Growth conditions, structure and crystal morphology of rare earth potassium double tungstates

Abstract

Growth conditions and crystal morphology of erbium KEr(WO 4 ) 2 (KEW) and samarium KSm(WO 4 ) 2 (KSW) potassium double tungstates have been investigated. Monoclinic single crystals have been grown by TSSG method using K 2 W 2 O 7 solvent. It was found that the vertical temperature gradient in a range of 0.3 -0.5 K/mm is optimal for crystal growth. The morphology of grown crystals and their quality strongly depend on the seed orientation. The best results are achieved when the growth takes place on seeds oriented along [010] direction. For KEW, crystal growth is possible by lowering the temperature without pulling. In this case the surfaces of the grown crystals are natural crystallographic planes. KSW crystals grow into the solution down to the depth of 4-6 mm only. Structure analysis of crystals is obtained by X-Ray powder diffraction measurements. The diffraction patterns were analyzed by the Rietveld refinement method. XRD measurements shows the symmetry of monoclinic space group C2/c (C 6 2h ).

Growth and EPR properties of KSm(WO4)2 and KEr(WO4)2 single crystals

“…Alkaline rare-earth double tungstates have low local symmetry, strong magnetic anisotropy, strong spinlattice coupling and low-dimensional magnetic structure [1][2][3].…”

“…The potassium-erbium/samarium double tungstate (KEr(WO 4 [2]. This structure is characteristic for several others rare earth double tungstates and belongs to the chain-layered systems.…”