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Simultaneous bandgap and quantum-well distribution regulation of quasi-2D perovskites realized using a bromide-terminated ligand for pure red emission, exhibiting the highest external quantum efficiency in the wavelength range of 620–660 nm.

Temperature sensitive electrical parameters (TSEPs) are used to determine the chip temperature of a single-chip insulated gate bipolar transistors (IGBT) power module by measuring one electrical device parameter. Commonly, most TSEPs have a linear relationship between the chip temperature and the electrical parameter. Like any sensor, preferred attributes of TSEPs include good accuracy, linearity, and sensitivity. For multichip IGBTs (mIGBTs) modules, these can only be achieved when all chips have the same temperature. Equal chip temperatures among different semiconductor chips can be achieved when placing mIGBTs in environmental chambers to produce a homogeneous temperature distribution (HTD). In real applications, however, mIGBTs are power cycled and are exposed to inhomogeneous temperature distribution (ITD) where temperature differences exist between chips. Consequently, measuring one electric parameter only cannot represent each chip temperature which impacts the TSEP sensitivity, linearity, and accuracy. This article compares the performance of ten TSEPs applied to an mIGBT module operating at HTD and ITD conditions in order to determine which TSEPs are most suitable for mIGBTs in real applications.

Multichip insulated gate bipolar transistor (mIGBT) power modules (PMs) degrade over power cycling. Bond wire lift–off is one of the major failure modes. This article presents a technique to diagnose bond wire lift-off by analyzing the on -state voltages across collector and emitter terminals and the voltages across collector and Kelvin emitter terminals. The proposed method can indicate the first lift-off out of 37 bond wires in a mIGBT. The main novelty of the proposed technique is that it can locate the chip that has bond wire lift-off(s). In addition, the temperature dependence of the proposed approach is negligible. The article describes the proposed technique in detail and shows results and discussions based on practical tests which are carried out on two mIGBT PMs with different packages.

The operational stability is a current bottleneck facing the quantum dot light-emitting diodes (QLEDs). In particular, the device working around turn-on voltage suffers from unbalanced charge injection and heavy power loss. Here, we investigate the operational stability of red emissive CdSe QLEDs operated at different applied voltages. Compared to the rising luminance at higher voltages, the device luminance quickly decreases when loaded around the turn-on voltage, but recovers after unloading or slight heat treatment, which is termed fatigue effects of operational QLED. The electroluminescence and photoluminescence spectra before and after a period of operation at low voltages show that the abrupt decrease in device luminance derives from the reduction of quantum yield in quantum dots. Combined with transient photoluminescence and electroluminescence measurements, as well as equivalent circuit model analysis, the electron accumulation in quantum dots mainly accounts for the observed fatigue effects of a QLED during the operation around turn-on voltage. The underlying mechanisms at the low-voltage working regime will be very helpful for the industrialization of QLED.

This paper proposes a novel health-sensitive parameter, called the gate–emitter pre-threshold voltage V GE(pre-th), for detecting IGBT chip failures in multichip IGBT power modules. The proposed method has been applied in an IGBT gate driver and measures the V GE at a fixed time instant of the V GE transient before the threshold voltage occurs. To validate the proposed method, theoretical analysis and practical results for a 16-chip IGBT power module are presented in the paper. The results show a 500 mV average shift in the measured V GE(pre-th) for each IGBT chip failure.

Luminescence properties of the Cr3+-doped LiGaW2O8 crystals are investigated by laser excitation spectroscopy. The powder samples for various Cr3+ concentration were prepared by high-temperature solid state reaction. The temperature behaviors of the emission intensity and the decay time of the self-activated LiGaW2O8 host are discussed. The emission spectra and decay times of LiGa1-xW2O8:xCr3+ are measured under UV excitation in the temperature range 10–300 K. The luminescence quenching of LiGaW2O8:Cr3+ as functions of temperature and Cr3+-concentration is explained by structural and spectral characteristics.

