Determining the chemical composition of diamagnetic mixed solids via measurements of their magnetic susceptibility

Abstract

Mixed solid compounds are employed in a vast array of applications so an accurate determination of their chemical compositions is of crucial importance. All current characterization methods require specially treated samples, so the availability of a more practical method with similar accuracy should alleviate the quantification process. In this work, we show how the doping concentration δ (or isotope concentration) of a mixed solid compound in the powdered form, where both parent compounds are diamagnetic, can be obtained from the measurement of its mass magnetization. We exploit the additive nature of the molar magnetic susceptibility χ_Mol and molar mass quantities to construct two equations with the same two unknown variables in the χ_Molvs. δ plot to simultaneously obtain χ_Mol and δ of a mixed solid. Eight examples are provided to show the wide applicability of this method: NH_4(1−δ)D_4δBr (where D = ²H), NH₄I_1−δBr_δ, (NH₄H₂)_1−δ(ND₄D₂)_δPO₄, C₄₈H_22+6δBr_6(1−δ)O₃₂Zr₆, [creatine]_1−δ[D-glucose]_δ, [L-glutamic acid]_1−δ[L-leucine]_δ, [terephthalic acid]_1−δ[trimesic acid]_δ and [p-terphenyl]_1−δ[triphenylphosphine]_δ. Experimental errors of ±1.2% were obtained for δ from an average sample mass of 16.6 mg in the powdered form rendering the presented approach an attractive choice for characterizing the ratios of mixed solids.