Deformation Of Crystal Structure Research Articles

High quality perovskite thin films synthesized by low-temperature supercritical carbon dioxide annealing method

Thermal annealing is a conventional method used to eliminate residual solvents in perovskite films, reducing internal and interfacial defects. However, due to the high saturation vapor pressure of the residual solvent dimethyl sulfoxide, it is difficult to quickly remove the residual solvent at low temperatures. In this paper, the high permeability and diffusion of supercritical CO2 (ScCO2) were used to quickly remove the residual solvent of film at low temperatures. The effects of ScCO2 annealing on the surface morphology, residual solvents, internal and interfacial defects of perovskite thin films were investigated. The experimental results indicate that ScCO2 annealing significantly improves the removal efficiency of residual solvents compared to low-temperature annealing, effectively minimizing internal and interfacial defects. Additionally, the interaction energy of CO2 with the perovskite crystal plane reduces the surface energy of the crystal, resulting in a significant increase in the average grain size of the crystal by about 91.2%. Notably, the average crystal size of the film prepared by chlorobenzene as an antisolvent increased from 209.35 nm to 704.57 nm. The high penetration of ScCO2 also promoted uniform crystal growth, thereby reducing crystal structure deformation and defects. The carrier lifetime of perovskite thin films after ScCO2 annealing increased by over 58.8% on average.

Petrogenesis of lunar granulitic breccia meteorites Northwest Africa 15062 and 15063

AbstractWe present petrology and mineralogy for two lunar granulitic breccia meteorites that were detected in Northwest Africa (NWA), the samples NWA 15062 and NWA 15063. The fragments primarily consist of plagioclase and olivine mineral clasts, with minor amounts of anorthosite clasts and one troctolite clast. The anorthosite clasts are dominated by plagioclase/maskelynite, with minor olivine and pyroxene. A troctolite clast, composed of olivine and maskelynite, occurs in NWA 15063. The olivine clasts display mosaic extinction and usually have a homogeneous Mg‐rich composition. However, all olivine mineral clasts exhibit two distinct ranges of their major element composition (Mg#: 85–88 and 77–78, respectively). Large individual plagioclase clasts show heterogeneous compositions (Ab content: 2.5–4.8) and have different Raman peak positions in different domains. The matrix of the meteorites appears semitransparent and is composed of olivine and pyroxene aggregates associated with maskelynite, constituting a granoblastic texture. Pyroxenes of the matrix are dominantly enstatites, associated with a few augites. Both meteorite samples exhibit shock‐induced melt veins ranging from 50 to 200 μm width. These melt veins traverse the entire samples and contain rare, very fine‐grained (2–3 μm) Mg‐rich olivine clasts (Mg# = 90–93) and mafic silicate glass. Some Cr‐spinel grains exhibit slight compositional zonation, characterized by a magnesium‐rich core (Mg# = 56, Cr# = 23) and Cr‐rich rims (Mg# = 50, Cr# = 28), with decomposition at the edges. The significantly differing Mg# contents of the mafic silicate minerals in the matrix, lithic clasts, and mineral clasts of the two meteorites indicate a diverse origin of the clasts. Based on their petrology, mineral chemistry, and bulk composition, NWA 15062 and NWA 15063 are classified as anorthositic troctolitic granulitic polymict breccia. Textural evidence suggests that the parent rocks of NWA 15062 and NWA 15063 were affected by high pressure of up to 30 GPa during impact‐induced shock metamorphism, causing crystal structure deformation in olivine and the transformation of plagioclase to maskelynite. During cooling from peak temperatures of 1600–1700°C, the coarse‐grained maskelynite mineral clasts were partially devitrified, and the granoblastic texture of the matrix was developed. Mg‐rich anorthosite was formed before this shock event. Cr‐spinel was formed in a troctolitic melt, which was probably differentiated after the crystallization of anorthite and magnesium‐rich olivine. However, the possibility of the formation of the Mg‐rich melt through interaction with the lunar anorthositic crust cannot be ruled out. The meteorite NWA 15062/15063 strongly resembles the textural, chemical, and mineralogical characteristics of the NWA 5744 meteorite group. Therefore, we interpret the two samples as a new member of the NWA 5744 meteorite group.