The amounts of uric acid (UA) in non-invasive biological samples, such as saliva, are critical for diagnosis and therapy of gout, hyperuricemia, Lesch-Nyhan syndrome, and several other diseases. Here, disposable UA biosensors were fabricated with the screen printing technique on the substrate of flexible PET. The working electrode was modified with carbon nanotubes followed by uricase for UA detection with excellent selectivity. The biosensor showed good electrocatalytic activity toward UA with high sensitivity, low detection limit, and wide linear range, which covers the full range of UA levels in human saliva. We demonstrate that UA can be directly detected in human saliva with the biosensor and the experimental data were consistent with the clinical analysis. This study indicated that the non-invasive biosensor is an attractive and possible approach for the monitoring of salivary UA. Graphical abstract A disposable uric acid biosensor modified with carbon nanotubes followed by uricase was fabricated on flexible PET and applied for the monitoring of salivary uric acid in human saliva.

The expression of Hic-5 was detected in osteosarcoma patients and osteosarcoma cell lines by RT-PCR. Then RFP-sh-Hic-5 was transfected into osteosarcoma cell lines. The effect of Hic-5 on cell viability, proliferation and apoptosis were assessed by MTT, EdU kit and Flow cytometry. The exosomes were isolated from MG-63 cell supernatant by an Exosome Isolation Kit. The exosome-Hic-5 was confirmed by transmission electron microscope, particle size detection and RT-PCR. Next, exosome-Hic-5 treated cells were explored the cell viability, proliferation and apoptosis. Further, Co-IP assay was employed for identifying the relationship between Hic-5 and smad4. TCF/LEF and the protein level of components of wnt/β-catenin signals were detected by TOP luciferase assay and western blot. Hic-5 was upregulated in osteosarcoma tissues and cell. Forced decreased expression Hic-5 inhibited the proliferation of osteosarcoma cell lines, and induced apoptosis of MG-63 and HOS. In vivo, silencing Hic-5 remitted the tumor progression. Further, we isolated the exosomes from MG-63 supernatant, exosomes concluding Hic-5 would regulated the proliferation and apoptosis level of MG-63 and HOS cells. Further, Hic-5 interacted with smad4 and regulated Wnt/β-catenin signal by decreasing TCF/LEF activity. Silencing Hic-5 inhibited the proliferation and induced apoptosis of osteosarcoma cell via inactivating Wnt/β-catenin signal by exosome pathway.

Luminescence properties of sodalite Zn4B6O13:Mn2+ are investigated by optical and laser excitation spectroscopy in the temperature range 10 – 300 K. The samples of Zn4B6O13:Mn2+ are prepared in the carbon reducing atmosphere. The green emission at 540 nm are observed in Zn4B6O13:Mn2+ for various Mn2+ concentration. Optimum Mn2+ concentration and critical distances between Mn2+ ions in Zn4B6O13 are obtained by the luminescence intensity as functions of Mn2+ concentration. The decays of Mn2+ emission depend strongly on Mn2+ concentration due to the energy transfer and energy diffusion in Zn4B6O13:Mn2+. The fine structures consisting of the intense zero phonon line (ZPL) and weak vibrational sidebands are observed at low temperature. The relevant mechanism of excitation bands, ZPL, vibrational sidebands and the bandwidth as functions of temperature are interpreted in detail by energy level diagram of the 3d5 transition metal ions and configuration coordinated diagram. The high thermal stability of the Zn4B6O13:Mn2+ phosphor are observed in the temperature range 10–300 K.

The Y2WO6:Yb3+/Er3+ crystals were synthesized by the hydrothermal method. The needle-shaped morphology is controllably formed and a number of crystals aggregate as spheres by adding the surfactant of sodium dodecylbenzenesulfonate (SDBS) into the reaction system. The crystal structure, morphology and upconversion luminescence properties of the Y2WO6:Yb3+/Er3+ crystals are conducted on the basis of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), FTIR and emission spectra. The different emission intensity ratio of the red and green bands is observed for the Y2WO6:Yb3+/Er3+ precursors under different heat treatments. The different intensity ratio are illustrated according to the upconversion mechanism.

