Perovskite Compounds Research Articles

Ab initio study of fundamental properties of XInO3 (X = K, Rb, Cs) perovskites

Abstract The structural, elastic, anisotropic, and lattice dynamical properties of cubic perovskite compounds XInO3 (X = K, Rb, and Cs) are investigated using first-principles calculations. Electronic band structures and state densities revealed that the electronic nature of the studied materials exhibited half-metallicity properties. The existence of O p–d states close to the Fermi level contributes to the half-metallic properties. Moreover, polycrystalline properties, such as bulk, Young, and shear moduli and Pugh and Poisson ratios, have been determined. As a result of these characteristics, the compounds under consideration exhibited ductility behavior. As far as is known, since this is the first study of XInO3 (X = K, Rb, and Cs) compounds, this work sheds light on future works.

Charge multipole correlations and order in Cs2TaCl6

A combined density functional theory and resonant elastic x-ray scattering technique is implemented to demonstrate the role of charge multipole correlation and order in a 5$d$${}^{1}$ double perovskite compound that is driven by a complex coupled spin, charge, multipole, and structural order.

Strengthening chlorobenzene catalytic degradation rate over LaxSr1-xMnO3±δ by anchoring interfacial oxygen vacancy

Surficial lattice oxygen in perovskite compounds is a common participant during chloroaromatic catalytic degradation. Herein, we proposed a facile oxygen vacancy construction strategy for preparing high active LaxSr1-xMnO3±δ (LSMO) via NaBH4 treatment. Results reveal that LSMO composites are not only reduced by NaBH4 under mild condition, but also triggering a significant Sr segregation effect, which plays a key role in oxygen vacancy formation accounting to the electron donation from Sr to Mn acceptor and subsequent lattice oxygen activation. Moreover, the concentration of interfacial active oxygen species can be regulated by taming the La-Sr interaction with different Sr substitution proportions. The anchored oxygen vacancies (OVs) take advantage of electron capture or transfer and induce molecule oxygen into active oxygen species to react with chlorobenzene molecules, resulting in a preferential catalytic oxidation capacity. Amongst, reduced La0.5Sr0.5MnO3±δ catalyst displays superior chlorobenzene destruction efficiency with 90% of which converted as low as 236 °C, which also exhibits a stable performance in long-time operation. However, the OVs would be refilled by H2O molecules and results in a weaker water resistance for OVs anchored catalyst. In summary, the annihilation of OVs is the most important factor for catalyst deactivation. The research offers a new avenue to construct interfacial oxygen species in perovskite oxides during the chlorobenzene deep oxidation process.

Universal scaling laws for charge-carrier interactions with quantum confinement in lead-halide perovskites

Lead halide perovskites open great prospects for optoelectronics and a wealth of potential applications in quantum optical and spin-based technologies. Precise knowledge of the fundamental optical and spin properties of charge-carrier complexes at the origin of their luminescence is crucial in view of the development of these applications. On nearly bulk Cesium-Lead-Bromide single perovskite nanocrystals, which are the test bench materials for next-generation devices as well as theoretical modeling, we perform low temperature magneto-optical spectroscopy to reveal their entire band-edge exciton fine structure and charge-complex binding energies. We demonstrate that the ground exciton state is dark and lays several millielectronvolts below the lowest bright exciton sublevels, which settles the debate on the bright-dark exciton level ordering in these materials. More importantly, combining these results with spectroscopic measurements on various perovskite nanocrystal compounds, we show evidence for universal scaling laws relating the exciton fine structure splitting, the trion and biexciton binding energies to the band-edge exciton energy in lead-halide perovskite nanostructures, regardless of their chemical composition. These scaling laws solely based on quantum confinement effects and dimensionless energies offer a general predictive picture for the interaction energies within charge-carrier complexes photo-generated in these emerging semiconductor nanostructures.

Anomalies of Brillouin Light Scattering in Selected Perovskite Relaxor Ferroelectric Crystals.

