Ca Mn Research Articles

Effect of annealing treatment on the microstructure and mechanical properties of warm-rolled Mg–Zn–Gd–Ca–Mn alloys

Effect of annealing treatment on the microstructure and mechanical properties of warm-rolled Mg–Zn–Gd–Ca–Mn alloys

Karlleuite Ca2MnO4 – a first mineral with the Ruddlesden-Popper type structure from Bellerberg volcano, Germany

AbstractKarlleuite, ideally Ca2MnO4, is a newly approved accessory mineral found in the xenolith sample within the basaltic lava from the Caspar quarry, Bellerberg volcano, Eifel, Germany. It usually occurs as thin tabular/plate crystals, which range from 40 to 80 μm in diameter, and is associated with other members of the perovskite supergroup such as srebrodolskite, brownmillerite, sharyginite, perovskite, and lakargiite distributed within rock-forming minerals represented by reinhardbraunsite, fluorellestadite, fluorapatite, larnite, gehlenite, and several hydrated Ca aluminosilicates. Karlleuite crystals are brown with sub-metallic lustre, a light brown streak, and a good cleavage along (001). It is non-fluorescent, brittle and has an uneven fracture, a Mohs hardness of 3.5 and calculated density Dx = 3.79 g/cm3. The empirical formula of the holotype karlleuite calculated based on O = 4 atoms per formula is (Ca1.97Ce3+0.06)2.03(Mn4 + 0.39Ti0.36Fe3+0.19Al0.09)1.03O4, which shows that it is a multicomponent phase characterised by various substituents at the octahedral site. Karlleuite is tetragonal I4/mmm (no. 139), with a = 3.7683(2) Å, c = 11.9893(8) Å, V = 170.254(17) Å3, and Z = 2. The calculated strongest lines in the X-ray powder diffraction pattern are [d in Å (I) hkl]: 5.995 (43), 2.742 (100), 2.665 (91), 2.023 (25), 1.998 (28), 1.884 (61), 1.553 (38), 1.371 (24). The new mineral is the first natural phase which exhibits a first order of Ruddlesden-Popper type structure, which indicates a modular nature and consists of Ca(Mn, Ti, Fe, Al)O3 perovskite layers, packed between CaO rock-salt layers arranged along the c-axis. Raman spectroscopy supports the interpretation of the chemical and structural data. Mineral association, structural data, as well as the study of the synthetic Ca-Mn-O system suggest that karlleuite could form under high-temperature conditions, above 1000˚C.

Influence of manganese alloying on the structure and properties of electrospark coatings of EP741NP heat-resistant nickel LPBF alloy

The paper investigates the impact of Mn content (Mn = 0; 0.5; 0.6; 1; 1.5 at.%) in the composition of the electrodes of the Al–Ca–Mn system on the structure and properties of electrospark coatings formed on LPBF substrates made of EP741NP alloy. It was found that the highest weight gain of the substrate (5.8·10–4 g) was recorded when the Al–7%Ca–1%Mn electrode with a low degree of supercooling of the melt (Δt = 5 °C) was subject to electrospark treatment (EST). EST with this electrode with a fine eutectic structure enables the formation of coatings with minimal surface roughness (Ra = 3.51±0.14 μm). The nanocrystalline structure of the coatings was confirmed by transmission electron microscopy, including HRTEM. Comparative tribological tests revealed that the coating with maximum hardness (10.7±0.8 GPa) formed during EST with an electrode containing 1.5 at.% Mn had the minimal wear rate (1.86 ·10–5 mm3/(N· m)). We proved that EST with Al–Ca–Mn electrodes enables to reduce the specific weight gain of the LPBF EP741NP alloy during isothermal (t = 1000 °C) curing in air due to in situ formation of a complex thermal barrier layer consisting of oxides (α-Al2O3, CaMoO4) and intermetallides (γ ′-Ni3Al and β-NiAl). We determined the concentration limit of Mn (1.0 at.%) in the electrode, at which the barrier layer retains its integrity and functionality.

