[en] Lead-free $CsSn{X}_3$ perovskite NCs are becoming a promising alternative to $CsPb{X}_3$ (X=Cl, Br, I), but suffer from extremely poor stability. Herein, we highlight the significant effect of $S{n}^{II}$ precursors used in the synthesis on the stability of the resultant $CsSn{X}_3$ NCs. A method is proposed for synthesizing $CsSn{X}_3$ NCs using $C{s}_{2}C{O}_3$, $Sn{C}_2{O}_4$, and NH${}_4$X as corresponding constituent precursors, wherein the ratio of reactants can be easily adjusted. Stable $CsSn{X}_3$ NCs can be obtained with the use of antioxidative $Sn{C}_2{O}_4$ as the $S{n}^{II}$ precursor. Experimental results show that the improvement of NCs stability is mainly ascribed to the role of oxalate in the $Sn{C}_2{O}_4$ precursor. Oxalate ion has a strong antioxidative ability and can effectively inhibit the oxidation of $S{n}^{II}$ during the synthesis. Besides, oxalate as a bidentate capping ligand is shown to be coordinated on the surface of formed NCs. This can not only passivate the uncoordinated Sn on the surface but also prevent the oxidation of the NCs. (© 2020 Wiley‐VCH GmbH)

[en] Herein, new spin correlated-plasmons in Pr${}_{0.6}$Sr${}_{0.4}$Co${}_{1-<!--\; ???\; -->x}$Mn${}_x$O${}_3$ (x = 0-0.4) that are tunable and stable at room temperature are demonstrated. Using advanced spectroscopic techniques, the charge, spin, and orbital interaction that triggers the spin correlated-plasmons in spin-polarized Co${}^{4+}$, O${}^{2-<!--\; ???\; -->}$, and Mn${}^{4+}$ is identified. As a function of x, Co${}^{4+}$ systematically changes the spin state of the spin correlated-plasmons (from high, intermediate, to low spin), which also sequentially transforms the metallic cobaltite into a Mott insulator. Spin correlated-plasmons in the IR range, being excited from Co${}^{4+}$, tend to dominate in the metallic phase of the cobaltites, whereas Mn${}^{4+}$ and O${}^{2-<!--\; ???\; -->}$ are the primary source for the spin correlated-plasmons in the UV-vis ranges in the insulating phase. (© 2020 Wiley‐VCH GmbH)

[en] Herein, undoped and antimony (Sb)-doped zinc oxide (ZnO) thin films are prepared by a sol-gel spin-coating method. The influence of different annealing atmospheres including nitrogen and argon on pertinent properties of the prepared films is scrutinized. Structural, optical, morphological, and electrical properties of all annealed films are investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopy (PL), ultraviolet-visible spectroscopy, and current-voltage measurement. The XRD results exhibit that the films possess ZnO hexagonal wurtzite without impurity. The deterioration in the crystallinity of the film is highly influenced by Sb dopant and annealing atmosphere exhibiting the decrease in nanoparticle size after annealing in nitrogen, argon atmosphere, and upon doping. XPS results confirm that Sb${}^{3+}$ is well incorporated in ZnO lattice and the shift of XPS spectra in the films annealed in nitrogen atmosphere indicates nitrogen bonding with zinc. The PL spectra exhibit blueshift of near band edge emission due to the Sb dopant substituting in Zn site in ZnO lattice and red-infrared emission induced by Sb dopant. The decrease in electrical resistance of ZnO film can be obtained by Sb doping and annealing in nitrogen atmosphere. (© 2020 Wiley‐VCH GmbH)

[en] Black titanium dioxide (TiO${}_2$) quantum dots (QDs) are grown by a solution-based electrochemical process and an effect of KCl concentration on the growth is investigated. The electrochemical process is demonstrated as a simple one-step process for the growth of black TiO${}_2$ QDs in the solutions via bottom-up process. From the absorption spectra, the absorption appears for an entire visible wavelength (400-700 nm) implying a black TiO${}_2$ property. The average size of the black TiO${}_2$ QDs is about 4.5 nm from the transmission electron microscopy results and is similar to all KCl concentrations. This indicates that KCl concentration has no effect on the particle size, but has effect on the hydrodynamic size of TiO${}_2$ QDs. The black TiO${}_2$ QDs can be produced by the hydrogenation process of hydrogen ions during electrochemical process. The obtained black TiO${}_2$ QDs can be further explored as an electron-transporting layer for a perovskite solar cell application. (© 2020 Wiley‐VCH GmbH)

[en] Coordination compounds are well-known compounds that are being used as new materials for lithium storage because of their unique advantages, that is, designable structures, abundant active sites, and facile as well as mild synthetic routes. However, the electrode stability, low rate performance, and cycle life of coordination compounds are currently the main issues preventing their application as electrode materials, and the lithium-storage mechanism in coordination networks is not well understood. Herein, isostructural one-dimensional coordination compounds were synthesized to study their lithium-storage performance. Co-HIPA and Ni-HIPA showed superior electrolyte stability than other M-HIPAs, and Co-HIPA displayed a superior reversible capacity and cycle stability, excellent rate performance, and clear voltage platform. DFT calculations and kinetic analysis revealed the influence of the metal center with different electronic structures on the lithium-storage mechanism. (© 2020 Wiley‐VCH GmbH)