X-ray peak broadening analysis of Bougainvillea glabra assisted ultrasonic exfoliation of h-BN sheets

In this study, h-Boron Nitride (h-BN) nanosheets have been successfully exfoliated using Bougainvillea flower extract and ultrasonication process. The microstructural parameters such as microstrain, stress, and energy density were calculated using Williamson–Hall analysis. The time of ultrasonication and post-annealing temperature significantly alter the microstructure parameters such as crystal size, microstrain, stress, and energy density upon sonication. The lattice constants such as a-axis and c-axis, cell volume, and bond length did not alter significantly which confirms that there is no crystal structure deformation upon sonication and annealing processes. FESEM result revealed that exfoliation of h-BN and ultrasonication duration greatly influenced the exfoliation. Raman and FTIR studies confirm the pure phase of h-BN without secondary impurities. A simple ultrasonication process would effectively exfoliate h-BN layers and this could be used for tribological applications to reduce the friction between rubbing surfaces.

Imaging and ferroelectric orientation mapping of photostriction in a single Bismuth Ferrite nanocrystal

The exploration of multiferroic materials and their interaction with light at the nanoscale presents a captivating frontier in materials science. Bismuth Ferrite (BiFeO3, BFO), a standout among these materials, exhibits room-temperature ferroelectric and antiferromagnetic behaviour and magnetoelectric coupling. Of particular interest is the phenomenon of photostriction, the light-induced deformation of crystal structures, which enhances the prospect for device functionality based on these materials. Understanding and harnessing multiferroic phenomena holds significant promise in various technological applications, from optoelectronics to energy storage. The orientation of the ferroelectric axis is an important design parameter for devices formed from multiferroic materials. Determining its orientation in the laboratory frame of reference usually requires knowing multiple wavevector transfer (Q-Vector) directions, which can be challenging to establish due to the need for extensive reciprocal-space searches. Our study demonstrates a method to identify the ferroelectric axis orientation using Bragg Coherent X-ray Diffraction Imaging (BCDI) measurements at a single Q-vector direction. This method involves applying photostriction-inducing laser illumination across various laser polarisations. Our findings reveal that photostriction primarily occurs as a surface phenomenon at the nanoscale. Moreover, a photo-induced crystal length change ranging from 30 to 60 nm was observed, consistent with earlier findings on bulk material.

Correlation between the deformation of mineral crystal structures and fault activity: A case study of the Yingxiu-Beichuan fault and the Milin fault

Abstract The build-up and occurrence of earthquakes are due to the accumulation and release of stress in fault zones. When subjected to tectonic extrusion stress, the crystal structure of the minerals within a fault zone will change. In this study, Raman spectroscopy analysis was conducted on the concurrently deposited quartz veins from Shenxigou, along the Yingxiu-Beichuan fault, and from Niyang River mouth, in the southern section of the Milin fault. The test results reveal a 3.29 cm−1 shift in the characteristic 464 cm−1 peak of the quartz in the veins along the fault plane of the Yingxiu-Beichuan fault, which was significantly lower than the shifts in the quartz peaks of the quartz on both sides of the vein. The 464 cm−1 peak shifts of the samples collected 10 m to the NW and 21 m to the SE of the fault plane were approximately 4.40 and 4.62 cm−1. In the veins from the Milin fault, considerable shifts of the 464 cm−1 quartz peaks occurred at the fault plane and to both sides within 5.5 m of the fault plane. No significant change in the 464 cm−1 Raman peak of quartz was observed for the samples 5–28 m to the SE of the fault plane. These results indicate that the tectonic extrusion stress accumulated more easily in proximity to the fault plane, resulting in significant changes in the crystals near the fault plane. We conclude that there is a correlation between the degree of change in the crystal structures of the minerals in thrust fault zones and fault activity, and such a correlation can provide a new method for studying the activity of thrust faults in areas with bedrock.

