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Rational design of effective, stable and low-cost oxygen evolution reaction (OER) catalysts is vital for the overall efficiency of water splitting. As a novelty branch of transition metal nitrides, antiperovskite nitrides have been considered as potential alternative OER electrocatalysts due to their high flexibility in elemental composition and excellent conductivity. Particularly, high-entropy antiperovskite nitride materials with multiple elements occupying the equivalent lattice sites are considered as potentially effective application in field of catalysis. Here, we first report the OER results about Ni-based high-entropy antiperovskite nitrides. The Cu 0.5 Fe 0.5 NNi 2 Co 0.5 Fe 0.5 as the high-entropy antiperovskite nitride is designed for an OER catalyst with promising electrocatalytical OER performance in alkaline medium (low overpotential 370 mV at 10 mA cm−2, low overpotential 627 mV at high current density of 400 mA cm−2 (almost the same overpotential with commercial RuO 2), small Tafel slope 55 mV dec−1 and long-term stability). The results provide a novel OER catalyst based on high-entropy antiperovskite metal nitrides and will push forward the strategic guidelines for design of highly efficient catalysts. Antiperovskite nitrides ANM 3 as a typical type of transition metal nitride have been considered as a potential alternative oxygen evolution reaction (OER) electrocatalyst due to their highly flexibility in elemental composition and excellent conductivity. Particularly, high-entropy antiperovskite nitride materials with multiple elements occupying the equivalent lattice sites are considered as potentially effective application in field of catalysis. Here, we first report the OER results about Ni-based high-entropy antiperovskite nitrides. The Cu 0.5 Fe 0.5 NNi 2 Co 0.5 Fe 0.5 as the high-entropy antiperovskite nitride is designed for an OER electrocatalyst with promising electrocatalytical OER performance in alkaline medium (low overpotential 370 mV at 10 mA cm−2, small Tafel slope 55 mV dec−1 and long-term stability). The results provide a novel OER electrocatalyst based on high-entropy antiperovskite metal nitrides and will push forward the strategic guidelines for design of highly efficient electrocatalysts. [Display omitted] • Antiperovskite nitrides own high flexibility in elemental composition and eminent conductivity. • High-entropy materials possess sluggish diffusion kinetics and synergistic effect of multi-component properties. • High-entropy antiperovskite Cu 0.5 Fe 0.5 NNi 2 Co 0.5 Fe 0.5 shows promising OER activities. [ABSTRACT FROM AUTHOR]

In this work, the antiperovskite semiconductor compounds Mg3XN (X = P, As, Sb, Bi) are investigated using the first-principles calculations. The structural, electronic, optical, and elastic properties of the Mg3XN compounds are studied in detail. Meanwhile, the magnetism is introduced by doping Mn element in Mg3XN compounds. Mg3XN compounds are semiconductors with direct band gap from the analysis of electronic properties. In addition, the values of band gap decrease with the increasing of atomic number of X atoms. The results of elastic parameters show that the values of bulk (91.27 GPa) and shear (76.14 GPa) modulus of Mg3PN are the largest in the Mg3XN compounds. For the velocity of sound in different directions of Mg3XN compounds, the Mg3PN has the maximum average velocity of sound, which implies that the bonding strength of Mg3PN is at maximum. Moreover, the changes of bulk modulus, shear modulus, and Young's modulus under different pressure are explored. By substituting Mg atoms with Mn atoms, the chemical formula of Mg3XN compounds is updated to Mg2.5Mn0.5XN. The conclusions of the formation enthalpy and magnetic properties of Mg2.5Mn0.5XN compounds confirm that the possibility of Mg3XN compounds becomes photovoltaic materials. We hope that the present work can provide some reference for the application of Mg3XN compounds. [ABSTRACT FROM AUTHOR]

Antiperovskites have been studied since the 1980s because of their rich physical and chemical properties, but their linear and second‐order nonlinear optical responses remain largely unknown. Here we report a new polar crystal, Cs3Cl(HC3N3S3) (I), which features a quasi‐one‐dimensional antiperovskite structure composed of ClCs6 polyhedra and A‐site [HC3N3S3]2− rings. To our best knowledge, this kind of antiperovskite structure is reported for the first time. Remarkably, I exhibits a very strong nonlinear optical response up to 11.4 times that of the benchmark KH2PO4 and exceptionally large birefringence of 0.52. The first‐principles calculations and structural analyses reveal that [HC3N3S3]2− is the "material gene" while the antiperovskite structural feature making it in a favorable arrangement. This work provides a new structural platform for the rational design of integrated optoelectronic materials with linear and second‐order nonlinear optical responses. [ABSTRACT FROM AUTHOR]

Antiperovskites have been studied since the 1980s because of their rich physical and chemical properties, but their linear and second‐order nonlinear optical responses remain largely unknown. Here we report a new polar crystal, Cs3Cl(HC3N3S3) (I), which features a quasi‐one‐dimensional antiperovskite structure composed of ClCs6 polyhedra and A‐site [HC3N3S3]2− rings. To our best knowledge, this kind of antiperovskite structure is reported for the first time. Remarkably, I exhibits a very strong nonlinear optical response up to 11.4 times that of the benchmark KH2PO4 and exceptionally large birefringence of 0.52. The first‐principles calculations and structural analyses reveal that [HC3N3S3]2− is the "material gene" while the antiperovskite structural feature making it in a favorable arrangement. This work provides a new structural platform for the rational design of integrated optoelectronic materials with linear and second‐order nonlinear optical responses. [ABSTRACT FROM AUTHOR]

In this study, the critical behavior of the Fe-based carbide antiperovskite compound AlC1.1Fe3 has been presented. There is a second-order phase transition and the magnetic state will change from ferromagnetic state to paramagnetic state near Curie temperature. Critical exponents (β, γ, δ) representing different significance of magnetism are obtained by separate classical methods, which are exceedingly agreeable with the mean-field model theory, indicating that magnetic behavior of AlC1.1Fe3 is dominated by long-range ferromagnetic coupling. According to the scaling equation m = f ± (h), the experimental data obtained by the two experimental methods roughly overlap on the two curves, which demonstrates the reliability of these fitting parameters, and the convergence of the parameters also conforms to the mean-field model. Besides, the mutual exchange distance J(r) decreases as r−4.695 due to the competitive Fe–Fe metal bond and Fe–C covalent bond. We suggest that the competition between the localized metal bond magnetic interaction and itinerant covalent bond hybridization should be responsible for the critical behavior of AlC1.1Fe3. [ABSTRACT FROM AUTHOR]

