Impure materials are useful sometimes. Alloys are metals with impurities. Solar cells are made of silicon crystals, but a very small amount of impurity (0.001% to 0.01%) is needed in them to work.= = = Queen's Hall = = =
ɪ m p j ʊ ɹ WORD_BOUNDARY m ə t ɪ ɹ i ə l z WORD_BOUNDARY ɑ ɹ WORD_BOUNDARY j uː s f ə l WORD_BOUNDARY s ʌ m t aɪ m z WORD_BOUNDARY æ l ɔɪ z WORD_BOUNDARY ɑ ɹ WORD_BOUNDARY m ɛ t ə l z WORD_BOUNDARY w ɪ ð WORD_BOUNDARY ɪ m p j ʊ ɹ ɹ ɪ t i z WORD_BOUNDARY s oʊ l ə ɹ WORD_BOUNDARY s ɛ l z WORD_BOUNDARY ɑ ɹ WORD_BOUNDARY m eɪ d WORD_BOUNDARY ʌ v WORD_BOUNDARY s ɪ l ɪ k ə n WORD_BOUNDARY k ɹ ɪ s t ə l z WORD_BOUNDARY b ʌ t WORD_BOUNDARY ʌ WORD_BOUNDARY v ɛ ɹ i WORD_BOUNDARY s m ɔ l WORD_BOUNDARY ʌ m aʊ n t WORD_BOUNDARY ʌ v WORD_BOUNDARY ɪ m p j ʊ ɹ ɹ ɪ t i WORD_BOUNDARY z iə ɹ oʊ WORD_BOUNDARY z iə ɹ oʊ z iə ɹ oʊ WORD_BOUNDARY w ʌ n WORD_BOUNDARY p ə ɹ s ɛ n t WORD_BOUNDARY t ə WORD_BOUNDARY z iə ɹ oʊ WORD_BOUNDARY z iə ɹ oʊ WORD_BOUNDARY w ʌ n WORD_BOUNDARY p ə ɹ s ɛ n t WORD_BOUNDARY ɪ z WORD_BOUNDARY n iː d ɪ d WORD_BOUNDARY ɪ n WORD_BOUNDARY ð ɛ m WORD_BOUNDARY t ə WORD_BOUNDARY w ɜː k WORD_BOUNDARY iː k w ə l z WORD_BOUNDARY iː k w ə l z WORD_BOUNDARY iː k w ə l z WORD_BOUNDARY k w iː n z WORD_BOUNDARY h ɔ l WORD_BOUNDARY iː k w ə l z WORD_BOUNDARY iː k w ə l z WORD_BOUNDARY iː k w ə l z WORD_BOUNDARY