[en] The uranyl cation, (U(VI)O${}_2$)${}^{2+}$, has previously demonstrated photocatalytic reactivity in organic solutions, which results in the formation of uranyl peroxide species. Past studies indicated that the phototransformation process typically ends with the formation of uranyl peroxide solid phases. In the current study, we explore the transformation of uranyl nitrate crown ether complexes, (18-crown-6)[UO${}_2$(NO${}_3$)${}_2$(H${}_2$O)${}_2$] ⋅ 2 H${}_2$O (1 a), (18-crown-6)[UO${}_2$(NO${}_3$)${}_2$(H${}_2$O)${}_2$] (1 b), and (18-crown-6) [K(18-crown-6)] [(UO${}_2$)${}_2$(OH)${}_2$(NO${}_3$)${}_4$(H${}_2$O)${}_4$] (2) in the presence of ethanol to create a uranyl peroxide intermediate phase, (18-crown-6)[(UO${}_2$)${}_2$(O${}_2$)(NO${}_3$)${}_2$(H${}_2$O)${}_4$] (3), followed by a second alteration to a black solid (4). These compounds were structurally evaluated using both single-crystal and powder X-ray diffraction and then further characterized using Raman, NMR, and XPS spectroscopy. The initial transformation from the yellow uranyl nitrate phase (1 a, 1 b, and 2) to the uranyl peroxide (3) follow previously reported mechanisms. The second transformation to the black phase (4) is likely due to additional degradation of the 18-crown-6 molecule as a result of hydrogen abstraction and ring-opening. In addition, we discuss the nature of confinement effects to impact the hydrogen abstraction process and the possibility that nitrate anions in the system may synergistically enhance the degradation process and lead to the formation of 4. (© 2020 Wiley‐VCH GmbH)

[en] Effective capture of radioactive iodine is of paramount importance for the safe and long-term storage of fission products in the nuclear fuel cycle. Herein, a series of functionalized Th-UiO-66 MOFs was employed as a model to investigate the effects of substituents on iodine adsorption in both solution and vapor states. Sorption studies revealed that the electro-donating amino group exhibits the most positive role on increasing the removal rate of iodine from cyclohexane and the uptake capacity of iodine vapor. Particularly, the disubstituted Th-UiO-66-(NH${}_2$)${}_2$ can effectively remove 91.9 % of iodine (300 mg L${}^{-<!--\; ???\; -->1}$) from cyclohexane and capture 969 mg g${}^{-<!--\; ???\; -->1}$ iodine vapor, significantly higher than 59.6 % and 334 mg g${}^{-<!--\; ???\; -->1}$ of untagged Th-UiO-66, respectively. In addition, the substituent effect on the radiolytic stability of MOFs was for the first time investigated, leading to the unearthing of one of the most radioresistant MOFs Th-UiO-66-NH${}_2$ reported to date. (© 2020 Wiley‐VCH GmbH)

[en] The charge transport and trap nature responsible for the leakage current through thermally cured methyl-terminated organosilicate low-κ dielectric films are studied. It is found that the Frenkel emission does not describe correctly the charge transport in the studied films. The charge transport occurs via the phonon-assisted electron tunneling between neutral traps as described in the Nasyrov-Gritsenko model. The obtained thermal trap energy value 1.2 eV is close to that for the oxygen divacancy (Si - Si - Si cluster) in SiO${}_2$. The electron energy loss spectra, photoluminescence excitation of 2.7 eV blue band spectra, and data from the simulation within the density functional theory for the model SiCOH low-κ structure confirm the presence of oxygen vacancy and divacancy in the studied films. The thermal trap energy value estimated as half the Stokes shift of the blue luminescence also gives a value close to 1.2 eV. It proves the correctness of the Nasyrov-Gritsenko model for describing the charge transport mechanism and the conclusion that oxygen divacancies are traps responsible for the leakage current in the studied low-κ films. (© 2020 Wiley‐VCH GmbH)

[en] In our opinion, the ICREM organization is a well-motivated addition to the forums already available in the field of the radiation and emission in materials. We trust this pss(a) Special Issue comprising the highlights of the ICREM2019 can be of use for a wide and cross-disciplinary research community dealing with radiation effects, as well as for the students in the field to use the papers collected herein for studies, referencing, and inspirations. We thank all the authors and co-authors of the papers submitted to this Special Issue, as well as all participants of the ICREM2019 for attending the conference. Finally, we invite to participate in the future ICREM events regularly scheduled for mid-December in Thailand. In particular, the 4th edition of the conference is scheduled for the 14–17th December 2021 to take place in Bangkok (http://icrem2021. science.cmu.ac.th/). (© 2021 Wiley‐VCH GmbH)

[en] A low-resistance Ohmic contact of Pd/Pt/Au metallization scheme is formed on a p-type GaN film grown by metal-organic chemical vapor deposition (MOCVD). Two samples are prepared to explore the effect of contaminations at the metal and GaN interface on the properties of the Ohmic contact. One directly transfers the fresh GaN film from MOCVD to the metal deposition chamber through an ultrahigh vacuum (UHV) tube, without exposing the GaN surface to air; the other transfers the GaN film from MOCVD to metal deposition through the atmosphere. The results show a lower specific contact resistance (6.2 ± 0.9) × 10${}^{-<!--\; ???\; -->5}$ Ω cm${}^2$ for the directly UHV-transferred sample than the air-transferred sample (2.1 ± 0.9) × 10${}^{-<!--\; ???\; -->4}$ Ω cm${}^2$. Once exposed to air, carbonaceous particles and an amorphous oxide layer easily adhere to the p-type GaN surface, which not only increase the Schottky barrier height but also generate more grain boundaries in the Pd/Pt/Au stacks. The grain boundaries, acting as diffusion channels, make Au atoms diffuse easily into the Pd layer and propagate to the p-GaN surface layer after annealing. Therefore, the Ohmic contact fabricated in UHV ambience with lower oxygen and carbon contaminations at the interface shows superior characteristics than the samples prepared by the traditional method. (© 2020 Wiley‐VCH GmbH)