Compositionally disordered perovskite compounds have been one of the exotic topics of research during the past several years. Colossal piezoelectric and electrostrictive effects have been observed in disordered perovskite ferroelectric materials. The key ingredient in the physical behavior of disordered perovskites is the nucleation and growth of the local dipolar regions called polar nanoregions (PNRs). PNRs begin to nucleate far above the temperature of the dielectric maximum Tm and exhibit varied relaxation behavior with temperature. The evidence for the existence of various stages in the relaxation dynamics of PNRs was revealed through the study of the temperature evolution of optical phonons by Raman scattering. The quasi-static regime of PNRs is characterized by the strong coupling between the local polarization and strain with the local structural phase transition and the critical slowing of the relaxation time. Strong anomalies in the frequency and the width of the acoustic phonons, and emergence of the central peak in the quasi-static region of the relaxation dynamics of PNRs have been observed through Brillouin scattering studies. In this review, we discuss the anomalies observed in Brillouin scattering in selected disordered perovskite ferroelectrics crystals such as Pb(Mg1/3Ta2/3)O3, Pb(Sc1/2Ta1/2)O3, 0.65PIN-0.35PT and Sr0.97Ca0.03TiO3 to understand dynamical behavior of PNRs.

Magnetic critical behavior and room temperature magnetocaloric effect in Ba1.9Pr0.1FeMoO6 double perovskite compound

In this paper, we report the critical behavior related to the magnetocaloric effect of Ba1.9Pr0.1FeMoO6 double perovskite. A maximum magnetic entropy change, |ΔSMmax| ∼ 0.68 Jkg−1K−1 and relative cooling power, RCP ∼ 62 Jkg−1 were observed under applied field of H = 2.5 T. The critical exponents were evaluated by using modified Arrott plots, Kouvel-Fisher, critical isotherm analysis and Widom scaling relation methods. A second order phase transition (paramagnetic to ferromagnetic) was observed at Curie temperature, TC = 319.73 K with critical exponents β = 0.45, γ = 0.84, and δ = 2.91. The value of these critical exponents shows that this sample obeys mean field model and Widom scaling relation. Also, we observed that the different isothermal magnetization data are able to collapse into the two branches below and above TC based on the single scaling equationM(H,ε)=εβf±(H/εβ+γ) that affirms the authenticity of the critical exponents.

Rational Design of Non-Centrosymmetric Hybrid Halide Perovskites.

Structural non-centrosymmetry in semiconducting organic-inorganic hybrid halide perovskites can introduce functionalities like anomalous photovoltaics and nonlinear optical properties. Here we introduce a design principle to prepare Pb- and Bi-based two- and one-dimensional hybrid perovskites with polar non-centrosymmetric space groups. The design principle relies on creating dissimilar hydrogen and halogen bonding non-covalent interactions at the organic-inorganic interface. For example, in organic cations like I-(CH2)3-NH2(CH3)+ (MIPA), -CH3 is substituted by -CH2I at one end, and -NH3+ is substituted by -NH2(CH3)+ at the other end. These substitutions of two -H atoms by -I and -CH3 reduce the rotational symmetry of MIPA at both ends, compared to an unsubstituted cation, for example, H3C-(CH2)3-NH3+. Consequently, the dissimilar hydrogen-iodine and iodine-iodine interactions at the organic-inorganic interface of (MIPA)2PbI4 2D perovskites break the local inversion symmetries of Pb-I octahedra. Owing to this non-centrosymmetry, (MIPA)2PbI4 displays visible to infrared tunable nonlinear optical properties with second and third harmonic generation susceptibility values of 5.73 pm V-1 and 3.45 × 10-18 m2 V-2, respectively. Also, the single crystal shows photocurrent on shining visible light at no external bias, exhibiting anomalous photovoltaic effect arising from the structural asymmetry. The design strategy was extended to synthesize four new non-centrosymmetric hybrid perovskite compounds. Among them, one-dimensional (H3N-(CH2)3-NH(CH3)2)BiI5 shows a second harmonic generation susceptibility of 7.3 pm V-1 and a high anomalous photovoltaic open-circuit voltage of 22.6 V.

First-principles study on structural, electronic and optical properties of halide double perovskite Cs2AgBX6 (B = In, Sb; X = F, Cl, Br, I).

All-inorganic halide double perovskites (HDPs) attract significant attention in the field of perovskite solar cells (PSCs) and light-emitting diodes. In this work, we present a first-principles study on structural, elastic, electronic and optical properties of all-inorganic HDPs Cs2AgBX6 (B = In, Sb; X = F, Cl, Br, I), aiming at finding the possibility of using them as photoabsorbers for PSCs. Confirming that the cubic perovskite structure can be formed safely thanks to the proper geometric factors, we find that the lattice constants are gradually increased on increasing the atomic number of the halogen atom from F to I, indicating the weakening of Ag-X and B-X interactions. Our calculations reveal that all the perovskite compounds are mechanically stable due to their elastic constants satisfying the stability criteria, whereas only the Cl-based compounds are dynamically stable in the cubic phase by observing their phonon dispersions without soft modes. The electronic band structures are calculated with the Heyd-Scuseria-Ernzerhof hybrid functional, demonstrating that the In (Sb)-based HDPs show direct (indirect) transition of electrons and the band gaps are decreased from 4.94 to 0.06 eV on going from X = F to I. Finally, we investigate the macroscopic dielectric functions, photo-absorption coefficients, reflectivity and exciton properties, predicting that the exciton binding strength becomes weaker on going from F to I.