In this work, we comprehensively analyzed the structure, thermodynamics, mechanical, thermoelectric, and photoelectric properties of antiperovskite Mg 3 XN (X = As, Sb, and Bi) using first-principles calculations and semi-classical Boltzmann transport theory. Our calculations of phonon spectra and elastic constants suggest that Mg 3 XN (X = As, Sb, and Bi) exhibit excellent dynamic and mechanical stability, characterized as brittle materials with Vickers hardness (H V) values exceeding 10 GPa. Electronic structure analysis reveals that Mg 3 AsN is a direct bandgap semiconductor with a 2.25 eV gap, whereas Mg 3 SbN and Mg 3 BiN are indirect bandgap semiconductors with gaps of 1.58 eV and 1.41 eV, respectively. At room temperature, the lattice thermal conductivities (κ L) for Mg 3 AsN, Mg 3 SbN, and Mg 3 BiN are 13.63, 9.93, and 7.26 Wm−1K−1, respectively, with ZT values of 0.32, 0.08, and 0.10 at optimal doping concentrations. At 1000 K, κ L values decrease to 3.19, 2.29, and 1.65 Wm−1K−1, respectively, with ZT values reaching 2.12, 0.98, and 0.92. Our analysis of optical properties demonstrates that these materials exhibit absorbance in the visible and ultraviolet spectra, with negligible energy loss in the respective energy ranges, thereby rendering them suitable for photovoltaic applications. [ABSTRACT FROM AUTHOR]

The experimental study on temperature and frequency dependent impedance spectroscopy study of an antiperovskite is being reported for the first time in this work as until now only the theoretical studies on dielectric behavior of various antiperovskites have been reported. Additionally, the effect of the presence of alkaline earth metals at A-site on the physical properties of an antiperovskite has been investigated for the first time. The structural and impedance characteristics of Mn 1.5 Y 1.5 CSr 1.5 Ba 1.5 antiperovskite, synthesized by mixed oxide method, have been reported in this work. X-Ray Diffraction (XRD) analysis of this antiperovskite indexes it in a cubic crystal system with Ia 3 ‾ space group. The impedance spectroscopy study reveals that the persistent rise in the magnitude of relative dielectric constant (ε r) and dielectric loss (tan δ), with increasing temperature, is due to thermally activated charge carriers which results in the surge in conductivity of the sample. The dielectric dispersion in this antiperovskite is ascribed to Maxwell–Wagner form of interfacial polarization that is explained on the basis of Koop's phenomenological theory. The complex impedance analysis signifies a non-Debye relaxation process for this compound. [ABSTRACT FROM AUTHOR]

Summary: We present a comparative study on the structural, electronic, elastic, and thermoelectric properties of the cubic inverse‐perovskites A3OX (where A = Li, Na, K and X = Cl, Br, I) by density functional theory (DFT). The cohesive, formation, and elastic properties analysis indicates that all studied materials are chemically, thermodynamically, and mechanically stable. Electronic properties reveal that all the inverse A3OX perovskite are direct bandgap semiconductors except Li3OCl and Li3OBr with ionic nature which is confirmed by electron localization function (ELF) analysis. We have also calculated Debye temperature (ΘD) and Grüneisen parameter (γ) to determine the lattice thermal conductivity for all the A3OX materials. Furthermore, thermoelectric (TE) properties are explored by calculating the Seebeck coefficient (S), electronic thermal conductivity, power factor (PF), electrical conductivity (σ/τ), lattice thermal conductivity, and ZT value. Our investigated A3OX inverse‐perovskites provide a fertile base that can improve the overall TE performance for TE applications and green energy production. [ABSTRACT FROM AUTHOR]

Ab initio computations are performed to study the structural, elastic, electronic, and vibrational characteristics of the cubic antiperovskite compound PbNCa3 under pressure up to 50 GPa. By using the generalized gradient approximation (GGA), the equilibrium structural parameters, energy band structure, density of states, elastic properties, and phonon frequencies for PbNCa3 have been examined. We have obtained some concerned feature as Young modulus and Poisson ratio for this compound using the elastic parameters. The computed elastic constant values show that PbNCa3 is stable up to 30 GPa as mechanically. To assess the stability of this compound dynamically, we have investigated the one-phonon DOS and phonon dispersion relations under pressure. Our results indicate that the calculated structural parameter values at 0 GPa are in accord with the existing data. [ABSTRACT FROM AUTHOR]

In this paper, the structure and magnetic behaviour of antiperovskite In x Fe 4- x N have been investigated systematically. The crystal lattice becomes larger and the Curie temperature decreases with increasing x. The magnetic state changes from a ferromagnetic to a glassy state. In addition, an obvious spin glass (SG) behaviour has been revealed in In 0.6 Fe 3.4 N (x = 0.6) with a freezing temperature of T 0 = 73 K, dynamical exponent of zν = 5.51, and flipping time of τ 0 = 4.26 × 10−11 s. The origin of the SG behaviour in In 0.6 Fe 3.4 N may be attributed to atomic disorders at Wyckoff position 1 a or ferromagnetic frustrations, or the both. [ABSTRACT FROM AUTHOR]

Negative thermal expansion (NTE) materials can compensate for the coefficient of thermal expansion (CTE) of normal metals. Currently, it is challenging to prepare NTE/metal composites facing the practical demands. We report the tunable CTEs between –0.39 and 6.19 ppm/K around room temperature in Zn/Si/Zn 0.75 Sn 0.2 Mn 0.05 NMn 3 composites. The low-melting Zn acts as the adhesive, while Zn 0.75 Sn 0.2 Mn 0.05 NMn 3 is the CTE compensator. Moreover, the composites have high compression strength (225 MPa) and thermal conductivity (52 W/K m), showing great potentials as electronic thermal management materials. Our results suggest an effective way to realize low-CTE composites with excellent performance based on NTE compounds. Image, graphical abstract [ABSTRACT FROM AUTHOR]

In this study, we systematically investigate the electronic, magnetic, and magnetocaloric properties of Mn 3 AlN antiperovskite. This system is examined through first-principles computations using density functional theory (DFT) and Monte Carlo (MC) simulations. Based on the density of state and band structure, it is found that Mn 3 AlN behaves as a ferromagnetic metallic material. Additionally, we calculate the magnetic anisotropy and exchange interactions, which are parameters of the Hamiltonian, and incorporate them into the MC simulation. Concerning the magnetic properties, the critical temperature of the antiperovskite ( T c = 811 K) is almost similar to the experimental value ( T c = 818 K). Furthermore, we also investigate the magnetocaloric properties and find that the relative cooling power (RCP) values and maximum entropy change for a magnetic field strength of 5 T are 93.96 J/kg and 12.55 J/kg K, respectively. These results suggest that Mn 3 AlN is a promising candidate for magnetic refrigeration applications. [Display omitted] • The electronic, magnetic and magnetocaloric effect properties of Mn 3 AlN antiperovskite are studied. • The density of states and band structures were calculated using the GGA+U technique. • Mn 3 AlN can be widely used in the fields of magnetic refrigeration. [ABSTRACT FROM AUTHOR]

