Occupation Of Octahedral Sites Research Articles

Prior implantation of hydrogen as a mechanism to delay helium bubbles, blistering, and exfoliation in titanium

This study explores the delaying of the formation of helium bubbles and blisters in pure titanium by hydrogen pre-implantation. Titanium, implanted with helium (40 KeV, 5 × 1017 ions/cm²), exhibited large bubbles that cause exfoliation after heat treatment, whereas hydrogen pre-implantation inhibited bubble growth at room temperature and reduced the exfoliation after heat treatment.In the samples pre-implanted with hydrogen, we found evidence of helium diffusion delay by: (a) a fourfold reduction in bubble pressure (b) faceted cavities in the samples (c) a smaller increase in titanium lattice parameters (d) a 16-fold reduction in average bubble size and a sixfold reduction in bubble area fraction (e) a more than twofold decrease in exfoliation (f) a tendency toward the formation of larger bubbles as a result of heat treatment. We believe that it is reasonable to assume that the inhibition of helium diffusion between tetrahedral interstitial lattice sites takes place because of the occupation of the intermediate octahedral sites by hydrogen atoms.Evidence for the opposite effect, that is inhibition of the diffusion of hydrogen in the presence of helium, is found in the retention of hydrogen in the specimens at elevated temperatures. This retention allowed the existence of titanium hydride after heat treatment at 680 °C. The present study sheds light on the intricate interplay between hydrogen and helium in titanium, providing insights into mechanisms that can potentially mitigate helium-induced damage in materials.

Probing temperature-dependent magnetism in cobalt and zinc ferrites: A study through bulk and atomic-level magnetic measurements for spintronics

Spinel ferrites (MFe2O4) are integral to various industries, particularly spintronics, which utilizes the intrinsic spin of electrons as well as the electronic charge to develop devices that dictate spin-based transport, advancing new memory, logic applications, and improving magnetic storage technologies. These materials are valued for their exceptional optical, magnetic and electrical properties, and their easily tunable shape and size. This flexibility of spinel ferrites and their connection to the material’s magnetic behavior can be investigated by studying a range of spinel ferrite structures. In this study, the magnetic behaviors of cobalt ferrite (CFO) and zinc ferrite (ZFO) nanoparticles were examined using a vibrating sample magnetometer (VSM, bulk magnetometry) and X-ray Magnetic Circular Dichroism (XMCD, atomic magnetometry). The Rietveld refinement of XRD data supported single phase spinel structure, while X-ray Absorption Spectroscopy (XAS), particularly through the Co L-edge XANES analysis, detected both Co2+ and Co3+ ions in CFO, suggesting significant ferromagnetic behavior due to octahedral site occupation. In contrast, ZFO exhibited antiferromagnetic character, with Zn2+ ions in tetrahedral sites, and canted antiferromagnetism manifesting as a hysteresis loop below 300 K, potentially related to lattice distortions or strain. At the atomic scale, XMCD analysis, along with sum rules, estimated the average magnetic moments for cobalt and zinc ferrites to be 3.045 ± 0.1 (1.448 ± 0.1) and 0.657 ± 0.1 (2.12 ± 0.1) μB at temperatures of 300 K (90 K), respectively. However, VSM-based bulk measurements indicated magnetic moments of 2.566 (2.288) and 0.281 × 10−3 (0.6503 × 10−3) μB for CFO and ZFO, respectively, at the same temperatures. The observed variation between bulk and atomic-scale magnetic moments points to complex interstitial interactions within the spinel ferrite’s sublattices. This discrepancy between the atomic-scale and bulk magnetic moments suggests intricate interstitial interactions within the spinel ferrite’s sublattices. These insights into the structural and magnetic intricacies of spinel ferrite nanoparticles enhance our understanding, facilitating the design of cutting-edge spintronic devices.

Phase transitions and spectral shifts: a quantum mechanical exploration of vibrational frequency in magnesium ferrite.

