Insertion of Li into the vacant sites (channels) of certain NZP phases (ATi2P3O12, A = Li, Na, and NbTiP 3O12) using BunLi at room temperature has been established; the preparation and preliminary structural and i.r. data of the phases are described.

Upadhyayula V Varadaraju

Department Of Chemistry

K. Antony Thomas

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Lithium insertion into phases with NZP structure

Journal of the Chemical Society, Chemical Communications

The synthesis of a mixed valent LixEuII xEuIII0.33-xZr2(PO4) 3 with the NZP structure, using soft chemistry was reported. Stoichiometric amounts of starting materials Eu2O3 and ZrOCl2.8H2O were dissolved in 2 N HNO3, addition of NH4H2PO4 to the metal nitrate solution under constant stirring resulted in a colorless gel. Electrochemical lithium insertion studies were carried out by using Swagelok type cells with lithium metal as the negative electrode. The mixture was pressed onto a stainless steel plate to form the electrode. The photoluminescence (PL) spectrum of the reduced phase shows signature of both Eu3+ and Eu 2+ excitation and emission bands. It was observed that The CIE coordinates are significantly changed upon Li insertion and shift towards the white region as the concentration of Li increases in the host.

Chemistry of Materials

Facile chemical insertion of lithium in Eu0.33Zr2(PO 4)3-An elegant approach for tuning the photoluminescence properties

A new niobium-substituted hollandite K2Ti5NbFe 2O16 has been synthesised for the first time. The compound is crystallised in tetragonal structure. A two to three orders change in electrical resistivity is observed with temperature as compared to the parent phase K2Ti6Fe2O16. The niobium-substituted phase shows antiferromagnetic ordering with TN = 37K at a field of 0.1T and the antiferromagnetic ordering disappears at higher field (0.2T) indicating field induced magnetic behaviour. The Mössbauer spectrum of K2Ti5NbFe2O16 shows majority of the Fe ions are 3+ oxidation state (96%). For the first time, we have intercalated lithium into K2Ti6M2O 16 (M = Cr, Fe and Ga) and K2Ti5NbFe 2O16 hollandite type phases using n-butyllithium in hexane. The estimated lithium content for all the phases are in the range 1.7-2.7mol per formula unit. © 2003 Elsevier B.V. All rights reserved.

Materials Chemistry and Physics

Solid state studies on K2Ti6-xNbxFe 2O16 (x = 0 and 1) and lithium insertion into K 2Ti6M2O16 (M = Cr, Fe and Ga) and K2Ti5NbFe2O16 hollandite type phases

Alkali metals like Li and Na are inserted into the tunnels of anion excess fluorite related structure compound Bi2Te2W3O16 using n-butyllithium and NaN3, respectively without any perceptible change of crystal structure. The insertion process is not completely reversible. The alkali metal inserted phases have room temperature resistivity values three orders less than that of the parent phase. The parent phase Bi2Te2W3O16 shows anomalous increase in dielectric constant with temperature.

Alkali metal insertion and dielectric studies on anion excess fluorite related mixed oxide Bi2Te2W3O16

New NZP-type phosphates of the formula PbM3+M4+P3O12 (M3+=Cr, Fe, and In; M4+=Ti, Zr, Hf, and Sn) were synthesized. The evolution of lattice parameters with radii of M3+ and M4+ cations indicates the anomalous behavior of tin-containing compounds. The room temperature structure of PbFeZrP3O12 has been refined using powder neutron diffraction data. The compounds were characterized by infrared and electronic spectroscopic methods. Pb0.5Mo2P3O12 with molybdenum present in the reduced state (+4) was synthesized. It is found that Pb0.5Mo2P3O12 is structurally related to TlMo2P3O12 and crystallizes in an orthorhombic system with parameters a= 8.621Å; b=9.492 Å; c=12.486 Å. © 1999 Academic Press.

Journal	Journal of the Chemical Society, Chemical Communications
ISSN	00224936
Open Access	No