Teller Distortion Research Articles

Ce-substituted P2-type layered cathode with interfacial/ bulk stability for sodium ion batteries

Addressing a changing energy environment, sodium-ion batteries (SIBs) have emerged as one of the most potentially applicable energy resources in the world. Nevertheless, its further application is hindered owing to high degree of interfacial degradation and structural changes, which caused rapid capacity fading. Herein, a novel Ce modified P2-type layered structure cathode material Na0.67Mn0.8Co0.17Ce0.03O2 @ CeO2 is introduced, the stability of cell is improved by simultaneous bulk doping and surface coating in one scalable step. The doping of Ce4+ increases sodium ion transport rate by shrinking transition metal layer ions and expanding Na layer spacing. Irreversible phase transition can be mitigated from the stronger the bond energy between TM and O, which is conducive to the decrease in the Mn3+/Mn4+ ratio, and suppression of the Jahn−Teller distortion. Besides, the doping of larger radius Ce4+ extends the internal paths of crystal structure, which decreases the barrier of Na+, correspondingly, the Na+ diffusion rate was increased. Meanwhile, the CeO2 coating layer effectively inhibits parasitic reactions on the surface and improves the stability of the interface. Which display excellent capacity with a remarkable retention of 86.9 % after 100 cycles at 0.5 C and outstanding discharge rate performance of 87 mA h g−1 at 20 C. This study provides a simple process to concurrently stabilize the bulk structure and interface for the future application for sodium-ion batteries.

Theoretical insight on structure, electronic, and optical properties of two d 0–d 10 electron transition-metal oxyhalides SHG materials

Materials containing mixed anions, particularly, oxyhalides containing asymmetric functional building units, may lead to the discovery of excellent nonlinear optical (NLO) materials. In the present work, the geometric structure, mechanical properties, electronic structure and optical properties of two d 0–d 10 electron transition-metal oxyhalides Cs2CdV2O6Cl2 and Cs3CdV4O12Br have been systematically determined based on density functional theory. The asymmetric functional building units [V2O7], [V4O13], [CdO2Cl4] and [CdO4Br2] exhibit varying degrees of second-order Jahn−Teller distortions, contributing differently to the macroscopic nonlinearity. Mechanical properties reveal that the two oxyhalides are structurally and mechanically stable. Detailed electronic and optical properties of the two oxyhalides are provided. Optical anisotropy character is exhibited along different polarization vectors, giving a large birefringence for satisfying the phase-matching condition. Maximum absolute values of static second harmonic generation (SHG) coefficients are 4.47 pm V−1 for Cs2CdV2O6Cl2 and 3.72 pm V−1 for Cs3CdV4O12Br, suggesting that Cs2CdV2O6Cl2 and Cs3CdV4O12Br are potential NLO crystals with large SHG coefficients. In particular, unique 3D framework structures give a polar structure superposition of individual moments for asymmetric functional building units. Thus, maximum magnitudes of the total microscopic dipole are achieved, having the largest influence on the SHG response. This study elucidates the relationship between the structure and properties of transition-metal oxyhalides, providing valuable insights for designing NLO materials with excellent performance.

Unique Aluminum Clusters Stabilized by Cation‐Ligand Cooperativity

AbstractTwo novel cyclic Al3 clusters, Li2[Al3(PR2)6] ⋅ 2(Et2O) [R=Ph (1), Cy (2)] were synthesized through salt metathesis of metastable AlCl ⋅ (Et2O)n solutions with LiPR2. Both complexes were characterized by single crystal X‐Ray diffraction and their solid state and electronic structures are compared to previously reported cyclic Al3 clusters. Compounds 1 and 2 were further characterized using density functional theory (DFT) methods to understand the nature of the free electron and the three‐center two‐electron Al−Al bonds. Calculations revealed that both clusters are influenced by pseudo Jahn‐Teller distortion and are likely in equilibrium between two low energy bonding states. The solid‐state structures of 1 and 2 are unique among Al3 clusters, while the electronic structure is similar to the previously reported [Sit4Al3]. In aluminum chemistry, 1 and 2 are rare examples of clusters containing isoelectronic cores in different ligand environments. The effects of the phosphide ligand sphere and strongly coordinated lithium atoms are discussed in detail.

