Hydrothermal Synthesis of Dy (0.8 at%)-doped BaTiO₃ Powders at 90°C, Their Sintering
Behavior, and Microstructures of Dy:BaTiO₃ Powders Heated on Ti-Strips
 

Ersin Emre OREN and  A. Cüneyt TAS
Department of Metallurgical and Materials Engineering,
Middle East Technical University,
Ankara 06531, Turkey.   (1993-1999)

 

* E. E. Oren and A. C. TAS, “Hydrothermal Synthesis of Dy-Doped BaTiO3 Powders,” Metallurgical and Materials Transactions, Vol. 30B, 1089-1093 (1999).  Download PDF copy of this paper

* E. E. Oren and A. C. TAS, "Hydrothermal Synthesis of Pure and Dy:BaTiO3 Powders at 90°C, Their Sintering Behavior, and Microstructures of Dy:BaTiO3 Powders Heated on Ti-Strips," 100th Annual Meeting of The American Ceramic Society, Oral Presentation, May 3-6, 1998, Cincinnati, OH, USA.

* E. E. Oren and A. C. TAS, "Hydrothermal Synthesis of Pure and Dy (0.8 at%)-doped BaTiO3 Powders at 90°C and their Sintering Behavior," in "Dielectric Ceramic Materials," Ceramic Transactions, Vol. 100, pp. 95-104, (Eds.) K.M. Nair and A.S. Bhalla, 1999, The American Ceramic Society, USA, ISBN 1-57498-066-1.

* A. C. TAS, “Hydrothermal Synthesis of Crystalline and BaCO3-free, Pure BaTiO3 Powders at 90°C in Air” Patent Application, Date: June 27, 1996, Turkish Patent Institute, Ankara, Turkey.  No: 96/00539

* A. C. TAS, "Synthesis of Crystalline and Pure BaTiO3 Powders at 90°C," III. Ceramics Congress, Proceedings Book, Vol. 2, pp. 66-73, Istanbul, October 1996, Turkey.      PDF

* E. E. Oren and A. C. Tas, "Hydrothermal Synthesis of Pure and Dy:BaTiO3 Powders at 90°C and Their Sintering Behavior," IV. Ceramics Congress, Proceedings Book, pp. 627-633, Eskisehir, September 1998, Turkey.
 

Abstract

Sub-micron (150-200 nm), monodisperse and spherical powders of Dy-doped (0.8 at%) BaTiO₃ have been prepared by “hydrothermal synthesis” at 90°C in an air atmosphere. The slightly modified hydrothermal synthesis procedure adopted in this work did not necessitate the utilization of strict and expensive measures which were commonly required for the removal of free CO₂ present in the atmosphere. The synthesized powders were crystalline, pure, and did not contain BaCO₃ as an impurity phase. Dy-doped BaTiO₃ powders synthesized at  90°C possessed the cubic (space group: Pm-3m) crystal structure.
 

Download the crystal structure drawing                                     Download the SEM pic of powders synthesized
 

Download the XRD charts of our barium titanate powders

A Tentative XRD Pattern for Hydrothermally Synthesized (90°C) "Pure" BaTiO₃ Powders

                        (Cu-K-alpha radiation, Step: 0.02°, Count: 5 sec)

Lattice Parameters: Cubic, Pm-3m, a = 4.0186 Å, V = 64.89 ų

 No     h   k   l        d(obs)      d(calc)      res(d)        2th.obs   2th.calc    I/Io

  1     1   0   0       4.02000   4.01850   0.00140      22.094    22.101    21
  2     1   1   0       2.84200   2.84158   0.00042      31.451    31.456    100
  3     1   1   1       2.32050   2.32014   0.00036      38.774    38.780    22
  4     2   0   0       2.00990   2.00930   0.00060    45.069    45.083   28
  5     2   1   0       1.79730   1.79717   0.00013      50.754    50.758    7
  6     2   1   1       1.64060   1.64059   0.00001      56.005    56.005    24
  7     2   2   0       1.42090   1.42079   0.00011      65.654    65.660    12
  8     3   0   0       1.33950   1.33953  -0.00003    70.206    70.204     4
  9     3   1   0       1.27080   1.27079   0.00001      74.621    74.622     9
 10    3   1   1       1.21160   1.21165  -0.00005        78.951    78.947     5
 11    2   2   2       1.16000   1.16007  -0.00007      83.216    83.210     5
 12    3   2   0       1.11450   1.11456  -0.00006      87.441    87.435     2
 13    3   2   1       1.07400   1.07402  -0.00002      91.648    91.646    11
 

Dy:BaTiO₃ powders were deposited onto titanium strips in concentrated ceramic suspensions with the aid of ultrasonification. Grain growth characteristics of pure and Dy-doped BaTiO₃ pellets were investigated during sintering in an air atmosphere and compared with one another over the temperature range of 1200 to 1500°C. Sample characterization was achieved by XRD (X-ray diffraction), SEM (scanning electron microscopy), EDXS (energy dispersive X-ray spectroscopy), and Rietveld analysis.