Boron substitution in diopside evaluated through B-11 nuclear reaction analysis

Nuclear reaction analyses on boron in flux-grown Me3+ - and Na+ -doped diop side crystals utilising the B-11(p,2 alpha)He-4 reaction in conjunction wit h EMP analyses for major elements and optical absorption spectroscopy for d etermination of Me-valence state distributions show that appreciable amount s of B may enter the diopside lattice in crystals produced in Na2B4O7 fluxe s. The results indicate that the substitution (Me3+[4]B3+[6])-Me-[6] Mg-12[4]Si-14+ operates in the present diopside samples in addition to the coupl ed substitution (Me3+[8]Na+[6])-Me-[6] Mg-12+[8]Ca-12+. The specific NRA te chnique applied allows for quantitative, high resolution (ca. 5 mum)B analy ses at ppm level as well as high-resolution and high-contrast imaging of B- concentration patterns in minerals. The estimated detection limit and relat ive error of the B analyses are 10 ppm and 5-10%, respectively.