## Abstract

Solid-solution Zintl compounds with the formula Eu<inf>11</inf>Cd<inf>6-x</inf>Zn<inf>x</inf>Sb<inf>12</inf> have been synthesized from the elements as single crystals using a tin flux according to the stoichiometry Eu:Cd:Zn:Sb:Sn of 11:6-x<inf>p</inf>:x<inf>p</inf>:12:30 with x<inf>p</inf> = 0, 1, 2, 3, 4, 5, and 6, where x<inf>p</inf> is the preparative amount of Zn employed in the reaction. The crystal structures and the compositions were established by single-crystal as well as powder X-ray diffraction and wavelength-dispersive X-ray analysis measurements. The title solid-solution Zintl compounds crystallize isostructurally in the centrosymmetric monoclinic space group C 2/m (No. 12, Z = 2) as the Sr<inf>11</inf>Cd<inf>6</inf>Sb<inf>12</inf> structure type (Pearson symbol mC58). There is a miscibility gap at 3 x<inf>p</inf> 4 where the major product crystallizes in a disordered structure related to the Ca<inf>9</inf>Mn<inf>4</inf>Bi<inf>9</inf> structure type; otherwise, for all other compositions, the Sr<inf>11</inf>Cd<inf>6</inf>Sb<inf>12</inf> structure is the majority phase. Eu<inf>11</inf>Cd<inf>6</inf>Sb<inf>12</inf> shows lower lattice thermal conductivity relative to Eu<inf>11</inf>Zn<inf>6</inf>Sb<inf>12</inf> consistent with its higher mean atomic weight, and as anticipated, the solid-solution samples of Eu<inf>11</inf>Cd<inf>6-x</inf>Zn<inf>x</inf>Sb<inf>12</inf> have effectively reduced lattice thermal conductivities relative to the end member compounds. Eu<inf>11.0(1)</inf>Cd<inf>4.5(2)</inf>Zn<inf>1.5(2)</inf>Sb<inf>12.0(1)</inf> exhibits the highest zT value of >0.5 at around 800 K which is twice as large as the end member compounds.

Original language | English (US) |
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Pages (from-to) | 4413-4421 |

Number of pages | 9 |

Journal | Chemistry of Materials |

Volume | 27 |

Issue number | 12 |

DOIs | |

State | Published - Jun 23 2015 |

## ASJC Scopus subject areas

- Materials Chemistry
- Chemical Engineering(all)
- Chemistry(all)