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Currently, the exploration of non-rare-earth Mn 4+ -activated oxide red phosphor is of great demand for phosphor-converted warm white-light-emitting diodes (W-LEDs). Here, Mg 2 TiO 4 :Mn 4+ and Mg 2 TiO 4 :Mn 4+ ,Zn 2+ red phosphors were prepared using a solid-state reaction route and exhibited a strong red emission peaked at ∼657 nm. The microstructure and luminescent performance of the obtained red phosphors were investigated. Additionally, the concentration quenching and nephelauxetic effect of Mn 4+ in the Mg 2 TiO 4 host lattice were evaluated in detail. Moreover, Mg 2 TiO 4 :Mn 4+ ,Zn 2+ manifests an enhanced luminescence intensity compared to the sample without Zn 2+ doping with a quantum efficiency of 38.2% and good thermal resistance of Δ E = 0.36 eV. As proof of concept, when we incorporated Mg 2 TiO 4 :Mn 4+ ,Zn 2+ and commercial YAG:Ce 3+ into the package of a blue LED chip, a warm white light was produced with a high colour rendering index and a low correlated colour temperature; thus, they have promise as an application as a colour converter in the field of warm W-LEDs. [ABSTRACT FROM AUTHOR]

Detection of slow or limited landslide movement within broad areas of forested terrain has long been problematic, particularly for the Cascade landslide complex (Washington) located along the Columbia River Gorge. Although parts of the landslide complex have been found reactivated in recent years, the timing and magnitude of motion have not been systematically monitored or interpreted. Here we apply novel time-series strategies to study the spatial distribution and temporal behavior of the landslide movement between 2007 and 2011 using InSAR images from two overlapping L-band ALOS PALSAR-1 satellite tracks. Our results show that the reactivated part has moved approximately 700 mm downslope during the 4-year observation period, while other parts of the landslide complex have generally remained stable. However, we also detect about 300 mm of seasonal downslope creep in a terrain block upslope of the Cascade landslide complex—terrain previously thought to be stable. The temporal oscillation of the seasonal movement can be correlated with precipitation, implying that seasonal movement here is hydrology-driven. The seasonal movement also has a frequency similar to GPS-derived regional ground oscillations due to mass loading by stored rainfall and subsequent rebound but with much smaller magnitude, suggesting different hydrological loading effects. From the time-series amplitude information on terrain upslope of the headscarp, we also re-evaluate the incipient motion related to the 2008 Greenleaf Basin rock avalanche, not previously recognized by traditional SAR/InSAR methods. The approach used in this study can be used to identify active landslides in forested terrain, to track the seasonal movement of landslides, and to identify previously unknown landslide hazards. [ABSTRACT FROM AUTHOR]

Landslides are common geohazards associated with natural drivers such as precipitation, land degradation, toe erosion by rivers and wave attack, and ground shaking. On the other hand, human alterations such as inundation by water impoundment or rapid drawdown may also destabilize the surrounding slopes. The Guobu slope is an ancient rockslide on the banks of the Laxiwa hydropower station reservoir (China), which reactivated during the reservoir impoundment in 2009. We extracted three-dimensional surface displacements with azimuth and range radar interferometry using European Space Agency's Copernicus Sentinel-1 and German Aerospace Center's TerraSAR-X data during 20152019. The upper part of the Guobu rockslide is characterized by toppling and is mostly subsiding with maximum rates over 0.4 m/yr and 0.7 m/yr in the vertical and horizontal directions, respectively. During filling of the reservoir prior to 2014, there was a long-wavelength in-phase response between rising reservoir level and GPS-observed increased slope movements. After the reservoir water level stabilized from 2015 to 2019, the slide movement became seasonal and we see a correlation between rainfall and landslide movement. These observations suggest that the slide motion is now primarily controlled by rainfall. The spatiotemporal landslide displacements allow us to estimate the hydraulic diffusivity of the rock mass, to be on the order (~1.05 × 10‐7 m2/s) and the thickness of the moving rock mass (~200 m). Our results demonstrate that InSAR is a useful tool for monitoring the rockslide movement as a function of seasonal precipitation. • Map 3D surface motion of Guobu slope using traditional and split-bandwidth InSAR. • Control of the slope stability shifted from river level to rainfall in 2014–2015. • Vertical and horizontal rates are 0.4+ and 0.7+ m/yr respectively during 2015–2019. • The hydraulic diffusivity is ~1.05 × 10‐7 m2/s, in the range for fractured rocks. • The inferred mass movement is ~200-m thick and ~107-m3 in volume. [ABSTRACT FROM AUTHOR]