The development of efficient, stable and low-cost dual-function electrocatalysts and applicated it to Zn-air batteries are very important for the development of renewable energy storage and conversion technologies. Antiperovskite catalysts have attracted much attention recently due to their advantages of adjustable structure and high element selectivity. In this work, a flexible and adjustable antiperovskite catalyst ZnCCe 3−x Ni x (0 ≤ x ≤ 3) loaded on carbon fiber (ZnCCe 3−x Ni x /CNFs) was prepared by electrospinning technology and used as an air cathode catalyst for rechargeable Zn-air batteries. By doping the X-site with highly conductive transition metal Ni, the electronic structure of the catalyst ZnCCe 3−x Ni x /CNFs was optimized, and the catalytic activity of the antiperovskite bimetallic X-site was tuned to achieve an efficient and synergistic catalytic reaction. Among them, ZnCCe 2.7 Ni 0.3 /CNFs showed excellent OER/ORR bi-functional catalytic activity (Δ E = 0.82 V) and good stability. When ZnCCe 2.7 Ni 0.3 /CNFs is used as the cathode catalyst for rechargeable Zn-air batteries, it shows a power density of 117.99 mW cm−2, and the cycle stability can be maintained for up to 300 h, indicating its application potential in the field of Zn-air batteries. • Antiperovskite ZnCCe 3−x Ni x /CNFs were prepared by electrospinning method. • The OER/ORR bifunctional activity of ZnCCe 3−x Ni x /CNFs were optimized by doping Ni. • The power density of ZnCCe 2.7 Ni 0.3 /CNFs based zinc-air batteries was 117.99 mW cm−2. [ABSTRACT FROM AUTHOR]

Antiperovskite materials based on M n 3 C u N with Cu partially replaced by Ag or Ni and simultaneous substitution of N by C were synthesized and their magneto-structural transition was studied. By replacing Cu partially with Ag or Ni, Curie temperatures increase, the magnetostructural transition becomes isosymmetric and presents a more second order character. Simultaneous replacement of N by C reverses this trend as the Curie temperature decreases with increasing Ag/Ni content while the structural transition remains non-isosymmetric. Additionally, moderate magnetocaloric effects with magnetic entropy changes around 6 J/Kkg in the range of 130–150 K at a 2 T field change are observed. Finally, the influence of the change in number of valence electrons and cell size by substitution on the transition is discussed. • 8 previously unknown antiperovskite materials based on M n 3 C u N have been studied. • Low T XRD reveals that symmetry below T T depends on degree of N substitution by C. • Also, C content reverses trends seen in T C when Cu is substituted by Ag/Ni. • A Δ S M around 6 J/Kkg in the range of 130–150 K at a 2 T field changes is observed. • The influence of N(VE) and cell size on the FOMST is comprehensively discussed. [ABSTRACT FROM AUTHOR]

The present study is focused on a relatively new class of solid-state lithium halide electrolytes with antiperovskite crystal structure that are designed to alleviate safety concerns related to conventional lithium-ion batteries. The solid-state Li 3 ClO electrolyte membranes were produced by a casting/delamination method and deposited on a graphite-based working electrode. The electrolyte charge transfer resistances, electrochemical performance, and chemical stability in a half-cell configuration were evaluated over a broad temperature range from room temperature up to 100 °C. The electrochemical cells with lithium metal as a reference electrode demonstrated linear Arrhenius behavior in the temperature range of 25–100 °C confirming the absence of phase transformations. Cyclic voltammetry at 50 °C and 100 °C confirms that the electrochemical cell performance during lithiation/delithiation from 0.05 to 1.00 V is reproducible within at least 100 cycles. The solid-state electrolyte electrochemical stability in contact with lithium metal is confirmed for the first time by demonstrating the constant values of charge transfer resistances during charge/discharge operations in 575 cycles at 50 °C and 1/5 C -rate. Transport of lithium ions between the lithium metal and Li 3 ClO electrolyte in contact with a graphite working electrode provides evidence that lithium halide antiperovskites can serve as effective and electrochemically stable electrolytes for a new generation of all-solid-state lithium-ion or lithium metal batteries. Image 1031 • A solid-state electrolyte with antiperovskite structure was tested in a half-cell vs. lithium anode. • Electrolyte chemical stability in presence of Li-metal at 50 °C is confirmed by AC impedance. • Continuous cycling within 6 months at 50 and 100 °C demonstrate >80% specific capacity retention. [ABSTRACT FROM AUTHOR]

The substitution of Mn for Zn was found to broaden the abnormal lattice shrinkage in Zn 1− x Mn x NMn 3 . When x = 0.3, a large constant coefficient of negative thermal expansion (NTE) α L is found between 74 K and 150 K, which, though rare, is beneficial to practical applications of NTE materials. The magnetism studies indicate that the ferromagnetic clusters appear in the paramagnetic (PM) region and restrain the transformation from PM to antiferromagnetic (AFM), leading to the broadened NTE window. Moreover, the sample x = 0.3 shows a linear PM-AFM transformation in the whole NTE window, resulting in the constant α L . [ABSTRACT FROM AUTHOR]

Materials in the Na-rich antiperovskite family are promising candidates as solid electrolytes (SEs) for all-solid-state Na-ion batteries (NIBs). In this work, we carry out ab-initio calculations to study various properties of Na 3 OCl , namely the formation energies of various neutral defect pairs, the defect hopping barriers, the solution energies of high valence alkali earth metal substitutes to the Na atoms, and the effect of such substitution to the Na migration. While the introduction of alkali earth metal ions increases the Na vacancy concentration, the activation energy of Na transport also increases. Furthermore, we identify Ca as the most promising alkali earth metal to be doped into Na 3 OCl due to its low binding energy and relatively small impact on the migration barrier. Our work provides a theoretical framework for further improving the Na conductivity of materials in the antiperovskite family for all-solid-state NIBs. [ABSTRACT FROM AUTHOR]

The structural, magnetic and magnetocaloric properties of the antiperovskite materials M n 3 C u N 1 − x C x have been studied. Substituting N with C increases the temperature of the magnetostructural transition between a paramagnetic cubic high temperature phase and a ferrimagnetic tetragonal low temperature phase. Furthermore, the first order character of the phase transition is retained upon substitution with a hysteresis below 2 K for all compositions. The magnetostructural transition gives rise to giant magnetocaloric effects in a tunable 30 K temperature range with a maximum entropy change of 11.8 J/Kkg at a 2 T field change, making these compounds promising for low temperature magnetic refrigeration applications. [ABSTRACT FROM AUTHOR]

The structure, magnetic and electronic transport properties of the compounds Mn 3 Sn 1- x Zn x C (0 ≤ x ≤ 0.5) are investigated. The studies have shown that Zn-doping in the anti-perovskite structure Mn 3 SnC reduces the cell parameter, but the compounds Mn 3 Sn 1- x Zn x C remain cubic anti-perovskite structure. When the temperature is reduced, the magnetization curve changes from PM-FM for Mn 3 SnC and Mn 3 Sn 0.9 Zn 0.1 C into PM-FM-AFM for Mn 3 Sn 1- x Zn x C(x ≥ 0.2). With the increase of doping amount x, both the Tc and the T T reduce, but when x = 0.5, they are raised. In addition, the magnetization of Mn 3 Sn 1- x Zn x C is reduced as the doping amount increases. For Mn 3 Sn 1- x Zn x C(x = 0, 0.1, 0.2,0.3, 0.4, 0.5) compounds, there exists an anomalous increase in resistivity at a certain temperature that is in agreement with their magnetic transition temperature, and doping Zn in Mn 3 SnC reduces the resistivity of Mn 3 SnC. [ABSTRACT FROM AUTHOR]

