Midget cave spiders (Araneae, Leptonetidae) from Jiangxi and Fujian Province, China.

Eleven leptonetid species belonging to four genera collected in Jiangxi and Fujian Provinces, China are presented. Ten new species of midget cave spiders from southern China are diagnosed, described, and illustrated: Leptoneteladawu Yao & Liu, sp. nov., L.yuanhaoi Yao & Liu, sp. nov. and L.zuojiashanensis Yao & Liu, sp. nov. from Jiangxi; Longileptonetaguadunensis Yao & Liu, sp. nov., L.huboliao Yao & Liu, sp. nov., L.jiaxiani Yao & Liu, sp. nov., L.letuensis Yao & Liu, sp. nov., L.renzhouensis Yao & Liu, sp. nov., L.tianmenensis Yao & Liu, sp. nov., and Pararanamingxuani Yao & Liu, sp. nov. from Fujian. Furthermore, Falcileptonetamonodactyla (Yin, Wang & Wang, 1984) is recorded from Jiangxi province for the first time. Distributions records are given for all investigated species.

A new species of Mallinella Strand, 1906 (Araneae, Zodariidae) from South China.

Background: Only one zodariid species, Storenomorphalushanensis Yu & Chen, 2009 was found from Jiangxi Province. No other Mallinella species have been recorded from this Province. New information: A new species, Mallinellashahu sp. n. is described from Jiangxi Province, China. Morphological illustrations, living photos and distribution map are given.

Three new species of Otacilia Thorell, 1897 (Araneae, Phrurolithidae) from South China.

Three new Otacilia species were collected from Jiangxi Provinces, China during a survey of the spider fauna of the region: Otaciliaanfu Liu, sp. nov. (♂♀), O.guanshan Liu, sp. nov. (♂♀), and O.mingyueshan Liu, sp. nov. (♂♀). All species are described and illustrated with photographs and SEM micrographs, and their distribution is also mapped.

Pressure-Induced Structural Phase Transition, Anomalous Insulator-to-Metal Transition, and n-p Conduction-Type Switching in Defective, NiAs-Type Cr1-δTe.

Cr1-δTe, as a unique series of defective compounds with a NiAs-type structure and periodic metal vacancies, has attracted intensive research interest because of its diversity in structure and property dependent on the tunable stoichiometric ratio. Another feature of these compounds is their ability to switch between NiAs- and MnP-type structures, in which there often exist composition-, temperature-, or pressure-induced phase transitions accompanied by intriguing physical property switching. Herein, we report the syntheses of a series of Cr1-δTe compounds with similar compositions but distinct crystal structures, their phase transitions, anomalous transport, and photoelectric conduction behaviors under high pressure (HP). For the three Cr1-δTe compounds with δ = 0, 0.25, 0.375, CrTe undergoes pressure-induced NiAs-to-MnP phase transition at around 15 GPa, while Cr3Te4 and Cr5Te8 undergo isostructural phase transitions at around 12 and 11 GPa, respectively. Electrical transport measurements indicate anomalous conduction behaviors: CrTe undergoes a semiconductor-to-metal transition at around 24 GPa, while Cr3Te4 and Cr5Te8 show unexpected metal-semiconductor-metal transitions sequentially upon compression. Besides, CrTe and Cr5Te8 exhibit pressure-induced n-p conduction-type switching at around 9 and 3 GPa, respectively, while Cr3Te4 shows p-type conductivity in the full pressure range. Local structure analyses based on in situ HP Raman spectra are performed to understand the structure and property evolutions of Cr1-δTe under HP. Defective transition-metal chalcogenides with pressure-induced NiAs-to-MnP phase transition and conduction-type conversion provide a potential platform for the rational design of photoelectric conversion devices.

Pressure-Driven Two-Step Second-Harmonic-Generation Switching in BiOIO3.

Materials with multi-stabilities controllable by external stimuli have potential for high-capacity information storage and switch devices. Herein, we report the observation of pressure-driven two-step second-harmonic-generation (SHG) switching in polar BiOIO3 for the first time. Structure analyses reveal two pressure-induced phase transitions in BiOIO3 from the ambient noncentrosymmetric phase (SHG-high) to an intermediate noncentrosymmetric phase (SHG-intermediate) and then to a centrosymmetric phase (SHG-off). The three-state SHG switching was inspected by in situ high-pressure powder SHG and polarization-dependent single-crystal SHG measurements. Local structure analyses based on the in situ Raman spectra and X-ray absorption spectra reveal that the SHG switching is caused by the step-wise suppression of lone-pair electrons on the [IO3 ]- units. The dramatic evolution of the functional units under compression also leads to subtle changes of the optical absorption edge of BiOIO3 . Materials with switchable multi-stabilities provide a state-of-art platform for next-generation switch and information storage devices.

