Compound Sr Research Articles

Low-dimensional magnetism of BaCuTe2O6

X-ray diffraction, thermodynamic measurements, and density-functional band-structure calculations are used to study the magnetic behavior of BaCuTe$_{2}$O$_{6}$, a member of the $A$CuTe$_2$O$_6$ structural family that hosts complex three-dimensional frustrated spin networks with possible spin-liquid physics. Temperature-dependent magnetic susceptibility and heat capacity of the Ba compound are well described by the one-dimensional spin-$\frac12$ Heisenberg chain model reminiscent of the Sr analog SrCuTe$_2$O$_6$. While the intrachain coupling $J/k_{\rm B}\simeq 37$ K is reduced compared to 49 K in the Sr compound, the N\'eel temperature increases from 5.5 K (Sr) to 6.1 K (Ba). Unlike the Sr compound, BaCuTe$_2$O$_6$ undergoes only one magnetic transition as a function of temperature and shows signatures of weak spin canting. We elucidate the microscopic difference between the Sr and Ba compounds and suggest that one of the interchain couplings changes sign as a result of negative pressure caused by the Sr/Ba substitution. The N\'eel temperature of BaCuTe$_2$O$_6$ is remarkably insensitive to the magnetic dilution with Zn$^{2+}$ up to the highest reachable level of about 20%.

Ab initio study of the phonon and thermodynamic properties of the scheelite MWO4 (M = Ba, Sr or Ca) compounds

In this work, we performed the calculations based on density functional theory with different exchange and correlation energy approximations and employed the method of the constant force within the harmonic approximation, to study the phonon and thermodynamic properties of the three MWO4 (M = Ca, Sr or Ba) compounds with scheelite-type structure. In the first part of the work, we carried out an analysis of the performance of the local density approximation (LDA) and generalized gradient approximation of the Perdew-Burke-Ernzerhof revised for solids (GGA-PBEsol) on the computed phonon density of states, specific heat at constant volume, entropy and Gibbs free energy of the scheelite BaWO4 compound. Comparisons between calculated and experimental data showed that the GGA-PBEsol approach exhibited better performance. In the second part of the work, we extended the study of the thermodynamic properties to the SrWO4 and CaWO4 compounds, which are not presented in the literature, using the GGA-PBEsol approximation. It was found that the magnitude of the specific heat at the constant volume at high temperature respects the following order: BaWO4 > CaWO4 > SrWO4. Moreover, it was verified a relation between M2+ ionic radius in the scheelite MWO4 (M = Ba, Sr or Ca) and their entropy, Gibbs energy, and Helmholtz free energy.

Investigation of the reaction mechanism between cyclohexyl isocyanide and dimethyl acetylenedicarboxylate in the presence of 2-mercaptobenzoxazole: a theoretical study

The one-pot, three-component reaction mechanism consisting of cyclohexyl isocyanide R1, dimethylacetylenedicarboxylate R2, and 2-mercaptobenzoxazole R3 has been investigated theoretically at the B3LYP/6-311++G(d,p) level. The solvent effect was also studied in dichloromethane using the SCRF (PCM) method. Four possible reaction pathways (including a, b, c and d) were suggested. The results showed that the first step of the reaction mechanism in all pathways was determined as a rate-determining step. Theoretical data indicate that the rate of the overall reaction is second order, depending on the concentrations of compounds R1 and R2. NBO analyses were applied to determine the importance of hyper conjugative interactions in the conformational equilibrium and understanding of the molecular interactions. the best reaction pathway and the best product were predicted according to the theoretical study.