The magnetic, electrical transport and thermal expansion properties of Mn3Zn1−xCoxN (x = 0.2, 0.4, 0.5, 0.7, 0.9) have been systematically investigated. Co-doping in Mn3ZnN complicates the magnetic interactions, leading to a competition between antiferromagnetism and ferromagnetism. Abrupt resistivity jump phenomenon and negative thermal expansion behavior, both associated with the complex magnetic transition, are revealed in all studied cases. Furthermore, semiconductor-like transport behavior is found in sample x = 0.7, distinct from the metallic behavior in other samples. Below 50 K, resistivity minimum is observed in samples x = 0.4, 0.7, and 0.9, mainly caused by e-e scattering mechanism. We finally discussed the strong correlation among unusual electrical transport, negative thermal expansion and magnetic transition in Mn3Zn1−xCoxN, which allows us to conclude that the observed unusual electrical transport properties are attributed to the shift of the Fermi energy surface entailed by the abrupt lattice contraction. [ABSTRACT FROM AUTHOR]

Abstract: Li‐halide hydroxides (Li2OHX) and Li‐oxyhalides (Li3OX) have emerged as new classes of low‐cost, lightweight solid state electrolytes (SSE) showing promising Li‐ion conductivities. The similarity in the lattice parameters between them, careless synthesis, and insufficient rigor in characterization often lead to erroneous interpretations of their compositions. Finally, moisture remaining in the synthesis or cell assembling environment and variability in the equivalent circuit models additionally contribute to significant errors in their properties. Thus, there remains a controversy about the real values of Li‐ion conductivities in such SSEs. Here an ultra‐fast synthesis and comprehensive material characterization is utilized to report on the ionic conductivities of contaminant‐free Li2+xOH1−xCl (x=0‐0.7), and Li2OHBr not exceeding 10‐4 S cm‐1 at 110 °C. Using powerful combination of experimental and numerical approaches, it is demonstrated that the presence of H in these SSEs yields significantly higher Li+ ‐ionic conductivity. Born‐Oppenheimer molecular dynamics simulations show excellent agreement with experimental results and reveal an unexpected mechanism for faster Li+ transport. It involves rotation of a short OH‐group in SSEs, which opens lower‐energy pathways for the formation of Frenkel defects and highly‐correlated Li+ jumps. These findings will reduce the existing confusions and show new avenues for tuning SSE compositions for further improved Li‐ion conductivities. [ABSTRACT FROM AUTHOR]

Enjoying great safety, high power, and high energy densities, allsolid- state batteries play a key role in the next generation energy storage devices. However, their development is limited by the lack of solid electrolyte materials that can reach the practically useful conductivities of 10-2 S/cm at room temperature (RT). Here, by exploring a set of lithium-rich antiperovskites composed of cluster ions, we report a lithium superionic conductor, Li3SBF4, that has an estimated 3D RT conductivity of 10-2 S/cm, a low activation energy of 0.210 eV, a giant band gap of 8.5 eV, a small formation energy, a high melting point, and desired mechanical properties. A mixed phase of the material, Li3S(BF4)0.5Cl0.5, with the same simple crystal structure exhibits an RT conductivity as high as 10-1S/cm and a low activation energy of 0.176 eV. The high ionic conductivity of the crystals is enabled by the thermal-excited vibrational modes of the cluster ions and the large channel size created by mixing the large cluster ion with the small elementary ion [ABSTRACT FROM AUTHOR]

In this work, we have theoretically investigated the band structure of antiperovskite chromium-based carbides and nitrides Cr 3 PX (X = C and N) using the first-principles calculation based on the FP-APW+LO method. The principal structural properties i.e., lattice constants ( a , b , c ) and internal parameters are in accordance with the experimental results. The calculated values of elastic constants indicated that the mechanical strength for both Cr 3 PC and Cr 3 PN compounds at (001) plane is higher than the (100) and (010) planes. Moreover, the Cr 3 PX compounds are expected to be hard materials with ductile nature. In addition, we have found that the FM ground state of herein materials Cr 3 PC and Cr 3 PN are energetically favorable with low magnetic moments of about 2.27 and 2.94 μ B , respectively, confirming that these are weak ferromagnets. Based on the spin-polarized electronic band structure we have found that both alloys have metallic behavior, such behavior has been shown in the calculated electrical conductivity. We have also estimated other thermoelectric constants like the Seebeck coefficient, thermal conductivity, power factor and electrical resistivity of Cr 3 PC and Cr 3 PN compounds. [ABSTRACT FROM AUTHOR]

(Gadolinium) Gd-doped antiperovskite compounds Mn 3 Cu 1−x Gd x N were synthesized by the conventional solid-state reaction. With increasing Gd concentration, two magnetic transitions appeared at a high Curie temperature (T C1 ) corresponding to paramagnetic (PM)-ferromagnetic (FM) transition and a low temperature (T C2 ) ascribed to the FM-antiferromagnetic (AFM) transition. The magnetic relaxation results show the formation of a magnetic metastable state after the FM-AFM transition at low temperature (lower than T C2 ), forming a novel magnetic-step feature in the process from AFM to FM under a certain magnetic field. [ABSTRACT FROM AUTHOR]

Effects of Co doping on the crystal structure, magnetic, electrical transport properties, and magnetocaloric effect (MCE) of antiperovskite ZnCFe 3− x Co x (0 ≤ x ≤ 3) were investigated. The value of lattice constant decreases with increasing x . The Curie temperature ( T C ) decreases from 358 K in ZnCFe 3 to 5 K in ZnCCo 3 and the saturated magnetization declines monotonously. The reduced ferromagnetic state is explained by the band filling effect resulted from the Co substitution. For x ≥ 2.3, the negative magnetoresistance (MR) below T C starts to increase as x or magnetic field increases, reaching −16% for x = 2.9 under H = 45 kOe, which is three times larger than that of GaCMn 3 at 250 K. MCE was investigated for selected compositions. The temperature range of MCE is tuned covering 5–350 K as a function of Co-level. Although the maximal entropy change decreases a little with increasing x , the refrigeration ranges across room temperature. At the optimal composition x = 0.5, T C is 312 K with a magnetic entropy change of 2.09 J/kg K and relative cooling power (RCP) of 283 J/kg (Δ H = 45 kOe), make it a room-temperature MCE candidate. [ABSTRACT FROM AUTHOR]

[Display omitted] • The limitation of scaling laws of the magnetocaloric effect. • The reliability of the Banerjee criterion in antiperovskite materials. • The temperature and field dependences of magnetic entropy changes. For materials with magnetic phase transition, researchers have tried to find a simple magnetic method that can replace the calorimetric technique for determining the type of phase transition. Recently, the researchers provide a quantitative characteristic of first-order magnetic phase transitions, which is believed to have wide application prospect. The maximum exponent n , calculated from field dependence of magnetic entropy change, is>2 only for first-order phase transitions. This method has been tested in Bean-Rodbell model and for various types of materials with first-order phase transitions from ferromagnetic to paramagnetic or antiferromagnetic to ferromagnetic state. However, in this work, the determination of the order of phase transitions based on field dependence of magnetic entropy change contradicts the results of calorimetric measurements in antiperovskite compounds Mn 3 SnC and MnCu 0.97 N. This discrepancy may be associated with a first-order magnetic transition from ferrimagnetic to paramagnetic state in antiperovskite materials. [ABSTRACT FROM AUTHOR]