Stellar Abundances at the Center of Early-type Galaxies with Fine Structure

Our understanding of early-type galaxies (ETGs) has grown in the past decade with the advance of full-spectrum fitting techniques used to infer the properties of the stellar populations that make up the galaxy. We present ages, central velocity dispersions, and abundance ratios relative to Fe of C, N, O, Mg, Si, Ca, Ti, Cr, Mn, Co, Ni, Cu, Sr, Ba, and Eu, derived using full-spectrum fitting techniques for three ETGs, NGC 2865, NGC 3818, and NGC 4915. Each of these three galaxies were selected because they have optical, disturbed structures (fine structure) that are linked to major merger events that occurred 1, 7, and 6 Gyr ago, respectively. Two of the ETGs, NGC 3818 and NGC 4915, show chemical signatures similar to ETGs without fine structure, which is consistent with a gas-poor merger of elliptical galaxies in which substantial star formation is not expected. For NGC 2865, we find a statistically higher abundance of Ca (an α element) and Cr and Mn (Fe-peak elements). We show that for NGC 2865, a simple gas-rich merger scenario fails to explain the larger abundance ratios compared to ETGs without fine structure. These three ETGs with fine structure exhibit a range of abundances, suggesting ETGs with fine structure can form via multiple pathways and types of galaxy mergers.

Tailoring the electrochemical behavior and discharge performance of Mg–Al–Ca–Mn anodes for Mg-air batteries by different extrusion ratios

This work investigates the electrochemical behavior and discharge performance of Mg–3Al-0.4Ca-0.7Mn alloys with three extrusion ratios (ER) of 10, 16 and 25 as anodes for Mg-air batteries. The results show that the ER16 sample has the lowest corrosion current density and the highest corrosion resistance. The corrosion performance of the ER25 sample is slightly reduced due to the excessive discontinuous second phase leading to elevated self-corrosion rate. The alloy exhibits higher discharge voltage and stable discharge process with increasing extrusion ratio. Increasing the extrusion ratio has a homogeneous microstructure, the increase in the area fraction of non-basal oriented grains is conducive to the homogeneous dissolution of the anode and the inhibition of the “chunk effect”. The ER25 sample showed the highest anode efficiency, specific capacity and energy density of 55.73 %, 1306.67 mA h g-1 and 1635.947 mW h g−1 at 20 mA cm−2, respectively.

Achieving low tension-compression yield asymmetry and ultrahigh strength in Mg–1Al–1Ca–0.2Mn (wt%) alloy via sub-micron grain refinement

Traditional low-alloyed Mg–Al–Ca–Mn extrusion alloys always show a low strength and a high tension-compression yield asymmetry. In the present work, Mg–1Al–1Ca–0.2Mn (AXM1102, wt.%) alloys were extruded at 150–350 °C to produce different grain structure and mechanical properties. It is shown that AXM1102-150 (extruded at 150 °C) sample exhibits superhigh strength in both tension and compression, which exhibited a yield strength (YS) of 428 MPa in tension and 416 MPa in compression. Namely, ultrahigh strength and low tension-compression yield asymmetry were both obtained. The ultrahigh strength was found to be ascribed to the ultra-fine dynamically recrystallized (DRXed) grains (0.47 μm) together with grain boundary co-segregation of Ca and Al atoms. Submicron DRXed grains accounts for the improved tension-compression yield asymmetry through suppressing {10-12} twining during compression. Additionally, the discontinuous yielding was detected during tension of AXM1102-150 alloy, which is potentially related with the high energy barrier required for dislocation emission caused by grain boundary co-segregation of Al and Ca atoms. Once the tensile stress reaches the peak value, the mobile dislocation density increases immediately, thus the tensile stress-strain behavior of the AXM1102-150 alloy is dominated by strain softening. The results indicate that low-alloyed Mg–Al–Ca–Mn alloys demonstrate tremendous potential as next generation ultrahigh-strength and low tension-compression yield asymmetry wrought Mg alloys.

