Liquid-phase Method Research Articles

Facile synthesis of high iron content activated carbon-supported nanoscale zero-valent iron for enhanced Cr(VI) removal in aqueous solution

Nanoscale zero-valent iron (nZVI) based materials are considered as one of the most promising in situ remediation materials in the remediation of groundwater contaminated by a variety of pollutants. Supporting nZVI on activated carbon (AC) could reduce the aggregation of nZVI and lead to better utilization during application. The most used method for synthesizing nZVI/AC is liquid-phase reduction synthesis. However, the problem of nZVI shedding during the synthesis remains unsolved. In this study, an improved liquid-phase reduction synthesis method of nZVI/AC was developed. Compared to the conventional method, the improved method could significantly increase the Fe content of the obtain nZVI/AC (from 3.8% to 5.9%) and the utilization of reactant FeSO4·7H2O (from 49% to 77%) easily by changing the addition order and form of reactants, while using the same reaction precursors. The improved method reduced the shedding of nZVI from AC by taking advantage of the different solubility of FeSO4 in ethanol and water, and the different reactivity of NaBH4 in ethanol and water. The characterization results demonstrated that more nZVI was supported to the pores and outer surface of AC. The removal experiments of Cr(VI) (5.0 mg/L) from water showed that the nZVI/AC synthesized using the improved method exhibited better removal efficiency (85.6%) than that of the nZVI/AC synthesized using the conventional method (67.4%). These results suggested that selecting the appropriate solvent and optimizing the synthesis process may greatly improve the performance of nZVI-based materials.

Structure formation of dispersion hardened organomineral mixtures

The relevance of the work is determined by the need to improve the properties of the road pavement layers. Under conditions of increasing carrying capacity of vehicles and traffic intensity, pavements designed and constructed in accordance with the regulatory documents are destroyed without reaching the required service life. The pavement reinforcement with chemical fibers is one of the ways to solve this problem. The aim of this work is to study the structure formation of dispersion reinforcement of the pavement layers made of organomineral mixtures. Theoretical calculations are presented for the structural formation with directional reinforcement by using meshes and interlayers with dispersed reinforcement. It is shown that directional reinforcement of the structural layers provides compensation of tensile stresses only at the bottom layer, where the mesh locates. At the edges of the deflection bowl in the upper layer, tensile stresses are not compensated because the reinforcing mesh locates at the bottom layer. With dispersed reinforcement, chemical fiber penetrates in the structural layer, including its top and perceive tensile loads and reduce the likelihood of cracking. The implementation of the liquidphase method of dispersed reinforcement of organomineral mixtures improves the bitumen adhesion to the fiber surface of the dispersed reinforcement.

Photoelectrochemical properties of butane flame-treated niobium-doped hematite thin films grown by the liquid-phase deposition method

In this study, thin films of undoped and Nb-doped hematite were grown on FTO-coated glass substrates via the liquid-phase deposition method as photoanodes for PEC water splitting applications. The samples were then annealed and flame-treated for 90 s with a butane flame. At all doping concentrations, the thinnest films (~200 nm) yielded the best properties. FESEM images showed that film morphology is not dependent on Nb-doping concentration. Compared with the undoped hematite film, the optimum Nb-doped sample showed an approximately five-fold increase in photocurrent density at 1.6 V vs. RHE and a ~0.3 eV decrease in energy band gap value. The charge carrier density value of the optimum Nb-doped sample was shown to increase from 1.38 × 1017 to 3.54 × 1018 cm-3 after flame treatment due to the introduction of oxygen vacancies. The number of times the reducing butane flame is applied was shown to affect the PEC performance, both positively and negatively, giving rise to an approximately sixteen-fold increase in photocurrent density at 1.6 V vs. RHE in comparison with the untreated sample after four times of application. Butane flame treatment was also shown to facilitate the process of charge transfer in Nb-doped hematite and its interface with the electrolyte.

