Microwave dielectric relaxation of some lithium salts in dimethyl carbonate

Saar, David; Brauner, Joseph W.; Farber, H.; Petrucci, Sergio

doi:10.1021/j100494a010

Cited by 14 publications

(4 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, these studies were confined to some alkali perchlorates in THF1,2 and to lithium salts in DMC. 3 It was of interest to try to generalize the above conclusions for electrolytes of different nature and structure in the same solvent. Therefore, we have now extended our studies to include LiN03, sodium picrate, and Bu4NN03 in THF in the same concentration range as used previously.…”

Section: Introductionmentioning

confidence: 99%

Dielectric relaxation of some 1:1 electrolytes in tetrahydrofuran and diethyl carbonate

Saar¹,

Brauner²,

Farber³

et al. 1978

J. Phys. Chem.

Self Cite

View full text Add to dashboard Cite

Complex permittivities in the frequency range of 0.3-67 GHz are reported for the systems 0.1 M LiN03,0.05 M sodium picrate, 0.1 M Bu4NN03 in THF at 25 °C and for the systems 0.1 M LiC104, and 0.1 M LiSCN in diethyl carbonate (DEC) at 25 °C. The permittivities of the electrolyte solutions can be described within experimental error by the sum of two Debye relaxation processes. The high frequency process is comparable to the one observed for the pure solvents while the low frequency process is due to the presence of the electrolytes.Apparent dipole radii aT for the electrolytes in the THF solutions are calculated from the Debye relation using the macroscopic viscosity of the solvent. Charge to charge separation distances µ are calculated from the Bottcher relation which relates the change in dielectric strength (e0 -e^), for a dipolar relaxation process, with the apparent dipole moment. These two parameters oT and o" determined for the present systems and two previous systems (LiC104 and NaC104 in THF) are linearly related to each other (correlation coefficient r2 = 0.89). The oT's also correlate linearly (r2 = 0.91) with the sums of the crystallographic radii. These relations reinforce our previous conclusions that the solute relaxation process in THF is mainly due to the rotation of ion-pair dipoles. For DEC solutions the appearance of a single relaxation process for the solute (instead of a distribution of relaxation times as the presence of two molecular species would suggest) is discussed in terms of the structure of the quadrupoles. Recent Raman and IR spectra in the literature suggest a centrosymmetric structure for (LiSCN)2 in ethers. This structure if present for the carbonate solutions would predict the absence of a quadrupole dielectric relaxation process in accord with our results in dimethyl carbonate (DMC) and DEC.

show abstract

Section: Introductionmentioning

confidence: 99%

Dielectric relaxation of some 1:1 electrolytes in tetrahydrofuran and diethyl carbonate

Saar¹,

Brauner²,

Farber³

et al. 1978

J. Phys. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…In Figure 4 the data for diethyl carbonate show a deviation The dependence of density on temperature for the last three liquids, in the temperature range 25-55 °C, can be expressed by the relations determined by the following linear regressions: (diethyl carbonate) p = 0.9969 -1.11 X 10"3£, °C r2 = 0.999; (dipropyl carbonate) p = 0.9586 -0.907 X 10"3f, °C r2 = 0.993; (dibutyl carbonate) p = 0.9439 -0.975 X 10"3f, °C r2 = 0.999. 6 Real part e' and coefficient of the imaginary part e" of the complex permittivity plotted vs. the frequency f (GHz) for dimethyl, diethyl, dipropyl, and dibutyl carbonates at 25 °C. The solid lines are calculated functions according to a single Debye relaxation function.…”

Section: Results and Calculationsmentioning

confidence: 99%

“…The dielectric equipment and procedures have been described elsewhere. 6 Cannon viscometers no. 0 and 1 (Cannon, University Park, Pa.) with manufacturer calibration certificates were used.…”