Effect of number of ECAP passes on structure and mechanical properties of Al–Ca–Mn–Fe alloy

The effect of number of equal-channel angular pressing (ECAP) passes on the structure and mechanical properties of the as-cast 4% Ca–1.3% Fe–0.8% Mn–0.1% Zr–0.1% Sc Al alloy is studied. ECAP was carried out at room temperature, through BC path using an angle between the channels of 110°. The number of ECAP passes was N = 2, 3, and 4. The as-cast alloy consisted of the solid solution dendrites (Al) and the [(Al) + Al10CaFe2 + Al4Ca] eutectic, as well as of a small fraction of the Al6(Fe, Mn) particles. As a result of ECAP, the dendrites are elongated approximately at an angle of 30° relative to the direction of ECAP. After two passes of ECAP, the dislocation density increased, but with an increase in the number of passes, the dislocation density slightly decreased as a result of the rearrangement of the dislocation structure; besides calcium segregated from the eutectic. After ECAP, a significant hardening of the alloy was observed. The highest strength observed after two passes (the ultimate tensile strength of the as-cast alloy was 130 MPa, and after the second pass it was 305 MPa), and the lowest one was after four passes (the ultimate strength was 219 MPa). The relative elongation of the ECAP-processed samples did not depend on the number of passes and it was about 1%.

Investigation of enhanced strength anisotropy in an extruded Mg–Al–Ca–Mn alloy at cryogenic temperature

This study systematically compared the microstructural evolution and mechanical behavior of the extruded AXM10304 alloy during tensile deformation along both the extrusion direction (ED) and transverse direction (TD) at cryogenic temperature (CT) and room temperature (RT). The results indicate that the variations in work hardening mechanisms contribute to the observed strength anisotropy in both the ED and TD samples. The yield strength discrepancy between different orientations is ∼88 MPa at RT and ∼179 MPa at CT. It is evident that the alloy exhibits more pronounced strength anisotropy during cryogenic deformation. It is noteworthy that in the CT-ED samples, the ratio of the critical resolved shear stress (CRSS) for pyramidal I and II to that of basal <a> dislocations is relatively minimal, facilitating the activation of more pyramidal dislocations. Cross-slip in CT-ED provides a relatively facile path for dislocation slip, resulting in material softening during straining. The CT-TD sample exhibits the highest work hardening capacity and a consistent dislocation storage rate. Twinning significantly contributes to the hardening observed in the TD samples. This study also illustrates that tailoring twinning morphology to a refined needle-like shape through temperature manipulation can further enhance the work hardening of Mg alloys.

Cristobalite Clinker and Paralavas of Ferroan and Melilite–Nepheline Types in the Khamaryn-Khural–Khiid Combustion Methamorphic Complex, East Mongolia: Formation Conditions and Processes