Lithium storage properties of Li2MoO3 and its effect as a cathode additive in full cells

High-performance lithium–ion batteries (LIBs) are the main development direction of future energy storage devices. However, most LIBs still face a problem of high first irreversible capacity loss. Pre-lithiation technology can increase the content of active lithium source and compensate the loss of active lithium during the first cycle. Adding lithium supplement additive to the cathode provides an effective way to improve the electrochemical performance of LIBs. Here, Li2MoO3 has been investigated as a cathode additive in the full cells. In order to optimize its preparation, Li2MoO3 has been prepared by three different methods, including solid-phase method, liquid-phase method and ultrasonic method. Based on material characterization and electrochemical performance tests, Li2MoO3 material prepared by liquid-phase method shows the best lithium storage properties and chosen as a cathode additive in the LiNi[Formula: see text]Co[Formula: see text]Mn[Formula: see text]O2/SiO@C full cells. The addition of Li2MoO3 has successfully improved the electrochemical performance of the full cell. The first discharge specific capacity increases from 103.9 mAh g[Formula: see text] to 130.4 mAh g[Formula: see text]. In short, Li2MoO3 material is a promising cathode additive for LIBs.

Preparation of antimonene nanosheets and their thermoelectric nanocomposites

Having high stability, carrier mobility and band gap tunability, antimonene nanosheets hold promise for thermoelectric applications. However, due to low production yield and oxidization, relevant studies have focused on theoretical prediction and numerical simulation. We herein report a liquid-phase exfoliation method with a novel solvent system of amine-terminated polyether (Jeffamine ED 2003): ethanol = 1:4 (weight ratio) for preparation of antimonene nanosheets. This method not only effectively inhibited the oxidation of antimonene nanosheets but produced a low thickness of 2.0 ± 0.5 nm; a film consisting of the nanosheets exhibited an electrical conductivity of 1800.1 ± 97.4 S/cm and a thermoelectric power factor of 118.9 ± 5.6 μW m−1 K−2. An epoxy nanocomposite film containing 99 vol% antimonene nanosheets demonstrated sufficient mechanical resilience for assembling of a thermoelectric generator. With a human body temperature gradient of 11 °C, the generator created a voltage of 0.471 mV and a current of 21.578 μA, leading to a power output of 10.16 nW. This study also investigated the lithium-ion intercalation method as a benchmark for preparation of antimonene nanosheets.

Interfacial Behavior and Shear Strength of Al-25Si-4Cu-1Mg Joints by Transient Liquid Phase Bonding with Cu as Interlayer

Spray-formed hypereutectic Al-Si-Cu-Mg alloy is the candidate for automotive and aerospace industries due to its superior wear resistance, lower thermal expansion coefficient and density, and higher thermal conductivity. This paper aims to investigate the bonding properties of hypereutectic Al-25Si-4Cu-1Mg alloys using the transient liquid phase (TLP) method with Cu as an interlayer. To obtain the suitable bonding parameters, the interfacial microstructure and shear strength of Al-25Si-4Cu-1Mg joints were investigated with the effect of different bonding temperatures and holding times. The results showed that TLP bonding between Al-Si-Mg-Cu alloy was mainly realized by large amounts of Al2Cu intermetallic compounds (IMCs), primary Si and α-Al phases. With the brazing temperature increasing, the width of the brazing seam gradually increased, and the voids began to be produced. With the holding time increasing, θ-Al2Cu phases approached into the base metal and Si particles in the brazing seam were obviously coarsened. With the formation of θ-Al2Cu phases into the base metal, more Si particles were segregated at the interface between brazing seam and base metal, and the shear test confirmed that it was the weakest bonding location. Finally, the effect of bonding parameters on the joint strength indicated that the joint brazed at 540 °C for 7.5 min presented the best shear performance with the shear strength reaching 75 MPa because the size of Si particles in the brazing seam was closest to the size of Si particles in base metal under this parameter.

Improving the photostability and water resistance stability of chalcogenide red phosphor with inert CaF2 shells

(Ca,Sr)S:Eu2+ as an important commercial red phosphor has been widely used in our daily life. However, (Ca,Sr)S:Eu2+ is extremely sensitive to moisture and ultraviolet (UV) light, which severely limits its service life and wide applications. Here epitaxial growth of dense CaF2 shell on the surface of (Ca,Sr)S:Eu2+ particles is successfully achieved by a liquid-phase thermal decomposition method. The red emission of the (Ca,Sr)S:Eu2+ phosphor is increased as much as 40% after coating with a CaF2 shell. This is attributed to the effective protection of luminescent center of Eu2+ ions in the core from surface quenching. Moreover, after continuous exposure to intense sunlight in air for 9 days, no luminescence degradation is observed for the (Ca,Sr)S:Eu2+@CaF2 sample, while the red emission of the (Ca,Sr)S:Eu2+ phosphor is severely quenched by 66%. The water resistance experiments show that the dense shell of CaF2 can protect the crystal structure of (Ca,Sr)S by suppressing the hydrolysis reaction. The red emission of the (Ca,Sr)S:Eu2+@CaF2 sample after being fully soaked in water for 30 min is comparable to that of the original (Ca,Sr)S:Eu2+ phosphors. Our results provide a new and versatile avenue to improve the stabilities of chalcogenide phosphors, thus making them attractive for wide applications.