Spin moment cancelation of high Curie temperature Ir doped ZrO2 gradual atomic change

This paper presents the structural, magnetic properties, and spin moment cancelation phenomenon of the zirconium oxide with a gradual change of zirconium for Iridium. The density functional theory (DFT) is shown to be a key feature of magnetic properties of solid materials treatment. It is shown that a small adjustment of the spin moment (less than 6%) is allowed. The Zr1-xIrxO2 crystal structure deformation leads to a magnetic compensation that occurs at x=0.06. Spin and orbital moments behaviors are discussed. The stability of the alloy compounds is confirmed by energy calculations. The material presents ferromagnetic stability and an indirect exchange coupling with a hybridization effect that permitted the evolution from a non-magnetic to a host material with magnetic properties. The Ir orbitals are set at the Fermi level and are spin polarized which indicates a half metallic behavior then makes the material a good candidate for spintronics’ applications.

The effect of the synthesis conditions on the crystal structure of palladium(II) oxide nanofilms

Nanocrystalline films of palladium(II) oxide obtained by oxidation of the initial metallic Pd layers with a thickness of 35 nm on Si (100) substrates in atmospheric air were studied using XRD analysis, TEM, and RHEED. PdO/SiO2/Si (100) heterostructures were synthesised in two stages. First, we obtained finely dispersed layers of metallic Pd on SiO2/Si (100) substrates with an ~ 300 nm SiO2 buffer layer using thermal sublimation in a high vacuum. The Pd layers were then oxidised in the temperature range Tox = 620 – 1100 K in atmospheric air (with the partial pressure of oxygen of about 21 kPa). The study determined that the deformation of the tetragonal crystal structure of homogeneous nanocrystalline PdO films is explained by an increase in the values of lattice parameters with the oxidation temperature. The deformation reaches its maximum values at Tox ~ 970 K. Comparison of the obtained results with the earlier data regarding PdO/SiO2/Si (100) heterostructures synthesised in a dry oxygen atmosphere (with the partial pressure of oxygen of about 101.3 kPa) demonstrated that PdO films synthesized in an oxygen atmosphere are characterized by a higher degree of deformation of the crystal structure. The effect of the oxidation temperature and O2 partial pressure on the increase in the tetragonal lattice parameters of the PdO films can be explained by the formation of interstitial oxygen atoms in the octahedral void in the centre of the palladium(II) oxide unit cell.

Efficient and Stable Perovskite Nanocrystal Light-Emitting Diodes with Sulfobetaine-Based Ligand Treatment

Perovskite nanocrystals (PNCs) possess outstanding optical properties such as narrow full-width at half-maximum (fwhm) emission and color tunability. However, the labile ionic nature and weakly bound surface ligands of PNCs result in colloidal instability and crystal structure deformation, thus degrading their optical properties. In this study, we treated CsPbBr3 PNCs with 3-(dodecyldimethyl-ammonio)propane-1-sulfonate (12-SBE) ligands and successfully stabilized the PNCs under ambient air and heat. Under optimum ligand exchange conditions, 12-SBE PNCs showed near 100% photoluminescence quantum yield (PLQY) without an increase in the size of the PNCs. After 12-SBE treatment, the agglomeration of PNCs in solution due to ligand loss was suppressed, and PNC size growth induced by moisture and oxygen under heating was reduced. Finally, we fabricated 12-SBE PNC LEDs exhibiting 6.7% external quantum efficiency (EQE). Moreover, the PL lifetime of 12-SBE PNC LEDs was enhanced 2-fold compared to oleylamine (OAM) PNC LEDs.