Abstract —Rock samples from the Khamaryn-Khural–Khiid combustion metamorphic (CM) complex, including cristobalite clinker, ferroan tridymite–sekaninaite and cristobalite–fayalite paralavas, which are rock types new to the complex, as well as clinker xenoliths in melilite–nepheline paralava, have been studied in terms of chemistry and mineralogy. The obtained data on rock-forming, minor, accessory, and rare phases (silica polymorphs, cordierite-group minerals, fayalite, Fe and Ti oxides, ferrosilite, etc.) have implications for the formation conditions and processes of the CM rocks. The Raman spectra of sekaninaite, indialite, ferroindialite, mullite, and anhydrous Fe–Ca–Mn phosphate, presumably from the graftonite group, have several specific features. The diversity of mineral assemblages in the CM rocks is due to heterogeneous lithology of the sedimentary protolith and to local effects in the multistage history of the Khamaryn-Khural–Khiid complex. According to geochemical data, all CM rocks of the complex are derived from the Early Cretaceous Dzunbain Formation, their protolith molten to different degrees. The cristobalite clinker and tridymite–sekaninaite and cristobalite–fayalite paralavas were produced by partial melting of pelitic rocks containing different amounts of iron in a wide temperature range. The formation of mullite developed from dehydration–dehydroxylation and incongruent partial melting of amorphous pelitic matter. Large-scale crystallization of mullite in clinker, occurred from the high-silica potassic aluminosilicate melt at &amp;gt;850 °C. Combustion of subsurface coal seams heated the overburden to &amp;gt;1050 °C or locally to &amp;gt;1300–1400 °C (melting point of detrital quartz) or even, possibly, to &amp;gt;1470 °C corresponding to the stability field of β-cristobalite. Melilite–nepheline paralava was formed by incongruent melting of silicate (pelitic) and carbonate (calcite) components of marly limestone under elevated CO2 partial pressure. Oxygen fugacity (fO2) during combustion metamorphism changed from strongly reducing conditions favorable for crystallization of Fe phosphides (barringerite, schreibersite) and metallic iron from silica-undersaturated melts parental to melilite–nepheline paralava to high fO2 values that can maintain the formation of hematite in Fe-rich CM rocks.

Effect of Al and Ca Elements on the Atmospheric Corrosion of Field-Exposed Mg–Al–Zn–Ca–Mn Magnesium Alloys

Three different extruded Mg–Al–Zn–Ca–Mn magnesium alloys with varying alloying elements and a diecast AZ91D alloy were exposed to two coastal environments for five years. Under unsheltered exposure, Mg–Al type layered double hydroxide was primarily formed, and the mass loss corrosion rate was decreased with increasing Al content in the alloys. Under sheltered exposure, magnesium hydroxy carbonate was the main corrosion product. Additionally, Mg alloys with high Al content tended to exhibit localized corrosion. Furthermore, the negative impact of Ca addition on atmospheric corrosion occurred when the alloys were exposed under sheltered conditions.

The acquisition of macro- and micronutrients is synergistic in species mixtures: example of mixed crucifer-legume cover crops

Cover crops are often mentioned as a way to decrease nutrient losses during the fallow period. Species mixtures of crucifer-legume have been shown to effectively take up nitrogen (N) and sulphur (S) to decrease losses due to leaching, but their ability to simultaneously take up other key macro- and micronutrients remains unknown. Our study assessed the performances of a wide variety of bispecific crucifer-legume mixtures to provide synergetic uptake of multiple nutrients to target nutrient-recycling ecosystem services. Cultivars from eight crucifer and seven legume species were tested as sole and bispecific cover crops at an experimental site near Toulouse, France. Seven macronutrients (C, N, P, K, S, Ca and Mg) and six micronutrients (B, Cu, Mn, Zn, Fe and Na) were measured in both species. Crucifer-legume mixtures showed synergetic uptake of nutrients per ha compared to sole cover crops for some nutrients through niche complementarity and facilitation processes and net competition for other nutrients. Species mixtures induced both i) higher nutrient concentrations for Mn and Fe in crucifers and Ca and B in legumes) and ii) lower concentrations for P, K, Ca and B in crucifers and Cu and Fe in legumes, indicating that the interactions differed among the species mixtures. Nevertheless, the nutrient uptake measured in shoots were always higher in species mixtures than in sole crops (LER &amp;gt; 1) demonstrating the compatibility and complementarity of crucifer and legume mixtures in providing multiple-nutrient catch-crop and recycling related ecosystem services. Despite overall positive interactions and synergetic complementarities, the results also highlight that some net negative competition occurred for some nutrients. Thus, further investigation is still necessary to completely understand the processes behind multiple-nutrient acquisition in species mixtures.