Nanostructure and functional group engineering of black phosphorus via plasma treatment for CO2 photoreduction

As an emerging two-dimensional (2D) semiconductor, black phosphorus (BP) has attracted great interest in photocatalytic CO2 reduction, but the performance is restricted by the low surface reactivity and poor stability. Exfoliating BP into the 2D structure is an effective method to increase the exposure of active sites. However, the intrinsic surface reactivity and stability cannot be improved, and, the widely used liquid-phase exfoliation method is time-consuming and laborious. In this work, we successfully exfoliates the bulk BP into ultrathin BP nanosheets with dense surface amino-functional groups (BP-NH2) using NH3 plasma treatment. The 2D structure can shorten the photo-excited charges migration distance and improve the exposure of surface-active sites. Furthermore, the amino-functional groups on ultrathin BP nanosheets can prevent the destruction of BP nanosheets in ambient air, favoring the charge separation, CO2 adsorption and activation during the catalytic process. Benefiting from integrated advantages of amino functional groups, the optimal BP-NH2 exhibits a photocatalytic CO2 reduction rate to CO of 27.6 μmol g−1 h−1 with a selectivity of 87.0 %, both of which are higher than those of pristine bulk BP. This work presents ideas for stabilizing BP and improving the CO2 reduction performance simultaneously.

Optimization of Fe@Ag core–shell nanowires with improved impedance matching and microwave absorption properties

Ag-coated Fe (Fe@Ag) core–shell nanowires (NWs) with enhanced electromagnetic wave absorption were successfully synthesized by the liquid-phase reduction method and the layer-plus-island growth mode. Changing the molar ratio of Fe to Ag controlled the Ag shell thickness to produce different impedance matching and attenuation constants of the Fe@Ag core–shell NWs. The Fe@Ag core–shell NWs with a Fe:Ag ratio of 2:1 significantly improved optimal microwave absorption performance as compared to raw Fe NWs. At a mass fraction of 25%, the minimum reflection loss (RLmin) can reach − 58.69 dB at 7.53 GHz with a matching absorber thickness of 3.36 mm. In addition, the effective absorption bandwidth (EAB, RL ≤ − 10 dB) can be extended to 7.32 GHz, to cover the majority of the C and X bands. Three major aspects contribute to the superior microwave absorption performance: the complementary effect of the polarization of Fe-Ag interface, the impedance matching improvement stems from a proper eddy current, and the small-scale effect caused by a one-dimensional structure. This study demonstrates the promising high-efficiency microwave absorbing capabilities of Fe@Ag core–shell NWs for future use in practical applications.

Real-time quality monitoring and organic pollutants degradation of water using atomically thin Magnesiochromite

Here, we report the synthesis of atomically thin Magnesiochromite by an easily scalable liquid-phase exfoliation method. Two-dimensional (2D) MgCr2O4 was studied in detail by microscopy analysis. Thickness and average lateral dimensions of the 2D sheets, measured by atomic force microscopy were 4–5 nm and 100–350 nm respectively. Formation of atomically thin structure was also confirmed by Raman spectroscopy which also confirmed the phonon confinement along 2D. Catalytic activity of the 2D MgCr2O4 was studied under visible light and ultrasonic irradiation. Organic dye pollutants such as Methylene Blue, Methyl Orange, and Rhodamine B dye shows degradation efficiency of ∼98.6% within 20 min. The hydrophilic nature of the 2D catalyst is fruitfully utilized by the self-cleaning of cotton fabric and ∼67% decolorization was observed within 3 h of sunlight irradiation. Additionally, a smartphone-based colorimetric measurement technique was used to study the degradation efficiency of the catalyst making it cost efficient and user friendly.

