Faraday method for magnetic susceptibility

Fig. 7.3. Internally pressured cell for magnetic susceptibility measurements of fluid selenium by the Faraday method (Freyland and Cutler, 1980). The sealed quartz capsule containing the sample is mechanically supported by the surrounding molybdenum pressure cell.

Electrobalances suitable for thermogravimetry are readily adapted for measurements of magnetic susceptibility [333—336] by the Faraday method, with or without variable temperature [337] and data processing facilities [338]. This approach has been particularly valuable in determinations of the changes in oxidation states which occur during the decompositions of iron, cobalt and chromium oxides and hydroxides [339] and during the formation of ferrites [340]. The method requires higher concentrations of ions than those needed in Mossbauer spectroscopy, but the apparatus, techniques and interpretation of observations are often simpler. 

The magnetic susceptibilities (x) or magnetization (a = x H) for the systems described here were measured by the In-sltu Faraday method described by Mulay [1]. The Mossbauer Spectra were obtained with an Austin Associates spectrometer with a 57co/Rh matrix source (50 mCi) and Nuclear data electronics. In-sltu measurements were made, using a cell similar to that described by Delgass et al. [7]. 

Magnetic Susceptibility Measurements. Magnetic susceptibilities were measured by the Faraday method and were accurate to 2%. Samples, usually as powders, were placed in a cylindrical Teflon boat having an internal volume of 0.30 cc. Measurements were made at 2963, 4357, 5724, 7077, and 8243 G, and at temperatures 77°-295°K. It was possible to correct for ferromagnetic impurities from any field dependent effects. 

Although for p-azoxyanisole (PAA) a number of measurements in electric fields have been reported (I, 5), only Foex ( ) reported measurements in a high magnetic field. In this paper we report the results of magnetic susceptibility measurements on PAA, which have been obtained by using the Faraday method with a sensitive balance described by Poulis et al. (6). The sample consisted of 0.2841 gram of PAA held in an evacuated spherical quartz container. Measurements were made at fields of 2550, 1050, 275, and 200 oersteds at a number of temperatures in the liquid crystal and liquid phase. The absolute accuracy of the susceptibility measurements was about 3%, determined by the irreproducibility in the adjustment of... 

Magnetic Susceptibility Measurements. The magnetic susceptibility of the solids was measured by the Faraday method with Hg[Co(SCN)4] used as the calibrant. Corrections for diamagnetism were made using Pascals constants. Solution measurements were made in CHCI3 by NMR techniques (17),... 

There will be described first the most widely used method for determination of diamagnetic and paramagnetic susceptibilities, namely the method of Gouy. Second, a very satisfactory alternative method, that of Faraday, will be described briefly. Third, reference will be made to possible methods for studying the magnetic properties of catalysts in situ, that is, while they are actually being active. And last, a method... 

The standard method for the determination of magnetic susceptibilities of diamagnetic samples is the Faraday-Curie method [8]. The method is based on the measurement of the force on a sample with susceptibility X in an inhomogeneous magnetic field. For diamagnetic substances... 

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