Synthesis of Calcium Manganese Oxide Films Using a Sol–Gel Method and Evaluation of Color and Photocatalytic Properties

Herein, for developing colored photocatalysts, calcium manganese oxide (Ca–Mn–O) film and powder samples are synthesized by a sol–gel method using acetylacetone (acac) or citric acid as a chelating agent, and their color and photocatalytic properties are evaluated. Thin‐film X‐ray diffraction experiments clarify the precipitation of Ca–Mn–O phases, such as Ca3Mn2O7 (Ca/Mn = 1.5) and Ca2MnO4 (Ca/Mn = 2), in the film samples with drop‐cast coating. These films strongly absorb all visible light due to the interband transition between O 2p and Mn 3d orbitals, resulting in dark gray coloration. By testing photocatalytic activities using methylene blue dyes, it is revealed that the film sample (acac, 4‐drops) exhibits photocatalytic activities, which makes Ca–Mn–O films dual functional with photocatalytic functions and coloration.

Influence of minor RE addition on microstructures, tensile properties, and creep resistance in a die-cast Mg–Al–Ca–Mn alloy

In this work, we have investigated the influence of RE content on the tensile property, creep resistance, and microstructures of a die-cast Mg–9Al-0.3Ca-0.2Mn (wt. %). Minor content of RE elements simultaneously increases the strength and ductility, which is mostly since RE addition refined primary dendritic α-Mg and eutectic α-Mg matrix and eutectic β-Mg17Al12 phases and formed thermally stable Al11RE3 phases. The 0.6% RE adding alloy obtains the best strength-ductility synergy along with the UTS of 245 MPa, TYS of 170 MPa, and EL of 5.7%. The 0.6−1.0% RE addition gives rise to a reduction of the minimum creep rate by over one order of magnitude of the alloy, indicating a significant enhancement in creep resistance, which can be mainly attributed to RE addition introducing Al11RE3 phases to prevent grain boundary sliding, and suppressing dynamic precipitation of γ-Mg17Al12 phases during high-temperature creep. These results can provide important references for the design of creep-resistant die-cast Mg alloys and promote the application of commercial Mg–Al based alloys at high temperatures.

Improving tensile properties and corrosion resistance of Mg–Zn–Ca–Mn alloy via Gd addition

Effects of various Gd additions on the microstructure evolution, tensile properties and corrosion resistance of Mg–6Zn-0.5Ca–1Mn (ZMX6105) alloys were investigated. Results showed that the second phases of as-cast ZMX6105-xGd alloys (x = 0, 0.2, 1.0 wt%) were mainly composed of Mg7Zn3 phase, Ca2Mg6Zn3 phase, Mg3Zn6Gd phase. Gd addition promoted the formation of Ca2Mg6Zn3 phase during solidification, but decreased the fraction of Mg7Zn3 phase. Microstructure observation of as-extruded alloys revealed that Gd addition inhibited dynamic recrystallization, refined dynamic recrystallized (DRXed) grains and strengthened basal texture. As-extruded ZMX6105-0.2Gd alloy exhibited excellent tensile properties with yield strength of 276 MPa, ultimate tensile strength of 354 MPa and elongation of 11%, and simultaneously had optimal corrosion resistance with corrosion rate of 22.06 mm/year based on the weight loss tests in 3.5 wt% NaCl solution.

Achieving low activation energy and double-peak texture after hot deformation of Mg–Al–Zn–Ca–Mn–Zr alloy and enabling the strength and ductility

