bɪkˈʌz ʌv ɪts vˈɛɹi hˈaɪ mˈɛltɪŋ pˈɔɪnt, hˈæfniə ɪz ˈɔːlsoʊ jˈuːzd æz ɐ ɹᵻfɹˈæktɚɹi mətˈɪɹiəl ɪnðɪ ˌɪnsəlˈeɪʃən ʌv sˈʌtʃ dɪvˈaɪsᵻz æz θˈɜːməkˌʌpəlz, wˌɛɹ ɪt kæn ˈɑːpɚɹˌeɪt æt tˈɛmpɹɪtʃɚz ˌʌp tə tˈuː θˈaʊzənd fˈaɪvhˈʌndɹɪd dᵻɡɹˈiːz sˈiː.
Because of its very high melting point, hafnia is also used as a refractory material in the insulation of such devices as thermocouples, where it can operate at temperatures up to 2500 °C.