Temperature sensitive electrical parameters (TSEPs) are promising for measurement of the insulated gate bipolar transistor (IGBT) junction temperature. Many TSEPs have been proposed in the literature and most require current sensors, and convoluted hardware and data processing, which are associated with increased complexity and cost. In this letter, a new TSEP is proposed called prethreshold TSEP, $V_{{\rm GE}({\rm pre}\text{-}{\rm th})}$ . $V_{{\rm GE}({\rm pre}\text{-}{\rm th})}$ requires only a voltage sensor and a counter. Besides less hardware requirement, $V_{{\rm GE}({\rm pre}\text{-}{\rm th})}$ does not suffer from self-heating—a problem that most TSEPs encounter. This letter presents the operation of $V_{{\rm GE}({\rm pre}\text{-}{\rm th})}$ with the help of simulation. Experimental tests on a 3.3 kV, 800 A IGBT were conducted to characterize $V_{{\rm GE}({\rm pre}\text{-}{\rm th})}$ . It is shown that the new TSEP proposed has a sensitivity of −2.2 mV/°C .

Luminescence properties of impurity-trapped excitons (ITEs) in LiBaF3:Eu2+ crystals are investigated by optical and time-resolved laser-excitation spectroscopy. The three excited states of 4f65d, 4f7(6P7/2) and ITE are identified in the excitation and emission spectra. The intensity of ITEs’ emission increases unexpectedly with increasing temperature and excitation energy. The initial intensity of the ITE emission just after pulsed-laser excitation increases continuously with temperature in the temperature range 7–600 K. The results are discussed in relation to radiative and nonradiative rates and excitonic processes in this system. The theoretical model that includes the ITE, 4f7(6P7/2) and 4f6(7FJ)5d(eg) states is developed to describe and support the experimental observations.

Eu3+-doped Gd10(1-x)Eu10xV2O20 (x = 0 – 1) phosphors were synthesized via the sol-gel process. The formation of a single phase compound was verified through the X-ray diffraction studies. Luminescence properties of Gd10V2O20:Eu3+ are investigated by optical and laser excitation spectroscopy. The emission and excitation spectra, luminescence decays were measured in the temperature region 7–300 K. The strong emission due to the vanadate group of Gd10V2O20:Eu3+ is observed at low temperature. The charge transfer transition of Eu3+ depends strongly on the Eu3+-concentration in Gd10V2O20:Eu3+. The emission intensity as a function of Eu3+ concentration under excitation of charge transfer band is inconsistent with that of the 4f7 states (the 5L6 state) of Eu3+. The energy transfer occurs between two Eu3+ ions at low Eu3+ concentration (

Ba5Al3F19:Eu2+ blue-emitting phosphors were synthesized by the solid state reaction in a reductive atmosphere. The crystal structure of Ba5Al3F19:Eu2+ phosphors were characterized by using the X-ray powder diffraction (XRD) measurement. The luminescence properties are investigated systematically based on the crystal structure. Emission and excitation spectra of the Ba5Al3F19:Eu2+ phosphor along with the decay curves were characterized. Under the excitation of UV light, the phosphor exhibits a broad band emission around 410 nm ascribed to the allowed 4f65d→4f7(8S7/2) transition, together with a sharp line at 360 nm corresponding to the forbidden 4f7(6P7/2)→4f7(8S7/2) transition of the Eu2+ ions. The temperature dependent emission spectra and decay curves were measured to investigate the origins of the emission and the thermal stabilities of the as-prepared phosphors. The as-prepared Ba5Al3F19:Eu2+ phosphors display interesting and stable luminescence properties, which can act as promising blue-emitting phosphor candidates.

Yb3+ (0.5–30 mol %) activated Y4CdMo3O16 phosphors have been prepared by the traditional solid-state reaction method. The phase formation was investigated by the XRD structural refinements. The surface properties of the powder phosphors were verified by SEM, TEM and EDS measurements. The optical properties were evaluated by the reflectance spectra, photoluminescence excitation and emission spectra, decay curves (lifetimes), and the absolute quantum efficiency (QE). Under the excitation of UV light, Yb3+-activated Y4CdMo3O16 shows the efficient near-infrared (NIR) emission bands (900–1100 nm), which is ascribed to the 2F5/2 → 2F7/2 transitions of Yb3+ ions. The NIR emission intensity shows a dependence on Yb3+ contents, which has an optimal doping of 25 mol %. The energy transfer (ET) from MoO4 to Yb3+ ions in the lattices was discussed. The NIR emission around 1000 nm just corresponds to the optical response of Si-based solar cells. Consequently, the efficiency could be enhanced by arranging luminescent layers mixed with Y4CdMo3O16:Yb3+ phosphors and transparent matrix in the front surface of Si solar cells.