In this study, the hot-deformation behavior of a die-casted Mg–Al–Zn–Ca–Mn–Zr alloy was investigated in the temperature range of 548–673 K and the strain rate range of 0.0001–1 s−1. The constitutive equation and processing maps were also developed to describe the flow stress behavior. The numerical simulation result revealed an average activation energy of ∼139.4 kJ mol−1, which is lower than the previously reported AZ31 Mg alloys. Subsequently, the low activation energy imparted a high degree of dynamic recrystallization and was mainly attributed to alloying elements Ca, Mn, and Zr. For optimum hot working parameters, processing maps displayed two different domains, the temperature range of 573–673 K for a strain rate range of 0.001–0.01 s−1 with a peak efficiency of 33% and a temperature of 673 K at a high strain rate of 0.01 s−1 with a peak efficiency of 31%. The microstructure evolution confirmed the validity of parameters and revealed high dynamic recrystallization. The average grain size ∼21.1 μm, ∼15.4 μm, and ∼16.1 μm were achieved at temperatures of 573 K, 623 K, and 673 K under a strain rate of 0.001 s−1. The profuse grain refinement is attributed to the pronounced accumulation of dislocation on grain boundaries and on the eutectic phases. In addition, the morphology of the eutectic phases was broken with the increase in the strain rate and temperature. Thus, the α-Mg and eutectic phases bear the compressive stresses and promote the dynamic recrystallization activity. Last but not least, the double peak texture after hot deformation was developed, which is one of the engineers' main requirements for enhancing the Mg alloy's ductility. Based on the above discussion, the hot deformed specimens exhibited an ultimate compressive strength of ∼340 MPa and elongated to fracture >25%. Consequently, this study enables the understanding of the broad use of Mg–Zn–Al–Ca–Mn–Zr alloys for automobile applications.

Improvement of strength–ductility balance of Al–Ca–Mn–Fe alloy by severe plastic deformation

The as-cast Al–Ca–Mn–Fe alloy was processed by the high-pressure torsion (HPT) technique. HPT of the samples 20 mm in diameter was carried out at room temperature through 3 revolutions. HPT resulted in the formation of a predominantly nano-grain structure and almost complete disappearance of eutectic particles in the structure. As a result of HPT, a 5-fold increase in strength and a 1.5-fold increase in the relative elongation of the alloy were achieved. The relationship between the achieved complex of mechanical properties and microstructure features is discussed.

In‐house manufactured benchtop XRF spectrometer

AbstractThe growing efficiency of agribusiness depends on the development of technology. A key challenge regards the determination of plant mineral content, which help farmers to make a decision about fertilizer use. Currently, such nutritional status diagnoses are made based on wet chemical methods; they are usually slow and generate chemical wastess. In this context, an in‐house manufactured XRF benchtop for agri‐samples is proposed in this study. This XRF system was furnished with a manual primary filter changer, vacuum chamber, dual interlock radiological protection system, which were installed in the equipment cover, and light signals. Analytical capabilities were also evaluated. The equipment presented spurious peaks of Ti, Fe, Ni, and Zn, which is not ideal for some agronomical applications; this issue might be overcome in the future by means of additional primary filters. The total x‐ray spectrum counting rate is roughly one magnitude order lower than two other commercial XRF systems, but the signal‐to‐noise ratio is quite similar. The vacuum chamber under partial vacuum improves the Al, Si, P and S signals from 1.5 to 2.2. The limits of detection (LOD, mg kg−1) for P (261), S (168), K (68), and Ca (50) macronutrients and Mn (14), Fe (15), Cu (9), and Zn (8) micronutrients are close to the ones reported in the literature. The limits of detection for P, S, K, and Ca are suitable for plant analysis.

The 12-layer trimer-based hexagonal perovskite Cs4Ca0.7Mn3.3Cl12

We describe the crystal structure and basic magnetic properties of Cs4Ca0.7Mn3.3Cl12, a previously unreported twelve layer (12L-) hexagonal (R-3m) chloride perovskite. Its crystal structure features face sharing MnCl6 octahedra that form Mn3Cl12 trimers. The trimers, which form a triangular array, are separated by corner sharing to layers of disordered single Ca(Mn)Cl6 octahedra. The decreased intratrimer Mn–Mn distance yields stronger magnetic coupling within trimers than between trimers. The dominant magnetic interactions are antiferromagnetic (θCW = −105 K), the effective magnetic moment per Mn2+ is 6.5 μB, and potential signatures of magnetic frustration are observed. Behavior consistent with short- and long-range magnetic order is exhibited at approximately 37 and 0.7 K, respectively.