Analysis of the geometric features of T-x-y diagrams with melt immiscibility for silicate systems

Analysis of the geometric structure of phase diagrams for ternary systems with the two immiscible liquids has been carried out. T-x-y diagrams with the both types of the monotectic equilibriums (univariant and invariant ones) have been analyzed. Three-dimensional computer models of T-x-y diagrams for the four silicate systems with mono- and invariant equilibriums and different variants of the immiscibility surfaces location have been built. T-x-y diagram of the ZrO2-SiO2-Al2O3 system includes one immiscibility cupola, located in the ZrO2 crystallization field, which adjoins the ZrO2-SiO2 side. The 3D model of T-x-y diagram includes four invariant transformations: peritectic P: L+ZrO2+SiO2→R2, quasi-peritectic Q: L+ZrO2 →R1+R2, two eutectic E1: L→ZrO2+Al2O3+R1, E2: L→SiO2+R1+R2. Five surfaces of liquidus, which correspond to the beginning of primary crystallization of three initial components and two binary compounds R1=3Al2O3·2SiO2 and (congruently melting) and R2=ZrO2·SiO2 (decomposed without liquid) are formed in the system. T-x-y diagram TiO2-ZrO2-SiO2 is characterized by one eutectic E: L→TiO2+SiO2+ZrO2·TiO2 and one quasi-peritectic Q: L+ZrO2→SiO2+ZrO2·TiO2 transformations and includes two immiscibility surfaces from the sides of TiO2-SiO2 and ZrO2-SiO2 binary systems. FeO-SiO2-Fe2O3 system with common immiscibility cupola, that prolongs from the system FeO-SiO2 to the system SiO2-Fe2O3, is characterized by three invariant transformations of eutectic type, and one metatectic transformation V: B1 →L+B2+C, which corresponds to the transfer from high-temperature allotropy of silica (B1 - cristobalite) to the low-temperature one (B2 – tridymite). T-x-y diagram KAlSi2O6-Fe2SiO4-SiO2 has two immiscibility surfaces: one of them adjoins to the Fe2SiO4-SiO2 binary system and the second one is located on the Fe2SiO4 and tridymite liquidus surfaces, dividing the univariant curve on their boundary into two parts, and has three points of the maximum and three points of the minimum. Using of the computer models of T-x-y diagrams allows you to take into account different variants of the geometric structure of the investigated silicate systems.

Structure stability, half metallic ferromagnetism, magneto-electronic and thermoelectric properties of new zintl XCr2Bi2 (X=Ca, Sr) compounds for spintronic and renewable energy applications

Employing full-potential linearized augmented plane waves (FP-LAPW) methods, the structural stability, electronic nature, magnetic and thermoelectric properties of XCr2Bi2 (X = Ca, Sr) were theoretically investigated for the first time. The structure stability of these materials was confirmed by formation energy and cohesive energy. Based on its electronic properties, the energy band gaps were decreased from 1.55 eV to 1.53 eV and from 1.93 eV to 1.6 eV for CaCr2Bi2 and SrCr2Bi2 respectively in the spin down channel in the valence band regime, when we used GGA + U instead of PBE-GGA approximation. The calculated magnetic optimization and larger magnetic moments shows strong ferromagnetism in these compounds. The computed partial density of states (PDOS) plots predicts that the bonding is mainly achieved due to hybridization of Cr-d with Bi-p states. Using Boltztrap code we have calculated the variation of thermoelectric properties of these compounds that is electrical conductivity (σ/τ), Seebeck coefficient (S), electronic thermal conductivity (k/τ) and essentially Power factor (PF) in both spin channels.

Physical Parameters of the Synthesized Complex Compound of Cobalt (II) with N, N'-Bis(salicylidene)semicarbazide

A new material of strontium tetraaquad[N, N'-bis(salicylidene)semicarbazidatocobalt(II)] dihydrate (I) with the following composition: Sr[CoL'(Н2О)2]22Н2О, where H3L = N,N'-bis(salicylidene)semicarbazide was synthesized. The molar mass of the extracted and dehydrated complex compound Sr[Co (C15H14N3O5)]2 is 838.07 g/mol, and the number of valence electrons in one molecule is 256. A cylindrical sample with a mass of 0.09 g and a volume of 17.67∙10-9 m3 was utilized for experimental studies. Experimental measurements and theoretical calculations for the main physical parameters of the synthesized material were performed. Such quantities were calculated: the substance density, the molecule mass, the number of molecules in the test cylindrical sample, the number of valence electrons, the bandgap. Dependences of specific conductivity, current density, resistance, the Hall coefficient, and charge carrier concentration on temperature were obtained.

