Microwave-assisted synthesis of PrZrSiO 4, VZrSiO 4 and CrYAlO 3 ceramic pigments

An innovative two-steps route was successfuly applied to the microwave-assisted synthesis of Pr-ZrSiO4, V-ZrSiO4 and Cr-YAlO3 ceramic pigments. It is able to reduce the total synthesis time from many hours down to a few minutes. Industrial batches were pelletized and underwent a short time pre-heating in conventional electric furnace (from 300 up to 1000°C) prior dielectric heating in microwave oven (2.45 GHz, 800 W continuous or paused). Pre-heating is necessary to reach a thermal level at which pigment precursors are activated under microwave irradiation (high enough tan δ of dielectric properties). Activation kinetics was followed by measuring (optical pyrometer) the external temperature of crucible during MW irradiation and the internal temperature at the end of heating process. Pigments were characterized by colourimetry (CIE Lab) and XRPD with Rietveld refinement. The V-ZrSiO4 system is easily activated, already at pre-heating of 300°C, with good reaction yield and colour performance; nevertheless it is difficult to keep under control, as temperatures exceeding 1200°C are rapidly reached. The Pr-ZrSiO4 system is activated after pre-heating over 600°C and exhibits a slow kinetics, resulting in a low reaction yield and unsatisfactory colour. The Cr-YAlO3 pigment is formed with colour and reaction yield close to those of the correspondent industrial product, even though after pre-heating at 800°C or more. A peculiar behaviour of silica phases was observed in zircon systems, particularly after lower pre-heating temperatures. It consists in an early transformation of quartz (present as precursor) into cristobalite and abundant amorphous phase, before the SiO2 + ZrO2 ZrSiO4 transformation occurred.

[1]  Markus Niederberger,et al.  One-minute synthesis of crystalline binary and ternary metal oxide nanoparticles. , 2008, Chemical communications.

[2]  P. P. Rao,et al.  The synthesis and characterization of environmentally benign praseodymium-doped TiCeO4 pigments , 2008 .

[3]  M. Toprak,et al.  Microwave-assisted combustion synthesis of CoFe2O4 with urea, and its magnetic characterization , 2007 .

[4]  D. Lamas,et al.  Synthesis and characterization La0.6Sr0.4CoO3 and La0.6Sr0.4Co0.2Fe0.8O3 nanotubes for cathode of solid-oxide fuel cells , 2007 .

[5]  D. Bahadur,et al.  Synthesis and properties of nanograined La-Ca-manganite–Ni-ferrite composites , 2007 .

[6]  Ying-Jie Zhu,et al.  Microwave-assisted synthesis and magnetic property of magnetite and hematite nanoparticles , 2007 .

[7]  A. Lagashetty,et al.  Microwave-assisted route for synthesis of nanosized metal oxides , 2007 .

[8]  L. Menabue,et al.  Multitechnique approach to V-ZrSiO4 pigment characterization and synthesis optimization , 2007 .

[9]  M. Dondi,et al.  Colour development of red perovskite pigment Y(Al, Cr)O3 in various ceramic applications , 2006 .

[10]  G. Tompsett,et al.  Microwave synthesis of nanoporous materials. , 2006, Chemphyschem : a European journal of chemical physics and physical chemistry.

[11]  S. Ardizzone,et al.  Structural and spectroscopic investigations of blue, vanadium-doped ZrSiO4 pigments prepared by a sol-gel route. , 2005, The journal of physical chemistry. B.

[12]  M. Dondi,et al.  Structural variations of Cr-doped (Y,REE)AlO3 perovskites , 2005 .

[13]  C. Leonelli,et al.  Microwave‐Hydrothermal Synthesis and Hyperfine Characterization of Praseodymium‐Doped Nanometric Zirconia Powders , 2005 .

[14]  S. Nannarone,et al.  Synthesis and characterization of praseodymium-doped ceria powders by a microwave-assisted hydrothermal (MH) route , 2005 .

[15]  C. Serna,et al.  Spectroscopic Studies on the Localization of Vanadium(IV) in Vanadium-Doped Zircon Pigments , 2005 .

[16]  Tadashi Endo,et al.  Microwave Synthesis of Yttrium Iron Garnet Powder , 2005 .

[17]  S. Komarneni,et al.  Microwave‐Hydrothermal Synthesis of Monodispersed Nanophase α‐Fe2O3 , 2004 .

[18]  S. Ardizzone,et al.  Yellow Pr-zircon pigments: The role of praseodymium and of the mineralizer , 2004 .

[19]  S. Dharwadkar,et al.  Synthesis of LaCoO3 from lanthanum trisoxalatocobaltate(III) (LTC) precursor employing microwave heating technique , 2004 .

[20]  T. Mathews,et al.  Microwave assisted synthesis and sintering of La0.8Sr0.2Ga0.83Mg0.17O2.815 , 2003 .

[21]  M. A. Tena,et al.  Rietveld refinement study of vanadium distribution in V+4–ZrSiO4 solid solutions obtained from gels , 2002 .

[22]  M. Llusar,et al.  The nature of Pr-ZrSiO4 yellow ceramic pigment , 2002 .

[23]  A. Pradhan,et al.  Influence of the Fuel Used in the Microwave Synthesis of Cr2O3 , 2002 .

[24]  H. Seifert,et al.  The assessment of thermodynamic parameters in the Al2O3‐Y2O3 system and phase relations in the Y‐Al‐O system , 2001 .

[25]  Brian H. Toby,et al.  EXPGUI, a graphical user interface for GSAS , 2001 .

[26]  C. Leonelli,et al.  The application of microwaves in the synthesis of Ce0.9Pr0.1O2 nanostructured powders , 2001 .

[27]  J. Alarcón.  Crystallization behaviour and microstructural development in ZrSiO4 and V-ZrSiO4 solid solutions from colloidal gels , 2000 .

[28]  S. A. Suvorov,et al.  Microwave Synthesis of Materials from Aluminum Oxide Powders , 2000 .

[29]  M. Llusar,et al.  Environmental optimisation of blue vanadium zircon ceramic pigment , 1999 .

[30]  B. Vaidhyanathan,et al.  Synthesis of inorganic solids using microwaves , 1999 .

[31]  C. Leonelli,et al.  Microwave Synthesis of Al2O3/CR2O3 (SS) Ceramic Pigments , 1998 .