Unveiling the role of Ni doping in the electrochemical performance improvement of the LiMn2O4 cathodes

Ni doping is a commonly used strategy to improve the electrochemical performance of LiMn2O4. Uncovering the structural changes of Ni-doped LiMn2O4 during electrochemical cycling, particularly at the atomic level, is important to understand the mechanism of the relationship between Ni doping and performance improvement. Herein, we investigate the chemical and structural evolutions of the Ni-doped LiMn2O4 electrodes before and after 1000 cycles at 10 C with atomic resolution and correlate them with changes in the electrochemical properties. We found that Ni2+ ions doped into the Mn 16d sites to form a more steady LiNixMn2-xO4 phase construction, which can effectively stabilize the spinel structure by hindering Jahn − Teller distortion. Comprehensive atomic imaging demonstrated that Ni doping can suppress the formation of the unexpected Mn3O4, and rock-salt MnO phases on the surface and subsurface of LiMn2O4 during cycling, which is conducive to stabilizing the MnO6 octahedron and inhibiting the migration of Mn. Resultantly, splendid long cycling stability of 88.92 % after 1000 cycles at 10 C (1 C = 148 mAh g−1) for the optimized LiNi0.05Mn1.95O4 sample is presented. Our study provides an ingenious avenue for regulating the surface optimization and reconstruction of electrode materials.

Atomically Interlocked Chemistry Activated by Interstitial Sites in LiMn2O4 Cathode

AbstractThe extensive applications of spinel LiMn2O4 (LMO) are severely plagued by grievous capacity degradation and structural collapse, mainly ascribed to deleterious Jahn−Teller distortion and subsequent dissolution of Mn2+. Herein, highly stable LMO with atomic interlocking effect is rationally designed via engineering Al into the unoccupied 16c sites. The local coordination environment of the surficial MnO6 octahedron is reconstructed by robust Al−O band coherency, giving strengthened lattice oxygen skeleton and constraining heterophase evolution with the suppression of Jahn−Teller distortion, validated by theoretical calculations coupled with synchrotron X‐ray absorption spectrum. Concomitantly, with the occupation of Al in interstitial site, the migration of Mn is effectively restrained, directly observed by scanning transmission electron microscopy, leading to the inhibition of inactivation as well as dissolution loss of Mn. Resultantly, splendid long cycling stability of Al‐LMO after 1000 loops with only 0.019% capacity fading per cycle is presented. Given this, this elaborate study can provide an ingenious avenue for regulating the structure/interface chemistry architecture in electrode materials.

Symmetry and strain analysis of combined electronic and structural instabilities in tungsten trioxide, WO3

Lattice parameter data from the literature have been used to provide a complete description of spontaneous strain variations across each of the six known phase transitions of WO3 in the temperature interval 5–1273 K. Analysis of strain/order parameter coupling reveals the character of each phase transition, a unified description of strain across the full temperature range, the relationship between strain and electronic effects, and new insights into the strain gradients likely to be present in each of the different domain walls that develop in four different ferroelastic phases. Tetragonal and orthorhombic shear strains have values of 4%–6% and 2%–3%, respectively, and are dominated by coupling with the order parameter for antiferroelectric-type displacements. Conversely, shear strains, e4, e5, and e6, of up to 2% are controlled by octahedral tilting. Changes in electronic structure and properties have been related back to the susceptibility of W6+ to develop cooperative second-order-Jahn–Teller distortions. Proximity to tilt instabilities along with group–subgroup relationships in the P4/nmm parent structure results in two overlapping sequences of structural phase transitions, which differ in the form of their electronic structure. The possibility of a ground state structure in space group P21/c can be rationalized in terms of the efficiency by which different combinations of shearing and tilting of the WO6 octahedra can reduce the unit cell volume and would imply that WO3 has a re-entrant phase transition. Gradients in up to three order parameters coupled with gradients in strain of up to 12% across ferroelastic domain walls indicate that the different ferroelastic phases of WO3 should have domain walls with varied and potentially exotic electronic properties for device applications such as in nanoelectronics and neuromorphic computing.