Spinel ferrites represent an integral subset of magnetic materials, with their inherent properties largely influenced by cation occupancy and spin interaction. In this study, we present an in-depth theoretical exploration of the phase transition landscape of pure magnesium-ferrite, deploying hybrid functionals and a local Gaussian basis set to scrutinize the relaxed lattice structure, relative energy, magnetic properties, electronic characteristics, and vibrational frequencies. Our investigation reveals that the ground state of magnesium-ferrite is an open-shell system with an inverse structure. This is characterized by the complete occupancy of octahedral sites by magnesium atoms, with Iron atoms dispersed between both tetrahedral and octahedral sites. We found a relative energy difference of 0.41 eV between the antiferromagnetic ground configuration and the ferro arrangement within the inverse structure. Furthermore, our research also delved into the impact of spin rearrangement and inversion (X = 0.0, 0.5 and 1) on Raman and infrared spectra. Notably, the lattice distortion from the cubic form, apparent in the optimized structure, resonates in the IR and Raman spectra, resulting in significant splitting. The frequencies calculated in this study align well with experimental values, suggesting that the literature's current assignments warrant reevaluation in light of this new data. The results presented herein can be instrumental in detecting the phase of Mg ferrites from experimental spectra, thereby paving the way for a more profound comprehension of their properties and possible uses.

Enhancing optical and resistive characteristics of MnFe2O4 spinel ferrite through Ni2+ doping: An advancement in structural refinement

Spinel ferrites are highly notable magnetic materials with vast potential for applications in microwave and high-frequency transformer applications. Manganese ferrites (MnFe2O4) are selected for their excellent optical, magnetic, and resistive properties. This research presents a co-precipitation method for nickel (Ni2+) doping in manganese spinel ferrite (MnFe2O4) to advance structural refinement and subsequently enhance optical and resistive properties. It is confirmed that Ni2+ doping has affected the crystal lattice and possesses a single crystalline phase. The diffraction peak at 36.2° suggests increased Ni2+ ion incorporation, impacting unit cell dimensions, lattice parameters, and phase composition. The Ni2+ doping introduces the strong covalent M − O bonds at octahedral and tetrahedral sites which impacts the grain size to 20∼35 nm and crystallite size to 33.29–21.23 nm. Infrared analysis reveals that the increasing Ni2+ shifts the M − O stretch in the octahedral site to higher frequencies, indicating stronger and more covalent M − O bonding. The band gap reduction from 1.41 eV to 1.28 eV results from Ni2+ and Mn2+ ion substitution in the ferrite lattice, driven by sp-d exchange interactions with their localized electrons. The resistivity of MnFe2O4 is increased from 9.37 × 103 to 9.43 × 103 Ω m with Ni2+ doping. This effect is ascribed to the occupation of both octahedral and tetrahedral lattice sites by Ni2+ ions. This communication conclusively establishes nickel as the optimal dopant for spinel ferrite, showcasing its versatility for a wide range of applications.

Correlation of MgO loading to spinel inversion, octahedral site occupancy, site generation and performance of bimetal Co–Ni catalyst for dry reforming of CH4

The influence of MgO content on the structural characteristics and performance of bimetallic Co–Ni catalyst was investigated for CO2 reforming of CH4. Three different catalysts with the same amount of active metals (Co and Ni) but different Mg loading in the Mg–Al support were prepared by co-precipitation method. The catalysts were subjected to different characterization techniques to obtain information about their bulk, structural, textural properties, site formation and performance for DRM. Results showed there was reduction in the surface area (N2 adsorption), a change from a single bulk phase spinel to dual-phase (XRD), and an increase in the degree of spinel inversion (Al-NMR) from 0.29 to 0.57, as the MgO loading changed from 25% to 65% in the support. There was also improved support basicity (CO2-TPD), metal support interaction changed (STEM EDX), the ease of metal reduction and site formation (Ni/Co K-edge XANES) became better as the MgO loading increased. Improved MgO loading facilitated the formation of inverse spinel and MgO - Ni/Co solid phase, which enhanced better reactants conversion and faster conversion of deposited carbon from the catalysts surface during DRM.

Effect of reaction path on high-pressure synthesis and stability of ruthenium hydrides

This study explores the behavior of ruthenium hydrides under high-pressure conditions through three thermodynamical paths using laser-heated diamond anvil cells. The synthesis of RuH0.9 occurs gradually exceeding the pressure of 23.5 GPa in the ambient temperature path, while RuH is successfully synthesized at pressures above 20 GPa and a temperature of 1500 K. High-temperature conditions are found to reduce the pressure required for synthesis. The results demonstrate that the hydrogen occupancy of octahedral interstitial sites in the ruthenium hydrides is found to reach saturation with complete hydrogen absorption in the high-temperature path. Moreover, the crystallinity of the ruthenium hydride samples improves at higher temperatures, with the grain size increasing from 10 nm in the ambient temperature path to submicron in the high-temperature path. However, the predicted RuH6 and RuH3 were not observed in the present work.