Attempt to correlate dislocations network and distribution to macroscale plane rotations in <001> cast-mono ingots

This work aims to contribute to the understanding of the mechanisms behind electrically active crystalline defect formation in cast-mono (cm) ingots grown along the <001> axis. Both the spatial distributions of background dislocations in the cellular dislocation array and the driving force for dislocation multiplication in the sub-grains are not perfectly understood. Macroscale length crystal rotations are here characterized by the (θ/2θ) X-ray diffraction (XRD) method at different ingot heights and along two perpendicular sample axes. XRD measurements show the presence of crystal rotations in the large single grain domain. Two orthogonal misorientations components are found to evolve linearly along each sample axis forming plane orientation gradients up to (0.05 ± 0.02) degree/cm extending over 12 cm inside the cast-mono grain. (001) crystal structure deformation are also analysed by rocking curve imaging (RCI) using synchrotron radiation on wafers of a neighboring brick. First, results confirm the presence of the plane orientation gradient measured by XRD and its order of magnitude. Second, RCI results demonstrate that the plane orientation gradient is associated to the cellular dislocation network. Therefore, these results strongly suggest that background dislocations network of a cellular form can create an organized orientation gradient at large distance within the ingot. The involvement of the characterized orientation gradients in the formation and extension of electrically active SGBs in cast-mono ingots is discussed. • Crystal structure deformation measurements of cm-Si ingots. • Evidence of the presence of {001} planes orientation gradients. • Plane orientation gradients almost constant along the sample axes. • Orientation gradients increase with the ingot height. • Orientation gradients associated to the cellular network of dislocations.

Study of Radiation-Induced Damage Processes in CeZrO4–YZrO3 Ceramics Caused by Helium Irradiation

Composite oxide ceramics CeZrO4-YZrO3 obtained by mechanochemical synthesis were chosen as objects of study. The most dangerous type of radiation defect in structural materials is associated with helium accumulation in the structure of the near-surface layer. This can lead to the destruction and swelling of the material, resulting in a decrease in its strength and thermal characteristics. During the studies, it was found that the most significant structural changes (deformation of the crystal lattice, the magnitude of microdistortions of the crystal lattice) are observed with irradiation fluence above 5×1016 ion/cm2, while the nature of the changes is exponential. X-ray diffraction analysis found that the nature of the crystal structure deformation has a pronounced type of stretching due to the accumulation of implanted helium and its subsequent agglomeration. A comparative analysis with data on microdistortions of the crystal lattice and the values of microhardness and softening of ZrO2 and CeO2 showed that two-phase ceramics of the cubic type CeZrO4-YZrO3 are more resistant to radiation-induced degradation than single-phase ZrO2 and CeO2. Results of strength and thermophysical characteristics showed that the presence of two phases increases resistance to destruction and disorder, leading to a decrease in strength and thermal conductivity.

Hollow core-shell PANI-encapsuled Ni-Prussian blue analogue (H-NP@PANI) with omnidirectional conductive layer for efficient capacitive desalination

Prussian blue analogue (PBA) as a typical Faraday electrode material has important application value in capacitive deionization (CDI) for its rigid open framework and unique ion storage properties. But poor electrical conductivity and deformation of crystal structure during the desalination process restrict its development. To enhance the stability of PBA and provide rapid charge transfer, a new composite hollow core-shell polyaniline-encapsuled Ni-Prussian blue analogue (H-NP@PANI) is constructed. Experiments illustrate that PANI formed an omnidirectional uniform and highly conductive layer on the crystal surface, which tremendously improved the electrochemical capacity of H-NP@PANI (242.24 F·g−1). In constant voltage mode, the adsorption capacity of AC║H-NP@PANI cell is 35.86 mg·g−1, which was the highest to H-NP (20.82 mg·g−1) and pure Ni-PBA (16.08 mg·g−1). The retention rate remains 96.1 % after 50 cycles. XRD tests show that superior cycle stability is due to the hollow structure and buffer space provided by PANI shell, which can effectively inhibit the degree of crystal transformation. Furthermore, DFT calculation confirms the existence of a highly stable tight electron coupling between H-NP and PANI, and the electron aggregation center around Fe atom facilitates the Fe3+/Fe2+ redox cycle. Hence, this work can provide a feasible strategy for designing stable and efficient electrodes.