A fluorine-doped antiperovskite Li-ion conductor Li2(OH)X (X=Cl, Br) is shown to be a promising candidate for a solid electrolyte in an all-solid-state Li-ion rechargeable battery. Substitution of F− for OH− transforms orthorhombic Li2OHCl to a room-temperature cubic phase, which shows electrochemical stability to 9 V versus Li+/Li and two orders of magnitude higher Li-ion conductivity than that of orthorhombic Li2OHCl. An all-solid-state Li/LiFePO4 with F-doped Li2OHCl as the solid electrolyte showed good cyclability and a high coulombic efficiency over 40 charge/discharge cycles. [ABSTRACT FROM AUTHOR]

We report on the tunnel magnetoresistance (TMR) effect of perpendicular magnetic tunnel junctions (p-MTJs) composed of a ferromagnetic antiperovskite MnGaN film with perpendicular magnetic anisotropy. The p-MTJ multilayer stack with MnGaN/Mg/MgO/Fe/CoFeB was used to control the MgO interface conditions by the Mg and Fe insertion layers. The Mg insertion under the MgO barrier enhanced the perpendicular anisotropy of the top Fe/CoFeB layers with post-annealing process, and thus nearly perfect perpendicular magnetization was realized. A perpendicular TMR ratio up to 3.7% $\sim 3.8$ % was obtained at room temperature. The obtained low TMR ratio is mainly attributed to the imperfect MgO barrier, which includes many lattice-misfit dislocations at the MnGaN/MgO interface due to the large lattice mismatch of 8%. This paper suggests that improving the interface state and reducing the lattice mismatch will be required to observe a higher perpendicular TMR ratio using an MnGaN electrode. [ABSTRACT FROM PUBLISHER]

Antiperovskite intermetallic Mn 3− x Cr x ZnN (0≤ x ≤0.5) compounds have been prepared to study the Cr doping effect on the electronic transport properties. The temperature dependent resistivity ρ ( T ) for x ≤0.3 shows notable and broader slope change. Meanwhile, with increasing Cr doping, the slope change shifts to lower temperatures and is gradually suppressed for x >0.3. For x =0.0 and 0.5, the measurements of magnetization from 10 K to 350 K reveal that Mn 3− x Cr x ZnN compounds go through a transition from the dominant AFM interactions to one where the FM and AFM interactions coexist. For low-temperature region (15–80 K), the electron–electron scattering is dominant, and the number of phonons abruptly increases with increasing temperature. Small polaron hopping model (SPH) is used to understand the temperature dependence of electrical resistivity in the high-temperature range of 200–300 K and a clear decrease of the polaron activation energy was observed for x ≤0.2. The residual resistivity ratio (RRR) decreases while the residual resistivity increases ( ρ 0 ) with increasing Cr-doping level. The maximum total entropy change (Δ S max ) decreases by increasing the Cr doping from x =0.0 to 0.2. [ABSTRACT FROM AUTHOR]

The Cr doping effect on the lattice and magnetic properties in Mn 3− x Cr x ZnN was reported in the antiferromagnetic intermetallic host material Mn 3 ZnN. The lattice parameter decreases with the increase of the Cr concentration. Measurements of magnetization from 10 K to 350 K reveal that sharp antiferromagnetic (AFM)-to-paramagnetic (PM) transitions of the host material exist at 185 K (ZFC) and 177 K (FC). The peak is broadened clearly as the Cr doping was increased and when the Cr concentration exceeded 0.3, a significant ferromagnetic (FM) character was found to coexist with an AFM phase. At x =0.4 and 0.5, the M–H curves exhibit small magnetic hysteresis loop, indicating the dominant FM interactions in these samples. Also, a positive value of Weiss Temperature ( Θ W ) at x =0.5 in H/M–T plot suggests that the FM interaction is dominant when the Cr doping increases. [ABSTRACT FROM AUTHOR]

Magnetic/structural phase diagram of GaCFe 3− x Co x (0 ≤ x ≤ 3.0) were investigated systematically. It was found that the antiperovskite phase collapses at x = 0.90 and recovers again at x = 2.3 with Co doping. Along with this transformation, the ferromagnetic state in GaCFe 3 is suppressed and replaced by the reentrant spin-glass state (2.3 ≤ x ≤ 2.6) or enhanced magnetic fluctuations (2.7 ≤ x ≤ 3.0). Ac susceptibility and magnetic relaxation were adopted to validate this spin-glass state for x = 2.5. It indicates that the contractive lattice as well as the resultant enhanced magnetic couplings may be an important origin of the collapsed antiperovskite structure. Zero temperature coefficient of resistivity (TCR) was achieved by Co-doping where the sign of TCR changes from positive to negative across the room temperature. The optimized TCR ∼ 0.0346 ppm/K spanning 110 K are three orders of magnitude smaller than those of CuNMn 3 or GaCFe 3 . The physical mechanism was discussed. [ABSTRACT FROM AUTHOR]

Antiferromagnetic antiperovskites, of the form Mn 3 B N (B = Ni, Cu, Zn, Sn, Ir, and Pt), have shown an outstanding behavior in which, giant negative thermal expansion and chiral magnetic structures are intertwined. As such, aiming to shed light on the magnetostructural behavior, related to the magnetic ordering and crystalline structure of this type of materials, we studied theoretically, based-on first-principles calculations, the lattice dynamics and spin–phonon coupling in the Manganese-based antiperovskite Mn 3 NiN, as a prototype in the Mn 3 B N family. We found a strong spin–lattice coupling by means of the understanding of the phonon-dispersion curves obtained when including the chiral noncollinear magnetic structures. To do so, we highlight the importance of the exchange–correlation scheme selected and its influence on the structural, electronic, magnetic, and vibrational degrees of freedom. Finally, we found two unstable vibrational modes at the M - and R -points when the magnetic ordering is switched to ferromagnetic from the chiral Γ 4 g and Γ 5 g. These octahedral-associated modes with spin–phonon coupling parameters, λ , as large as 10.74 cm−1 and −2.53 cm−1 for the R 5 − , and M 2 + , respectively. The latter coupling is observed as a key signature of the strong spin–lattice interaction. [ABSTRACT FROM AUTHOR]