Octahedral Tilting and Modulation Structure in Perovskite‐Related Compound La1/3NbO3

The crystal structure of the A‐site‐deficient perovskite La1/3NbO3 is investigated using X‐ray powder diffraction, transmission electron microscopy (TEM), and computational methods. The NbO6 octahedral tilting is observed and confirmed to be in an a − b 0 c 0 manner in Glazer's notation. An incommensurate modulation structure in La1/3NbO3 is observed. Using scanning TEM (STEM) analyses and Monte Carlo simulations, the modulated structure is shown to originate from a striped arrangement of La and vacancies. The satellite reflections arising from the modulation structure are observed as a diffuse scatter in the electron diffraction patterns. By analyses with STEM and molecular dynamics calculations, it is concluded that the origin of diffuse scattering is the existence of nanoscale twin variants with different crystal orientations. The Nb ions in NbO6 octahedra represent an off‐center shift like a pseudo‐Jahn–Teller distortion. The shift of Nb ions is found to be cooperative with the concentration modulation of La ions.

First-principles investigation on multiferroic properties of BiFeO3-REMnO3 (RE = Er, Eu, Gd, Ho, La, Tb)

Structural and multiferroic properties of BiFeO3-REMnO3 solid solution (RE = Er, Eu, Gd, Ho, La, Tb) have been investigated using the first-principle calculations. Simultaneous substitution of Gd and Mn in BiFeO3 of 12.5% has been carried out. We found that the total magnetic moment in BiFeO3-REMnO3 is decisively governed by the magnetic moments of rare-earth elements. Our calculations achieved a total magnetic moment of 3.58, 4.69, 5.8, 4.27, 1.5 and 6.31μB in BiFeO3-REMnO3 for RE = Er, Eu, Gd, Ho, La and Tb, respectively. The calculated total densities of states for all studied materials are clearly asymmetrical with metal characteristics. Further, a pseudo Jahn−Teller distortion was predicted for BiFeO3-GdMnO3 with the changes in the octahedral tilting angle θ which is responsible for higher magnetization in this system. The spontaneous polarization of BiFeO3-REMnO3 systems was determined by berry phase methods. The obtained results are close to the experimental and other theoretical results.

Colossal magnetoresistive polycrystalline La0.61Sm0.06Ca0.33MnO3 with large and unperturbed temperature coefficient of resistivity under a magnetic field

Reducing the loss of temperature coefficient of resistivity (TCR) in the magnetic field and increasing the low−field magnetoresistance (MR) are two crucial issues to be solved for large scale practical applications of perovskite materials. In this work, polycrystalline La0.67−ySmyCa0.33MnO3 (shortly LCMO:Smy, where y = 0.02, 0.04, 0.06, 0.08) ceramics were synthesized via optimized sol−gel technology. Colossal intrinsic MR up to 71 % was achieved in produced composites by applying only the magnetic field of 1 T. Lattice distortion was found to be a key factor governing the intrinsic MR response. In presence of magnetic field, the most unperturbed TCR up to 24 %·K−1 was attained in LCMO:Sm0.06 system, where the TCR−loss was only 1 %·K−1. This was explained by the opposite external field direction with respect to Jahn−Teller distortion, which enabled one to solve the problem of large attenuation of TCR under the magnetic field. These findings reveal great potential of the LCMO:Sm0.06 ceramic for applications in infrared bolometers and magnetic recording devices in complex electromagnetic environments.

Unraveling the Roles of La Substitution for Different Transition Metals on P2-Na0.67Mn0.6Ni0.2Co0.2O2 Cathode Materials

P2-type layered transitional metal oxides as the promising cathode materials for sodium-ion batteries (SIBs) have attracted great attention. But their poor cycling stability and inferior rate capability restrict the practical applications. Foreign elements doping has been considered as one effective strategy to overcome these shortcomings. But the roles of the dopants are still poorly understood. Herein, we have taken La doping to modulate the crystal and electronic structure, and systematically investigated the different effects of La substitution for Mn, Ni and Co on the structure and electrochemical properties of P2-Na0.67Mn0.6Ni0.2Co0.2O2 cathode materials. The substitution of La reduces Mn3+ in the crystal lattice which alleviates Jahn−Teller distortion and reduces the collapse of the transition metal layer caused by the dissolution of Mn3+. Due to the large La–O bonding energy, the substitution of La for Mn, Ni and Co shortens O–O and TM–O bond length, and the thickness of TMO2, which all enhance the structure stability. In addition, the substitution of La for Mn, Ni and Co also expands the interlayer spacing and Na–O bond length enhancing Na+ diffusion kinetics. The substitution of La for Mn shows better rate capability and cycling stability than the substitution for Ni and Co. It can provide a discharge capacity of 86 mAh g−1 at a high current density of 8C (1600 mA g−1) with a capacity retention rate of 95%. This study also presents some insights into modulating the lattice and electronic structure by elements doping to optimize the electrochemical performances.

