GROWTH AND PHYSICO-CHEMICAL CHARACTERIZATION OF LANTHANUM NEODYMIUM OXALATE SINGLE-CRYSTALS

Single crystals of lanthanum neodymium oxalate (LNO) are grown in sodi um meta silicate gels, by the diffusion of a mixture of aqueous soluti ons of lanthanum nitrate and neodymium nitrate into the test tube havi ng the set gel containing oxalic acid. The bluish pink coloured tabula r crystals of LNO having well defined hexagonal basal planes appear ei ther as 'foggy' or 'clear', the latter at the greater depths inside th e gel. The colouration of LNO visually observed is evidenced in UV-vis ible spectrum, by the revelation of well pronounced characteristic pea ks in the visible region (500-900 nm). X-ray diffraction (XRD) of powd ered LNO is ordered, meaning crystalline in nature, besides ifs 'isost ructurality',vith similarly grown lanthanum samarium oxalate crystals. The single crystallinity of LNO is established by its oscillation XRD pattern. Thermogravimetric analysis (TGA) and differential scanning c olorimetry (DSC) support that LNO loses water of crystallization aroun d 120 degrees C and CO and CO2 around 350-450 degrees C, while the inf rared absorption (IR) spectrum of LNO establishes the presence of oxal ate (C2O4)(2-) ions. Energy dispersive X-ray analysis (EDAX) confirms the presence of La and Nd in the sample. X-ray photoelectron spectrosc opic (XPS) studies of LNO establish the presence of La and Nd in their respective oxide states. An empirical structure for LNO has been prop osed on the basis of these findings. The 'smokiness' in,the foggy LNO crystal has been attributed due to the 'gel inclusion' during the grow th process.