Layered Metallic Vanadium Disulfide for Doubly Q-Switched Tm:YAP Laser with EOM: Experimental and Theoretical Investigations.

In the current study, layered metallic vanadium disulfide (VS2) is fabricated by a liquid-phase exfoliation method, and its microstructures as well as optical characteristics are investigated. Based on first-principles calculations, the band structure and density of the states of both bulk T-VS2 and monolayer H-VS2 are illustrated, showing the metallic behavior with a zero band gap. By using VS2 as the saturable absorber in a doubly Q-switched Tm:YAP laser with an EOM, the Q-switching laser pulses at 2 μm with 22 ns and 200 Hz are generated, corresponding to the single pulse energy of 755 μJ and the peak power of 34.3 kW. The coupled rate equations of the doubly Q-switched laser are given, and the numerical simulations agree with the experimental results. The results indicate that VS2 is a promising nanomaterial due to its nonlinear optical property. The doubly Q-switched laser demonstrates a high level of performance in reducing pulse width and enhancing pulse peak power.

Effects of Oxygenated Acids on Graphene Oxide: The Source of Oxygen-Containing Functional Group.

Graphene oxide is an important member of the graphene family which has a wide range of applications. The chemical method, especially the liquid phase method, is one of the most common and important methods for its preparation. However, the complex solution environment not only gives them rich structure, but also brings great challenges for its large-scale industrial synthesis. In order to better realize its industrial application, it is important to understand its structure, such as the source of oxygen-containing functional groups. Here we studied the contribution of four oxygenated acids to oxygen-containing functional groups in Hummers’ method using first principles. We found that the permanganic acid molecules that exist instantaneously due to energy fluctuations can be the source of oxygen-containing functional group. In addition, Stone-Wales defect have a certain effect on the formation of oxygen-containing functional groups, but this effect is not as good as that of solvation effect. This work provides a guide for exploring the source of oxygen-containing functional groups on graphene oxide.

Stretched-pulse generation in all-fiber mode-locked erbium-doped fiber laser using Lawsone dye saturable absorber

This paper describes the generation of mode locked pulses by an erbium-doped fiber laser (EDFL) cavity with a Lawsone dye saturable absorber (SA). The Lawsone SA is made of a piece of thin film, which is obtained using a liquid-phase exfoliation method. Characterization of the film reveals that its saturation intensity and modulation depth are 2.9 MW/cm2 and 12 % respectively. When the Lawsone SA is added to the EDFL cavity, a stable mode-locked pulse train is achieved at 1567.5 nm wavelength. The laser operates within a pump power of 33.6 mW to 43.3 mW at a repetition rate of 3.4 MHz and pulse width of 1.47 ps. The results indicate that the Lawsone dye can be used as a SA for laser pulse generation.

Progress in Preparation of ZrB2 Nanopowders Based on Traditional Solid-State Synthesis.

ZrB2 is of particular interest among ultra-high temperature ceramics because it exhibits excellent thermal resistance at high temperature, as well as chemical stability, high hardness, low cost, and good electrical and thermal conductivity, which meet the requirements of high-temperature components of hyper-sonic aircraft in extreme environments. As raw materials and basic units of ultra-high temperature ceramics and their composites, ZrB2 powders provide an important way for researchers to improve material properties and explore new properties by way of synthesis design and innovation. In recent years, the development of ZrB2 powders’ synthesis method has broken through the classification of traditional solid-phase method, liquid-phase method, and gas-phase method, and there is a trend of integration of them. The present review covers the most important methods used in ZrB2 nanopowder synthesis, focusing on the solid-phase synthesis and its improved process, including modified self-propagating high-temperature synthesis, solution-derived precursor method, and plasma-enhanced exothermic reaction. Specific examples and strategies in synthesis of ZrB2 nano powders are introduced, followed by challenges and the perspectives on future directions. The integration of various synthesis methods, the combination of different material components, and the connection between synthesis and its subsequent application process is the trend of development in the future.

Br-Doped CuO Multilamellar Mesoporous Nanosheets with Oxygen Vacancies and Cetyltrimethyl Ammonium Cations Adsorption for Optimizing Intermediate Species and Their Adsorption Behaviors toward CO2 Electroreduction to Ethanol with a High Faradaic Efficiency.