Band structure calculation and rietveld refinement of nanoscale GdFeO3 with affirmation of Jahn Teller's distortion on electric and magnetic properties

We report the meticulous study of freshly synthesized rare earth element substituted R-FeO3 (R-Gd) orthoferrite via co-precipitation route and subsequent sintering. The R-FeO3 powder sample is characterized by X-ray Diffractometer (XRD) for the investigation of crystal structure and is confirmed as orthorhombic with space group Pbnm structure. Nanoparticle dimension is captured by Scanning Electron microscope (SEM). Magnetic character of the sample is examined using vibrating sample magnetometer (VSM), it discloses a nearly linear magnetisation behaviour (paramagnetic behaviour). Dielectric studies and electric Polarization (PE loop) are investigated. A shift is observed in the dielectric constant εr from 250 °C to 300 °C. The Rietveld refinement of the crystal structure from the powder XRD confirms GdFeO3 is distorted at octahedral site of FeO6. This distortion is ascertained as weak Jahn -Teller's distortion leads to the unsaturated electric polarization. The electronic properties, total and partial density of states of GdFeO3 are studied and calculated using Tight - Binding Linear Muffin-Tin Orbital (TBLMTO) method with the Atomic Sphere Approximation (ASA). The band gap of the GdFeO3 is found to be 0.32 eV.

Development of Low Cost and Safe Cathode Material for High Energy Storage Lithium-ion Battery

Spinel LiMn2O4 is a low-cost, eco-friendly, and highly abundant cathode materials for Liion battery, however it has a drastic capacity loss with cycling due to the distortion in crystal structure during discharge. In order to overcome the capacity loss, Mg-doped manganese oxide was synthesised and investigated in order to have a structure with suppressed Jahn- Teller distortion. The distorted Li- Mg-Mn complex has potential merit for lithium ion battery cathode. To fulfil this objective, oxides of Mg and Mn were prepared in different compositions. The synthesized compounds are found to consist of MgMn2O4 as a major phase along with a minor fraction of Mg6MnO8. Lithium insertion was carried out by adding Li2CO3 in appropriate proportion to MgMnO mixture in order to form a single phase LiMgMnO complex. The LiMgMnO complex as a cathode material was successfully demonstrated in a coin cell.

In-Situ XAFS Measurement of K:MnO x Oxygen Evolution Catalyst

[Introduction] Water splitting using solar energy is a promising approach to produce renewable hydrogen gas toward a sustainable society. For the realization of efficient photovoltaic and photoelectrochemical systems for water splitting, oxygen evolution reaction (OER) electrocatalysts have been used to catalyze water oxidation. Thus, the development of highly active OER catalysts has attracted considerable attention. Recently, manganese oxide electrodeposited in a potassium phosphate electrolyte (K:MnO x ) was reported to function as an efficient OER electrocatalyst over a wide pH range.[1,2] Therefore, in this study, the K:MnO x catalyst was investigated by in-situ Mn K-edge XAFS measurements under potential control conditions. [Experimental] Electrochemical measurements were performed in a three-electrode Teflon cell equipped with a Pt counter electrode and an Ag/AgCl (saturated KCl) reference electrode. The K:MnO x catalyst was electrodeposited on a gold-coated film in a 50 mM methanesulfonic acid electrolyte containing 0.5 mM MnCl2. In-situ XAFS spectra of the prepared samples were measured at various potentials in a 0.1 M potassium phosphate buffer electrolyte at BL 9A of the Photon factory and BL01B1 of SPring-8 as fluorescence excitation spectra. [Result and discussion] Figure 1 shows the Mn K-edge XAFS spectra for the K:MnO x catalyst at various electrode potentials between 0.2 and 1.0 V. At the potential of 0.2 V, the position of half edge energy for K:MnO x was observed at ca. 6549.3 eV, similar to those of the Mn3O4 and Mn2O3 references, which indicates that the electronic structure of Mn species in the K:MnO x is most likely the same as that of Mn3+. As the potential was changed from 0.2 to 1.0 V, the position of half edge energy gradually shifted to the higher energy around 0.6 V and then remained constant at 6552.3 eV up to 1.0 V, which shows that the Mn species in K:MnOx catalyst was oxidized from Mn3+ to Mn4+ by positive electrode potential. Figure 2 shows Fourier transformed extended X-ray absorption fine structure (EXAFS) spectra of the K:MnO x catalyst. The Mn-O and Mn-Mn peaks of the spectrum at 0.2 V were observed at the same positions with those of δ-MnO2, exhibiting that the structure of K:MnO x is similar to that of δ-MnO2. Moreover, those peaks increased when the electrode potential was changed to 1.0 V, which probably implies that the Jahn−Teller distortion with nonequivalent Mn−O and Mn−Mn distances was relaxed. Considering that the OER proceeds at higher electrode potential, the δ-MnO2 structure with lower distortion is likely to function as an active species for water oxidation catalysis. In this presentation, we will discuss more detailed assignment for the XAFS spectra and relationship with the OER activity. [1] Huynh, M.; Bediako, D. K.; Nocera, D., J. Am. Chem. Soc., 2014, 136, 6002. [2] Huynh, M.; Shi, C.; Billinge, S. J. L.; Nocera, D. G., J. Am. Chem. Soc. 2015, 2015, 137, 14887. Figure 1

