading.

scholarly journals A low-firing melilite ceramic Ba2CuGe2O7 and compositional modulation on microwave dielectric properties through Mg substitution

2020 ◽  
Author(s):  
Changzhi Yin ◽  
Zezong Yu ◽  
Longlong Shu ◽  
Laijun Liu ◽  
Yan Chen ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Dielectric Properties ◽  
Resonance Frequency ◽  
Temperature Coefficient ◽  
Quality Factor ◽  
Relative Permittivity ◽  
Microwave Dielectric Properties ◽  
Sintering Behavior ◽  
Magnesium Doping ◽  
Microwave Dielectric

AbstractA melilite Ba2CuGe2O7 ceramic was characterized by low sintering temperature and moderate microwave dielectric properties. Sintered at 960 °C, the Ba2CuGe2O7 ceramic had a high relative density 97%, a low relative permittivity (εr) 9.43, a quality factor (Q×f) of 20,000 GHz, and a temperature coefficient of resonance frequency (τf) −76 ppm/°C. To get a deep understanding of the relationship between composition, structure, and dielectric performances, magnesium substitution for copper in Ba2CuGe2O7 was conducted. Influences of magnesium doping on the sintering behavior, crystal structure, and microwave dielectric properties were studied. Mg doping in Ba2CuGe2O7 caused negligible changes in the macroscopic crystal structure, grain morphology, and size distribution, while induced visible variation in the local structure as revealed by Raman analysis. Microwave dielectric properties exhibit a remarkable dependence on composition. On increasing the magnesium content, the relative permittivity featured a continuous decrease, while both the quality factor and the temperature coefficient of resonance frequency increased monotonously. Such variations in dielectric performances were clarified in terms of the polarizability, packing fraction, and band valence theory.

Structure-dielectric property relationship in Nb-doped Ca4La2Ti5O17 ceramics

2016 ◽  
Vol 30 (18) ◽  
pp. 1650104 ◽  
Author(s):  
Raz Muhammad ◽  
Yaseen Iqbal
Keyword(s):  
Dielectric Property ◽  
Solid State ◽  
Resonance Frequency ◽  
Temperature Coefficient ◽  
Quality Factor ◽  
Mixed Oxide ◽  
Relative Permittivity ◽  
Property Relationship ◽  
Solid State Sintering

A number of compounds in the [Formula: see text] (x = 0–2) series were prepared through a mixed oxide solid-state sintering route. These compounds crystallized into orthorhombic (Pbnm) structure. The relative permittivity [Formula: see text] and temperature coefficient of resonance frequency [Formula: see text] depended on the polarizability of constituent cations while the quality factor [Formula: see text] was affected by ordering of cations. These compounds exhibited promising [Formula: see text] (74–90) and [Formula: see text] (10[Formula: see text]208–14[Formula: see text]116 GHz); however, the observed high [Formula: see text] (157–542 ppm/[Formula: see text]C) requires further investigations to tune it through zero.

MICROWAVE DIELECTRIC PROPERTIES AND RAMAN SPECTROSCOPY OF SCHEELITE SOLID SOLUTION [(Li0.5Bi0.5)1-xCax]MoO4 CERAMICS WITH ULTRA-LOW SINTERING TEMPERATURES

2010 ◽  
Vol 03 (04) ◽  
pp. 253-257 ◽  
Author(s):  
DI ZHOU ◽  
HONG WANG ◽  
QIU-PING WANG ◽  
XIN-GUANG WU ◽  
JING GUO ◽  
...  
Keyword(s):  
Solid Solution ◽  
Raman Spectroscopy ◽  
Dielectric Properties ◽  
Temperature Coefficient ◽  
Relative Permittivity ◽  
High Performance ◽  
Microwave Dielectric Properties ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Microwave Dielectric

A Scheelite solid solution was formed based on [( Li0.5Bi0.5 )1-x Ca x] MoO 4 ceramics and prepared via a solid state reaction method in the range 0.0 ≤ x ≤ 1.0. High performance microwave dielectric properties were obtained in the [(Li0.5Bi0.5)0.15Ca0.85]MoO4 ceramic sintered at 760°C with a relative permittivity of 14.1, a Qf value of 24,000 GHz (at 10.0 GHz), and a temperature coefficient value of +10.7 ppm/°C and the [(Li0.5Bi0.5)0.1Ca0.9]MoO4 ceramic sintered at 850°C with a relative permittivity of 12.7, a Qf value of 41,300 GHz (at 10.3 GHz), and a temperature coefficient value of -16.5 ppm/°C. X-ray diffraction, Raman spectroscopy and the classical damped oscillator model were applied to study the relationship between the microwave dielectric properties and structures.

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