It is a prospective tactic to actualize the carbon cycle via CO2 electroreduction reaction (CO2ER) into ethanol, where the crucial point is to design highly active and selective electrocatalysts. In this work, Br-doped CuO multilamellar mesoporous nanosheets with oxygen vacancies and cetyltrimethyl ammonium (CTA+) cations adsorption were synthesized on Cu foam by one-step liquid-phase method at room temperature. The nanosheets with numerous mesopores and rough edges provided abundant active sites for the adsorption of CO2 molecules and brought about a long retention time for intermediates. The dopant of Br- ions induced copious oxygen vacancies on CuO lattices, thereby reducing the activation energy of CO2 molecules and optimizing intermediate species and their adsorption behaviors, while adsorbed CTA+ cations modulated the O affinity of the Cu sites, favoring *OCH2CH3 intermediate converting to ethanol. The optimized Br1.95%-CuO can effectively catalyze CO2ER to C2H5OH in 0.1 M KHCO3. The faradaic efficiency of C2H5OH reached 53.3% with the partial current density of 7.1 mA cm-2 at a low potential of -0.6 V. In addition, after 14 h CO2ER test at -0.6 V, the current density and faradaic efficiency of C2H5OH on Br1.95%-CuO retained 99.6 and 93.9% of their original values, respectively, indicating its prominent catalytic stability. This work provided a novel strategy for designing a CuO catalyst by nonmetal doping and long-chain organic molecules adsorption with multiple active sites for optimizing intermediate species and their adsorption behaviors toward CO2ER to ethanol.

Well-designed oxidized Sb/g-C3N4 2D/2D nanosheets heterojunction with enhanced visible-light photocatalytic disinfection activity

2D/2D heterojunction photocatalysts with excellent photocatalytic activity highlight considerable potential in water disinfection. Here, an oxidized Sb/g-C3N4 2D/2D nanosheets heterojunction (Sb-SbOx/CNS) was constructed based on a facile one-step liquid-phase exfoliation method using concentrated sulfuric acid. By doing so, bulk Sb and g-C3N4 were exfoliated simultaneously and then, intercalated each other. Compared with CNS and Sb-SbOx, the obtained Sb-SbOx/CNS demonstrated better photocatalytic disinfection activity towards Escherichia coli K-12 (E. coli K-12) under visible light irradiation. The 5% oxidized Sb/g-C3N4 2D/2D nanosheets heterojunction (5.0% Sb-SbOx/CNS) exhibited the best photocatalytic performance and admirable cycling stability, which was ascribed to the unique structure where the interfacial charge separation was strengthened by the strong coupling effect between Sb-SbOx and CNS. Meanwhile, the fundamental mechanism of photocatalytic disinfection was also proposed. The photogenerated ROS (reactive oxygen species) violently attacked the E. coli K-12 membrane, creating massive and irreparable holes on the cell membrane. The leakage of cations (K+, Na+, Ca2+ and Mg2+), adenosine triphosphate, total soluble sugar and protein accelerated the destruction of E. coli K-12. Trapping experiments suggested that the photocatalytic disinfection process against E. coli K-12 was dominated by h+ generated on 5.0% Sb-SbOx/CNS. This work offers a new promising way to modify the 2D/2D heterojunction featuring efficient photocatalytic disinfection performance.

Performance analysis of photo-electrochemical photodetector based on liquid-phase exfoliation few-layered graphdiyne nanosheets

Abstract The band gap of two-dimensional (2D) materials become a hot issue for photoelectric detection. Recently, public attention is thoroughly aroused as to the remarkable electrical transport characteristic and super photoresponse of 2D graphdiyne. The simulation results show that the photoresponse can be adjusted in various solutions based on the graphdiyne nanosheets with different sizes and thicknesses. Based on few-layered graphdiyne nanosheets prepared by a liquid-phase exfoliation method, a photoelectrochemical (PEC)-type few-layered graphdiyne photodetector is demonstrated in this paper. A group of PEC tests are carried out in neutral solution to verify the simulation results. The as-prepared graphdiyne photodetector possesses high photocurrent density, effective responsivity and excellent cycle stability in condition of KCl electrolyte and solar illuminance. The detectivity of the PEC-type graphdiyne photodetector can be easy to adjust by altering electrolyte concentration and other corresponding parameters, which indicates the proposed equipment can be a good candidate for photoelectric detection.