First-principlesDFT+GWstudy of oxygen-doped CdTe

The role of oxygen doping in CdTe is addressed by first-principles calculations. Formation energies, charge transition levels, and quasiparticle defect states are calculated within the $\text{DFT}+GW$ formalism. The formation of a new defect is identified, the $({\text{O}}_{\text{Te}}{\text{-Te}}_{\text{Cd}})$ complex. This complex is energetically favored over both isovalent $({\mathrm{O}}_{\text{Te}})$ and interstitial oxygen $({\mathrm{O}}_{\text{i}})$, in the Te-rich limit. We find that the incorporation of oxygen passivates the harmful deep energy levels associated with $({\mathrm{Te}}_{\text{Cd}})$, suggesting an improvement in the efficiency of CdTe based solar cells. Substitutional $({\text{O}}_{\text{Cd}})$ is only stable in the neutral charge state and undergoes a Jahn--Teller distortion. We also investigate the diffusion profiles of interstitial oxygen and find a low-energy diffusion barrier of only 0.14 eV between two structurally distinct interstitial sites.

Tantalum and vanadium substitution in hexagonal K0.3WO3 bronze: synthesis and characterization

Abstract Polycrystalline samples of tantalum and vanadium single and double substituted hexagonal potassium tungsten bronzes (K-HTB’s) with nominal compositions of K0.3(W6+ 0.7W5+ 0.3–yTa5+ y)O3 (0≤y≤0.3), K0.3(W6+ 0.7W5+ 0.3–y V5+ y)O3 (0≤y≤0.18) and K0.3(W6+ 0.7W5+ 0.3–yTa5+ y/2V5+ y/2)O3 (0≤y≤0.3) were synthesized by solid state reactions in quartz tubes at 10–7 MPa and 1073 K. The applied synthesis condition allowed K0.3WO3 to crystallize in space group P6322, confirmed by X-ray powder diffration and Raman spectroscopic analyses. In this K-HTB composition, W5+ could fully be replaced by Ta5+, whereas V5+ could only be substituted up to y=0.16. The degree of W5+ substitution was explained in terms of second-order Jahn–Teller (SOJT) distortion of the d0 cations W6+, Ta5+ and V5+. The applied distortion index also demonstrates why a complete substitution of W5+ in K0.3(W6+W5+)O3 was allowed by a concomitant sharing of Ta5+ and V5+, which are statistically distributed on the W5+/W6+ sites. As W5+(d1) is not SOJT susceptible, it is also shown that the concentration of W5+ in tungsten bronzes plays an important role in the local WO6 octahedral symmetry as well as in its coordination.

ChemInform Abstract: Polyarene Anions. Interplay Between Theory and Experiment

AbstractReview: 137 refs.

