Solid solutions based on potassium aluminate are among solid potassium-cation conductors with high conductance [1]. The best characteristics are inherent in electrolytes where ions Al 3+ are partially replaced by ions Ti 4+ with the charge compensated by the formation of potassium vacancies. With a phase transition in plain KAlO 2 at 540° C [2] the crystal lattice turns more symmetrical. Adding Ti 4+ , Si 4+ , and Ge 4+ [3] stabilizes the high-temperature γ -modification of KAlO 2 , which raises electroconductance of such electrolytes.Structures of both modifications of KAlO 2 had not been studied in detail for a long time, which hindered gaining deeper insight into the mechanism of potassium-cation conduction and its dependence on the phase transition and modifying additives. An in-depth neutron diffraction investigation of structures of lowtemperature beta-and high-temperature gamma-modifications of KAlO 2 was performed in [4]. A major conclusion was that, due to specific orientation of the [AlO 4 ] tetrahedrons that make up the rigid core of KAlO 2 , the motion of potassium cations in the direction of axis c is hindered, which probably pointed to a perceptible anisotropy of conduction. The phase transition rearrange the tetrahedrons, making the transport of the cations isotropic.In this work we investigate the structure of high-conductance electrolytes on the basis ofThe samples to be studied were obtained by means of solid-phase synthesis [3]. Their structure was studied with the aid of neutron diffractometry (the procedure is described in [4]) at 25 and 575°ë , i.e. above the phase transition temperature in KAlO 2 . Structural parameters (coordinates of atoms, interatomic distances, degree of occupation of positions, etc.) were determined by a fullprofile Rietveld [5] analysis using program Fullprof.From the neutron diffraction patterns (NDP) for the electrolytes (Fig. 1) we infer that adding titanium ions eliminates some diffraction peaks, indicating that the crystal lattice turns more symmetrical and that NDP for both electrolytes practically coincide with NDP for KAlO 2 [4]. According to the decay rule, the peaks in NDP for titanium-containing samples correspond to a face-centered cubic (fcc) lattice, space group F d 3 m . Parameter a of an elementary cell is 0.777 and 0.782 nm for x of 0.1 and 0.2. The following relationships exist between parameters of a cubic lattice and an orthorhombic lattice, which is typical for beta-KAlO 2 (Fig. 1a) cells: a c ≈ a 0 ≈ b 0 /2 ≈ c 0 /2 . Figure 2 shows how a depends on x . For KAlO 2 we took the averaged quasi-cubic parameter recalculated with the 2 2Abstract -The structure of solid high-conductance potassium electrolytes K 1 -x Al 1 -x Ti x O 2 ( x = 0.1; 0.2) at 25 and 575°ë is studied by a powder neutron diffraction analysis with the application of full-profile Rietveld analysis. Inserting titanium ions removes in potassium aluminate the phase transition at 540°ë and the conductance anisotropy typical for its low-temperature form. Both structures are identical (f...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.