Structural, magnetic and magnetocaloric properties in distorted RE 2NiTiO6 double perovskite compounds

The magnetocaloric effect based Magnetic refrigeration (MR) was considered a novel energy-efficient and environmentally benign cooling method. However, the lack of suitable magnetic solids has slowed the development of its practical applications. We herein fabricated the RE 2NiTiO6 (RE = Gd, Tb and Ho) double perovskite (DP) compounds and systematically determined their structural, magnetic and magnetocaloric properties by experimental determination and density functional theory calculations, in which the Gd2NiTiO6 was realized to exhibit promising cryogenic magnetocaloric performances. The results indicated that all the RE 2NiTiO6 DP compounds crystallized in a distorted monoclinic structure with P21/n space group and underwent a second order type magnetic phase transition around 4.3, 4.5 and 3.9 K, for Gd2NiTiO6, Tb2NiTiO6 and Ho2NiTiO6, respectively. The magnetocaloric performances were checked by the parameters of maximum magnetic entropy change and relative cooling power, which are 31.28 J·kg−1·K−1 and 242.11 J·kg−1 for Gd2NiTiO6, 13.08 J·kg−1·K−1 and 213.41 J·kg−1 for Tb2NiTiO6, 11.98 J·kg−1·K−1 and 221.73 J·kg−1 for Ho2NiTiO6 under the magnetic field change of 0–50 kOe, respectively. Evidently, the Gd2NiTiO6 compound exhibit promising magnetocaloric performances and therefore is of potential for practical cryogenic MR applications.

Giant dielectric response, nonlinear characteristics, and humidity sensing properties of a novel perovskite: Na1/3Sr1/3Tb1/3Cu3Ti4O12.

In this study, we unveil a novel perovskite compound, Na1/3Sr1/3Tb1/3Cu3Ti4O12, synthesized through a solid-state reaction method, exhibiting remarkable giant dielectric response, nonlinear characteristics, and humidity sensing capabilities. This research highlights the emergence of a Cu-rich phase, the properties of which undergo significant alterations depending on the sintering conditions. The optimization of sintering parameters, encompassing a temperature range of 1040-1450 °C for 1-8 h, resulted in substantial dielectric permittivity (ε') values (∼2800-6000). The temperature dependence of ε' demonstrated relationship to the particular sintering conditions utilized. The acquired loss tangent values were situated within encouraging values, ranging from 0.06 to 0.16 at 1 kHz. Furthermore, the material revealed distinct nonlinear electrical characteristics at 25 °C, with the nonlinear coefficient values of 5-127, depending on ceramic microstructures. Additionally, we delved deeply into the humidity-sensing properties of the Na1/3Sr1/3Tb1/3Cu3Ti4O12 material, showing a considerable variation in ε' in response to fluctuations in relative humidity, thereby indicating its prospective application in humidity sensing technologies. The hysteresis error and response/recovery times were calculated, highlighting the versatility of this compound and its promising potential across multiple applications. The Na1/3Sr1/3Tb1/3Cu3Ti4O12 not only shows remarkable giant dielectric responses but also portrays significant promise for nonlinear and humidity sensing applications, marking it as a significant participant in the advancement of perovskite-based functional materials.

Exploring bismuth-doped polycrystalline ceramic Ba0.75Bi0.25Ni0.7Mn0.3O3: synthesis, structure, and electrical properties for advanced electronic applications.

