Sintering, microstructure and microwave dielectric properties of rare earth orthophosphates, RePO{sub 4} (Re = La, Ce, Nd, Sm, Tb, Dy, Y, Yb)
- School of Materials Science and Engineering, Seoul National University, Seoul 151-744 (Korea, Republic of)
- 168 Materials Research Lab., Pennstate University, University Park, PA 16802 (United States)
Various rare earth orthophosphates, such as monazite and xenotime RePO{sub 4} (Re = La, Ce, Nd, Sm, Tb, Dy, Y, Yb) were prepared by a conventional solid-state reaction method. The crystal structure and microstructure of the sintered ceramics were investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. The dielectric properties were measured in the microwave region using a network analyzer. It was found that the monazite RePO{sub 4} could be sintered near 1400 deg. C, although the xenotime RePO{sub 4}, which had a smaller Re{sup 3+} ionic radius, could be sintered above 1600 deg. C. The permittivity ({epsilon}{sub r}) of the monazite structures was higher than that of the xenotime structures. This difference was explained by the differences in ionic polarizability and bond strength. Both monazite and xenotime rare earth orthophosphates, however, exhibited a high quality factor (Q x f), where Q = 1/tan {delta} and f is the measuring frequency, of greater than 60,000 GHz. The temperature coefficient of resonant frequency ({tau}{sub f}) was a negative value, ranging between -17 and -56 ppm/deg. C.
- OSTI ID:
- 21195071
- Journal Information:
- Materials Research Bulletin, Vol. 44, Issue 1; Other Information: DOI: 10.1016/j.materresbull.2008.03.016; PII: S0025-5408(08)00094-9; Copyright (c) 2008 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CERAMICS
CERIUM PHOSPHATES
DYSPROSIUM PHOSPHATES
LANTHANUM PHOSPHATES
MICROSTRUCTURE
MICROWAVE RADIATION
MONAZITES
NEODYMIUM PHOSPHATES
PERMITTIVITY
POLARIZABILITY
RHENIUM IONS
SAMARIUM PHOSPHATES
SCANNING ELECTRON MICROSCOPY
SINTERING
TERBIUM PHOSPHATES
X-RAY DIFFRACTION
XENOTIME
YTTERBIUM PHOSPHATES
YTTRIUM PHOSPHATES