Precise control of Jeff=12 magnetic properties in Sr2IrO4 epitaxial thin films by variation of strain and thin film thickness

We report on a comprehensive investigation of the effects of strain and film thickness on the structural and magnetic properties of epitaxial thin films of the prototypal $J_\mathrm{eff}=1/2$ compound Sr$_2$IrO$_4$ by advanced X-ray scattering. We find that the Sr$_2$IrO$_4$ thin films can be grown fully strained up to a thickness of 108 nm. By using X-ray resonant scattering, we show that the out-of-plane magnetic correlation length is strongly dependent on the thin film thickness, but independent of the strain state of the thin films. This can be used as a finely tuned dial to adjust the out-of-plane magnetic correlation length and transform the magnetic anisotropy from two-dimensional (2D) to three-dimensional (3D) behavior by incrementing film thickness. These results provide a clearer picture for the systematic control of the magnetic degrees of freedom in epitaxial thin films of Sr$_2$IrO$_4$ and bring to light the potential for a rich playground to explore the physics of $5d$-transition metal compounds.

Synthesis and Characterization of Strontium N,N-Dimethylaminodiboranates as Possible Chemical Vapor Deposition Precursors.

The reaction of SrBr2 with 2 equiv of sodium N,N-dimethylaminodiboranate (DMADB; Na(H3BNMe2BH3)) in Et2O at 0 °C followed by crystallization and drying under vacuum gives the unsolvated strontium compound Sr(H3BNMe2BH3)2 (1). Before the vacuum-drying step, the colorless crystals obtained by crystallization consist of the diethyl ether adduct Sr(H3BNMe2BH3)2(Et2O)2 (2). If the reaction of SrBr2 with 2 equiv of Na(H3BNMe2BH3) is carried out in the more strongly coordinating solvent thf, the solvate Sr(H3BNMe2BH3)2(thf)3 (3) is obtained. Treating the thf adduct 3 with 1,2-dimethoxyethane (dme), bis(2-methoxyethyl) ether (diglyme), or N,N,N',N'-tetramethylethylenediamine (tmeda) in thf affords the new compounds Sr(H3BNMe2BH3)2(dme)2 (4), Sr(H3BNMe2BH3)2(diglyme) (5), and Sr(H3BNMe2BH3)2(tmeda) (6), respectively, in greater than 60% yields. Treatment of 3 with 2 equiv of the crown ether 12-crown-4 affords the charge-separated salt [Sr(H3BNMe2BH3)(12-crown-4)2][H3BNMe2BH3] (7). Crystal structures of all the Lewis base adducts are described. Compounds 2-6 all possess chelating κ2-BH3NMe2BH3-κ2 groups, in which two hydrogen atoms on each boron center are bound to strontium. Compound 6 is dinuclear because each metal atom is also coordinated to one hydrogen atom on a BH3NMe2BH3- ligand that chelates to the neighboring metal center. Compound 7 possesses an unusual κ1-BH3NMe2BH3- group owing to the near-complete encapsulation of the Sr atom by two 12-crown-4 molecules; the other BH3NMe2BH3- anion is a charge-separated counterion. When they are heated, the diglyme and tmeda compounds 5 and 6 melt without decomposition and can be sublimed readily under reduced pressure (1 Torr) at 120 °C. The diglyme and tmeda adducts are some of the most volatile strontium compounds known and are promising candidates as CVD precursors for the growth of strontium-containing thin films.