Synthesis of spinel ferrites and application in the photodegradation of Rhodamine in water via pH control assistance

Nanostructured powders of cobalt ferrite with stoichiometry CoxFe3-xO4, where 0.4 ≤ x ≤ 1.2, were synthesized by the wet chemical route from the Co-precipitation method. Single-phase and crystalline nanopowders of spinel type structure with cubic symmetry and space group Fd3‾m were characterized by X-ray diffraction. The structural refinement was carried out by the Rietveld Method showing a transition of normal spinel to an inverse spinel, as a function of Co2+concentration. Both spectra, Infrared Spectroscopy and Diffuse reflectance spectroscopy were used to characterize chemical bonds Co2+ in tetrahedral coordination, for higher cobalt concentration, and band gap analysis, respectively. The photoactivity of powders was evaluated from the photodegradation of the Rhodamine 6G dye under UV light. CoFe2O4 nanoparticles showed the best photocatalytic degradation with 90.9% in an alkaline medium, which obeys a pseudo-first order kinetic reaction, being the maximum apparent rate constant equal to 10.23 × 10−3. Effects of the occupation of tetrahedral and octahedral sites in the spinel structure in the photoactivity parameter are discussed.

Enhancing the Liquefied Petroleum Gas Sensing Sensitivity of Mn-Ferrite with Vanadium Doping

Mn-Ferrite with a nanostructure is a highly valuable material in various technological fields, such as electronics, catalysis, and sensors. The proposed article presents the hydrothermal synthesis of Mn-ferrite doped with V (V) ions. The range of the doping level was from 0.0 to x to 0.20. The fluctuation in tetrahedral and octahedral site occupancies with Fe (III), Mn (II), and V (V) ions was coupled to the variation in unit cell dimensions, saturation magnetization, and LPG sensing sensitivity. The total magnetic moment shows a slow decrease with V-doping up to x = 0.1 (Ms = 51.034 emu/g), then sharply decreases with x = 0.2 (Ms = 34.789 emu/g). The dimension of the unit cell increases as x goes up to x = 0.1, then lowers to x = 0.2. As the level of V (V) ion substitution increases, the microstrain (ε) also begins to rise. The ε of a pure MnFe2O4 sample is 3.4 × 10−5, whereas for MnFe2−1.67 xVxO4 (x = 0.2) it increases to 28.5 × 10−5. The differential in ionic sizes between V (V) and Fe (III) and the generation of cation vacancies contribute to the increase in ε. The latter is created when a V (V) ion replaces 1.6 Fe (III) ions. V-doped MnFe2O4 displays improved gas-sensing ability compared to MnFe2O4 at lower operating temperature. The maximum sensing efficiency was observed for 2 wt% V-doped MnFe2O4 at a 200 °C optimum operating temperature.

A detailed structural analysis, morphological and optical study of Mg-Zn nano ferrite

Mg-Zn nanoferrite with the composition of Mg0.4Zn0.6Fe2O4 was prepared using the citrate precursor process. Detailed structural analysis was performed on Mg-Zn nanoferrite to calculate crystallite size, lattice constant, X-ray density, bulk density, and porosity using XRD data. Also, the strain on the sample was calculated by plotting Williamson – Hall (W-H) plot. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) were performed to study morphological and optical properties. The spinel structure was confirmed by XRD with a crystallite size of 38 nm. SEM micrograph of the sample showed almost spherical-shaped nanoparticles. FTIR spectra disclosed two characteristic bands showing tetrahedral (A) and octahedral (B) site occupancies. Under UV–visible light irradiation, photocatalytic degradation of rhodamine B dye and the degradation efficiency is obtained to be 70 % in 60 min. Therefore, it is concluded that Mg0.4Zn0.6Fe2O4 is a promising material for water purification.