A new species of Orthobula Simon, 1897 (Araneae, Trachelidae) from South China.

Background: Only one trachelid species, Trachelassinensis Chen, Peng & Zhao, 1995 has been recorded from Jiangxi Province to date. New information: A new species, Orthobulajiangxi Liu, sp. n., is described from Jiangxi Province of China, based on both sexes. Morphological illustrations are provided and its distribution is mapped.

Description of two new species of the genus Spinirta Jin & Zhang, 2020 (Araneae, Corinnidae) from southern China.

Two new species of Spinirta Jin & Zhang, 2020 (Araneae: Corinnidae) from Jiangxi Province, China are described here: S.sanxiandian sp. nov. (♂♀) and S.sishuishan sp. nov. (♂). Detailed descriptions and photographs of the new species are provided.

Controllable Syntheses, Crystal Structure Evolution, and Photoluminescence of Polymorphic Zirconium Oxyfluorides.

Precise synthesis of polymorphic phases with similar components but distinct crystal structures is one of the key problems in inorganic chemistry. In this work, we report a fluorination method adopting ZrO2 as the starting material and NH4F as the fluoridation agent that can afford multiphases in the Zr-O-F system, including Zr7O9F10, Zr3O2F8, ZrO0.46F3.08, ZrO0.33F3.33, ß-ZrF4, NH4Zr2F9, and NH4ZrF5. A preliminary phase formation diagram was established as a function of the fluorination temperature (T), reaction time (t), and F/Zr ratio after systematic optimization of the preparation conditions. Among the as-obtained phases, the detailed crystal structures of Zr7O9F10 and ZrO0.33F3.33 were refined based on the powder X-ray diffraction patterns. As the F/O ratio increases, the crystal structures of Zr-O-F phases transform gradually from an anion-deficient α-UO3-related structure of Zr7O9F10 to an anion-excess ReO3-related structure of ZrO0.33F3.33. At last, we also prepared Ti-doped ZrO2, Zr7O9F10, ZrO0.46F3.08, and ZrO0.33F3.33 to study the host-lattice-dependent photoluminescence properties of zirconium oxyfluorides. The four materials show distinct photoluminescence in the UV and visible regions due to different local coordination environments of Zr/Ti. This work demonstrates the low-temperature fluorination method as an efficient route to phase-selective polymorphic metal oxyfluorides, which can be employed in further structure-property relationship studies.

Pressure-Induced Phase Transition, Jahn-Teller Suppression, Optical and Electronic Property Evolutions in Ruddlesden-Popper Perovskites Rb2 CuCl4-x Brx.

Transition-metal containing halides with Ruddlesden-Popper (RP) perovskite structures have received extensive attention owing to their emerging and anisotropic photoelectric functionalities. Among them, A2 CuX4 (A=alkali metal or organic cations, X=Cl, Br, I) series are particular, because of the Jahn-Teller distortion of Cu2+ sensitive to external stimuli such as temperature and pressure. In this article, we report the structure evolution and physical property responses of RP perovskites Rb2 CuCl4-x Brx (x=1, 2) to external pressure. Dramatic structural phase transitions from orthorhombic to monoclinic occur around 3.0 GPa in both materials regardless of their distinct compositions. Structure analyses reveal the suppression and final vanishing of the Jahn-Teller distortion of Cu2+ cations under compression and crossing the phase transition, respectively. Rb2 CuCl4-x Brx perovskites exhibit abrupt bandgap narrowing (from reddish-brown to black) along with the structural phase transition, and an overall bandgap narrowing of 75% up to ∼27 GPa but still keeping semiconductive. During the compression processes, the resistances of Rb2 CuCl4-x Brx have been greatly reduced by 5-orders of magnitude. Moreover, all of the pressure-induced phenomena in Rb2 CuCl4-x Brx perovskites are reversible upon decompression and no obvious difference is observed for the pressure responses between [CuCl4 Br2 ] and [CuCl4 (Cl,Br)2 ] coordination environments. The impact of pressure on the structural and physical properties in two-dimensional Rb2 CuCl4-x Brx provides in-depth understanding on the structure design of functional halide perovskites at ambient conditions.

