Abstract Hybrid organic–inorganic perovskites (HOIPs) are promising candidates for next‐generation photovoltaic materials. However, there is a debate regarding the impact of interactions between the organic center and the surrounding inorganic cage on the solar cell's high diffusion lengths. It remains unclear whether the diffusion mechanism is consistent across various halide perovskite families and how light illumination affects carrier lifetimes. The focus is on ion kinetics of (CH3NH3)PbX3 (X = Br, Cl) perovskite halide single crystals. Muon spectroscopy (μ+SR)is employed to investigate the fluctuations and diffusion of ions via the relaxation of muon spins in local nuclear field environments. Within a temperature range of 30–340 K, ion kinetics are studied with and without white‐light illumination. The results show a temperature shift of the tetragonal‐orthorhombic phase transition on the illuminated samples, as an effect of increased organic molecule fluctuations. This relation is supported by density functional theory (DFT) calculations along the reduction of the nuclear field distribution width between the phase transitions. The analysis shows that, depending on the halide ion, the motional narrowing from H and N nuclear moments represents the molecular fluctuations. The results demonstrate the importance of the halide ion and the effect of illumination on the compound's structural stability and electronic properties.

Advanced Physics ResearchVolume 3, Issue 3 2470008 Back CoverOpen Access Photophysical Ion Dynamics in Hybrid Perovskite MAPbX3 (X=Br, Cl) Single Crystals (Adv. Phys. Res. 3/2024) Konstantinos Papadopoulos, Konstantinos PapadopoulosSearch for more papers by this authorOla Kenji Forslund, Ola Kenji ForslundSearch for more papers by this authorStephen Cottrell, Stephen CottrellSearch for more papers by this authorKoji Yokoyama, Koji YokoyamaSearch for more papers by this authorPabitra K. Nayak, Pabitra K. NayakSearch for more papers by this authorFrancoise M. Amombo Noa, Francoise M. Amombo NoaSearch for more papers by this authorLars Öhrström, Lars ÖhrströmSearch for more papers by this authorElisabetta Nocerino, Elisabetta NocerinoSearch for more papers by this authorLars Börjesson, Lars BörjessonSearch for more papers by this authorJun Sugiyama, Jun SugiyamaSearch for more papers by this authorMartin Månsson, Martin MånssonSearch for more papers by this authorYasmine Sassa, Yasmine SassaSearch for more papers by this author Konstantinos Papadopoulos, Konstantinos PapadopoulosSearch for more papers by this authorOla Kenji Forslund, Ola Kenji ForslundSearch for more papers by this authorStephen Cottrell, Stephen CottrellSearch for more papers by this authorKoji Yokoyama, Koji YokoyamaSearch for more papers by this authorPabitra K. Nayak, Pabitra K. NayakSearch for more papers by this authorFrancoise M. Amombo Noa, Francoise M. Amombo NoaSearch for more papers by this authorLars Öhrström, Lars ÖhrströmSearch for more papers by this authorElisabetta Nocerino, Elisabetta NocerinoSearch for more papers by this authorLars Börjesson, Lars BörjessonSearch for more papers by this authorJun Sugiyama, Jun SugiyamaSearch for more papers by this authorMartin Månsson, Martin MånssonSearch for more papers by this authorYasmine Sassa, Yasmine SassaSearch for more papers by this author First published: 07 March 2024 https://doi.org/10.1002/apxr.202470008AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinkedInRedditWechat Graphical Abstract Photophysical Ion Dynamics In article number 2300120, Konstantinos Papadopoulos, Ola Kenji Forslund, Yasmine Sassa, and co-workers conduct a muon spin relaxation (μ+SR) study of hybrid perovskite MAPbX3 (X=Br, Cl) single crystals with and without illumination. The experimental and simulation results demonstrate an increase in organic molecule fluctuations under illumination, depending on the choice of the halide ion. These effects are correlated with the structural transformations and long carrier lifetimes observed in perovskite solar cells. Volume3, Issue3March 20242470008 RelatedInformation

The magnetism of double perovskites is a complex phenomenon, determined from intra- or interatomic magnetic moment interactions, and strongly influenced by geometry. We take advantage of the complementary length and timescales of the muon spin rotation, relaxation, and resonance (mu+SR) microscopic technique and bulk ac/dc magnetic susceptibility measurements to study the magnetic phases of the LaCaNiReO6 double perovskite. As a result, we are able to discern and report ferrimagnetic ordering below TC = 102 K and the formation of different magnetic domains above TC. Between TC < T < 270 K, the following two magnetic environments appear, a dense spin region and a static-dilute spin region. The paramagnetic state is obtained only above T > 270 K. An evolution of the interaction between Ni and Re magnetic sublattices, in this geometrically frustrated fcc perovskite structure, is revealed as a function of temperature through the critical behavior and thermal evolution of microscopic and macroscopic physical quantities.

