Structural features of phases (Na0.5R0.5)MO4 and (Na0.5R0.5)MO4:R′ (R = Gd, La; R′ = Er, Tm, Yb; M = W, Mo) of the scheelite family

Up/down conversion luminescence properties of (Na0.5Gd0.5)MoO4:Ln3+(Ln = Eu, Tb, Dy, Yb/Er, Yb/Tm, and Yb/Ho) microstructures: synthesis, morphology, structural and magnetic investigation

“…The compound (Na 0.5 Gd 0.5 )MoO 4 :Eu 3+ crystallizes in the scheelite (CaWO 4 ) structure (space group I4 1 /a). [34][35][36] In this tetragonal phase molybdenum atoms (Mo 6+ ) occupy W sites located at the centers of tetrahedra and surrounded by four equivalent oxygen (O 2À ) atoms with two different bond angles a 1(O-M-O) and a 2(O-M-O) . 34 The degree of tetrahedral distortion is given by…”

“…The monovalent sodium (Na + ) ions and trivalent gadolinium ions (Gd 3+ ) are likely to occupy the dodecahedral Ca 2+ sites in the tetrahedral symmetry with two different inter atomic distances (d, Å), 4d 1(Na,R-O) and 4d 2(Na,R-O) . 34 The degree of dodecahedral distortion is given by…”

Synthesis and up/down conversion luminescence properties of Na0.5R0.5MoO4:Ln3+ (R3+ = La, Gd), (Ln3+ = Eu, Tb, Dy, Yb/Er) thin phosphor films grown by pulsed laser deposition technique

“…26,28 Such a distorted dodecahedron influences the 70 homogeneity of the crystal field around the optically active ions, inducing a slight improvement in the emission intensity of NLM than NGM. 26,28 Under 980 nm infrared laser excitation on Yb/Er doped (Na 0.5 R 0.5 )MoO 4 thin films, Yb 3+ ions are initially excited from 2 F 7/2 level to the 2 F 5/2 level via well known ground state 20 absorption process. 20 Also, the laser excitation populates the electrons from the 4 I 15/2 ground level to the 4 I 11/2 level of Er 3+ ions.…”

“…In the MoO 4 2À tetrahedra, interatomic distances between the Mo and O atoms is equal to the sum of their ionic radii and do not depend on the composition of dodecahedral site. 21 Further, the important characteristic of scheelite crystals is high possibility of electrodipole inter-Stark transitions of rare-earth ions in these crystals leads to higher luminescence intensity and high optical absorption bands. 21 In order to achieve a novel red, green, yellow emitting thin phosphor lms with proper Commission Internationale de L'Eclairage (CIE) chromaticity coordinates, Eu 3+ , Tb 3+ , and Dy 3+ ions are the best choice to be an activator ions in any host for DC luminescence applications.…”

Polarized spectral analysis of Er3+ ions in Er3+:LiGd(MoO4)2 crystal

“…Compared with the Joint Committee on Powder Diffraction Standard (JCPDS) card No:023-1179) [24], the as-grown Er 3+ :LiGd(MoO 4 ) 2 crystal had some split XRD peaks and the distorted shapes of the as-grown Er 3+ :LiGd(MoO 4 ) 2 crystal were observed. This could be resulted from the formation of ordered phase with lowering of the crystal symmetry and the formation of the super-structure [23,[25][26][27]. X-ray diffraction analysis by using …”