During the last century, inorganic oxide compounds laid foundations for materials synthesis, characterization, and technology translation by adding new functions into devices previously dominated by main-group element semiconductor compounds. Today, compounds with multiple anions beyond the single-oxide ion, such as oxyhalides and oxyhydrides, offer a new materials platform from which superior functionality may arise. Here we review the recent progress, status, and future prospects and challenges facing the development and deployment of mixed-anion compounds, focusing mainly on oxide-derived materials. We devote attention to the crucial roles that multiple anions play during synthesis, characterization, and in the physical properties of these materials. We discuss the opportunities enabled by recent advances in synthetic approaches for design of both local and overall structure, state-of-the-art characterization techniques to distinguish unique structural and chemical states, and chemical/physical properties emerging from the synergy of multiple anions for catalysis, energy conversion, and electronic materials.

The magnetic ground state of single crystalline ${\mathrm{RuO}}_2$ was investigated by the muon spin rotation and relaxation ($\mu \mathrm{SR}$) experiment. The spin precession signal due to the spontaneous internal magnetic field $B_{\mathrm{loc}}$, which is expected in the magnetically ordered phase, was not observed in the temperature range 5–400 K. Muon sites were evaluated by first-principles calculations using dilute hydrogen simulating muon as pseudohydrogen, and $B_{\mathrm{loc}}$ was simulated for the antiferromagnetic structures with a Ru magnetic moment $|{\mathit{m}}_{\mathrm{Ru}}|\approx 0.05{\mu }_{\mathrm{B}}$ suggested from diffraction experiments. As a result, the possibility was ruled out that muons are localized at sites where $B_{\mathrm{loc}}$ accidentally cancels. Conversely, assuming that the slow relaxation observed in $\mu \mathrm{SR}$ spectra was part of the precession signal, the upper limit for the magnitude of $|{\mathit{m}}_{\mathrm{Ru}}|$ was estimated to be $4.8(2)\times {10}^{-4}{\mu }_{\mathrm{B}}$, which is significantly less than $0.05{\mu }_{\mathrm{B}}$. These results indicate that the antiferromagnetic order, as reported, is unlikely to exist in the bulk crystal.

We report on the cubic double perovskite Ba2MgReO6 containing Re6+ ions with the 5d1 electron configuration. Resistivity, magnetization, and heat capacity measurements using single crystals show th...

The effects of ultraviolet light irradiation on the conducting properties of ${\text{SnO}}_{2-x}$ thin films grown epitaxially on ${\text{TiO}}_2$ or ${\text{Al}}_2{\text{O}}_3$ single-crystal substrates are studied at room temperature. A large increase in conductivity by two to four orders of magnitude is observed with light irradiation in an inert atmosphere and remains after the light is removed. The high-conducting state reverts to the original low-conducting state by exposing it to oxygen gas. These reversible phenomena are ascribed to the desorption and adsorption of negatively charged oxygen species at the grain boundaries, which critically change the mobility of electron carriers already present inside grains by changing the potential barrier height at the grain boundary. The UV light irradiation provides us with an easy and useful route to achieve a high-conducting state even at low carrier density in transparent conducting oxides and also to draw an invisible conducting wire or a specific pattern on an insulating film.

The magnetization of two spin-$\frac{1}{2}$ kagome antiferromagnets, volborthite and vesignieite, has been measured in pulsed magnetic fields up to 68 T. A magnetization plateau is observed for each compound near the highest magnetic field. Magnetizations at saturation are approximately equal to $0.40M_{\mathrm{s}}$ for both compounds, where $M_{\mathrm{s}}$ is the fully saturated magnetization, irrespective of a difference in the distortion of the kagome lattice between the two compounds. It should be noted that these values of magnetizations are significantly larger than $M_{\mathrm{s}}$/3 predicted theoretically for the one-third magnetization plateau in the spin-$\frac{1}{2}$ kagome antiferromagnet. The excess magnetization over $M_{\mathrm{s}}$/3 is nearly equal to the sum of the magnetizations gained at the second and third magnetization steps in volborthite, suggesting that there is a common origin for the excess magnetization and the magnetization steps.