Magnetic Susceptibility Brochure.qxp ... - Sherwood Scientific

1 T.+44 (0) 1223 243444f.+44 (0) 1223 Scientific Magnetic SUSCEPTIBILITYBALANCESFOR THE STUDY OF DIAMAGNETIC AND PARAMAGNETIC PROPERTIES OF MATERIALSM agnetic Susceptibility 1 09/06/2015 14:24 Page 1 Sherwood Scientific MSB MK1 & AUTOt. +44 (0) 1223 243444f. +44 (0) 1223 243300e. Susceptibility is defined as The ratio of the intensityof magnetism induced in a substance to the magnetising forceor intensity of field to which it is subject. Sherwood Scientific S Magnetic Susceptibility BALANCESare recognised in hundreds of teaching and research laboratoriesthroughout the world.

2 Based on a design by the Late ProfessorEvans of Imperial College London, they offer a number o f signifi-cant advantages over traditional methods. The Mk 1 balanceadheres closely to Evans original design. The MSB AUTO is amicro-processor controlled state of the art balance for detectingthe Magnetic properties of gases, liquids and solids. The improvedsensitivity, versatility and overall performance make it ideallysuited for new analytical applications in the research laboratoryand indus trial quality control. Both balances are exclusivelymanufactured by Sherwood Scientific in Cambridge PRINCIPLES OFMAGNETIC BEHAVIOURB ased on their Magnetic properties, all substances can beclassified into one of three groups, those attracted by a strongmagnetic field; known as paramagnetic, those repelled;designated diamagnetic and finally, the most recognised class,ferromagnetic, unique in their ability to retain their own magneticfield.

3 Ferromagnets are able to retain a permanent Magnetic fieldsince their free electrons are in close proximity and remainaligned even after the external Magnetic field is removed. Unlikethe ferromagnets, the Magnetic properties of the diamagnetic orparamagnetic materials may only be observed and measuredwhen they are held within a Magnetic field applied SUSCEPTIBILITYAT THE MOLECULAR LEVELThe nature of the electrons within a sample determine itsmagnetic properties. The Magnetic forces that are generated aremore or less neutralised when two electrons become paired.

4 Free,unpaired, electrons give rise to Magnetic forces which areattracted to a strong Magnetic field and the strength of theseattractive forces are in direct proportion to the number of freeelectrons. The presence of free electrons results in materialsbeing classified a s paramagnetic and the lack of them results ina compound being diamagnetic. Crystallinity, chemical reactions,oxidation states, and virtually anything that can alter theelectronic configuration of a compound, may also change itsmagnetic properties. Analogous to spectral measurements, Magnetic Susceptibility measurements are both qualitative andquantitative in MK1 and the AUTO work on the basis ofstationary sample andmoving magnets.

5 Twopairs of magnets areplaced at opposite endsof a beam making a bal-anced system having amagnetic field at eachend. Introduction of thesample into the magneticfield attempts to deflectthe beam and themovement is optically detected. A compensating force is applied byintroducing a current through a coil between the other pair of current required to maintain the original balance beam position isproportional to the force created by the sample and the direction inwhich the beam ( Magnetic field) moves indicates whether the sampleis paramagnetic or diamagnetic.

6 Shown by a plus or minus indicationon the OF Magnetic SUSCEPTIBILITYThe Volume Susceptibility ( v) is defined by v= I HWhere I = Intensity of magnetism produced in a substanceH = Intensity of Magnetic field applied externallyThe Mass Susceptibility (Xg) is defined by g= v dWhere d = density of substanceThe calculation of gfrom the readings on the MSB is simple: g= CBal*I (R-R0)m 109 Where C = calibration constant of the balanceL = length of sample in cm. (L >1 .5 cm)m = mass of sample in gramsR = reading on MSB of sample in tubeR0= reading of empty tubeThe traditional technique,developed by Gouy,employs a conventionalbalance and a largepermanent magnet.

7 Themagnet remains stationarywhile the sample is causedto move, giving apparentgain or loss in sampleweightBASIC DESIGN PRINCIPLEM agnetic Susceptibility 1 09/06/2015 14:24 Page 2 APPLICATIONS OF Magnetic SUSCEPTIBILITYMEASUREMENTS Sherwood Scientific has been collecting and developing methodsfor many years and the following list illustrates the wide varietyof possible applications: Wear particulate analysis directly on lubricating oils Pesticide and pharmaceutical analysis by generation of free radicals Examination of chemical reactions on a micro scale Characterisation of Ion exchange adsorption and desorption processes Measurement of concentration and size of Magnetic beads Analysis of rare earth elements and their oxidation states Qualitative analysis of metal complexes QC of catalysts in the petrochemical and plastics industries QC of Industrial diamonds for trace metal contaminants Measurement of synthetic diamonds

8 Archaeological studies of soil sample s to indicate human occupation Measurement of the oxidation state of haemoglobin Quality control in the fabrication of superconductors Sherwood Scientific MSB MK1 & AUTOt. +44 (0) 1223 243444f. +44 (0) 1223 243300e. substances exhibit Magnetic properties so it is possible touse Magnetic phenomena to identify, differentiate andquantitatively measure components and contaminants inmixtures non-destructively. Occasionally the magneticsusceptibility measurement offers a unique solution to adifficult analytical problem.

9 We are happy to consider any newapplications for the Sherwood MK1 EXHIBITS MANYADVANTAG ES COMPARED WITH THEGOUY BALANCE: Ease and speed of use; place the sample tube in the balance and get an immediate digital read out. Measurements can be made on a wide range of diamagnetic and paramagnetic materials. The fixed sample tube allows Susceptibility measurement of solids, liquids and gases. The technique has comparable sensitivity and is as accurate as traditional methods of measure ment. The cost of the balance is significantly lower than a complete Gouy balance system.

10 The instantaneous digital read-out can be used to calculate Magnetic Susceptibility using a simple equation. This gives significant time savings in both set-up and measurement. Small sample size; normally a sample weight of around 250mg is used but by using a narrow bore sample tube, as little as 50mg is re quired to give an accurate measurement. Analogue output: Using a flow cell allows a chemical reaction resulting in a change of Susceptibility to be monitored dynamically. This allows new applications to be investigated, for example, redox reactions. External power supply: The MSB is a low voltage instrument enhancing the safety aspects by removing high voltage from the detection end in contact with the chemicals.