Drill cuttings in the environment: possible ways to improve their properties

The disposal of drill cuttings (DCs) in landfills is one of the major impacts of oil extraction on the environment. The DC composition is predetermined by the type of drilling fluid and can include petroleum hydrocarbons (PHCs), salts, and metals. Designing effective approaches to DC recycling is a key problem. We propose the use of certain additives to reduce the toxicity of DC mixtures and improve properties to enable their utilization as artificial soils. Samples of DCs with different contents of PHCs (from 0 to 50 g kg−1) were taken from landfills and collectors, tested in mixtures with different additives (sand, shungite, diatomite, glauconite, peat, phosphogypsum, and cement). Physical and chemical characteristics of DCs and their mixtures with additives were analyzed. We conducted the leaching experiment by applying amounts of water equal to mean annual precipitation to both pure DCs and their mixtures and analyzed the composition of the leachates. Concentrations of PHCs, chlorides, and metals were measured using gas chromatography, ion liquid chromatography, and inductively coupled plasma mass spectrometry, respectively. We conducted bioassays involving pot experiments with terrestrial plants and aquatic tests on crustaceans and unicellular ciliates to evaluate the toxicity of mixtures. Sand was the best additive for diluting DCs and improving the structure of mixtures. Phosphogypsum additions caused an intensification of Sr leaching. Cement additions resulted in a dramatic pH increase in mixtures and triggered the formation of soluble Sr and Cu compounds. Additions of 13% peat resulted in the formation of soluble metal-organic complexes, while 5–10% peat additions increased oat and clover biomass. Diatomite was the most efficient additive to absorb PHCs. Mixtures with the PHC concentrations of 1.5–15 g kg−1 caused root and sprout elongation in oat, mustard, and barley. Shungite was efficient in reducing DC contamination levels at pH ≤ 8.5. Paramecium did not show any correlations with contaminants, but the activity of daphnids significantly depended on pH levels and PHC contents. We were able to design soil-like mixtures to be organically integrated into the environment. DCs with PHC contents of ≤ 30 g kg−1 and Cl contents of ≤ 6 g kg−1 could be safely used in mixtures with ≤ 0.7 DC, ≥ 0.2 sand, and ≥ 0.04 diatomite (% v/v) that form soil-like materials. DCs with high HCO3− and low Cl− contents could be utilized with sand and peat to form fertile horizons of artificial soils.

Effect of Pb Substitution in Sr2-xPbxGeSe4 on Crystal Structures and Nonlinear Optical Properties Predicted by DFT Calculations.

We investigated the Sr2-xPbxGeSe4 series from 0 ≤ x ≤ 2 to study the impact of Pb on structure and properties. While the noncentrosymmetric (NCS) compounds γ-Sr2GeSe4 and α-Pb2GeSe4 have already been reported previously, the substitution variants Sr1.31Pb0.69GeSe4 (space group Ama2, a = 10.31220(1) Å, b = 10.39320(1) Å, c = 7.42140(1) Å) and Sr0.19Pb1.81GeSe4 (I4̅3d, a = 14.6177(3) Å) are introduced here for the first time. The experimentally determined optical band gaps decrease as predicted with increasing Pb content from γ-Sr2GeSe4 to Sr1.31Pb0.69GeSe4, Sr0.25Pb1.75GeSe4, and α-Pb2GeSe4 from 2.00, to 1.65, 1.45 and 1.42 eV, respectively. The nonlinear optical (NLO) properties of the orthorhombic compounds γ-Sr2GeSe4 and Sr1.3Pb0.7GeSe4 (approximated with the supercell "Sr3PbGe2Se8") were studied both theoretically, using first-principle calculations, and experimentally. The calculations found the effective nonlinear susceptibility, deff, of γ-Sr2GeSe4 and "Sr3PbGe2Se8" at the static limit to be 10.8 and 8.8 pm V-1, respectively. The experimental deff values of γ-Sr2GeSe4, Sr1.31Pb0.69GeSe4, Sr0.25Pb1.75GeSe4, and α-Pb2GeSe4 were 2.6, 2.3, 0.68, and 0.79 pm V-1, respectively.

Primer development and functional classification of EST-SSR markers in Ulmus species