Landslides represent one of the most damaging natural hazards and often lead to unexpected casualties and property damage. They also continually modify our natural environment and landscapes. Knowledge of landslide systems is largely restricted by the stochastic nature, subjective interpretation and infrequent or spatially sparse surveying of landslides. Characterized by persistent daily movements of a couple of centimeters over multi-centennial timescales and a long narrow shape as long as ~4 km, the Slumgullion landslide in Colorado, USA represents an ideal natural laboratory to study slow-moving landslides. Here we demonstrate the capability of the highly accurate, spatially continuous airborne Synthetic Aperture Radar (SAR) system of the NASA Uninhabited Aerial Vehicle SAR (UAVSAR) to characterize the kinematic details of internal deformation of the Slumgullion landslide using SAR interferometry (InSAR). We develop a phase-based approach to automatically extract the boundaries of the mobile geological structures without unwrapping. Comparison with historic field observations from 1991 reveals the 40-m advance of the frontal toe and shift of an internal fault. The UAVSAR data also resolve an internal minislide (100 by 70 m), which moves more southerly than the main body at 5 mm/day in the lower part of the landslide. A Light Detection and Ranging (LiDAR) Digital Elevation Model (DEM) shows that the minislide is associated with the opening of a 30 by 10 m pull-apart basin and bounding strike-slip faults. These extensional structures, nearby incised streams, and steepened local slopes helped establish the kinematic environment for the formation of the secondary minislide. The disparity between the UAVSAR InSAR-derived horizontal moving directions and the LiDAR DEM-derived slope aspects suggest that while the surface topography governs the first-order orientation, the local kinematics is also subject to the variable nature of heterogeneous landslide materials and the irregular basal bedrock surface. The landslide velocity and precipitation show similar multi-annual variations. Our study demonstrates that the freely available, high-resolution UAVSAR data, have great potential for characterizing landslide kinematics and other small-scale geological and geomorphological processes. • Characterization of kinematic and geomorphologic features by UAVSAR and LiDAR data. • Automatic identification of kinematic boundaries using wrapped interferograms. • Investigation on the formation of a secondary minislide. • The moving direction and the slope aspect may differ. • The fastest motions occur along a central, narrow segment during snowmelt. [ABSTRACT FROM AUTHOR]

• SLV aquifer deforms seasonally with ∼50-mm vertical and ∼30-mm horizontal amplitude. • Seasonal water storage cycles of the target aquifer are 0.03-0.06-km3. • Phase shifts across active faults exist in both water level and deformation. • Seasonal stress changes from volume strain are ∼100 times larger than from water load. • Insignificant annual periodicity of SLV seismicity. Aquifers and fault zones may interact through groundwater flow and stress redistribution, yet their spatiotemporal relationship remains enigmatic. Here we quantify changes in water storage and associated stress along the Wasatch Fault Zone in Salt Lake Valley, recently shaken by a M5.7 earthquake on March 18th, 2020. Ground deformation mapped by Sentinel-1 SAR imagery (2014-2019) reveals an elongated area with ∼50-mm seasonal uplift corresponding to 0.03-0.06-km3 water storage cycles. Phase shifts across active faults in both water level and deformation suggest control by the low-permeability structures. The seasonal stress changes on the adjoining faults from poroelastic volume strain are two orders of magnitude larger than those from hydrological surface loading, but both are small compared to the annual increase of tectonic loading at seismogenic depths. Historic seismic events, limited in number, do not exhibit statistically significant annual periodicity and hydrological modulation of microseismicity or triggering of the recent M5.7 event is not evident. [ABSTRACT FROM AUTHOR]