This manuscript investigates the structural and electrical properties of a Ba0.75Bi0.25Ni0.7Mn0.3O3 (BNMO) perovskite compound synthesized through the sol-gel method. The orthorhombic crystal structure of the sample is confirmed by X-ray diffraction analysis. The electrical conductivity of BNMO is found to increase with frequency, indicating the presence of local charge carriers. The AC electrical conductivity follows Jonscher's equation, exhibiting a plateau at low frequencies and a power-law behavior at high frequencies. The activation energy for conduction is determined to be 0.654 eV. Impedance spectroscopy reveals the presence of grain and grain boundary contributions, which are modeled using an R-CPE combination circuit. Analysis of the electrical modulus demonstrates non-Debye type relaxation and indicates the presence of charge carrier hopping between Mn2+ and Mn3+ ions. The activation energy obtained from the relaxation peaks of the modulus is found to be 0.674 eV. The dielectric constant exhibits high values that increase with temperature. This observation suggests that the capacitance behavior holds promising potential for energy storage applications, making it a suitable candidate for various technological uses.

Probing the physical properties for prospective high energy applications of QMnF3 (Q = Ga, In) halide perovskites compounds employing the framework of density functional theory.

We use WIEN2K to conduct density functional theory computations to explore the structural, thermodynamic, optoelectronic, and mechanical properties of fluoroperovskites QMnF3 (Q = Ga, In). The application of the Birch-Murnaghan equation to the energy versus volume, formation energy, and tolerance factor confirms the structural stability of these two QMnF3 (Q = Ga, In) materials. The thermodynamic stability of the compounds is confirmed by the results of the phonon calculation, while the mechanical stability is confirmed from the values of the elastic constants. GaMnF3 demonstrates a high capacity to withstand both compressive and shear stresses. A lower bulk modulus is responsible for the weaker ability of InMnF3 to endure changes in volume. Compared to GaMnF3, InMnF3 possesses rigidity having greater shear modulus, indicating greater resistance to changes in shape. However, both compounds are characterized as mechanically brittle, anisotropic, and ductile. The band structure that was determined indicates that both GaMnF3 and InMnF3 exhibit a metallic character. The density of states analysis further supports the metallic nature of GaMnF3 and InMnF3. In GaMnF3, the "Mn" and "F" atoms in the valence band significantly participate in the total density of states, whereas in InMnF3, both "Mn" and "F" atoms also dominate the total density of states. The values of ε1(0) computed for GaMnF3 and InMnF3 are positive i.e. > 0, and agree with Penn's model. We calculate the optical properties for both GaMnF3 and InMnF3 and the potential of these materials of interest for applications in optoelectronic gadgets including light-emitting diodes is attributed to their absorption in the ultraviolet-visible zone. We believe that this work may provide comprehensive insight, encouraging further exploration of experimental studies.

Evolution of the valence state of Ru metal ions in correlation with the structural and electronic properties of double perovskite ruthenates; A2SmRuO6 (where A = Ba & Sr)

This novel study is crucial in understanding the intriguing electronic, structural and chemical properties of special double perovskite compounds, Ba2SmRuO6 and Sr2SmRuO6, for their applications as “Spintronics based devices”.

First-principle insight into the structural, electronic, elastic and optical properties of Cs-based double perovskites Cs2XCrCl6 (X = K, Na).

This study communicates the theoretical investigations on the cubic double perovskite compounds Cs2XCrCl6 (X = K or Na). Density functional theory (DFT) calculations were carried out using the TB-mBJ approximation. These compounds were found to be stable in the cubic perovskite structure having lattice constants in the range of 10.58-10.20. The stability of the investigated materials was assessed by the Gold-Schmidt tolerance method, which resulted in the tolerance factor values of 0.891 and 0.951 for Cs2KCrCl6 and Cs2NaCrCl6, respectively. The calculated values of the elastic constants C11, C12, and C44 of the cubic compounds studied by our research team confirm the elastic stability. The values of the formation energies were also calculated for both the compounds and were found in the range from -2.1 to -2.3. The electronic behavior of the presently investigated materials was examined by inspecting their band structures and the density of states. It was observed that both the materials have half-metallic nature. To check the suitability of the studied compounds in optical applications, we determined the real and imaginary parts of their respective dielectric functions, absorption coefficients, optical conductivities, refractive index, and reflectivity as a function of a wide range of incident photon energies up to 40 eV.

Computational study of the physical characteristics of Si-based oxide perovskites for energy generation using DFT

SiMO3 (M = Sn, Ge) silicon-based oxide perovskite compounds are studied using density functional theory (DFT) and Wien2k software to examine their structural, elastic, optical, and electronic properties.

First-principles calculations to investigate physical properties of orthorhombic perovskite YBO3 (B = Ti & Fe) for high energy applications.