At present, the available SSR markers of elm (Ulmus) have been seriously deficient, which can not meet the needs of molecular marker-assisted breeding and evaluation of germplasm resources. In this study, transcriptome data of Ulmus pumila were used as materials to develop EST-SSR markers of elms. EST-SSR markers were also classified according to gene function for the first time. In this study, 8288 perfect and 569 compound SSR loci were detected from 17,624 EST sequences (36,609,384 bp). Most of the perfect SSR sequences were based on short sequence lengths of 10–22 bp. The most common SSR repeat units were A/T (3330, 40.18%), AG/CT (1211, 14.61%), and AAG/CTT (568, 6.85%). All EST-SSR loci were function classified based on the Cluster of Orthologous Groups (COG) database. There were substantial differences in the type and proportion of SSR repeat units among the functional classes. Most EST-SSR loci were located in gene-coding regions. Ninety pairs were randomly selected and tested for validation using polymerase chain reaction amplification. Forty-nine primers were verified with clear bands. The number of alleles per locus (Na) ranged from 2 to 6; the number of effective alleles (Ne) ranged from 1.061 to 3.261; the observational heterozygosity (Ho) and expected heterozygosity (He) ranged from 0 to 0.968 and 0.112 to 0.651, respectively. The clustering pattern is consistent with traditional taxonomy that provides a molecular basis for the classification of elm. There were differences in the effective amplification and percentage of polymorphic loci among different functional SSR loci. The analysis of 880 primer combinations showed that markers within a single COG group were less effective than across groups. This study clarified the importance of SSR primer selection for clustering results. This study developed a large number of SSR markers in elm, providing effective markers for molecular marker-assisted breeding, genetic mapping, and other related research.

Synthesis, crystal structure, IR, Raman-spectroscopy and DFT computation of monostrontium phosphate monohydrate, Sr(H2PO4)2·H2O

The compound Sr(H2PO4)2·H2O has been synthesized and studied by single crystal X-ray diffraction analysis, infrared and Raman vibrational spectroscopy and density functional theory calculations. This compound crystallizes in the triclinic centrosymmetric space group P-1(Z = 2) with a = 5.7641(4) Å, b = 6.4549(4) Å, c = 12.0746(9) Å, α = 93.386(2)°, β = 95.730(2)° and γ = 114.114(2)°. The three-dimensional structure contains Sr(H2PO4)+ chains, which form corrugated layers. Between these layers are placed layers of (H2PO4)- ions and water molecules. The bands observed in the infrared and Raman spectra of Sr(H2PO4)2·H2O are assigned based on the results obtained in the literature and upon theoretical group analyses made in the factor group Ci. The optimal molecular geometry, harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by using density function theory (DFT/B3LYP) methods with the LanL2DZ basis set. The HOMO-LUMO properties and geometries of this compound have been determined and discussed. The computational structural parameters are generally in agreement with the experimental investigations. The theoretical infrared and Raman spectra for the title compound have been constructed.

Direct Visualization of Ambipolar Mott Transition in Cuprate CuO2 Planes

Identifying the essence of doped Mott insulators is one of the major outstanding problems in condensed matter physics and the key to understanding the high-temperature superconductivity in cuprates. We report real space visualization of Mott insulator-metal transition in Sr_{1-x}La_{x}CuO_{2+y} cuprate films that cover both the electron- and hole-doped regimes. Tunneling conductance measurements directly on the copper-oxide (CuO_{2}) planes reveal a systematic shift in the Fermi level, while the fundamental Mott-Hubbard band structure remains unchanged. This is further demonstrated by exploring the atomic-scale electronic response of CuO_{2} to substitutional dopants and intrinsic defects in a sister compound Sr_{0.92}Nd_{0.08}CuO_{2}. The results may be better explained in the framework of self-modulation doping, similar to that in semiconductor heterostructures, and form a basis for developing any microscopic theories for cuprate superconductivity.

Study of half metallic nature and transport properties of XMnSe2 (X = Ca, Sr and Ba) compounds via ab-initio calculations

In this work, we examine the half-metallic nature, optical and transport properties of ternary manganese selenides XMnSe2 (X = Ca, Sr and Ba) by means of the ab-initio calculations. Hexagonal structures of these selenides have been explored using generalized gradient approximation (GGA) and predicted ground states parameters exhibits good agreement with experimental data. Half-metallic nature of studied ternary manganese selenides is confirmed by investigating band structure with spin polarized density of states (DOS). In addition, half-metallic nature has been investigated in terms of integer values of the magnetic moment. Materials response toward electromagnetic radiation of energy 0−60 eV is calculated in terms of dielectric constant. Minimum loss of energy and maximum absorption of electromagnetic radiation at low energy region make these materials applicable to Infra-red (IR) devices. Transport properties are also calculated by using BoltzTraP code at temperature 0–800 K. Our computed results of half-metallic nature and transport properties have been suggested that studied ternary manganese selenides play vital role in the field of spintronic and energy devices.