Groundwater overexploitation has caused dramatic land subsidence over the metropolitan areas in the Yangtze River Delta (YRD) and many other economic centers worldwide. Suzhou (China) is such a sinking city and faces enhanced flood risks. Restrictions on groundwater exploitation (RGE) have been imposed by the government since 1997 to prevent further elevation loss. However, knowledge on the spatiotemporal evolution of the urban land deformation during the RGE is limited by sparse and infrequent field measurements, which may bias the evaluation of the RGE policy and the strategy formulation of water management. Interferometric synthetic aperture radar (InSAR) provides regional surface deformation at a regular temporal interval of dozens of days. Here we present the decadal evolution of ground deformation in Suzhou using multiple InSAR datasets from ERS1/2, ENVISAT-ASAR, and ALOS-1 PALSAR-1 during 1993–2010, spanning the entire RGE period. An elongated zone from southern to northwestern Suzhou is highlighted by a drastic cumulative land subsidence exceeding 0.9 m due to inelastic aquifer compaction. We characterize the spatiotemporal ground deformation response to the RGE policy using an exponential decay function, from which we also infer the subsurface boundaries with sharp bedrock gradients. We identify a corridor connecting the Yangcheng and Taihu lakes, which is highly sensitive to RGE during the decelerated subsidence. Our analysis also suggests that urban subsidence in Suzhou was under control by 2006 −0.4 +1.4. • ·InSAR reveals 18-year land subsidence in Suzhou due to groundwater overpumping. • ·The groundwater exploitation restriction (RGE) regulates the ground motion. • ·Subsurface boundary of sharp gradient in bedrock depth was inferred from InSAR. • ·Time response to the implementation of RGE was defined and estimated. • ·Subsidence in Suzhou was effectively controlled around 2006 −0.4 +1.4. [ABSTRACT FROM AUTHOR]

The titanate, is a material of interest for various energy applications, including photovoltaics, catalysts, and high-rate energy storage devices. Herein, its related materials, CuO/CaTi 4 O 9 [CCTO] thin films, were successfully fabricated on SrTiO 3 (100) substrates by RF magnetron sputtering assisted with subsequent oxygen annealing. This obtained CCTO thin films were then systemically studied by X-ray powder diffraction (XRD), atomic force microscopy (AFM), scan electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). It was found that CuO and CaTi 4 O 9 (001) particles were closely accumulated together on the surface of the substrate in the annealing process after comparing with that of the as-prepared thin film, which was verified by SEM and AFM results. Furthermore, we investigated the third-order nonlinear optical (NLO) properties of the as-prepared and annealed CCTO thin film by means of the Z-scan technique using 650 nm femtosecond laser pulse. Post-deposition oxygen annealing was found to modify the morphological characteristics of the films, resulting in enhancing their NLO properties. The observation of NLO performance of annealed CCTO thin film indicates that RF magnetron sputtering is a feasible method for the fabrication of optical thin films, which can be expanded to fabricate other NLO materials from the corresponding dispersions. Naturally, we concluded that the CCTO thin film occupy a better NLO property, and thus enlarge its application in nonlinear optics. [ABSTRACT FROM AUTHOR]

A two-step synthetic method was used to obtain a Pb glass film containing micro-crystalline Ca 2 CuO 3 particles on a K 9 glass substrate. The Ca 2 CuO 3 micro-crystals were prepared for the first time by a high-temperature solid state method. The synthesized films were obtained on K 9 glass substrates by screen-printing and co-sintering techniques, using Pb glass powder and Ca 2 CuO 3 micro-crystals as reagents under different sintering temperatures. Secondly, micro-crystalline Ca 2 CuO 3 Pb-glass films with different thickness were obtained by mechanical polishing for various times. The analysis of the surface structure, purity of the Ca 2 CuO 3 phase and confirmation of the Pb-glass components in the given composites were provided by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The interactions between phonons and atoms of the micro-crystalline Ca 2 CuO 3 particles embedded in the Pb-glass matrix were characterized by means of Raman scattering spectra. Moreover, the nonlinear optical property of the film was detected by a top-hat Z-scan technique with a laser duration of 190 ns at 532 nm. The results showed that the film polished for 120 min exhibited a large third-order non-linear susceptibility χ (3) of 6.1×10 −12 esu, suggesting its potential application in all-optical switches and integrated electron devices. [ABSTRACT FROM AUTHOR]