The magnetism of double perovskites is a complex phenomenon, determined from intra- or interatomic magnetic moment interactions, and strongly influenced by geometry. We take advantage of the complementary length and time scales of the muon spin rotation, relaxation and resonance ($μ^+$SR) microscopic technique and bulk AC/DC magnetic susceptibility measurements to study the magnetic phases of the LaCaNiReO$_6$ double perovskite. As a result we are able to discern and report a newly found dynamic phase transition and the formation of magnetic domains below and above the known magnetic transition of this compound at T$_N$ = 103 K. $μ^+$SR, serving as a local probe at crystallographic interstitial sites, reveals a transition from a metastable ferrimagnetic ordering below T = 103 K to a stable one below T = 30 K. The fast and slow collective dynamic state of this system are investigated. Between 103 K < T < 230 K, the following two magnetic environments appear, a dense spin region and a static-dilute spin region. The paramagnetic state is obtained only above T > 270 K. An evolution of the interaction between Ni and Re magnetic sublattices in this geometrically frustrated fcc perovskite structure, is revealed as a function of temperature and magnetic field, through the critical behaviour and thermal evolution of microscopic and macroscopic physical quantities.

We report results from visible and UV Raman spectroscopy studies of the phonon spectra of a polycrystalline sample of the prototypical perovskite type oxide BaZrO(3)and a 500 nm thick film of its Y-doped, proton conducting, counterpart BaZr0.8Y0.2O2.9. Analysis of the Raman spectra measured using different excitation energies (between 3.44 eV and 5.17 eV) reveals the activation of strong resonance Raman effects involving all lattice vibrational modes. Specifically, two characteristic energies were identified for BaZrO3, one around 5 eV and one at higher energy, respectively, and one for BaZr0.8Y0.2O2.9, above 5 eV. Apart from the large difference in spectral intensity between the non-resonant and resonant conditions, the spectra are overall similar to each other, suggesting that the vibrational spectra of the perovskites are stable when investigated using an UV laser as excitation source. These results encourage further use of UV Raman spectroscopy as a novel approach for the study of lattice vibrational dynamics and local structure in proton conducting perovskites, and open up for, e.g., time-resolved experiments on thin films targeted at understanding the role of lattice vibrations in proton transport in these kinds of materials.

Combined INS and DFT study on BaTiO3−xHx unravels the effect of oxygen vacancies on the vibrational dynamics of hydride ions.

Acceptor-doped barium zirconate-based proton conductors are currently receiving considerable attention because of their promise as electrolytes in future electrochemical devices, such as solid oxide fuel cells, but the defect chemistry, especially in regard to the local coordination environment and dynamics of protons in these materials, is unclear. Here, we investigate the local coordination environments and vibrational dynamics of protons in samples of the proton conducting material BaZr1-xMxO3Hx with M = In and Sc, and x = 0.1 and 0.5, using inelastic neutron scattering (INS), infrared (IR), and Raman spectroscopy together with ab initio molecular dynamics (AIMD) simulations. The local coordination of protons is shown to exhibit a rather peculiar dependence on the type and concentration of dopant atoms, as they are found to be similar for BaZr1-xScxO3Hx with x = 0.1 and 0.5 and BaZr1-xInxO3Hx with x = 0.1, whereas for BaZr1-xInxO3Hx with x = 0.5 additional proton sites seem to be present. It is argued that these additional proton sites are characterized by local structural arrangements reminiscent of the fully In-substituted material BaInO3H. The presence of these local structural arrangements points toward different local proton mobilities between BaZr1-xInxO3Hx with x = 0.5 and the other three materials and a higher rate of proton transfer events in brownrnillerite-type local structures.

Long-range proton diffusion through a percolation pathway of dopant atoms in acceptor doped barium zirconate.

Epitaxial thin films of the proton-conducting perovskite BaZr0.53In0.47O3-delta H0.47-2 delta, grown by pulsed laser deposition, were investigated in their hydrated and dehydrated conditions through a multitechniqu approach with the aim to study the structure and proton concentration depth profile and their relationship to proton conductivity. The techniques used were X-ray diffraction, X-ray and neutron reflectivity, nuclear reaction analysis, and Rutherford backscattering, together with impedance spectroscopy. The obtained proton conductivity and activation energy are comparable to literature values for the bulk conductivity of similar materials, thus showing that grain-boundary conductivity is negligible due to the high crystallinity of the film. The results reveal an uneven proton concentration depth profile, with the presence of a 3-4 nm thick, proton-rich layer with altered composition, likely characterized by cationic deficiency. While this surface layer either retains or reobtains protons after desorption and cooling to room temperature, the bulk of the film absorbs and desorbs protons in the expected mariner. It is suggested that the protons in the near-surface, proton rich region are located in proton sites characterized by relatively strong O-H bonds due to weak hydrogen-bond interactions to neighboring oxygen atoms and that the mobility of protons in these sites is generally lower than in proton sites associated with stronger hydrogen bonds. It follows that strongly hydrogen-bonding configurations are important for high proton mobility.

