Synthesis and structure of some nano-sized rare-earth metal ions doped potassium hexacyanoferrates Himanshu Narayan a,n , Hailemichael Alemu b , Pusetso F. Nketsa a , Toka J. Manatha b , And Madhavi Thakurdesai c a Department of Physics and Electronics, National University of Lesotho, Roma 180, Lesotho b Department of Chemistry and Chemical Technology, National University of Lesotho, Roma 180, Lesotho c Thin Film Research Laboratory, Department of Physics, Birla College, Kalyan 421304, India HIGHLIGHTS  Nanosized powders of rare-earth metal-ions doped potassium hexacyanoferrate have been investigated.  KRFe(CN) 6  3H 2 O (with R ¼Y, Gd and Yb) powders were synthesized through precipitation.  X-ray diffraction data has been analyzed with FullProf software suite.  All samples were found to crystallize in the Orthorhombic unit-cell with P mmm space group.  Crystal parameters were determined and refined with FullProf. article info Article history: Received 5 November 2014 Received in revised form 12 December 2014 Accepted 5 January 2015 Available online 6 January 2015 Keywords: Hexacyanoferrates Rare-earth ions doping Crystal structure X-ray diffraction abstract Rare-earth ions doped potassium hexacyanoferrates (KR-HCF); with the general formula KRFe ( CN ) 3H O 6 2 · [with, R≡Y, Gd and Yb] nanoparticles were synthesized through precipitation. Char- acterization was done through particle-size analyzer, scanning electron microscopy (SEM), Fourier Transform infra-red (FTIR) and Raman spectroscopy, and powder X-ray diffraction (XRD). The XRD data was analyzed on FullProf Software Suite program and the unit-cell structure and lattice parameters of KR-HCF samples were determined from scratch and refined further. All the three KR-HCF nanoparticles seem to crystallize in the orthorhombic primitive P MMM space-group. Reasonably good agreement was found with the previously reported lattice constants of KGd-HCF and KYb-HCF orthorhombic single- crystals, except that they assume different space-groups. The observed dissimilarity of space-groups may be attributed to the different time scales involved in the synthesis process. Moreover, the crystal structure of KYFe ( CN ) 3H O 6 2 · nanoparticles is being reported for the very first time. & 2015 Elsevier B.V. All rights reserved. 1. Introduction Potassium hexacyanoferrate [KHCF or K Fe( CN ) 3H O 4 6 2 · ], or potassium ferrocyanide-trihydrate (KFCT), belongs to a family of crystals with a general formula A [B(CN) ] 3H O 4 6 2 · , with A≡K or NH 3 ; and B Fe, Mn, Ru, Os ≡ [1]. A group of variants of KHCF, called the ‘potassium-metal-hexacyanoferrates (KM-HCF)’, or ‘metal-hexacyanoferrates (MHCF)’, can be obtained through the replacement of some, or all potassium atoms with metal ions (such as, Cu, Co, Ni, Cr, etc.), respectively. Similarly, another group of variants, the ‘metal-hexacyano-metalates (MHCM′)’, can also be obtained by replacing the iron with other metal (M′). One member of this group, the Prussian Blue ⎡ ⎣ ⎤ ⎦ K Fe Fe ( CN ) 4 4 II II 6 3 is one of the earliest known coordination compounds, and the possibility of its deposition on electrode surface has initiated a new field of study [2]. In fact, all these hexacyanoferrate (HCF) materials possess a number of interesting chemical and structural properties, such as electrocatalytic, electrochromic, charge storage, ion-exchange, ca- tion extraction, ion-sensing and photomagnetic properties, that can be exploited in many potential applications. Grouped under a general formula m A M [Fe(CN) ] HO p q r 6 2 · (where, p, q, r and m are stoichiometric numbers, A is an alkali metal cation, and M is usually a transition metal ion), most of these mixed-valence compounds can be easily deposited on the surface of metal elec- trodes for enhanced electrochemical properties. Therefore, this Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/physe Physica E http://dx.doi.org/10.1016/j.physe.2015.01.001 1386-9477/& 2015 Elsevier B.V. All rights reserved. n Corresponding author. Fax: þ266 2234 0000. E-mail address: h.narayan@nul.ls (H. Narayan). Physica E 69 (2015) 127–132