Engineering of Cation Occupancy of CoFe2O4 Oxidation Catalysts by Nanosecond, Single‐Pulse Laser Excitation in Water

AbstractDue to the variability of the cation occupancy of octahedral and tetrahedral sites, spinel ferrites and cobaltites are particularly interesting to investigate activity trends in oxidation catalysis. Yet, the preparation of the respective catalyst series remains challenging. We employed pulsed laser defect engineering of CoFe2O4 nanoparticles in water to gradually alter the cation occupancy of octahedral and tetrahedral sites by single laser pulses and study its effect on cinnamyl alcohol oxidation. Three CoFe2O4 catalysts from different synthesis methods resembling different initial site occupancy were chosen as starting materials. The laser‐induced randomization of the cation occupancy was verified by Mössbauer spectroscopy and linearly correlated with the conversion of cinnamyl alcohol while the size and Co : Fe ratio was maintained during laser processing. The study solidifies the importance of octahedral Co3+‐sites and the feasibility of pulsed laser processing for altering the cation occupancy and related crystallographic defect density in oxidation catalysis.

Li5 SnP3 - a Member of the Series Li10+4x Sn2-x P6 for x=0 Comprising the Fast Lithium-Ion Conductors Li8 SnP4 (x=0.5) and Li14 SnP6 (x=1).

The targeted search for suitable solid‐state ionic conductors requires a certain understanding of the conduction mechanism and the correlation of the structures and the resulting properties of the material. Thus, the investigation of various ionic conductors with respect to their structural composition is crucial for the design of next‐generation materials as demanded. We report here on Li5SnP3 which completes with x=0 the series Li10+4x Sn2−x P6 of the fast lithium‐ion conductors α‐ and β‐Li8SnP4 (x=0.5) and Li14SnP6 (x=1). Synthesis, crystal structure determination by single‐crystal and powder X‐ray diffraction methods, as well as 6Li, 31P and 119Sn MAS NMR and temperature‐dependent 7Li NMR spectroscopy together with electrochemical impedance studies are reported. The correlation between the ionic conductivity and the occupation of octahedral and tetrahedral sites in a close‐packed array of P atoms in the series of compounds is discussed. We conclude from this series that in order to receive fast ion conductors a partial occupation of the octahedral vacancies seems to be crucial.

Time-resolved x-ray diffraction and photoelectron spectroscopy investigation of the reactive molecular beam epitaxy of Fe3O4 ultrathin films

We present time-resolved high energy x-ray diffraction (tr-HEXRD), time-resolved hard x-ray photoelectron spectroscopy (tr-HAXPES) and time-resolved grazing incidence small angle x-ray scattering (tr-GISAXS) data of the reactive molecular beam epitaxy (RMBE) of $\mathrm{Fe_3O_4}$ ultrathin films on various substrates. Reciprocal space maps are recorded during the deposition of $\mathrm{Fe_3O_4}$ on $\mathrm{SrTiO_3(001)}$, MgO(001) and NiO/MgO(001) in order to observe the temporal evolution of Bragg reflections sensitive to the octahedral and tetrahedral sublattices of the inverse spinel structure of $\mathrm{Fe_3O_4}$. A time delay between the appearance of rock salt and spinel-exclusive reflections reveals that first, the iron oxide film grows with $\mathrm{Fe_{1-\delta}O}$ rock salt structure with exclusive occupation of octahedral lattice sites. When this film is 1.1$\,$nm thick, the further growth of the iron oxide film proceeds in the inverse spinel structure, with both octahedral and tetrahedral lattice sites being occupied. In addition, iron oxide on $\mathrm{SrTiO_3(001)}$ initially grows with none of these structures. Here, the formation of the rock salt structure starts when the film is 1.5$\,$nm thick. This is confirmed by tr-HAXPES data obtained during growth of iron oxide on $\mathrm{SrTiO_3(001)}$, which demonstrate an excess of $\mathrm{Fe^{2+}}$ cations in growing films thinner than 3.2$\,$nm. This rock salt phase only appears during growth and vanishes after the supply of the Fe molecular beam is stopped. Thus, it can be concluded the rock salt structure of the interlayer is a property of the dynamic growth process. The tr-GISAXS data link these structural results to an island growth mode of the first 2-3$\,$nm on both MgO(001) and $\mathrm{SrTiO_3(001)}$ substrates.

Structural Insights into Multi-Metal Spinel Oxide Nanoparticles for Boosting Oxygen Reduction Electrocatalysis.