The structure and dehydration mechanism of the proton conducting oxide Ba2In2O5(H2O)(x) are investigated by means of variable temperature (20-600 degrees C) Raman spectroscopy together with thermal gravimetric analysis and inelastic neutron scattering. At room temperature, Ba2In2O5(H2O)(x) is found to be fully hydrated (x = 1) and to have a perovskite-like structure, which dehydrates gradually with increasing temperature and at around 600 degrees C the material is essentially dehydrated (x approximate to 0.2). The dehydrated material exhibits a brownmillerite structure, which is featured by alternating layers of InO6 octahedra and InO4 tetrahedra. The transition from a perovskite-like to a brownmillerite-like structure upon increasing temperature occurs through the formation of an intermediate phase at ca. 370 degrees C, corresponding to a hydration degree of approximately 50%. The structure of the intermediate phase is similar to the structure of the dehydrated material, but with the difference that it exhibits a non-centrosymmetric distortion of the InO6 octahedra that is not present in the dehydrated material. The dehydration process upon heating is a two-stage mechanism; for temperatures below the hydrated-to-intermediate phase transition, dehydration is characterized by a homogenous release of protons over the entire oxide lattice, whereas above the transition a preferential desorption of protons originating in the nominally tetrahedral layers is observed. Furthermore, our spectroscopic results point towards the co-existence of two structural phases, which relate to the two lowest-energy proton configurations in the material. The relative contributions of the two proton configurations depend on how the sample is hydrated.

Proton conducting oxides are currently accumulating considerable attention due to their potential as efficient electrolytes in various electrochemical technologies, including intermediate temperature solid oxide fuel cells [1].An important material is the brownmillerite structured oxide Ba 2 In 2 O 5 , which may be described as an oxygen deficient variant of the perovskite structure, with alternating layers of InO 6 octahedra and InO 4 tetrahedra.Like many other oxygen-deficient oxides, Ba 2 In 2 O 5 transforms upon hydration into a hydrogen-containing material, Ba 2 In 2 O 5 (H 2 O) x , which show proton conducting properties.In this contribution, I will report on detailed investigations of the local structure and dehydration mechanism of Ba 2 In 2 O 5 (H 2 O) x , using a combination of variable temperature Raman spectroscopy together with inelastic neutron scattering and computer simulations [2,3].The results suggest that Ba 2 In 2 O 5 (H 2 O) x evolves upon heating from a perovskite-like structure for the fully hydrated material (x = 1) at room temperature, through a partially hydrated intermediate phase, appearing at ca. 370 °C, to an essentially fully dehydrated (x ≈ 0) brownmillerite material at 600 °C.The dehydration process appears to be a two-stage mechanism characterized by a homogenous release of protons below the hydrated-to-intermediate phase transition, whereas at higher temperatures a preferential desorption of protons originating in the nominally tetrahedral layers is observed.

The structure and dehydration mechanism of the proton conducting oxide Ba_2In_2O_5(H_2O)_x are investigated by means of variable temperature Raman spectroscopy together with inelastic neutron scattering. At room temperature, Ba_2In_2O_5(H_2O)_x is found to be fully hydrated (x=1) and to have a perovskite-like structure, which dehydrates gradually with increasing temperature and at around 600 ^∘C the material is essentially completely dehydrated (x=0). The dehydrated material exhibits a brownmillerite structure, which is featured by alternating layers of InO_6 octahedra and InO_4 tetrahedra. The transition from a perovskite-like to a brownmillerite-like structure is featured by a hydrated-to-intermediate phase transition at ca. 370 C. The structure of the intermediate phase is similar to the structure of the fully dehydrated material, but with the difference that it exhibits a non-centrosymmetric distortion of the InO_6 octahedra not present in the latter. For temperatures below the hydrated-to-intermediate phase transition, dehydration is featured by the release of protons confined to the layers of InO_4 tetrahedra, whereas above the transition also protons bound to oxygens of the layers of InO_6 are released. Finally, we found that the O-H stretch region of the vibrational spectra is not consistent with a single-phase spectrum, but is in agreement with the superposition of spectra associated with two different proton configurations. The relative contributions of the two proton configurations depend on how the sample is hydrated.