A method to prepare synthetically important 3,5-disubstituted phenol derivatives that relies on the sequential gold(I)-catalyzed dehydrogenative cycloisomerization of 1,4-enyne esters in the presence of 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) or N-fluorobenzenesulfonimide (NFSI) is described. The synthetic versatility of the methodology was exemplified by a gram-scale reaction of one example, the ease to realize subsequent functional transformations of an adduct, and the application of the method to the synthesis of the bioactive molecule LUF5771.\ud \ud

Eu 3+ -doped NaGd(WO 4 ) 2 nanophosphors were synthesized via a facile one-step hydrothermal method without any surfactants or a further heat treatment. X-ray powder diffraction (XRD), scanning electron microscope (SEM), fourier transform infrared spectroscopy (FT-IR), the photoluminescence (PL) excitation and emission spectra, and decay curves were used to characterize NaGd(WO 4 ) 2 :Eu 3+ phosphors. The results show that the Eu 3+ -concentration has little influence on the structure and morphology of the as-synthesized samples. However, pH value plays a vital role on the structure and morphology of NaGd(WO 4 ) 2 . The well-crystallized sheet-like NaGd(WO 4 ) 2 phosphors can be obtained only at pH = 5–7. On the basis of the time-dependent synthesis, a possible growth mechanism of sheet-like architectures is proposed. The luminescence properties of NaGd 1-x Eu x (WO 4 ) 2 (0 ≤ x ≤ 1) are investigated. It is found that the charge transfer band of Eu 3+ shifts to lower energy and broadens with increasing the Eu 3+ -concentration.

In this work, the photoluminescence (PL) of NaScP 2 O 7 :Eu 2+ and NaScP 2 O 7 :Eu 2+ ,Mn 2+ was investigated. Phase purity was checked using X-ray powder diffractometry (XRD). PL excitation and emission spectra were recorded to elucidate the PL properties of NaScP 2 O 7 :Eu 2+ and NaScP 2 O 7 :Eu 2+ ,Mn 2+ . Furthermore, fluorescence lifetime measurements were performed. PL and lifetime measurements were carried out from 10 to 525 K. Moreover, the Eu 2+ site occupation was discussed. It turned out that the incorporated Eu 2+ ions substituted for Na + site and occupied two different sites. Temperature dependent PL measurements indicated the emission intensity decreased with increasing temperature due to temperature quenching in NaScP 2 O 7 :Eu 2+ . Fluorescence lifetimes of Eu 2+ in NaScP 2 O 7 :Eu 2+ almost did not change with a decay constant τ =∼0.53 μs in the temperature range of 10–280 K, and then shortened due to temperature quenching. The luminescent lifetime reached ∼0.05 μs at T =525 K. Finally, it was found that energy transfer occurred from Eu 2+ to Mn 2+ in co-doped NaScP 2 O 7 :Eu 2+ ,Mn 2+ .

An efficient and expedient approach for the synthesis of unsymmetrical 3,3′-Bis-indolylmethanes via silica gel-mediated Friedel-Crafts alkylation of 3-indolylmethanols with diverse indoles is described. The synthetic utility of this transformation was demonstrated by reusing silica gel up to 10 times without apparent loss of reactivity .

Pretreatment of lignocellulosic biomass with ionic liquids (ILs) for the large-scale biorefinery remains challenging due to its high price. This study focused on the utilization of inorganic salts as adjuvants for ionic liquid–water pretreatment to improve the tolerance to water and the reusability of the ILs. After the pretreatment of rice straw by the mixture of 40% 1-ethyl-3-methylimidazolium chloride ([C(2)mim]Cl) + 53% water + 7% K(2)CO(3) at 110 °C for 1 h, the residues became highly susceptible to enzymatic hydrolysis; 93.70% of lignin was removed, and 92.07% sugar yield was achieved. [C(2)mim]Cl-K(2)CO(3) aqueous biphasic system was formed at room temperature when K(2)CO(3) concentration increased to more than 30%, and the [C(2)mim]Cl recovery of 94.32% was achieved. The results indicate that the addition of inorganic salts to IL aqueous solutions can significantly reduce the cost of IL pretreatment, while maintaining an efficient enzymatic hydrolysis of lignocellulosic biomass. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s13205-019-1788-3) contains supplementary material, which is available to authorized users.

