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A newly reported compound, CuAgBiI 5 , is synthesized as powder, crystals, and thin films. The structure consists of a 3D octahedral Ag + /Bi 3+ network as in spinel, but occupancy of the tetrahedral interstitials by Cu + differs from those in spinel. The 3D octahedral network of CuAgBiI 5 allows us to identify a relationship between octahedral site occupancy (composition) and octahedral motif (structure) across the whole CuI-AgI-BiI 3 phase field, giving the ability to chemically control structural dimensionality. To investigate composition-structure-property relationships, we compare the basic optoelectronic properties of CuAgBiI 5 with those of Cu 2 AgBiI 6 (which has a 2D octahedral network) and reveal a surprisingly low sensitivity to the dimensionality of the octahedral network. The absorption onset of CuAgBiI 5 (2.02 eV) barely changes compared with that of Cu 2 AgBiI 6 (2.06 eV) indicating no obvious signs of an increase in charge confinement. Such behavior contrasts with that for lead halide perovskites which show clear confinement effects upon lowering dimensionality of the octahedral network from 3D to 2D. Changes in photoluminescence spectra and lifetimes between the two compounds mostly derive from the difference in extrinsic defect densities rather than intrinsic effects. While both materials show good stability, bulk CuAgBiI 5 powder samples are found to be more sensitive to degradation under solar irradiation compared to Cu 2 AgBiI 6 .

The products of the solid-state reactions between potassium metal and tetracene (K:Tetracene, 1:1, 1.5:1, and 2:1) are fully structurally characterized. Synchrotron X-ray powder diffraction shows that only K 2 Tetracene forms under the reaction conditions studied, with unreacted tetracene always present for x < 2. Diffraction and 13 C MAS NMR show that K 2 Tetracene has a crystal structure that is analogous to that of K 2 Pentacene, but with the cations ordered on two sites because of the influence of the length of the hydrocarbon on possible cation positions. K 2 Tetracene is a nonmagnetic insulator, thus further questioning the nature of reported superconductivity in this class of materials.

Both layered multiple-anion compounds and homologous series are of interest for their electronic properties, including the ability to tune the properties by changing the nature or number of the layers. Here we expand, using both computational and experimental techniques, a recently reported three-anion material, Bi 4 O 4 Cu 1.7 Se 2.7 Cl 0.3 , to the homologous series Bi 2+2 n O 2+2 n Cu 2-δ Se 2+ n-δ X δ (X = Cl, Br), composed of parent blocks that are well-studied thermoelectric materials. All of the materials show exceptionally low thermal conductivity (0.2 W/mK and lower) parallel to the axis of pressing of the pellets, as well as narrow band gaps (as low as 0.28 eV). Changing the number of layers affects the band gap, thermal conductivity, carrier type, and presence of a phase transition. Furthermore, the way in which the different numbers of layers are accessed, by tuning the compensating Cu vacancy concentration and halide substitution, represents a novel route to homologous series. This homologous series shows tunable properties, and the route explored here could be used to build new homologous series out of known structural blocks.

It is challenging to achieve p-type doping of zinc oxides (ZnO), which are of interest as transparent conductors in optoelectronics. A ZnO-related ternary compound, SrZnO 2 , was investigated as a potential host for p-type conductivity. First-principles investigations were used to select from a range of candidate dopants the substitution of Li + for Zn 2+ as a stable, potentially p-type, doping mechanism in SrZnO 2 . Subsequently, single-phase bulk samples of a new p-type-doped oxide, SrZn 1- x Li x O 2 (0 < x < 0.06), were prepared. The structural, compositional, and physical properties of both the parent SrZnO 2 and SrZn 1- x Li x O 2 were experimentally verified. The band gap of SrZnO 2 was calculated using HSE06 at 3.80 eV and experimentally measured at 4.27 eV, which confirmed the optical transparency of the material. Powder X-ray diffraction and inductively coupled plasma analysis were combined to show that single-phase ceramic samples can be accessed in the compositional range x < 0.06. A positive Seebeck coefficient of 353(4) μV K -1 for SrZn 1- x Li x O 2 , where x = 0.021, confirmed that the compound is a p-type conductor, which is consistent with the p O 2 dependence of the electrical conductivity observed in all SrZn 1- x Li x O 2 samples. The conductivity of SrZn 1- x Li x O 2 is up to 15 times greater than that of undoped SrZnO 2 (for x = 0.028 σ = 2.53 μS cm -1 at 600 °C and 1 atm of O 2 ).