Metal to insulator transition in Ba2Ge2Te5: Synthesis, crystal structure, resistivity, thermal conductivity, and electronic structure

Germanium Antimony Bonding in Ba4Ge2Sb2Te10 with Low Thermal Conductivity

“…The Ba−Te distances in distorted square antiprism geometries of Ba(1)Te 8 , Ba(2)Te 8 , and Ba(3)Te 8 units range from 3.5120(7) Å to 3.9156(8) Å, which can be compared to the Ba−Te distances in BaGdCuTe 3 (3.4311(4)−3.8981(3) Å) 60 and BaCu 0.43(3) Te 2 (3.43(1)−3.64(2) Å). 61 The Ba−Te distances of 3.5231(8) Å−4.0181 (11) Å in distorted tricapped trigonal geometry of Ba(4)Te 9 are in good agreement with the distances in a similar coordination environment of BaBiTe 3 (3.417(2)−3.887(2) Å) 62 and Ba 3 ScTe 5 (3.405(1)−3.724(1) Å). 63…”

“…Also, it is common to have homoatomic Ge–Ge (or Sn–Sn) single bonding in chalcogenides with an average oxidation of Ge (or Sn) as +3. Examples of such compounds are Ba 2 Ge 2 Te 5 , Ba 4 Au 3.69 Ge 2 Te 9 , Sr 2 Ge 2 Se 5 , and K 6 Sn 2 Te 6 . Thus, incorporation of both Sb/Bi and Sn/Ge in one chalcogenide structure is expected to show intricate crystal chemistry.…”

Five coordinated Mn in Ba4Mn2Si2Te9: synthesis, crystal structure, physical properties, and electronic structure

“…For example, the Ba 2 Ge 2 Te 5 structure consists of chains of 1 1 [Ge 2 Te 5 ] 4− where Ge 3+ exists due to Ge-Ge bonding. 17 Therefore, multinary quaternary chalcogenides of Ak-M-Tt-Q are expected to show more complex unprecedented structures. The number of the quaternary compounds belonging to the Ak-M-Tt-Q system is minimal compared to the corresponding ternary and binary compounds.…”

Low thermal conductivity in a new mixed metal telluride Mn1.8(1)In0.8(1)Si2Te6

“…The ultra-low thermal conductivity of the Mn 1.8 In 0.8 Si 2 Te 6 sample can be compared with those of the reported metal chalcogenides showing ultra-low thermal conductivities such as Ba 2 Ge 2 Te 5 (0.41 W m −1 K −1 at 773 K), 45 AgSbSe 2 (0.43 W m −1 K −1 at 673 K), 46 Rb 2 Bi 8 Se 13 (0.25 W m −1 K −1 at 900 K), 47 BaIn 2 Te 4 (0.30 W m −1 K −1 at 965 K), 9 and Ag 2 BaGeSe 4 (0.35 W m −1 K −1 at 673 K). 48…”