Chronic inflammation may be a significant risk factor for prostatic adenocarcinoma.

The lead-halide perovskites, including CH3NH3PbBr3, are components in cost effective, highly efficient photovoltaics, where the interactions of the molecular cations with the inorganic framework are suggested to influence the electronic and ferroelectric properties. CH3NH3PbBr3 undergoes a series of structural transitions associated with orientational order of the CH3NH3 (MA) molecular cation and tilting of the PbBr3 host framework. We apply high-resolution neutron scattering to study the soft harmonic phonons associated with these transitions, and find a strong coupling between the PbBr3 framework and the quasistatic CH3NH3 dynamics at low energy transfers. At higher energy transfers, we observe a PbBr6 octahedra soft mode driving a transition at 150 K from bound molecular excitations at low temperatures to relatively fast relaxational excitations that extend up to ∼ 50-100 meV. We suggest that these temporally overdamped dynamics enables possible indirect band gap processes in these materials that are related to the enhanced photovoltaic properties.Organic-inorganic, hybrid perovskites (OIPs) are materials based upon an inorganic perovskite host framework with an organic molecular cation occupying the interstitial space. These materials have been studied for quite some time [1], but interest has recently surged owing to their use in photovoltaic devices and to possible ferroelectricity.[2] While earlier work centered on Snbased OIPs as possible sensor materials [3, 4], recent interest has been focused towards Pb-based OIPs, due to their potential advantages in inexpensive photovoltaic devices, with efficiencies of the order of 20%.[5] We apply neutron scattering to study the coupled dynamics of the host PbBr 3 framework and the methylamonium (MA) cation in CH 3 NH 3 PbBr 3 , and discuss the possible relation with the photovoltaic properties. We map out the soft phonons and low-temperature quasistatic molecular rotations, and show that the low-temperature, harmonic fluctuations cross over to temporally overdamped dynamics at high temperature.The OIPs are composed of two sublattices ( Fig. 1 (a) for CH 3 NH 3 PbBr 3 ): the inorganic sublattice, consisting of a fully corner-bonded framework of octahedra (PbBr − 6 ); and the organic sublattice consisting of the MA molecular cation, (CH 3 NH + 3 ). At high temperatures, the structure of CH 3 NH 3 PbBr 3 is cubic (space group Pm3m), and below 235 K has a tetragonal structure in symmetry I4/mcm. [6,7] At 150 K, a transition to an unknown structure (believed to be incommensurate [8]) occurs followed by further distortion to orthorhombic (Pnma) at 148 K. [9-12] Neutron diffraction measurements have suggested that these transitions originate from tilting of the PbBr 6 octahedra and orientational ordering of the MA cation. [6,13] We note that despite minor differences in the phase diagrams, for all MAPbX 3 (X=Cl,Br,I), a transition to an ordered phase, in which the octahedra are tilted and the MA cations have relatively well-defined orientations, occurs in the temperatu...

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