Antiperovskite compounds have been attracting a lot of attention because of their unique and remarkable properties. Although antiperovskite metallic compounds Mn 3 XN (X = Ni, Pd, Pt) have been successfully prepared as potential magnetic materials, the structural, electronic, elastic and thermodynamic properties are still unclear. So, in this work, we apply the first-principles calculations to investigate the physical properties of Mn 3 XN. The results of formation enthalpy show that Mn 3 XN compounds are thermodynamically stable and follow the order of Mn 3 NiN > Mn 3 PdN > Mn 3 PtN. The results of band structure and density of states prove that all Mn 3 XN compounds are magnetic metals and the magnetism of Mn 3 XN comes mainly from the contribution of Mn atoms. The calculated bulk modulus and shear modulus of Mn 3 PtN are bigger than the Mn 3 PdN and Mn 3 NiN. Especially, we give the three-dimensional Young's modulus surface and the projection surface on different planes for three compounds. With respect to the anisotropic characteristics, Mn 3 PdN may be a potentially isotropic material and Mn 3 NiN has the most obvious anisotropy. The sound velocities of the three compounds in different directions are calculated to obtain the Debye temperature. The Debye temperatures of Mn 3 NiN, Mn 3 PdN, Mn 3 PtN are calculated to be 445 K, 423 K and 408 K, respectively. Importantly, the Debye temperature increases with the increasing of pressure and the decreasing of temperature. Finally, we give the critical pressure and charge density difference of three compounds. • The physical properties of the Mn 3 XN (X = Ni, Pd, Pt) compounds are studied by using first-principles calculations.. • The magnetic moments of Mn 3 XN (X = Ni, Pd, Pt) compounds are discussed. • Using the magnetic transition, the critical pressures of Mn 3 XN (X = Ni, Pd, Pt) compounds are investigated. • The Debye temperatures of Mn 3 XN (X = Ni, Pd, Pt) compounds are evaluated under different temperature and pressure. • Bonding characteristics of Mn 3 XN (X = Ni, Pd, Pt) compounds are revealed by charge density difference. [ABSTRACT FROM AUTHOR]

Concerning the part of global warming caused by conventional refrigerant gasses, past decades of research on solid-state cooling technologies based on caloric effects present an attractive alternative with zero-greenhouse gas emission and higher operating efficiency. However, the search for materials with large caloric effects near room temperature has become a challenge in modern material physics. Mn-based antiperovskite compounds are favorable caloric materials which generate a reversible enthalpy change by applying an external field. We report a novel approach of piezo-enhanced elastocaloric-like effect on Mn 3 SnC for solid-state refrigeration application. In the as-designed Mn 3 SnC/PZT magnetoelectric hetero-composite, the reversible caloric effect of Mn 3 SnC was regulated by the electric field-induced strain in the PZT piezoelectricity layer without any external magnetic field. In addition, we proposed an experimental setup for the direct adiabatic temperature change measurement of the caloric effect. The adiabatic temperature change is as high as ∼ 0.57 K at 280 K under an electric field of 0.8 kV/cm, which is approximately 2 factors larger than that of the magnetocaloric effect value of Mn 3 SnC under 3 T. By adopting the first-principles theory, we estimated the entropy change is approximately 2.6 J Kg−1 K−1 at 280 K which is close to the previous reports. This work demonstrates a novel approach to effectively enhance reversible caloric effects in first-order phase transition materials via electric fields. The as-designed Mn 3 SnC/PZT magnetoelectric hetero-composite shows a large electricity-driven elastocaloric-like effect without magnetic field stimulating, and the adiabatic temperature change is directly sensed in our customized system. [Display omitted] [ABSTRACT FROM AUTHOR]

High-temperature phase transition of synthetic kogarkoite, Na 3 SO 4 F, has been studied by high-temperature X-ray powder and single-crystal diffraction. The temperature of the phase transition can be estimated as 112.5±12.5 °C. The low-temperature phase, α-Na 3 SO 4 F, at 293 K, is monoclinic, P 2 1 / m , a= 18.065(3), b= 6.958(1), c= 11.446(1) Å , β= 107.711(1)°, Z =12. The structure contains thirteen symmetrically independent Na sites with coordination numbers varying from 6 to 8, and six independent S sites. The high-temperature β-phase at 423 K is rhombohedral, R- 3 m , a= 6.94(1), c= 24.58(4) Å, Z =9. The crystal structure of both polymorphs of Na 3 SO 4 F can be described as a 9 R antiperovskite polytype based upon triplets of face-sharing [FNa 6 ] octahedra linked into a three-dimensional framework by sharing corners. In the α-modification, the SO 4 tetrahedra are completely ordered and located in the framework cavities. In the β-modification, there are only two symmetrically independent Na atoms in the structure. The main difference between the structures of the α- and β-phases is the degree of ordering of the SO 4 tetrahedra: in the α-modification, they are completely ordered, whereas, in the β-modification, the complete disorder is observed, which is manifested in a number of low-occupied O sites around fully occupied S sites. The phase transition is therefore has an order–disorder character and is associated with the decrease of structural complexity measured as an information content per unit cell [577.528 bits for the low- (α) and 154.830 bits for the high- (β) temperature modifications]. [ABSTRACT FROM AUTHOR]

High-performance solid electrolytes are critical for realizing all-solid-state batteries with enhanced safety and cycling efficiency. However, currently available candidates (sulfides and the NASICON-type ceramics) still suffer from drawbacks such as inflammability, high-cost and unfavorable machinability. Here we present the structural manipulation approaches to improve the sodium ionic conductivity in a series of affordable Na-rich antiperovskites. Experimentally, the whole solid solutions of Na 3 O X ( X = Cl, Br, I) are synthesized via a facile and timesaving route from the cheapest raw materials (Na, NaOH and Na X ). The materials are nonflammable, suitable for thermoplastic processing due to low melting temperatures (<300 °C) without decomposing. Notably, owing to the flexibility of perovskite-type structure, it's feasible to control the local structure features by means of size-mismatch substitution and unequivalent-doping for a favorable sodium ionic diffusion pathway. Enhancement of sodium ionic conductivity by 2 magnitudes is demonstrated by these chemical tuning methods. The optimized sodium ionic conductivity in Na 2.9 Sr 0.05 OBr 0.6 I 0.4 bulk samples reaches 1.9 × 10 −3 S/cm at 200 °C and even higher at elevated temperature. We believe further chemical tuning efforts on Na-rich antiperovskites will promote their performance greatly for practical all-solid state battery applications. [ABSTRACT FROM AUTHOR]