Mn4+-activated cubic phase Ba5AlF13 red phosphors were prepared by the two-step coprecipitation method. The structural and optical features were characterized on the basis of X-ray diffraction (XRD), transmission electron microscopy (TEM), emission and excitation spectra, and luminescence decay curves. The Ba5AlF13:Mn4+ phosphors can be efficiently excited by near-UV to blue light and exhibit bright red emission at around 627 nm, which is assigned to the 2Eg → 4A2g transition of the 3d3 electrons in [MnF6] octahedra. Temperature dependent emission spectra and decay curves from 10 to 550 K were measured to deeply understand the luminescence mechanism of Mn4+ in the Ba5AlF13 lattice. Notably, this novel red phosphor shows excellent anti-thermal quenching behaviour (∼700% of emission intensity at 300 K relative to 10 K).

A novel red emitting Cs2WO2F4:Mn4+ phosphor was successfully synthesized by a two-step wet chemical method. The crystal structure, morphology, and elemental composition were confirmed by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS), respectively. The luminescence properties were investigated from emission, excitation and luminescence decay curves in the temperature region of 10-500 K. The application of non-contact optical thermometry of Cs2WO2F4:Mn4+ based on the fluorescence intensity ratio (FIR) of the two coupled anti-Stokes and Stokes sidebands is discussed. The as-prepared Cs2WO2F4:Mn4+ phosphor shows a bright narrow red emission at 632 nm under excitation by a blue lamp at 470 nm and it also presents a broad and yellow-white intrinsic tungstate emission (∼520 nm) under UV excitation. The mechanism of energy transfer from [WO2F4]2- (the sensitizer) to Mn4+ (the activator) is discussed.

In this work, we report the preparation of lanthanide (Eu3+, Tb3+)-complex-grafted copolymer of methyl methacrylate and maleic anhydride films. The lanthanide complex with three amino groups was used to react with poly(methyl methacrylate-co-maleic anhydride) (P(MMA-MAH)) via the amidation method. Fourier transform infrared (FT-IR), Transmission electron microscope (TEM), Scanning electron microscope (SEM), Thermogravimetric analysis (TGA) were employed to characterize those polymers. Luminescent properties were evaluated through conducting Photoluminescence (PL) excitation spectra, emission spectra and fluorescence decay curves measurements. The infrared analysis reveals the amidation between amino groups and anhydride rings. The comparatively uniform morphology can be observed in the images of TEM and SEM. These polymers can emit intense characteristic lights including red light from Eu3+ ions and green light from Tb3+ ions under 294 nm excitation. The lifetimes of polymers are short (about 1 ms). Meanwhile, these luminescent polymers exhibit high thermal stability (T5 > 200 °C). We also stimulate a lamp to illustrate the possible application. All these approved interesting results suggest that they hold significant promising applications as luminous layers for optoelectronic devices.

Polycrystalline phosphors YK 3 B 6 O 12 :RE 3+ (RE = Eu, Ce, Tb) were prepared by the solid-state synthesis. The single crystal-phases of the samples were confirmed by X-ray powder diffraction (XRD) measurements and the structural refinements. The field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and electron dispersive X-ray (EDX) measurements were applied to analyze the morphologies of the phosphors. The photoluminescence excitation spectra (PLE) and emission (PL) spectra, decay curves and lifetimes were investigated. Under the near-UV light excitation, YK 3 B 6 O 12 :Eu 3+ , YK 3 B 6 O 12 :Ce 3+ , and YK 3 B 6 O 12 :Tb 3+ phosphors exhibit the characteristic emission transitions from Ce 3+ (5d→4f transitions in blue color), Eu 3+ ( 5 D 0 → 7 F 2 , red color), and Tb 3+ ( 5 D 4 → 7 F 5 , green color), respectively. The luminescence internal quantum efficiency (QE), the optimal doping level and the thermal stability with the activation energy (Δ E ) were measured. The result in this work could be useful for the further applications of this new host as a potential phosphor.

