ðə sˌiːˌɛmsˌiːˈɛm fˈeɪz, wˌɪtʃ ɪz stɹˈʌktʃɚɹəli ɹᵻlˈeɪɾᵻd tə ðə lˈoʊ tˈɛmpɹɪtʃɚ pˌiːˌɛnˌɛmˈeɪ fˈeɪz, ɛɡzˈɪbɪts ɐ səbstˈænʃəli ɹᵻdˈuːst ˈɛnɚdʒi ɡˈæp ænd ɛnhˈænst kˈæɹiɚ moʊbˈɪlᵻɾiz wˌaɪl meɪntˈeɪnɪŋ ðɪ ˌʊltɹɐlˈoʊ θˈɜːməl kɑːndəktˈɪvᵻɾi ðˈʌs jˈiːldɪŋ ðə ɹˈɛkɚd zˌiːtˈiː.
The Cmcm phase, which is structurally related to the low temperature Pnma phase, exhibits a substantially reduced energy gap and enhanced carrier mobilities while maintaining the ultralow thermal conductivity thus yielding the record ZT.