Passively Q-switched modulation based on antimonene in erbium-doped fiber laser with a long term stability

Antimonene, as a novel two-dimensional material, has received extensive attention in recent years. It has similar properties to most semiconductor materials and has many other materials unmatched characteristics. Herein, we prepare antimonene nanosheets by the liquid-phase exfoliation method, and fabricate antimonene-based saturable absorbers (SA) according to their saturable absorption characteristics and successfully apply them in fiber lasers to achieve stable passively Q-switched output with a center wavelength of 1558 nm. The saturation intensity of antimonene-based SA is 1.52 MW/cm 2 , and the modulation depth is 11.63% in our experiment. The pulse duration is varied from 5.10 μs to 1.42 μs, and the repetition frequency is changed from 25.6 kHz to 124.1 kHz, with the pump power from 81 mW to 445 mW in the passively Q-switched operation. The experimental results fully reveal the huge potential and nonlinear optical properties of antimonene used in pulsed fiber lasers and expand the scope of new optical applications. • Successfully employed Sb-SA in erbium-doped fiber lasers based on its saturated absorption characteristics. • The Q-switched pulse with a center wavelength of 1558 nm and pulse duration of 1.42 μs was realized. • The Q-switched output pulse has long-term stability without obvious spectral changes and intensity fluctuations.

Enhancement of the properties of a Beta-GA2 O3-based diode using fluorine-doped Ga2O3 films deposited by a liquid-phase method

The purpose of this research is to investigate a low-cost liquid-phase deposition (LPD) method for preparing gallium oxide ([Formula: see text]-Ga2O[Formula: see text] films. This approach has the advantages of being easy and not requiring a vacuum, and it is suitable for large-area manufacturing. First, the LPD method was used to precipitate GaOOH particles below a pH of 8 and at 80[Formula: see text]C; these were used as the precursor for the gallium oxide ([Formula: see text]-Ga2O[Formula: see text] films. Ammonium fluoride (NH4F) with concentrations of 0.1, 0.3, and 0.5 M was added to the solution to form fluorine-doped (F-doped) GaOOH. The precipitated F-doped GaOOH powders were analyzed using an energy-dispersive X-ray spectroscopy (EDS) on a field emission scanning electron microscope to identify elemental F, Ga, and O. We found that the concentration of F ions increased with the NH4F concentration. The deposited films were then annealed at 900[Formula: see text]C for 4 h to transform the F-doped GaOOH into F-doped [Formula: see text]-Ga2O3. EDS was used to analyze the F-doped [Formula: see text]-Ga2O3 films, and we found that their F[Formula: see text] ion concentration also increased with the NH4F concentration. XPS analysis was used to confirm the existence of F[Formula: see text] ions in the F-doped [Formula: see text]-Ga2O3 films. The analyzed results also showed that as the NH4F concentration increased, the electrical performance of F-doped gallium oxide improved. Finally, the F-doped [Formula: see text]-Ga2O3 films were used to fabricate F-doped [Formula: see text]-Ga2O3/p[Formula: see text]-Si junction diodes, and their J–V properties were thoroughly investigated. We found that the rectification characteristics of the F-doped [Formula: see text]-Ga2O3/p[Formula: see text]-Si diodes could be significantly improved.

Probing exchange bias at the surface of a doped ferrimagnetic insulator

With the realization of stress-induced perpendicular magnetic anisotropy, efficient spin-orbit torque switching, and room temperature topological Hall effect, interest in rare earth iron garnets has been revived in recent years for their potential in spintronic applications. In this study, we investigate the magnetic properties of micrometer-thick Bi and Ga substituted thulium iron garnets (BiGa:TmIG) grown by the liquid-phase epitaxy method. Above the magnetization compensation (MC) temperature, anomalous triple hysteresis is observed in BiGa:TmIG/Pt heterostructures by anomalous Hall effect measurements. X-ray magnetic circular dichroism and energy dispersive spectroscopy measurements reveal its origin as an internal exchange bias (EB) effect arising from inhomogeneities localized at the surface of the film. Possibly depending on the difference in thickness and defect realization of the EB layer, two types of magnetization reversal mechanisms, namely, the Stoner-Wohlfarth type and the reversible domain-wall motion type, are observed. Our results show that rich meta-magnetic phases exist in garnets close to MC, which can be robustly tuned by chemical composition engineering and conveniently probed by electrical transport measurements.