The effect of magnesium doping concentration on the structural and optical properties of zinc oxide nanoparticles

In this study, the optical and structural properties of Magnesium doped Zinc Oxide (Zn1-xMgxO) nanoparticles (x = 1%, 3%, and 5%) were examined. The synthesis was carried out at 300 oC by using a simple co-precipitation method. The structural samples were used to characterize the synthesized nanoparticles by using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD). Energy Dispersive X-Ray spectroscopy (EDX) was used to determine the chemical composition of the samples. Furthermore, UV-Vis spectroscopy was conducted to study our samples’ optical characteristics. As per XRD analysis, both pure and Mg doped ZnO samples possess wurtzite structure. The particle size was revealed to decrease significantly with Mg concentration, from 36 nm for pure sample to 23.87 nm with 5% Mg. In comparison to ZnO, the XRD pattern of Mg-doped ZnO shows a peak shift towards lower 2θ values. As a result of deformation of crystal structure caused by integrated Mg+2 ions onto Zn+2 sites. SEM images of synthesized samples reveal that the nanoparticles possess sheet, spherical and rod like morphologies for different values of x. The EDX analysis verifies the purity of samples within the detection limits. According to optical absorption spectra obtained from UV-Visible spectroscopy in the 200nm to 1000nm range affirmed that as Mg concentration increased, the band gap increased from 3.37 eV for pure sample to 3.74 eV with 5% Mg. The UV-Visible spectra of pure ZnO and Mg-doped ZnO samples also exhibit distinct peaks in the UV region at 335 nm, 311 nm, 310.6 nm, and 310 nm. Across the spectra of pure and Mg-doped ZnO samples, the UV peak is attributed to free exciton transitions, whereas, in the spectra of Mg-doped ZnO UV absorbance peak in the visible region is attributed to the radiative transitions of electrons captured at oxygen vacant sites with holes trapped at singly ionized oxygen vacancies.

Study of Radiation Damage Processes Caused by Hydrogen Embrittlement in Lithium Ceramics under High-Temperature Irradiation

The aim of this work is to study the hydrogenation processes in lithium-containing ceramics under high-temperature irradiation. Irradiation was carried out with protons with an energy of 1 MeV and fluences of 1015–1017 ion/cm2 at irradiation temperatures of 300–1000 K. The choice of irradiation conditions is due to the possibility of simulation of the radiation damage accumulation processes in the near-surface layer of Li2TiO3 ceramics, as well as establishing the dependences of changes in structural parameters during temperature heating of samples during irradiation. It has been established that at irradiation fluences of 1015–1016 ion/cm2, the formation of dislocation defects is observed, the density of which has a pronounced dependence on the irradiation temperature. At irradiation fluence above 5 × 1016 ion/cm2, an increase in the crystal structure deformation is observed, due to swelling processes as a result of implanted hydrogen accumulation in the near-surface layer structure. At the same time, an increase in the irradiation temperature leads to a decrease in the swelling value, which is due to the accelerated migration of implanted hydrogen in the near-surface layer and its release through the existing pores. Results of mechanical tests showed that the swelling of the crystal structure and its deformation leads to embrittlement and a partial decrease in the strength of the near-surface layer. The obtained research results will further allow us to evaluate the resistance of lithium ceramics to the processes of hydrogenation and destruction as a result of the formation of gas-filled cavities in the structure of the near-surface layer.

