▁power ▁in ▁a ▁remark ably ▁compact ▁package . ▁In ▁mobile ▁ph ones ▁' Ne o ' ▁magnet s ▁provide ▁the ▁magnetic ▁field ▁which ▁allows ▁tiny ▁speak ers ▁to ▁deliver ▁appreci able ▁audio ▁power . ▁ ▁Sh ield ing ▁and ▁neut ron ▁absor ber ▁in ▁nuclear ▁react ors ▁Bor on ▁shield ing ▁is ▁used ▁as ▁a ▁control ▁for ▁nuclear ▁react ors , ▁taking ▁advantage ▁of ▁its ▁high ▁cross - section ▁for ▁neut ron ▁capture . ▁ ▁In ▁press ur ized ▁water ▁react ors ▁a ▁variable ▁concentration ▁of ▁bor onic ▁acid ▁in ▁the ▁cool ing ▁water ▁is ▁used ▁as ▁a ▁neut ron ▁poison ▁to ▁compens ate ▁the ▁variable ▁react ivity ▁of ▁the ▁fuel . ▁When ▁new ▁ro ds ▁are ▁inserted ▁the ▁concentration ▁of ▁bor onic ▁acid ▁is ▁maximal , ▁and ▁is ▁reduced ▁during ▁the ▁lifetime . ▁ ▁Other ▁non med ical ▁uses ▁▁ ▁Because ▁of ▁its ▁distinct ive ▁green ▁fl ame , ▁am orph ous ▁bor on ▁is ▁used ▁in ▁py rote chn ic ▁fl ares . ▁ ▁St arch ▁and ▁case in - based ▁ad hes ives ▁contain ▁sod ium ▁t etra bor ate ▁dec ah yd rate ▁( Na 2 B 4 O 7 · 1 0 ▁H 2 O ) ▁ ▁Some ▁anti - cor ros ion ▁systems ▁contain ▁bor ax . ▁ ▁S od ium ▁bor ates ▁are ▁used ▁as ▁a ▁flux ▁for ▁sol der ing ▁silver ▁and ▁gold ▁and ▁with ▁am mon ium ▁ch lor ide ▁for ▁w eld ing ▁f err ous ▁met als . ▁They ▁are ▁also ▁fire