Charge disproportionation and Jahn-Teller distortion in LiNiO2and NaNiO2: A density functional theory study

Density functional theory calculations have been performed on three potential ground-state configurations of LiNiO${}_{2}$ and NaNiO${}_{2}$. These calculations show that, whereas NaNiO${}_{2}$ shows the expected cooperative Jahn--Teller distortion (and therefore a crystal structure with $C$2/$m$ symmetry), LiNiO${}_{2}$ shows at least two possible crystal structures very close in energy (within 3 meV/formula unit): $P$2${}_{1}$/$c$ and $P$2/$c$. Moreover, one of them ($P$2/$c$) shows charge disproportionation of the (expected) Ni${}^{3+}$ cations into Ni${}^{2+}$ and Ni${}^{4+}$. We discuss the implications of this complex ground state for the interpretation of the available electron and neutron structure data, its electronic and complex magnetic behavior.

Isotope Effects for Lattice Strain and Pseudo Jahn-Teller Distortion of Chiral Cyanide-Bridged Cu(II)-Co(III), Cr(III), and Fe(III) Bimetallic Assemblies

By substituting H/D and 18 O isotopes of water molecules, we prepared co-crystals of one-dimensional cyanide- bridged Cu(II)-Cr(III), Cu(II)-Co(III), and Cu(II)-Fe(III) bimetallic assemblies and mononuclear Cu(II) complexes, (CuL2)3(M(CN)6)2·4H2O (L = trans-cyclohexane-(1R, 2R)-diamine; M = Cr, Co, and Fe). Solid state CD and diffuse re- flectance electronic spectra exhibited typical difference of metal ions and little isotope effects. While H/D isotope effects emerged as differences of small intermolecular magnetic interactions and obvious shifts of IR bands. Though all com- pounds exhibited positive thermal expansion of lattice, crystal structures exhibited slight differences associated with Jahn- Teller distortion around Cu(II) coordination environment.

First-Principles Calculated Phase Diagram for Nanoclusters in the Na−Al−H System: A Single-Step Decomposition Pathway for NaAlH4

We present first-principles calculations of the phase diagram of small clusters composed of Na, Al, and H and determine their decomposition pathways as functions of Na:Al ratio and cluster size up to eight formula units. We consider ionic clusters of AlH3, NaH, and NaAlH4 and include as decomposition products metallic clusters of Na, Al, and mixed Na−Al. Small clusters of Na3AlH6 are found to be unstable because of a Jahn−Teller distortion that destabilizes the constituent [AlH6]3− anions and causes them to split into two H− ions and [AlH4]−. Cluster geometries for ionic clusters were obtained by relaxing prototype electrostatic ground state (PEGS) structures using density-functional theory calculations; vibrational free energy was also calculated for each of the clusters. We find that small clusters of AlH3 increase in stability with smaller cluster size from enthalpies of around 51 to 160 kJ/mol H2 for eight and one formula unit (fu), respectively. In contrast, small clusters of NaH have an enthalpy of ...

Griffiths Phase and Disorder in Perovskite Manganite Oxides La1−x Ca x MnO3 and La0.7Sr0.3MnO3

Polycrystalline samples La1−x Ca x MnO3 (x=0.17, 0.15, 0.10) and La0.7Sr0.3MnO3 were prepared in order to investigate the Griffiths-like features induced by disorder compared with their counterpart single crystals. The magnetization data exhibit the traditional transition from ferromagnetic phase to paramagnetic phase. From the temperature dependence of inverse susceptibility, it can be testified that the Griffiths-like features still exist in as-prepared Ca doped samples, while non-Griffiths-like features exist in La0.7Sr0.3MnO3. All these samples, however, exhibit the large effective spins resulting from formation of the short-order ferromagnetic clusters. The O K-edge X-ray absorption spectra indicate the Jahn–Teller (J-T) distortions are definitely present due to the J-T ion Mn3+, which indicate that static J-T distortion is not a sufficient condition for the existence of Griffiths phase in Sr-doped system. And, the size of J-T distortion is a little larger in polycrystalline La0.7Sr0.3MnO3 than that in polycrystalline samples La1−x Ca x MnO3 (x=0.17, 0.15, 0.10), revealed by X-ray diffraction parameters and extended X-ray fine structure absorption data of Mn K-edge. It also testifies that the disorder in La0.7Sr0.3MnO3 caused by both chemical doping and J-T distortions is lower than that in polycrystalline samples La1−x Ca x MnO3, which may be the reason of non-Griffiths-like phase existing in La0.7Sr0.3MnO3 samples.