The new mineral nabimusaite, KCa12(SiO4)4(SO4)2O2F (R3̅m, a = 7.1905(4), c = 41.251(3) Å, V = 1847.1(2) Å3, Z = 3), has been discovered in larnite-ye'elimite nodules of pyrometamorphic rocks of the Hatrurim Complex. Nabimusaite is colourless, transparent with awhite streak, has a vitreous lustre and does not show luminescence. It is brittle, but shows pronounced parting and imperfect cleavage along (001). Nabimusaite is uniaxial (-), ω = 1.644(2), ɛ = 1.640(2) (589 nm), nonpleochroic, Mohs' hardness is ~5 and the calculated density is 3.119 g cm-3. The crystal structure has been solved and refined to R1 = 0.0416. Its artificial analogue is known. The nabimusaite structure may be derived from that of hatrurite, also known as the clinker phase 'alite' (C3S=Ca3SiO5), and is built up by an intercalation of three positively charged hatrurite-like modules of composition [Ca12(SiO4)4O2F]3+ with inserted modules of [K(SO4)2]3-. The hatrurite-like modules in nabimusaite are characterized by octahedrally coordinated anion sites and tetrahedrally coordinated cation sites. The structure is representative of the intercalated antiperovskite type. In contrast to its synthetic analogue, nabimusaite is P-bearing. The shortened bond T-O lengths for one tetrahedral site indicates P preference at the Si2 site, located at the border of the hatrurite-like modules. Significant variations of isomorphous substitutions in nabimusaite suggest the possibility of other isostructural minerals occurring in Nature. It also seems likely that nabimusaite could serve as a prototype for new advanced synthetic materials, given the discovery of two other new minerals in the Hatrurim Complex with related modular structures, placed in the nabimusaite group. These are zadovite and aradite, as described in a companion paper (Galuskin et al., 2015a). The mineral assemblage and paragenesis of nabimusaite suggests that nabimusaite formed as a result of the reaction of potassium-enriched, sulfate-bearing melt with larnite and ellestadite. This contradicts the isochemical model that pyrometamorphic rocks of the Hatrurim Complex formed relatively fast in a practically dry system. [ABSTRACT FROM AUTHOR]

The thermal behavior of nacaphite, NaCaPOF, was studied by the powder high-temperature X-ray diffraction method. A monoclinic-to-orthorhombic phase transition has been observed at 330 °C associated with the appearance of the Ca/Na disorder at one of the two crystallographically inequivalent Na sites. At room temperature, nacaphite is monoclinic, P2 /c, a = 13.3185(14), b = 7.0964(8), c = 10.6490(11) Å, β = 113.526(1)°, V = 922.81(17) Å. The structure is based upon one-dimensional antiperovskite units consisting of face-sharing [FNaCa] anion-centered octahedra running parallel to the c axis. The structure is fully ordered and contains two Ca and four Na sites. The crystal structure of the high-temperature modification [refined by Rietveld method ( R 0.025) at 400 °C from the powder X-ray diffraction data] is orthorhombic, Pnma, a = 5.4123(1), b = 7.1196(1), c = 12.3171(1) Å, V = 474.62(1) Å. The structure has one fully occupied Na1 site and one mixed occupied Na2 site, the latter being equally occupied by Na and Ca. The Na1 and Na2 sites are coordinated by two F and four O anions each. The phase transition has an order-disorder character and is associated with the decrease of structural complexity measured as an information content per unit cell (300.235 bits for the low- and 98.117 bits for the high-temperature modifications). Thermal expansion of both modifications has an anisotropic character with the degree of anisotropy increasing from the low- to the high-temperature phase. The direction of the strongest thermal expansion is parallel to the direction of chains of face-sharing anion-centered octahedra that can be explained by the temperature-induced expansion of the F-Na/Ca bonds. [ABSTRACT FROM AUTHOR]

We report a comparison study of the critical behavior near the ferromagnetic (FM) transition ( T C ) for stoichiometric GaCMn 3 and carbon deficient GaC 0.8 Mn 3 . For GaCMn 3 , the obtained critical exponent β that describes the ferromagnetic (FM) coupling below T C is slightly reduced compared with the Mean Field (MF) value. In GaC 0.8 Mn 3 , the value of β is further decreased towards the anticipated value of the 3D Heisenberg model. However, another critical exponent γ relevant to the paramagnetic behavior is slightly larger than the MF magnitude and insensitive to the carbon deficiency. The change in critical behavior accords with the modification of the electronic structure, i.e., the carbon deficiency weakens the Mn 3 d -C 2 p hybridization and thus increases the localization of Mn 3 d states. Consistently, the specific heat study shows an enhancement of density of state at the Fermi level in GaC 0.8 Mn 3 compared with GaCMn 3 , which further confirms the weakening of Mn 3 d -C 2 p hybridization due to carbon vacancies. [ABSTRACT FROM AUTHOR]

Abstract: Effect of carbon content on magnetostructural transformation in antiperovskites of the type Mn3GaC x (x=0.8, 1.0 and 1.05) has been investigated. It is found that increase in carbon content changes the ground state from ferromagnetic metallic (x=0.8) to antiferromagnetic semiconducting (x=1.05) type. This has been attributed to localization of itinerant Mn 3d electrons due to increased Mn3d – C2p hybridization. Such a hybridization strengthens Mn–C–Mn antiferromagnetic interactions over Mn–Mn ferromagnetic interactions. Further, magnetic field can be used as a tool to modulate the relative strengths of these ferromagnetic and antiferromagnetic interactions thereby affecting the nature and strength of magnetocaloric properties. [Copyright &y& Elsevier]

Magnetostructural correlations in antiperovskite manganese nitrides were investigated systematically for stoichiometric and solid solution Mn3Cu1−xAxN (A = Co, Ni, Zn, Ga, Ge, Rh, Pd, Ag, In, Sn or Sb). This class of nitrides is attracting great attention because of their giant negative thermal expansion, which is achieved by doping Ge or Sn into the A site as a relaxant of the sharp volume contraction on heating (spontaneous volume magnetostriction ωs) because of the magnetovolume effects. The physical background of large ωs and mechanism of how the volume contraction becomes gradual with temperature are central concerns for the physics and applications of these nitrides. An entire dataset of thermal expansion, crystal structure and magnetization demonstrates that the cubic triangular antiferromagnetic state is crucial for large ωs. The intimate relationship between ωs and the magnetic structure is discussed in terms of geometrical frustration related to the Mn6N octahedron and magnetic stress concept. The results presented herein also show that ωs depends on the number of d electrons in the A atom, suggesting the important role of the d orbitals of the A atom. Not all the dopants in the A site, but the elements that disturb the cubic triangular antiferromagnetic state, are effective in broadening the volume change. This fact suggests that instability neighboring the phase boundary is related to the broadening. The relation between the gradual volume change and the local structure anomaly is suggested by recent microprobe studies. [ABSTRACT FROM AUTHOR]

Highlights: [•] The effects of Mn doping on physical properties of ZnCFe3−yMn y were reported. [•] The effects of dual doping on physcial properties of ZnC1−xN x Fe3−2xMn2x werereported. [•] The magnetocaloric working temperature is around 300K for ZnC0.5N0.5Fe2Mn. [•] The magnetic entropy change and RCP are 2.86J/kgK and 220J/kg for ZnC0.5N0.5Fe2Mn. [Copyright &y& Elsevier]