Response of Physicochemical Properties and Enzyme Activities in Rhizosphere Soil to Yellow Leaf Curl Virus Disease of Cherry Tomato (&amp;lt;i&amp;gt;Lycopersicon esulentum &amp;lt;/i&amp;gt;Mill.)

Tomato yellow leaf curl virus disease (TYLCVD) has become a devastating disease, which seriously threatens the healthy development of tomato industry in China. Creating a healthy soil environment may be the key to success in preventing TYLCVD. Field investigation and laboratory analysis were used to evaluate the response characteristics of macro elements, medium elements, micro elements and enzyme activities in the rhizosphere soil of cherry tomato to TYLCVD. The main objective of this study was to determine the suitable soil environment for the healthy survival of cherry tomato. Soil samples were collected from rhizosphere of healthy and diseased plants. The results showed that the occurrence of TYLCVD was related to the enzyme activities, pH value, macro elements N, P, K, medium elements Ca, Mg, S and micro elements Mn, Zn, Cu, Si in the rhizosphere soil of cherry tomato. Compared with healthy plants, the activities of urease, catalase and acid phosphatase were significantly decreased by 48.6%–77.4%, 23.7%–43.8% and 19.1%–31.0%, respectively, in rhizosphere soil of diseased cherry tomato plants (<I>P</I> < 0.05). The pH value, contents of alkaline hydrolysis N, available Mg, available S, available Mn, available Zn, available Cu and available Si in rhizosphere soil of diseased plants were significantly lower than those in healthy plants (<I>P</I> < 0.05). The pH value in rhizosphere soil of diseased plants was 0.18-0.25 units lower than that of healthy plants. And the contents of alkaline hydrolysis N, available Mg, available S, available Mn, available Zn, available Cu and available Si were reduced by 5.54%–20.0%, 29.7%–73.9%, 27.3%–48.8%, 6.95%–10.1%, 13.6%–-15.2%, 10.6%–25.0% and 4.97%-8.30%, respectively. However, the contents of available P, available K and available Ca in rhizosphere soil of diseased plants were significantly higher than those in healthy plants (<I>P</I> < 0.05), were increased by 3.77%–41.2%, 6.75%–37.4% and 16.7%–50.5%, respectively. Our findings improve our understanding of the links between the occurrence of TYLCVD and the soil environment, which have implications for developing strategies for the prevention of tomato yellow leaf curl virus disease.

Study on phase evolution and promoting the pozzolanic activity of electrolytic manganese residue during calcination

Electrolytic manganese residue (EMR) is a harmful by-product in the electrolytic manganese industry. Calcination is an efficient method for disposing EMR. In this study, thermogravimetric-mass spectrometry (TG-MS) combined with X-ray diffraction (XRD) was used for analysing the thermal reactions and phase transitions during calcination. The pozzolanic activity of calcined EMR was determined by the potential hydraulicity test and strength activity index (SAI) test. The leaching characteristics of Mn were determined by TCLP test and BCR SE method. The results showed that MnSO4 was converted into stable MnO2 during calcination. Meanwhile, Mn-rich bustamite (Ca0.228Mn0.772SiO3) was converted into Ca(Mn, Ca)Si2O6. The gypsum was transformed into anhydrite and then decomposed into CaO and SO2. Additionally, the organic pollutants and ammonia were completely removed following calcination at 700 °C. The leaching concentration of Mn decreased from 819.9 mg L−1 to 339.6 mg L−1 following calcination at 1100 °C. The chemical forms of Mn were transformed from acid-soluble fraction to residual fraction. The pozzolanic activity tests indicated that EMR1100-Gy maintained a complete shape. The compressive strength of EMR1100-PO reached 33.83 MPa. Finally, the leaching concentrations of heavy metals met the standard limits. This study provides a better understanding for the treatment and utilization of EMR.