Pressure-Driven Sequential Lattice Collapse and Magnetic Collapse in Transition-Metal-Intercalated Compounds FexNbS2.

Volume collapse under high pressure is an intriguing phenomenon involving subtle interplay between lattice, spin, and charge. The two most important causes of volume collapse are lattice collapse (low-density to high-density) and magnetic collapse (high-spin to low-spin). Herein we report the pressure-driven sequential volume collapses in partially intercalated FexNbS2 (x = 1/4, 1/3, 1/2, 2/3). Because of the distinct interlayer atomic occupancy, the low-iron-content samples exhibit both lattice and magnetic collapses under compression, whereas the high-iron-content samples exhibit only one magnetic collapse. Theoretical calculations indicate that the low-pressure volume collapses for x = 1/4 and x = 1/3 are lattice collapses, and the high-pressure volume collapses for all four samples are magnetic collapses. The magnetic collapse involving the high-spin to low-spin crossover of Fe2+ has also been verified by in situ X-ray emission measurements. Integrating two distinct volume collapses into one material provides a rare playground of lattice, spin, and charge.

Site-Specific Pressure-Driven Spin-Crossover in Lu1-xScxFeO3.

Pressure-driven spin-crossover (PSCO) is a collective quantum phenomenon frequently observed in transition-metal-based systems. According to the crystal-field theory, PSCO highly depends on the surrounding coordination environment of a given magnetic ion; nevertheless, it has never been verified experimentally up to now. Herein, we report the observation of a site-specific PSCO phenomenon in Lu1-xScxFeO3, in which octahedrally coordinated Fe3+ in orthorhombic LuFeO3 and trigonal-bipyramidally coordinated Fe3+ in hexagonal Lu0.5Sc0.5FeO3 show distinct PSCO response to external pressure. X-ray emission spectra and DFT calculations reveal the key role of coordination environment in a PSCO process and predict the occurrence of PSCO for trigonal-bipyramidally coordinated Fe3+ above 100 GPa, far beyond that of 50 GPa for octahedrally coordinated Fe3+ in LuFeO3. The demonstration of site-specific PSCO sheds light on the state-of-the-art design of PSCO materials for directional applications.

Urchin-Like Ni2/3Co1/3(CO3)1/2(OH)·0.11H2O for High-Performance Supercapacitors.

Here, we report our finding in the fabrication of novel porous urchin-like Ni2/3Co1/3(CO3)1/2(OH)·0. 11H2O (denoted as NC) nanomaterial composed of numerous nanoneedles through an one-step hydrothermal method, which deliveres a high specific capacity of 318 C g-1 at a current density of 1 A g-1. Moreover, an architectural composite electrode consisting of the porous NC nanoneedles wrapped by reduced graphene oxide (rGO) nanosheets exhibits large specific capacity (431 C g-1 at 1 A g-1), high rate capability and long cycling life (94% capacity retention after 5,000 cycles at 20 A g-1). The presence of rGO in the composite electrode greatly improves the electronic conductivity, providing efficient current collection for fast energy storage.

In-Situ Growth of NiAl-Layered Double Hydroxide on AZ31 Mg Alloy towards Enhanced Corrosion Protection.

NiAl-layered double hydroxide (NiAl-LDH) coatings grown in-situ on AZ31 Mg alloy were prepared for the first time utilizing a facile hydrothermal method. The surface morphologies, structures, and compositions of the NiAl-LDH coatings were characterized by scanning electron microscopy (SEM), three dimensional (3D) optical profilometer, X-ray diffractometer (XRD), Fourier transform infrared spectrometer (FT-IR), and X-ray photoelectron spectroscopy (XPS). The results show that NiAl-LDH coating could be successfully deposited on Mg alloy substrate using different nickel salts, i.e., carbonate, nitrate, and sulfate salts. Different coatings exhibit different surface morphologies, but all of which exhibit remarkable enhancement in corrosion protection in 3.5 wt % NaCl corrosive electrolyte. When nickel nitrate was employed especially, an extremely large impedance modulus at a low frequency of 0.1 Hz (|Z|f= 0.1 Hz), 11.6 MΩ cm², and a significant low corrosion current density (jcorr) down to 1.06 nA cm-2 are achieved, demonstrating NiAl-LDH coating's great potential application in harsh reaction conditions, particularly in a marine environment. The best corrosion inhibition of NiAl-LDH/CT coating deposited by carbonate may partially ascribed to the uniform and vertical orientation of the nanosheets in the coating.