La2W3O12:Dy3+ phosphors were synthesized by using a high-temperature solid-state reaction. The Dy3+ concentration in the La2W3O12 lattice was varied from 0.01 to 100 %. The crystalline phases of the samples were confirmed by using an X-ray diffraction analyses. Emission and excitation spectra and decay curves of Dy3+ ions in the La2W3O12 lattices were measured at room temperature. The two charge-transfer (CT) bands that overlapped in the wavelength region 210 - 320 nm were identified as being due to the CT transitions of O2−-Dy3+ and WO 4 2− . The decay times of the 4F9/2 emission were shortened with increasing Dy3+ concentration, and the decay curves were slightly nonexponential even at low Dy3+ concentration. The decay curves were well fitted by the Inokuti-Harayama model based on the energy-transfer process between two Dy3+ ions at concentrations lower than 10 mol%. On the other hand, the energy diffusion among Dy3+ ions dominate the energy-transfer process at higher Dy3+ concentrations up to 100 mol%.

Europium- (Eu-) doped BaNb2V2O11 powders with layered mixed-anion structure were prepared through the solid state method successfully. The obtained powders were characterized using X-ray powder diffraction (XRD), structural refinement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), ultraviolet visible (UV–vis) absorption spectra, and photoluminescence (PL) measurements. The experimental results demonstrate that BaNb2V2O11 powders could absorb the UV–vis light effectively with the band gap energy of 2.219 eV. The introduction of Eu3+ in the host contributes to the decrease of the band gap energy (2.137 eV). Moreover, the photocatalytic activities of the obtained powders were evaluated through the photocatalytic degradation of the methylene blue (MB) solutions under visible light irradiation as a function of time. All the results indicate that the BaNb2V2O11 powders can be used as a potential visible-light-driven photocatalyst. Notably, du...

New potassium gadolinium phosphate [K 3 Gd 5 (PO 4 ) 6 ] doped with Eu 3+ , Ce 3+ , Tb 3+ and co-doped with Ce 3+ and Tb 3+ phosphors were prepared by high temperature solid state synthesis. Phase purity of the powders was checked by X-ray powder diffraction. Luminescence and excitation spectra of samples were reported. In particular, the interaction mechanism between Eu 3+ ions was investigated in terms of the Inokuti–Hirayama model; it was found that the interactions between Eu 3+ can be assigned to dipole–dipole interaction. K 3 Gd 5 (PO 4 ) 6 :Eu 3+ could act as a candidate for solid state lighting due to its strong absorption band in the near-UV region (350–400 nm). The energy transfer from Ce 3+ to Tb 3+ was confirmed and the mechanism was studied using Dexter's theory; it is concluded that electric dipole–dipole interaction predominates in the energy transfer process from Ce 3+ to Tb 3+ in the K 3 Gd 5 (PO 4 ) 6 host. The energy transfer efficiency and critical distance were also investigated.

A green-emitting Tb(III) complex based on siloxane-modified pressure sensitive adhesives (SPSA-Tb(III)) was successfully synthesized by emulsion polymerization. Siloxane-modified pressure sensitive adhesives (SPSA) were used as host materials. The structural coordination, photoluminescence excitation (PLE) and luminescence (PL) spectra, and thermal characterization of this luminescent polymer were investigated. The result from the FT-IR spectra reveals that SPSA have successfully coordinated with the Tb(III) ions. The luminescent analysis indicates that SPSA-Tb(III) displays Tb(III) typical emission peaks at 489, 545, 583, and 622 nm under the excitation of 369 nm. When monitored at 545 nm, strong and sharp excitation bands appear from 300 to 500 nm. And SPSA-Tb(III) has short lifetime (0.25 ms). Meanwhile, SPSA-Tb(III) exhibits high thermal stability (T d = 402 °C) owing to the high bond dissociation energy of Si O bonds. All the results suggest that it is expected to be used as a superior green-emitting material under high temperature.

