Preparation and crystal structures of novel LaOAgS-type copper and silver fluoride chalcogenides

High-pressure Synthesis of Ba2CoO2Ag2Te2 with Extended CoO2 Planes

“…No appreciable vacancies were found at any sites. The Ag−Te bond length in the Ag 2 Te 2 layer is 2.86 Å, which is acceptable given the similar values for Ba 2 MnO 2 Ag 2 Te 2 , 11 SrFAgTe, 22 and LaOAgTe 22 (2.86−2.88 Å). However, the Co−O bond length of 2.19 Å (i.e., a/2) is significantly longer than any other compounds with Co(II) in square-planar coordination (Table 2).…”

Electronic structure, transport, and phonons ofSrAgChF(Ch = S, Se, Te): Bulk superlattice thermoelectrics

“…25 The crystal structure of SrAgChF (Ch=S,Se,Te) is tetragonal with the space group P4/nmm, 26 and may be viewed as alternating blocks of [SrF] and [AgCh] as shown in Fig. 1(a).…”

“…Thermoelectrics enable direct solid state conversion of thermal and electrical energy. 1,2 They are widely used in spacecraft power and in terrestrial cooling and may have wide applications in energy technologies such as waste heat recovery if their efficiencies can be improved. 3 The efficiency that can be achieved is limited by the properties of available thermoelectric materials, and in particular a dimensionless, but temperature dependent figure of merit ZT = σS 2 T /κ, where σ is electrical conductivity, T is absolute temperature, S is the Seebeck coefficient, also known as the thermopower, and κ is the thermal conductivity.…”

High‐Pressure Synthesis of A2NiO2Ag2Se2 (A=Sr, Ba) with a High‐Spin Ni2+ in Square‐Planar Coordination

“…The Ag-Se bonds in the Ag2Se2 slabs of Ba2NiO2Ag2Se2, Sr2NiO2Ag2Se2 and Ba2CuO2Ag2Se2 are 2.76 Å, 2.75 Å and 2.71 Å, being similar to those in Sr2CoO2Ag2Se2, [15] Ba2CoO2Ag2Se2, [13] and LaOAgSe [16] (2.74-2.76 Å). By contrast, the M-O bonds in the MO2 square lattice (i.e., a/2) are significantly elongated: The Ni-O bonds of 2.13 Å for Ba and 2.05 Å for Sr are much longer than any compounds with Ni II in square-planar coordination, for example Sr2Ni II O2Cl2 (2.02 Å), [17] Sr2Ni II O2Cu2S2 (1.96 Å), [1], [10] and LaNi II O2.5 (1.89 Å).…”