Orthorhombic oxide perovskite compounds are very promising materials for the applications of optoelectronics and thermal barrier coating. This work represents a numerical simulation of YBO3 compounds through the first-principles ab initio approach. The electronic and magnetic properties are investigated employing the general gradient approximation (GGA) coupled to the integration of the Hubbard U-term which is the GGA + U. The Ti and Fe-based YBO3 perovskite compounds are found to be actively promising within the ferromagnetic configuration and their lattice parameters are consistent with the previous studies. The calculations of formation energy signify that the compounds YBO3 are stable thermodynamically. The electronic properties are computed and evaluated by the band structure and density of states for both compounds and the results depict that these materials are ferromagnetic half-metallic. Mechanically these compounds are stable, ductile, anisotropic, and hard to scratch. The thermal properties are evaluated for YBO3 (B = Ti and Fe) compounds up to a temperature range of 2000 K. This work can open new opportunities for further exploration in this field.

Probing the physical properties of M2LiCeF6 (M = Rb and Cs) double perovskite compounds for prospective high-energy applications employing the DFT framework.

Herein, the optoelectronic, structural, thermoelectric, and elastic characteristics of M2LiCeF6 (M = Rb and Cs) double perovskite compounds were investigated using ab initio modeling in the DFT framework. The Birch-Murnaghan fitting curve used for the optimization showed that these two compounds are structurally stable. The elastic properties of the M2LiCeF6 (M = Rb and Cs) double perovskite compounds were examined using the IRelast code. The results showed that these two compounds possess mechanical stability, anisotropy, and toughness, and offer resistance to plastic deformation. The precise and accurate determination of their electronic properties was achieved via the Trans-Blaha-modified Becke-Johnson (TB-mBJ) approximation. The Rb2LiCeF6 and Cs2LiCeF6 compounds are narrow band gap semiconductors with band gaps of 0.6 eV and 0.8 eV at the high symmetrical points from (Γ-M), respectively, exhibiting an indirect nature. To further understand how the various states contribute to the different band structures, total and partial density of state (DOS) computations were performed. The optical properties in the energy range of 0-40 eV for Rb2LiCeF6 and Cs2LiCeF6 were explored. The selected materials show transparency in the low incident photon energy range and have large light absorption and transmission at higher photon energies. Thus, it can be concluded that Rb2LiCeF6 and Cs2LiCeF6 can be used in high-frequency UV devices based on their optical characteristics. Both materials exhibit high electrical conductivity, power factors, and figures of merit (ZT) and act as effective thermoelectric resources. To the best of our knowledge, this is the first theoretical research on the optoelectronic, structural, thermoelectric, and elastic features of M2LiCeF6 (M = Rb and Cs).

Investigation of the optoelectronic properties of cubic metal halide perovskite compound RbSiCl3

Lead free halide metal perovskite compounds have been exploring more since last decades due to their wide potential applications as well as their environmental friendly nature. Presented work agreements with the density functional investigation of the material properties (optoelectronic) of lead free halide metal perovskite compound RbSiCl3 by using WIEN2k code that is rely on FP-LAPW: full potential-linearized augmented plane wave method. The optoelectronic response are well explored by the Perdew Burke Ernzergof GGA exchange correlation functional. The computed energy band gap of this compound is 0.96 eV and results reveal that it is direct band gap semiconductor material. In addition, the integrated absorption coefficient also computed through absorption spectra, which gives the value 123.39 (×104 eV/cm). All computation proves the utility of the compound for photovoltaic and optoelectronic applications.

Use of Perovskites for Optosensors

The work is devoted to the determination of the place of perovskites among the other materials for optosensors. The features and advantages of this material are determined. The methods for the manufacture of perovskites and the latest technical developments in their application are analyzed. Perovskite and silicon photosensors are compared. A comparative table of perovskite compounds is drawn up. It is determined that perovskites have great potential for their use in low-voltage, inexpensive, high-speed, highly sensitive and ultra-highly integrated optoelectronic devices.

Comments on the paper “Structure, electric and dielectric properties of PbFe1/3Ti1/3W1/3O3 single perovskite compound” by P.G.R. Achary, R.N.P. Choudhary, S.K. Parida, published in Processing and Application of Ceramics 14 (2020) 146-153

My comments concern the errors in the crystallographic part and possible misconduct of the authors of the commented paper regarding their usage of the same SEM image in different subsequent works. Moreover, the true chemical composition of the studied sample is questionable since the authors claim different systems for the same SEM micrograph in five different papers mentioned here.