Synthesis and Magnon Thermal Transport Properties of Spin Ladder Sr14Cu24O41 Microstructures

AbstractThe spin ladder compound (Sr,Ca,La)14Cu24O41 exhibits an incommensurate layered structure with strong antiferromagnetic coupling. Besides intriguing superconducting behavior, recent experiments on bulk Sr14Cu24O41 single crystals have revealed a remarkable magnon thermal conductivity, which is the largest above 100 K among all known quantum magnets. Although bulk (Sr,Ca,La)14Cu24O41 crystals have been synthesized and studied extensively, there have been few reports on the synthesis and magnon thermal transport investigation of their microstructures. Here, the synthesis and thermal transport properties of Sr14Cu24O41 microrods are reported. Electron microscopy studies indicate that these microrods synthesized by a coprecipitation method are single crystals grown preferentially along the ladder axis. Based on a four‐probe thermal transport measurement, the thermal conductivity of the microrods reveals appreciable magnon transport in the microstructures. According to a kinetic model analysis, magnon transport in the microrods is suppressed mainly by increased point defect scattering compared to the bulk crystals, whereas surface scattering is negligible for anisotropic 1D magnon transport along the ladder. Moreover, the thermal conductivity is enhanced after annealing as a result of reduced oxygen vacancies. These results help to build the foundation for future heterogeneous integration of magnetic microstructures in microscale devices for the transport of energy and quantum information.

Electronic band profiles and magneto-electronic properties of ternary XCu2P2 (X = Ca, Sr) compounds: insight from ab initio calculations

Abstract Full-potential augmented plane waves (FP-APW) method is applied to determine the electronic band profiles and magneto-electronic properties of XCu2P2 (X = Ca, Sr) compounds. We have adopted Perdew, Burke and Ernzerhof's generalized gradient approximation (PBE-GGA) along with GGA plus Hubbard U parameter method (GGA+U) as exchange correlation potentials. The physical properties of interest for XCu2P2 (X = Ca, Sr) compounds were analyzed for the first time in the Zintl phase of tetragonal structure with space group I4/mmm (No. 139). From the structural parameters we have found that ferromagnetic phase is more stable as compared to paramagnetic and antiferromagnetic phase. Electronic band profiles predict the metallic nature of these compounds in FM phase. The projected densities of states computed in this work recognize that the bonding is accomplished through hybridization of Cu-3d with P-p states. The evaluated magnetic moments support weak ferromagnetism in these compounds. The compounds of interest are thermodynamically stable. In addition, the cohesive energies and Curie temperatures of the studied compounds were also predicted. Metallic and ferromagnetic nature of XCu2P2 (X = Ca, Sr) compounds predict the important of these compounds in spintronic devices.

Synthesis and thermal behavior of two Sr(II) compounds derived from isomeric 5-(n-pyridyl)tetrazole-2-isopropionic acid (n = 2, 3)

Isomers play a crucial role in the formation of coordination architectures. Herein we report two Sr(II) coordination compounds, mononuclear [Sr(2-pytzipa)2(H2O)4] (1) and 1D [Sr(3-pytzipa)2(H2O)2]n (2) derived from two isomers, 5-(n-pyridyl)tetrazole-2-isopropionic acid (Hn-pytzipa, n = 2, 3). Furthermore, differential scanning calorimetry and thermogravimetric-differential thermogravimetric analyses were applied to evaluate the thermal decomposition behavior of such compounds. The relevant thermodynamic parameters (ΔH, ΔS, and ΔG) of the decomposition process of 1 and 2 were calculated as well.

