Characterization of crystal lattice defects in calcium molybdate single crystals (CaMoO₄) by means of X‐ray diffraction topography

Abstract

Calcium molybdate CaMoO 4 crystals are perspective materials for many applications in acoustic-electronics, acoustic-optics and nonlinear optics. They are also used as laser hosts, scintillators, different kinds of substrates and active elements of ionizing radiation detectors. For all these applications large-sized single crystals of high structural quality are required.The samples of CaMoO 4 crystals have been investigated by means of synchrotron white beam topography, monochromatic beam topography and conventional X-ray Lang projection topography. The high-resolution rocking curves have also been taken using synchrotron and conventional arrangements.The topographs showed a rather good crystallographic perfection of the crystals. In particular, they did not reveal any segregation fringes proving high homogeneity of the chemical composition. Relatively high densities (<10 4 cm À2 ) of weak point-like diffraction contrasts were observed, which can be most probably interpreted as dislocation outcrops.The distinct main imperfection of the investigated crystals was variously developed block structure. The evaluation of lattice misorientation was realized by means of projection and section white beam synchrotron radiation topographs. The evaluated misorientation between various blocks was in the range of several arc minutes.

Phase evolution in calcium molybdate nanoparticles as a function of synthesis temperature and its electrochemical effect on energy storage

“…Among molybdates, alkaline-earth metal molybdates form an important class of functional materials, which has application in many areas such as luminescent devices, optical bers, catalysis, and energy storage. 12,13 They crystallize with a powellite-type structure, containing large bivalent cations (MMoO 4 , where M ¼ Ca, Mg or Ba), in which the molybdate ions are loosely connected to M cations and adopt a tetrahedral coordination. 12,13 Among the alkaline-earth metal molybdates, CaMoO 4 has been widely explored for applications such as luminescent hosts, catalysis, LEDs, and energy storage but all the studies related to energy storage are restricted to lithiumion batteries.…”

“…12,13 They crystallize with a powellite-type structure, containing large bivalent cations (MMoO 4 , where M ¼ Ca, Mg or Ba), in which the molybdate ions are loosely connected to M cations and adopt a tetrahedral coordination. 12,13 Among the alkaline-earth metal molybdates, CaMoO 4 has been widely explored for applications such as luminescent hosts, catalysis, LEDs, and energy storage but all the studies related to energy storage are restricted to lithiumion batteries. 14,15 Despite the merits of using lithium, serious concerns arise with its high and escalating cost and currently limited supply.…”