Lanthanum tritungstates, La2W3O12, were prepared by using a conventional high-temperature solid-state reaction. The formation of a single-phase compound with the monoclinic structure of La2W3O12 was verified through X-ray diffraction (XRD) studies. The luminescence propeities of La2W3O12 were investigated by using optical and laser-excitation spectroscopy. The excitation and the emission spectra and the decay curves were measured in the temperature range 7 − 300 K. The charge-transfer transition of WO 4 2− was identified in the excitation and the emission spectra under excitation by ultraviolet radiation. A strong green luminescence was observed at 500 nm with a bandwidth of 4240 cm −1 at temperatures lower than 60 K; then the thermal quenching occurred with increasing temperature. The thermal quenching behaviors of the luminescence intensity and the decay time could be explanined by using a simple thermal quenching model.

In this study, four deep eutectic solvents (DESs) were used as cheaper and “greener” alternatives to ionic liquids (ILs) to create novel microemulsions. Compared with 1-ethyl-3-methyl imidazolium acetate ([Emim]Ac), the DESs of lactic acid:glucose:water and lactic acid:fructose:water (molar ratio = 5:1:3) comprising acid hydrogen-bond donor (pKa = 3.86) showed stronger capability to form the microemulsions with Tween 20, methanol and cyclohexane. After the pretreatment of rice straw at 70 °C for 12 h by using the microemulsions (mass ratio of DES, Tween 20/methanol, cyclohexane = 0.1:0.8:0.1), 54.3% of lignin was removed, and the crystalline structure was significantly disrupted. When the content of DES (lactic acid:glucose:water) increased to 50%, the sugar yield of the residues was increased to 88.1%, which was 3 times than that of untreated one. Moreover, the enzymatic hydrolysis of the residues is linearly and positively correlated with the delignification abilities of the DES microemulsion.

It is of paramount importance to measure the operating temperature of power semiconductor devices that form the essential part of electric power drive trains for electric vehicles. This paper introduces an alternative method to determine the junction temperature of Insulated Gate Bipolar Transistor (IGBT) power modules. The proposed scheme relies upon injecting a high frequency/low power signal into the gate-emitter terminals of an IGBT and then analysing the corresponding frequency response characteristics of the gate-emitter circuit. A small-signal model for the gate-emitter impedance of a 100 A IGBT power module has been developed, and its frequency response is examined and analysed by SaberRD. The frequency response of the model is compared with experimental data obtained from a network analyser. Both, simulation and practical results confirm the feasibility to detect the junction temperature of IGBTs.

Mn

Na4La2−2xTb2x(CO3)5 (x=0–0.5) nanophosphors were prepared via hydrothermal method, and the photoluminescence, concentration quenching, luminescence color chromaticity and thermal activation energy of samples were measured. The results indicate that samples with x values of 0–0.5 possess the pure monoclinic phase with an absorption edge at 250 nm. Na4La2−2xTb2x(CO3)5 (x=0–0.5) phosphors exhibit green luminescence, attributed to the 5D4→7FJ (J=6, 5, 4, 3) transitions of Tb3+. The concentration quenching takes place at about x=0.3, but no decreased luminescence intensity is observed; moreover, the activation energy of thermal quenching of Na4LaTb(CO3)5 nanophosphor was calculated to be 0.116 eV. The luminescence properties of Na4La2−2xTb2x(CO3)5 are benefited from its structural characteristics: long distance between Tb3+ ions and the ordered distribution of Tb3+ ions.

Eu 3+ -doped Na 4 La 2 (CO 3 ) 5 rod-like nanophosphors were prepared by a hydrothermal method, and the photoluminescence excitation and emission spectra, the concentration quenching of the phosphors, the luminescence color chromaticity and the activation energy for thermal quenching were measured. The results indicate that all samples possess the pure monoclinic phase. Na 4 La 2−2 x Eu 2 x (CO 3 ) 5 ( x =0–1) phosphors exhibit reddish luminescence with the dominant 5 D 0 → 7 F 2 transition of Eu 3+ at 617 nm. Na 4 Eu 2 (CO 3 ) 5 has the strongest emission without luminescence quenching, which is benefited from its structural characteristics: long distance between Eu 3+ ions and the average La–O–La bond angle of 128.10°. Moreover, the activation energy of thermal quenching and quantum efficiency of Na 4 Eu 2 (CO 3 ) 5 nanophosphors are 0.356 eV and 13.5%, respectively.