Multi-metal oxide (MMO) materials have significant potential to facilitate various demanding reactions by providing additional degrees of freedom in catalyst design. However, a fundamental understanding of the (electro)catalytic activity of MMOs is limited because of the intrinsic complexity of their multi-element nature. Additional complexities arise when MMO catalysts have crystalline structures with two different metal site occupancies, such as the spinel structure, which makes it more challenging to investigate the origin of the (electro)catalytic activity of MMOs. Here, uniform-sized multi-metal spinel oxide nanoparticles composed of Mn, Co, and Fe as model MMO electrocatalysts are synthesized and the contributions of each element to the structural flexibility of the spinel oxides are systematically studied, which boosts the electrocatalytic oxygen reduction reaction (ORR) activity. Detailed crystal and electronic structure characterizations combined with electrochemical and computational studies reveal that the incorporation of Co not only increases the preferential octahedral site occupancy, but also modifies the electronic state of the ORR-active Mn site to enhance the intrinsic ORR activity. As a result, nanoparticles of the optimized catalyst, Co0.25 Mn0.75 Fe2.0 -MMO, exhibit a half-wave potential of 0.904V (versus RHE) and mass activity of 46.9 A goxide -1 (at 0.9V versus RHE) with promising stability.

Correlation of Mgo Loading, Spinel Inversion, Octahedral Site Occupancy, Site Generation and Performance of Bimetal Co-Ni Catalyst Agent for Dry Reforming

Correlation of Mgo Loading, Spinel Inversion, Octahedral Site Occupancy, Site Generation and Performance of Bimetal Co-Ni Catalyst Agent for Dry Reforming

The origin of anomalous hydrogen occupation in high entropy alloys

The hydrogen to metal ratio of high entropy alloys (HEAs) can exceed 2 due to the simultaneous occupation of tetrahedral and octahedral sites by hydrogen. Such anomalous hydrogen occupations originate from the chemical disordering in HEAs.

Crystal chemistry and partitioning of halogens in hydrous silicates

Understanding how halogens are distributed among usual hydrous silicates in the lithosphere is important to constrain their deep geochemical cycle and fluid-rock interactions in subduction zones. This article presents first-principles modelling of halogen (F−, Cl−, Br−) incorporation in hydrous silicates including mica, chlorite, serpentine, amphibole, epidote and carpholite. The approach allows studying the impact of crystal chemistry on halogen partitioning by quantification of the energetic cost of halogen incorporation in minerals. Calculations are carried out in large systems where halogens are in minor to trace concentrations. Estimations show that F-bearing defects must be separated at least 9 Å from one another to reproduce trace element behaviour, this value increasing to at least 10 Å for Cl and Br. Results highlight the competition between the effects of electrostatic interactions and steric hindrance for incorporation of halogens, where steric hindrance has greater importance for heavy halogens, in particular for Br. Interaction with alkalis is a major control for F incorporation, especially in mica. Other parameters such as octahedral site occupancy, Si/Al ratio of tetrahedral sites and the nature of alkalis in amphibole and mica (K or Na) appear to play subordinate roles. Partition coefficients have been estimated in mineral assemblages in an effort to be representative of subduction zone metamorphism. Results show that pargasite, biotite and lizardite are favoured hosts for all three halogens, followed by clinochlore, tremolite and carpholite. The energetic cost of incorporating halogens into dioctahedral phyllosilicates and epidote is comparatively higher, and partitioning is predicted as unfavourable to these minerals. Fractionation between halogens in subduction zones is predicted by the evolution of mineral assemblages and partition coefficients, a consequence of the influence of crystal chemistry over halogen incorporation in hydrous silicates.

Chemical Control of the Dimensionality of the Octahedral Network of Solar Absorbers from the CuI-AgI-BiI3 Phase Space by Synthesis of 3D CuAgBiI5.

A newly reported compound, CuAgBiI5, is synthesized as powder, crystals, and thin films. The structure consists of a 3D octahedral Ag+/Bi3+ network as in spinel, but occupancy of the tetrahedral interstitials by Cu+ differs from those in spinel. The 3D octahedral network of CuAgBiI5 allows us to identify a relationship between octahedral site occupancy (composition) and octahedral motif (structure) across the whole CuI–AgI–BiI3 phase field, giving the ability to chemically control structural dimensionality. To investigate composition–structure–property relationships, we compare the basic optoelectronic properties of CuAgBiI5 with those of Cu2AgBiI6 (which has a 2D octahedral network) and reveal a surprisingly low sensitivity to the dimensionality of the octahedral network. The absorption onset of CuAgBiI5 (2.02 eV) barely changes compared with that of Cu2AgBiI6 (2.06 eV) indicating no obvious signs of an increase in charge confinement. Such behavior contrasts with that for lead halide perovskites which show clear confinement effects upon lowering dimensionality of the octahedral network from 3D to 2D. Changes in photoluminescence spectra and lifetimes between the two compounds mostly derive from the difference in extrinsic defect densities rather than intrinsic effects. While both materials show good stability, bulk CuAgBiI5 powder samples are found to be more sensitive to degradation under solar irradiation compared to Cu2AgBiI6.