Section: Methodsmentioning

confidence: 99%

Ultrasonic and microwave dielectric relaxation of liquid dialkyl carbonates

Saar¹,

Brauner²,

Farber³

et al. 1978

J. Phys. Chem.

View full text Add to dashboard Cite

Ultrasonic absorption data for pure dimethyl, diethyl, dipropyl, dibutyl, and propylene carbonates in the frequency range 3-300 MHz and in the temperature range 25-55 °C are reported. An ultrasonic relaxation process of the Debye type with a relaxation frequency fR = 8.5-10 MHz at 25 °C, which is largely independent of the length of the alkyl chain in the alkoxy group, has been found for the noncyclic carbonates. No such process has been observed for the cyclic propylene carbonate and for dimethoxymethane which lacks the carbonyl group. The observed relaxation process is interpreted as being due to a cis-trans isomerization of the alkoxy groups.By using theories for thermal relaxation processes both the activation parameters AH* and AS* for the reverse step of the equilibrium and the thermodynamic parameters AH°and K for the equilibrium have been determined.Complex dielectric permittivities in the microwave frequency range 0.6-67 GHz for the above noncyclic carbonates at 25 °C are also reported. The data can be described over almost all the frequency range studied by a single Debye relaxation process. The high end of the frequency range shows some positive deviations of the loss in accord with literature data. The dielectric relaxation process is interpreted as due to a segmental motion of the molecule under the influence of the electric field. The different nature of the relaxation mechanisms for the ultrasonic and dielectric processes is attributed to the different type of perturbing function inherent in the two methods.

show abstract

“…As the first attempt, permittivity and conductivity behavior of binary aqueous mixtures of sodium chloride [ 124 ], ethanol [ 125 ], DMSO [ 126 ], DESO [ 127 ], glycine [ 128 ], ethylene glycol oligomer [ 129 ], 2-butoxyethanol [ 130 ], butyric acid [ 131 ], and 2-methoxyethanol [ 132 ] were reviewed. Later, other chemical compounds or their non-aqueous mixtures were also considered; among which methanol, 1-propanol, 2-propanol [ 133 ], dialkyl carbonates [ 134 ], 1-Hexanol/1-propenol [ 135 ], lithium salts/dimethyl carbonate [ 136 ], ethylene glycol - dimethyl sulfoxide [ 137 ], morpholine/n-butanol, and C16-ether-PN6-1ecith/methanol [ 131 ] can be named. Last efforts constituted reviewing a Ketone-like chemical, Dimethylketone (DMK), in mixture with 2–Butoxyethanol (2-BE) [ 138 ] and corn syrup [ 139 ].…”

Section: A Bimodal System: Dbt Plus Nrimentioning

confidence: 99%

Preliminary Results of a New Auxiliary Mechatronic Near-Field Radar System to 3D Mammography for Early Detection of Breast Cancer

Ghanbarzadeh-Dagheyan

Molaei

Obermeier

et al. 2018

Sensors

View full text Add to dashboard Cite

Accurate and early detection of breast cancer is of high importance, as it is directly associated with the patients' overall well-being during treatment and their chances of survival. Uncertainties in current breast imaging methods can potentially cause two main problems: (1) missing newly formed or small tumors; and (2) false alarms, which could be a source of stress for patients. A recent study at the Massachusetts General Hospital (MGH) indicates that using Digital Breast Tomosynthesis (DBT) can reduce the number of false alarms, when compared to conventional mammography. Despite the image quality enhancement DBT provides, the accurate detection of cancerous masses is still limited by low radiological contrast (about 1%) between the fibro-glandular tissue and affected tissue at X-ray frequencies. In a lower frequency region, at microwave frequencies, the contrast is comparatively higher (about 10%) between the aforementioned tissues; yet, microwave imaging suffers from low spatial resolution. This work reviews conventional X-ray breast imaging and describes the preliminary results of a novel near-field radar imaging mechatronic system (NRIMS) that can be fused with the DBT, in a co-registered fashion, to combine the advantages of both modalities. The NRIMS consists of two antipodal Vivaldi antennas, an XY positioner, and an ethanol container, all of which are particularly designed based on the DBT physical specifications. In this paper, the independent performance of the NRIMS is assessed by (1) imaging a bearing ball immersed in sunflower oil and (2) computing the heat Specific Absorption Rate (SAR) due to the electromagnetic power transmitted into the breast. The preliminary results demonstrate that the system is capable of generating images of the ball. Furthermore, the SAR results show that the system complies with the standards set for human trials. As a result, a configuration based on this design might be suitable for use in realistic clinical applications.

show abstract

Microwave dielectric relaxation of some lithium salts in dimethyl carbonate

Abstract: Dielectric Relaxation in Dimethyl Carbonate orbitals for the bis Ir(III) complexes are likely single ring delocalized orbitals, hence a similar situation for the other (tris, bisesquis) Ir(III) complexes would not be surprising.

Cited by 14 publications

References 1 publication

Dielectric relaxation of some 1:1 electrolytes in tetrahydrofuran and diethyl carbonate

Dielectric relaxation of some 1:1 electrolytes in tetrahydrofuran and diethyl carbonate

Ultrasonic and microwave dielectric relaxation of liquid dialkyl carbonates

Preliminary Results of a New Auxiliary Mechatronic Near-Field Radar System to 3D Mammography for Early Detection of Breast Cancer

Contact Info

Product

Resources

About