Design and synthesis of new drugs inhibitors of Candida albicans hyphae and biofilm formation by upregulating the expression of TUP1 transcription repressor gene

Candida albicans is a common human fungal pathogen that causes disease ranging from superficial to lethal infections. C. albicans grows as budding yeast which can transform into hyphae in response to various environmental or biological stimuli. Although both forms have been associated with virulence, the hyphae form is responsible for the formation of multi-drug resistance biofilm. Here, new compounds were designed to selectively inhibit C. albicans hyphae formation without affecting human cells to afford sufficient safety. The newly designed 5-[3-substitued-4-(4-substituedbenzyloxy)-benzylidene]-2-thioxo-thiazolidin-4-one derivatives, named SR, showed very specific and effective inhibition activity against C. albicans hyphae formation. SR compounds caused hyphae inhibition activity at concentrations 10–40 fold lower than the concentration required to inhibit Candida yeast and bacterial growths. The anti-hyphae inhibition activities of SR compounds were via activation of the hyphae transcription repressor gene, TUP1. Correlation studies between the expression of TUP1 gene and the activity of SR compounds confirmed that the anti-C. albicans activities of SR compounds were via inhibition of hyphae formation. The newly designed SR compounds showed 10–40% haemolytic activity on human erythrocytes when compared to 100% haemolysis by 0.1% triton employed as positive control. Furthermore, theoretical prediction of absorption, distribution, metabolism, excretion, and toxicity (ADMET) of SR compounds confirmed their safety, efficient metabolism and possible oral bioavailability. With the minimal toxicity and significant activity of the newly-designed SR compounds, a future optimization of pharmaceutical formulation may develop a promising inhibitor of hyphal formation not only for C. albicans but also for other TUP1- dependent dimorphic fungal infections.

Analysis of the magnetic and magnetocaloric properties of ALaFeMnO6 (A = Sr, Ba, and Ca) double perovskites

In previous studies, we have reported that double perovskite La2NiMnO6 presents non-negligible potential for room temperature magnetocaloric tasks. With the aim of improving even further the cooling performances and the working temperature range of double perovskites, we report the magnetic and magnetocaloric properties of La2MnFeO6 and ALaMnFeO6 (A = Sr, Ba, and Ca) compounds. X-ray diffraction and Rietveld refinement show that La2MnFeO6 (LMFO) and CaLaMnFeO6 (CLMFO) samples crystallize in an orthorhombic structure with the Pnma space group. However, a rhombohedral structure with the R3¯C space group is obtained for BaLaMnFeO6 (BLMFO) and SrLaMnFeO6 (SLMFO) samples. Substituting La by Ba or Sr in LMFO leads to a clear increase of the Curie temperature (Tc) compared to LMFO from 150 K for BLMFO up to 350 K for SLMFO. Moreover, CLMFO shows the smallest Tc down to 70 K. Ferromagnetic-like behavior is observed for SLMFO and BLMFO, while CLMFO's magnetism resembles that of LMFO. A clear connection between the structural parameters and the magnetic properties of these doped LMFO samples is unveiled as the highest Tc and the largest magnetization are observed for SLMFO which also shows bond angles closest to 180° and the smallest bond lengths, thus optimizing the superexchange interaction. The partial substitution of Sr for La leads, in fact, to a significant magnetocaloric effect over a wide operating temperature range extending beyond 300 K. For some optimal growth conditions, its entropy change varies slowly over an unusually large temperature range, which is of clear interest from a practical point of view.

Analysis of structure and magnetic behavior in M-type hexaferrite compounds Sr1−xYxFe10CoTiO19

Herein, we report the synthesis, structure and magnetic properties of Y-substituted CoTi-SrM hexaferrite Sr1−xYxFe10CoTiO19 (0.00 ≤ x ≤ 0.20) through a series of systematical measurements. The single phase of polycrystalline SrM hexaferrites can be obtained within the concentration x ≤ 0.15, and the lattice constants (a and c) show a corresponding variety due to the difference of substituted ionic radius (Δr). Besides, FTIR spectra also give the characteristic features of Fe3+–O2+ intrinsic vibration at tetrahedral and octahedral sites, which further confirm the integrity of M-type hexagonal magnetic structure. The comprehensive magnetic measurements [M(T) and M(H)] indicate a considerable results of temperature and magnetic properties. Especially, Ms can be improved to 79.19 emu/g under the definite substitution, and the soft magnetic behavior can also be preserved because of the fairly low Hcj. On the basis of the analyses in our present work, this substituted hexaferrite exhibits a quite promising candidate for high-frequency multilayer inductors.