Doped MgAl2O4 semiconductor host nanopowders for tunable primary color emissions for application as white LEDs

The emission of white light from hosts having a single phase and the compromised applicability of a very inert, chemically stable, and structurally diverse MgAl2O4 led to a quest for improving the structural, optical, thermal and electrical properties for more innovative applications. A slight modification in lattice site occupation can lead to antisite defects which alter the physical properties of the materials. The presence of larger alkaline earth Sr2+ cations at the T-sites have been found to improve the behavior of the activator Mn2+ cations which are substituted for Mg2+ at T-sites. In the current study, a series of Mn2+ doped derivatives having a general formula of Mg1−x−0.3Mn x Sr0.3Al2O4 (x = 0.1–0.5) were synthesized using the chemical co-precipitation method. Due to the larger radius of Sr2+ cations, the lattice strain was observed in the cubic crystal structure of magnesium aluminate spinel (MAS). A decrease in the bandgaps of the doped samples indicates the formation of defect states within the bandgap of MAS. Apart from the bandgap transitions, the capture of electrons at oxygen vacancies is also observed in the UV/Vis spectra. The strong tetrahedral site preference of Mn2+ is altered by the presence of Sr2+, hence, some octahedral site occupation of Mn2+ in the lattice is achieved. The antisite defects along with the occupation of both T- and O-sites by Mn2+ resulted in novel emission bands centered at 464 nm (blue), 515 nm (green), and 621 nm (red) at λ ex of 380 nm. The emission of the primary colors in a simple lattice with cost-effective and in-toxic constituents can be a possible alternative to the costly rare-earth ions doped complex materials in use to-date.

Low temperature synthesis and influence of Ce3+ substitution on structural and magnetic properties of nanocrystalline cobalt ferrite using citrate precursor sol-gel method

Rare earth element Ce3+ substituted spinel cobalt ferrite, CoFe2-xCexO4 for (x = 0.0, 0.05, 0.10, 0.15, 0.20) is synthesized using an economical sol–gel technique. The X-ray diffraction analysis reveals that all samples have spinel symmetry indexed to Fd3m space group. Fullprof Rietveld analysis is performed to find out lattice parameters that increase monotonically due to induced lattice strains in samples. The crystallite size was determined to be 54.9 nm using Williamson-Hall plots. The morphological analysis of samples has been performed using SEM imaging. FTIR spectrum confirms octahedral and tetrahedral site occupancy by metal–oxygen bonds for all samples. The magnetic properties of samples refine with Ce3+ doping at iron site, with magnetization ranging from 23.59 to 57.68 emu/g and retentivity 17.14 to 24.08 emu/g. The Coercive field values drastically increased from 739 to 1912 Gauss. Thus, we have explored the influence of rare earth Ce3+ (1.14 Å) substitution at the Fe3+ site (0.55 Å) in CoFe2O4 crystal lattice for improvement of its structural and magnetic properties in this paper.

The role of Li site occupancy on the Li-ion conductivity of Ta-doped Li6.75La3Zr1.75Ta0.25O12 solid electrolyte materials with high Li concentrations

Garnet-type Li7La3Zr2O12 has attracted much attention because of its promising properties of high ionic conductivity, good chemical stability against Li metal, and good mechanical strength. To better understand the Li conduction mechanism, the Li site occupancy and Li-ion conductivity are studied with a high Li concentration in the range of 6.70–7.15 mol per formula unit. Aluminum and silicon, which presumably were transferred to the sample from the Al2O3 crucible during processing, were included in the cubic garnet structure for the Rietveld refinements. The Li-ion conductivity increases with the occupancy of the octahedral Li site (Occupancy: 0.78–0.87, Li-ion conductivity: 3–5 × 10−4 S/cm). As the lithium content increases, the portion of lithium occupying the 96 h octahedral site increases and that occupying the 24d tetrahedral site decreases.