Our recent research on the Mn-based antiperovskite functional materials AXMn3 (A: metal or semiconducting elements; X: C or N) is outlined. Antiperovskite carbides (e.g., AlCMn3) show large magnetocaloric effect comparable to those of typical magnetic refrigerant materials. Enhanced giant magnetoresistance up to 70% at 50 kOe (1 Oe = 79.5775 A⋅m-1) over a wide temperature span was obtained in Ga1-xZnxCMn3 and GaCMn3-xNix. In Cu0.3Sn0.5NMn3.2, negative thermal expansion (NTE) was achieved in a wide temperature region covering room temperature (α = -6.8 ppm/K, 150 K-400 K). Neutron pair distribution function analysis suggests the Cu/Sn-Mn bond fluctuation is the driving force for the NTE in Cu1-xSnxNMn3. In CuN1-xCxMn3 and CuNMn3-yCoy, the temperature coefficient of resistivity (TCR) decreases monotonically from positive to negative as Co or C content increases. TCR is extremely low when the composition approaches the critical points. For example, TCR is ~ 1.29 ppm/K between 240 K and 320 K in CuN0.95C0.05Mn3, which is one twentieth of that in the typical low-TCR materials (~ 25 ppm/K). By studying the critical scaling behavior and X deficiency effect, some clues of localized-electron magnetism have been found against the background of electronic itinerant magnetism. [ABSTRACT FROM AUTHOR]

Abstract: We report the effects of substitution of Cu/Ag/Zn/Sn for Ga on the temperature coefficient of resistivity (TCR) of antiperovskite GaCFe3. With both Cu and Ag dopants increasing, the resistivity displays a peak over a broad temperature range (or low TCR value) around room temperature. As a result, the Cu/Ag dopant can sufficiently optimize the TCR value. For Ag0.05Ga0.95CFe3, the averaged TCR values are less than 10.74ppm/K (215–350K) and, especially, as low as 2.51ppm/K (260–300K). Similarly, the averaged TCR values are 28.87ppm/K (220–273K) in Cu0.05Ga0.95CFe3 and 19.20ppm/K (235–287K) in Cu0.1Ga0.9CFe3. Considering the extremely low averaged TCR value, broad temperature range around room temperature, friendly to the environment, and good thermostability, the series of Cu x Ga1− x CFe3 and Ag x Ga1− x CFe3 can be promising low TCR materials. [Copyright &y& Elsevier]

Abstract: We report the synthesis, crystal structure, magnetic, electrical/thermal transport properties and the magnetocaloric effect (MCE) of AlC1.1Fe3. With increase in the carbon concentration x, the single-phase AlC x Fe3 is obtained for x≥1.1 and the refined lattice constant is about 0.37802nm for AlC1.1Fe3. Magnetic measurements indicate that there exists a second-order ferromagnetic (FM)–paramagnetic (PM) phase transition around 292K. The electrical resistivity displays a good metallic behavior in the whole temperature range except for a broad slope change around the temperature of magnetic transition (∼292K). Meanwhile, a reversible MCE is observed around the FM–PM transition with the maximum value of magnetic entropy change () ∼1.61J/kgK (ΔH=45kOe) and the relative cooling power (RCP) of ∼126J/kg (∼281J/kg) under the magnetic field change ΔH=20kOe (45kOe). Furthermore, it is found that the dominant carriers in AlC1.1Fe3 are hole-type from the studies of thermoelectric power and Hall measurement. [Copyright &y& Elsevier]

Abstract: In this paper, we study the structural, electronic and elastic properties of the ternary AgSbTe2, AgSbSe2, Pr3AlC, Ce3AlC, Ce3AlN, La3AlC and La3AlN compounds using the full-potential linearized augmented plane wave (FP-LAPW) scheme and the pseudopotential plane wave (PP-PW) scheme in the frame of generalized gradient approximation (GGA). Results are given for the lattice parameters, bulk modulus, and its pressure derivative. The calculated lattice parameters are in good agreement with experimental results. We have determined the full set of first-order elastic constants, shear modulus, Young''s modulus and Poisson''s ratio of these compounds. Also, we have presented the results of the band structure, densities of states, it is found that this compounds metallic behavior, and a negative gap Г→R for Pr3AlC. The analysis charge densities show that bonding is of covalent–ionic and ionic nature for AgSbSe2 and AgSbTe2 compounds. [Copyright &y& Elsevier]

Two series of Cd1-xInxNNi3 (0 ≤ x ≤ 0.2) and Cd1-yCuyNNi3 (0 ≤ y ≤ 0.2) samples were prepared from CdO, In2O3, CuO, and nickel powders under NH3 atmosphere at 773 K. The structural and physical properties were investigated by means of X-ray powder diffraction temperature-dependent resistivity and magnetic measurements. X-ray powder diffraction results showed that the Cd1-xInxNNi3 and Cd1-yCuyNNi3 compounds have a typical antiperovskite structure, and the CdNNi3; Cd0.9In0.1NNi3, and Cd0.9Cu0.1NNi3 compounds show metallic temperature-dependent resistivity and exhibit a Fermi liquid behavior at low temperature. In contrast to the paramagnetism previously reported, the CdNNi3 sample exhibits very soft and weak ferromagnetism, and no superconductivity was found in the Cd1-xInxNNi3 and Cd1-yCuyNNi3 samples down to 2 K. Each sample exhibited very soft and weak ferromagnetism, and the temperature dependence of the magnetization of the Cd1-xInxNNi3 and Cd1-yCuyNNi3 samples can be well fitted to the combination of a Bloch term and a Curie-Weiss term. [ABSTRACT FROM AUTHOR]

Abstract: The effects of Mn substitutions on the crystal structure, magnetic properties, and magnetocaloric effect (MCE) of antiperovskite Sn1−x CMn3+x (0≤x≤0.40) have been investigated detailedly. Both the Curie temperature (T C ) and the magnetizations at 40kOe decrease with increasing x firstly for x≤0.10, and then increase with increasing x further. The type of magnetic transition changes from first-order to second-order around x=0.10 with increasing x. Chemical composition-dependent MCE is also studied around T C . With increasing x, the maximal magnetic entropy changes decrease and the magnetic phase transitions broaden. Accordingly, the relative cooling power (RCP) increases with increasing x, reaching the largest values of ∼0.56J/cm3 (∼75J/kg) and ∼1.66J/cm3 (∼221J/kg) with the magnetic changes of 20kOe and 48kOe, respectively. Considering the large RCP, inexpensive, and innoxious raw materials, these serial samples Sn1−x CMn3+x are suggested to be potential room-temperature magnetic refrigerant materials. [Copyright &y& Elsevier]

Abstract: The structural, magnetic and electrical transport properties of Zn-doped antiperovskite compounds Ga1−x Zn x CMn3 (0≤x≤0.30) have been investigated. After partial substitution of Zn for Ga, the Curie temperature increases monotonously and the ground antiferromagnetic (AFM)-ferromagnetic intermediate (FI) phase transition is gradually suppressed. With increasing the doping level x, the saturated magnetizations decreases gradually firstly for x≤0.20, then increases with increasing x. The electrical transport properties of Ga1−x Zn x CMn3 are studied at different magnetic fields. Enhanced giant magnetoresistance (GMR) was observed around the AFM-FI transition. With increasing x, the maximal values and peak widths of GMR increase. Particularly, for x=0.20, GMR reaches a maximum value of 75%, spanning a temperature range of 80K at 50kOe and displays the behavior of strongly depending on the magnetization history. The possible origins are discussed. [Copyright &y& Elsevier]