Crystal structure deformation and phase transition of AlScN thin films in whole Sc concentration range

This article reports lattice deformation and phase transition of AlScN thin films in the whole composition. AlScN films were deposited on Pt/Ta/SiO2/Si substrates by direct current magnetron reactive sputtering with Al and Sc targets. At Sc concentration up to 30%, AlScN has a wurtzite structure with piezoelectricity. Transition from a wurtzite phase to a two-phase mixture happens between 30% and 35% Sc concentration, and transition from a two-phase mixture to a cubic phase happens between 38% and 43% Sc concentration. The wurtzite structure gradually deforms with the decrease in lattice constant c from 16% to 35% Sc concentration. Lattice constant c at 38% Sc in the two-phase mixture region is larger than that of 35% Sc concentration. These increases mean that distortion of c axis for the wurtzite structure over 35% Sc concentration in the two-phase mixture region is considered to be released and/or eased due to the appearance of the cubic phase, and that Sc concentration of the wurtzite phase to be smaller and that of the cubic phase larger than the film composition measured by energy-dispersive x-ray spectroscopy and Rutherford backscattering spectroscopy. At higher Sc concentration up to 43%, the remained wurtzite phases are replaced by non-piezoelectric cubic phases, and the cubic structure approaches the rock-salt structure of ScN with a further increase in Sc concentration.

Molecular Dynamics Analysis of 6H-SiC Subsurface Damage by Nanofriction.

To investigate the subsurface damage of 6H-SiC nanofriction, this paper uses molecular dynamics analysis to analyze the loading process of friction 6H-SiC surfaces, thus providing an in-depth analysis of the formation mechanism of subsurface damage from microscopic crystal structure deformation characteristics. This paper constructs a diamond friction 6H-SiC nanomodel, combining the radial distribution function, dislocation extraction method, and diamond identification method with experimental analysis to verify the dislocation evolution process, stress distribution, and crack extension to investigate the subsurface damage mechanism. During the friction process, the kinetic and potential energies as well as the temperature of the 6H-SiC workpiece basically tend to rise, accompanied by the generation of dislocated lumps and cracks on the sides of the 6H-SiC workpiece. The stresses generated by friction during the plastic deformation phase lead to dislocations in the vicinity of the diamond tip friction, and the process of dislocation nucleation expansion is accompanied by energy exchange. Dislocation formation is found to be the basis for crack generation, and cracks and peeled blocks constitute the subsurface damage of 6H-SiC workpieces by diamond identification methods. Friction experiments validate microscopic crystal changes against macroscopic crack generation, which complements the analysis of the damage mechanism of the simulated 6H-sic nanofriction subsurface.

Quantum Chemical Study on Mefenamic Acid Polymorphic Forms.

Three polymorphic structures of mefenamic acid, which is a very popular drug, have been studied using quantum chemical methods. It has been shown that the centrosymmetric dimer formed due to two O–H···O hydrogen bonds is a complex building unit in all of the polymorphic structures under study. On the basis of an analysis of the pairwise interaction energies between molecules, the polymorphic forms I and II are classified as columnar-layered while the polymorphic form III has a columnar structure. The stabilities of the three polymorphic forms of mefenamic acid under ambient conditions (I > II > III) correlate with the degree of anisotropy of the interaction energies between columns (primary basic structural motifs) formed due to stacking interactions. The shear deformation modeling of strongly bound layers in all of the polymorphic structures has not revealed any possibility for deformation of the crystal structure. The construction of the shift energy profiles and calculation of the energy barriers for the displacement along the (100) crystallographic plane in the [100], [010], and [011] crystallographic directions make it possible to explain the experimental data obtained for commercially available polymorphic structure I in a diamond anvil cell. The absence of any local minimum near the starting point on the shift energy profile and the extremely high energy barrier can be considered as criteria for the impossibility of a crystal structure deformation under pressure.

Large negative thermal expansion induced by cation dimerization in ilmenite-type vanadate ceramic

A significant negative thermal expansion (NTE) in an ilmenite-type MgVO3 ceramic is reported in this paper. MgVO3 undergoes V–V dimerization at 500–550 K accompanied by a structural phase transition from the triclinic (low-temperature) to rhombohedral (high-temperature) phase. This transition induces a large anisotropic crystal structure deformation and results in a large NTE in the ceramic sample, which is caused by the microstructural effect. The NTE was observed over a temperature range of 450–630 K, and the total volume shrinkage reached approximately −0.7%. This study demonstrates that controlling the chemical bonding is a promising method for the creation of NTE materials.