Aurivillius-type photocatalyst of Bi4V2O11 nanoparticles with an average particle size of 45 nm was prepared by the modified Pechini method. The sample was investigated by X-ray powder diffraction (XRD) and the structural refinement. The nanoparticles were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopic (XPS) and UV–vis absorption spectrum. Bi4V2O11 nanoparticles show an efficient absorption in the UV–vis light wavelength region with a narrowed band gap energy of 2.08 eV and an indirect allowed electronic transition. The photocatalytic activities of Bi4V2O11 nanoparticles were evaluated by photodegradation of methylene blue (MB) under visible-light irradiation in air atmosphere. These results indicate that Bi4V2O11 could be a potential photocatalyst driven by visible-light. Hybridization of the 6s and 6p orbitals of Bi3+ and the resulting lone electron pair yields interesting properties. The effective photocatalytic activity was discussed on the base of the crystal structure characteristic such as polar (VO3.5□0.5)2− anionic groups, Aurivillius-type (Bi2O2)2+ layers and long distance of the nearest V–V in the lattices, etc.

Nanosized particles of strontium bismuth vanadate SrBi3VO8 were prepared via the Pechini method on the base of citrate-complexation route. The samples were characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectra (EDX), X-ray photoelectron spectroscopic (XPS), and UV–vis absorption spectrum. This bismuth-containing vanadate presents an efficient absorption in the UV–visible light wavelength region with a narrow band-gap energy of 2.36 eV and an indirect allowed electronic transition. It is well-known that hybridization of the 6s and 6p orbitals of Bi3+ could result in lone electron pair and yield some very interesting properties. The photocatalytic activities of SrBi3VO8 nanoparticles were evaluated by the photodegradation of methylene blue (MB) under visible light irradiation in air atmosphere. These results indicate that SrBi3VO8 could be a potential photocatalyst driven by visible light. To understand the charge generation and separation process, the luminescence as well as the decay lifetimes was investigated in the same samples for photocatalysis.

A visible-light-driven photocatalyst based on the well-known cathode material of NASICON-type Li2Ni2(MoO4)3 was prepared by a modified Pechini method. The sample was characterized by X-ray diffraction, scanning electron microscope, transmission electron microscopy, and UV-vis absorption spectrum. The average size of Li2Ni2(MoO4)3 particle is below 50 nm. NASICON nanoparticles Li2Ni2(MoO4)3 has an efficient absorption in the UV-visible light wavelength region with a direct allowed electronic transition of 2.07 eV. The photocatalytic properties of Li2Ni2(MoO4)3 were evaluated by the photodegradation of methylene blue (MB). Li2Ni2(MoO4)3 has an efficient photocatalytic activity and could be a potential photocatalyst driven by visible-light. The photocatalytic activity was discussed on the optical absorption and special hexagonal tunnel structure connected by optical active centers of MoO4 and NiO6 and its good conductivity.

A new visible-light-driven photocatalyst of Na 2 Ni(MoO 4 ) 2 particle was prepared by the modified Pechini method. The crystal structure was measured by X-ray diffraction (XRD) and the structural refinement. The sample was investigated by scanning electron microscope (SEM), transmission electron microscopy (TEM), and UV–vis absorption spectrum measurements. The average size of Na 2 Ni(MoO 4 ) 2 particle is about 180 nm. Na 2 Ni(MoO 4 ) 2 particle have an efficient optical absorption in the UV–visible light wavelength region with a direct allowed electronic transition of 2.06 eV. The effective photodegradation of methylene blue (MB) dye was demonstrated, which benefits from the special crystal structure of Na 2 Ni(MoO 4 ) 2 particle. This crystal lattice has two infinite chains formed by (Ni,Na)O 6 and MoO 4 polyhedra standing in lines alone with the inner wall of the hexagonal tunnels. This results in the efficient optical absorption and provides more chances for electron–hole separations, which can further react with dye molecules to oxidize the dye pollutant into non-toxic products.

The luminescence properties and site occupation of NaScP2O7:Ce3+ and KScP2O7:Ce3+ phosphors are reported for the first time. Two principal Ce3+ sites [Ce (I) and Ce (II)] are observed. One of the Ce3+ centers is found to be produced by the direct substitution of the dopant ion for Na+/K+ without a local charge compensation. Another center is ascribed to an associate of a Ce3+ ion and a cation vacancy. The zero-phonon line E0 and Stokes shift are calculated.