The vibrational spectra and short-range structure of the brownmillerite-type oxide Ba2In2O6 and its hydrated form BaInO3H, are investigated by means of Raman, infrared, and inelastic neutron scattering spectroscopies together with density functional theory calculations. For Ba2In2O6, which may be described as an oxygen deficient perovskite structure with alternating layers of InO6 octahedra and InO4 tetrahedra, the results affirm a short-range structure of Icmm symmetry, which is characterized by random orientation of successive layers of InO4 tetrahedra. For the hydrated, proton conducting, form, BaInO3H, the results suggest that the short-range structure is more complicated than the P4/mbm symmetry that has been proposed previously on the basis of neutron diffraction, but rather suggest a proton configuration close to the lowest energy structure predicted by Martinez et al. [J.-R. Martinez, C. E. Moen, S. Stoelen, N. L. Allan, J. Solid State Chem., 180, 3388, (2007)]. An intense Raman active vibration at 150 cm(-1) is identified as a unique fingerprint of this proton configuration.

We present results on the temperature dependence of ultrafast electron and lattice dynamics, measured with pump-probe transient reflectivity experiments, of an epitaxially grown LaCoO3 thin film under tensile strain. Probing spin-polarized transitions into the antibonding e(g) band provides a measure of the low-spin fraction, both as a function of temperature and time after photoexcitation. It is observed that femtosecond laser pulses destabilize the constant low-spin fraction (similar to 63%-64%) in equilibrium into a thermally activated state, driven by a subpicosecond change in spin gap Delta. From the time evolution of the low-spin fraction, it is possible to disentangle the thermal and lattice contributions to the spin state. A lattice mediated spin repulsion, identified as the governing factor determining the equilibrium spin state in thin-film LaCoO3, is observed. These results suggests that time-resolved spectroscopy is a sensitive probe of the spin state in LaCoO3 thin films, with the potential to bring forward quantitative insight into the complicated interplay between structure and spin state in LaCoO3.

The crystal and magnetic structures of multiferroic Bi0.9La0.1FeO3 have been studied using high resolution neutron powder diffraction in the pressure range 0-8 GPa. Two structural phase transitions are observed. The first, at similar to 1 GPa, transforms the polar R3c structure to an antipolar PbZrO3-like root 2a(p) x 2 root 2a(p) x 2a(p) perovskite superstructure; the second, at similar to 5 GPa, results in a smaller, root 2a(p) x root 2a(p) x 2a(p) unit cell and a structure described with Ibmm (nonstandard setting of Imma) symmetry, in which the a(-)a(-)b(0) octahedral tilt system is retained and the antipolar cation displacements lost. Accompanying the changes in the nuclear structure, the antiferromagnetic spin structure evolves from a cycloid, with a modulation length, lambda approximate to 770 angstrom, to collinear arrangements with the moments aligned along the b-axis (Pbam) and the a-axis (Ibmm) of the orthorhombic unit cells. In comparison with BiFeO3 the transition from a rhombohedral to an orthorhombic structure is suppressed by similar to 3 GPa, reflecting the dilution of the stereochemically active bismuth lone pair by lanthanum. A correlation between the cell contraction of Bi1-xLaxFeO3 (0.0 <= x <= 0.3) induced by chemical pressure and hydrostatic pressure on BiFeO3 is determined, with substitution of 1 mol % of La approximately equivalent to application of 0.05 GPa. Bi0.9La0.1FeO3 is found to have a higher bulk modulus than BiFeO3.

Background and aims: Primary sclerosing cholangitis (PSC) occurs in 2%-8% of patients who suffer from ulcerative colitis (UC). For patients who require colectomy, Real pouch-anal anastomosis (IPAA) or ileorectal anastomosis (IRA) is employed to preserve continence. We evaluated the outcomes after IPAA and IRA for patients with UC PSC, using patients with UC but without PSC as controls (UC-only group).Patients: In a case control study conducted at Sahlgrenska University Hospital, Sweden, patients with UC PSC (N = 48; 31 IPAA and 17 IRA) were compared to patients with UC only (N = 113; 62 IPAA and 51 IRA). Functional outcomes (Oresland score), pouchitis, surgical complications, and failure were evaluated.Results: For patients with IPAA, the median Oresland scores were similar for the two groups: 5 (range, 0-13) for the UC-PSC group and 5 for the UC-only group (range, 0-12; p > 0.05). However, the IRA scores were significantly different at 7 (range, 2-11) and 3 (range, 0-11) for the respective groups (p = 0.005). Pouchitis was more frequent in patients with UC PSC. Complication rates did not differ. For patients with IPAA, the failure rate was 16% for those in the UC-PSC group versus 6% for those in the UC-only group (p > 0.05); the corresponding results for IRA were 53% versus 22% (p = 0.03).Conclusions: For eases of IPAA, pouchitis seems to be more common in patients with UC-PSC. However, the functional outcomes and failure rates are unaffected by concurrent PSC. For patients with UC-PSC, functional outcome is poor and the failure rate is high after IRA. (C) 2013 European Crohn's and Colitis Organisation. Published by Elsevier B.V. All rights reserved.