Study on the infrared emissivity of nonstoichiometric titanium chromium nitride films

Nonstoichiometric titanium chromium nitride (TiCrN) thin films with different nitrogen stoichiometric ratio were prepared by reactive magnetron co-sputtering. The nitrogen stoichiometric ratio was adjusted by change in the sputtering power. The phase compositions, morphology, adhesion force, resistivity and infrared emissivity were studied systematically. The results show that the adhesion force increased with increasing of the nitrogen stoichiometric ratio. The crystallinity was poor and the grain size was small when the nitrogen stoichiometric ratio was 0.35, leading to a great increase of resistivity and infrared emissivity of TiCrN film. When the nitrogen stoichiometric ratio was 0.44, the films crystallized and severe deformation of TiCrN crystal structure led to high resistivity and infrared emissivity. After the nitrogen stoichiometric ratio reached 0.58, serious deformation of TiCrN crystal weakened, and the combined effect of crystal deformation and carrier density caused the variation of the infrared emissivity. The infrared emissivity value of TiCrN film with nitrogen stoichiometric ratio of 0.58 was almost close to the value with nitrogen stoichiometric ratio of 0.81. Reduction of nitrogen stoichiometric ratio appropriately or decrease of crystal deformation in nonstoichiometric crystal TiCrN films was beneficial to reduce the infrared emissivity. The infrared emissivity of TiCrN films could be reduced to about 0.3.

Study of Radiation Resistance to Helium Swelling of Li2ZrO3/LiO and Li2ZrO3 Ceramics

The key aim of this paper is to study the presence effect of LiO impurity phases in Li2ZrO3 ceramics on the resistance to helium swelling and structural degradation during implanted helium accumulation in the near-surface layer structure. The hypothesis put forward is based on a number of scientific papers, in which it was reported that the presence of two or more phases in lithium-containing ceramics led to a decrease in the rate of radiation damage and gas swelling due to the presence of additional interfacial boundaries that prevent the point defect accumulation. As a result of the evaluation of the crystal structure deformation, it was found that the presence of the LiO impurity phase in the structure of Li2ZrO3 ceramics led to a threefold decrease in the deformation of the crystal lattice due to helium swelling at doses of 5 × 1017–5 × 1018 ion/cm2. At the same time, the nature of the crystal lattice deformation for different ceramic types is different: in the case of Li2ZrO3 ceramics, an anisotropic distortion of the crystal structure is observed, in the case of Li2ZrO3/LiO ceramics, the crystal lattice deformation has an isotropic nature.

Crystal structure and octahedral deformation of orthorhombic perovskite ABO3: Case study of SrRuO3

Using density functional theory with local spin density approximation and taking SrRuO3 as an example, the crystal structure of ABO3 perovskite oxide and the rectangular deformation of the BO6 octahedron were studied. It was found that the degree of octahedral rectangular deformation of orthorhombic SrRuO3 is much larger than Jahn–Teller distortion, therefore, cannot be ignored. The lattice constant a is greater than b in SrRuO3 (as well as LaCrO3, LaGaO3, and PbRuO3) because the side length of rectangle along x direction, aoct, is larger than that along y direction, boct; and the tilting angle of the octahedron, φT, is smaller than arccos (boct/aoct). We found that in ABO3 oxide, BO6 octahedral rectangular deformation has a universality and, consequently, aoct ≠ boct. We discussed in detail the changes of lattice constants caused by rectangular deformation of the octahedron and divided orthorhombic ABO3 oxides into the following three categories: aoct ​> ​boct with a >b; aoct ​> ​boct with a <b; and aoct ​≤ ​boct with a <b. The relationship between the rectangular deformation and the rotation (tilting) angle or tolerance factor is analyzed. As the symmetry and lattice constants of SrRuO3 are rather inconsistent, we have analyzed and clarified them. The influence of rectangular deformation of the octahedron on the electronic structure and magnetic properties of SrRuO3 was also calculated using first principles.