Facile chemical insertion of lithium in Eu0.33Zr<inf>2</inf>(PO <inf>4</inf>)<inf>3</inf>-An elegant approach for tuning the photoluminescence properties

The synthesis of a mixed valent LixEuIIxEuIII0.33-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.