@article{FranzToebbensSteckhanetal.2018,
  author    = {Franz, Alexandra and T{\"o}bbens, Daniel M. and Steckhan, Julia and Schorr, Susan},
  title     = {Determination of the miscibility gap in the solid solutions series of methylammonium lead iodide/chloride},
  series = {Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials},
  volume    = {74},
  journal   = {Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials},
  publisher = {International Union of Crystallography},
  address   = {Chester},
  issn      = {2052-5206},
  doi       = {10.1107/S2052520618010764},
  pages     = {445 -- 449},
  year      = {2018},
  abstract  = {Perovskites are widely known for their enormous possibility of elemental substitution, which leads to a large variety of physical properties. Hybrid perovskites such as CH3NH3PbI3 (MAPbI(3)) and CH3NH3PbCl3 (MAPbCl(3)) are perovskites with an A([XII])B([VI)X(-)([II)(])structure, where A is an organic molecule, B is a lead(II) cation and X is a halide anion of iodine or chlorine. Whereas MAPbCl(3) crystallizes in the cubic space group Pm (3) over barm, MAPbI(3) is in the tetragonal space group I4/mcm. The substitution of I by Cl leads to an increased tolerance against humidity but is challenging or even impossible due to their large difference in ionic radii. Here, the influence of an increasing Cl content in the reaction solution on the miscibility of the solid solution members is examined systematically. Powders were synthesized by two different routes depending on the I:Cl ratio. High-resolution synchrotron X-ray data are used to establish values for the limits of the miscibility gap which are 3.1 (1.1) mol\% MAPbCl(3) in MAPI(3) and 1.0 (1) mol\% MAPbI(3) in MAPCl. The establishment of relations between average pseudo-cubic lattice parameters for both phases allows a determination of the degree of substitution from the observed lattice parameters.},
  language  = {en}
}
@article{LorenzAltenbergerTrumbulletal.2019,
  author    = {Lorenz, Melanie and Altenberger, Uwe and Trumbull, Robert B. and Lira, Raul and Lopez de Luchi, Monica Graciela and G{\"u}nter, Christina and Eidner, Sascha},
  title     = {Chemical and textural relations of britholite- and apatite-group minerals from hydrothermal REE mineralization at the Rodeo de los Molles deposit, Central Argentina},
  series = {American mineralogist : an international journal of earth and planetary materials},
  volume    = {104},
  journal   = {American mineralogist : an international journal of earth and planetary materials},
  number    = {12},
  publisher = {Mineralogical Society of America},
  address   = {Chantilly},
  issn      = {0003-004X},
  doi       = {10.2138/am-2019-6969},
  pages     = {1840 -- 1850},
  year      = {2019},
  abstract  = {Britholite group minerals (REE,Ca)(5)[(Si,P)O-4](3)(OH,F) are widespread rare-earth minerals in alkaline rocks and their associated metasomatic zones, where they usually are minor accessory phases. An exception is the REE deposit Rodeo de los Molles, Central Argentina, where fluorbritholite-(Ce) (FBri) is the main carrier of REE and is closely intergrown with fluorapatite (FAp). These minerals reach an abundance of locally up to 75 modal\% (FBri) and 20 modal\% (FAp) in the vein mineralizations. The Rodeo de los Molles deposit is hosted by a fenitized monzogranite of the Middle Devonian Las Chacras-Potrerillos batholith. The REE mineralization consists of fluorbritholite-(Ce), britholite-(Ce), fluorapatite, allanite-(Ce), and REE fluorcarbonates, and is associated with hydrothermal fluorite, quartz, albite, zircon, and titanite. The REE assemblage takes two forms: irregular patchy shaped REE-rich composites and discrete cross-cutting veins. The irregular composites are more common, but here fluorbritholite-(Ce) is mostly replaced by REE carbonates. The vein mineralization has more abundant and better-preserved britholite phases. The majority of britholite grains at Rodeo de los Molles are hydrothermally altered, and alteration is strongly enhanced by metamictization, which is indicated by darkening of the mineral, loss of birefringence, porosity, and volume changes leading to polygonal cracks in and around altered grains. A detailed electron microprobe study of apatite-britholite minerals from Rodeo de los Molles revealed compositional variations in fluorapatite and fluorbritholite-(Ce) consistent with the coupled substitution of REE3+ + Si4+ = Ca2+ + P5+ and a compositional gap of similar to 4 apfu between the two phases, which we interpret as a miscibility gap. Micrometer-scale intergrowths of fluorapatite in fluorbritholite-(Ce) minerals and vice versa are chemically characterized here for the first time and interpreted as exsolution textures that formed during cooling below the proposed solvus.},
  language  = {en}
}