MICROWAVE NONLINEAR DIELECTRIC MATERIALS
Rept. no. 16 (final) for 15 Sep 1963-14 Oct 1964
RAYTHEON CO WALTHAM MA RESEARCH DIV
Pagination or Media Count:
Microwave nonlinearity and loss tangent data for alumina and stannate-doped Ba0.5,Sr0.5TiO3 BST-50 near the Curie temperature are presented. A hot-pressed, annealed sample is included among the above materials. Similar data on alumina- and lanthana-doped Ba0.7,Sr0.3TiO3 BST- 70, including a hot-pressed, annealed sample are presented. No unusual behavior was observed, and it is concluded that hot-pressing and annealing do little to improve the behavior of mixed titanate ceramics near the Curie temperature. A BaTiO3 ceramic doped with two mole percent of lanthana La2O3 exhibited an extrapolated Curie temperature of 30C. Its nonlinearity and loss at the Curie peak were both comparable to those of BST-50 or BST-70. Lanthanum additions to SrTiO3 depressed the Curie temperature by an amount of 30-40Cmole percent lanthanum. The frequency dependence of the loss tangent of BST-50, BST- 70, and lanthana-doped BaTiO3 is seen to deviate strongly from linear dependence near the Curie temperature. The frequency ranges used were 2-4 Gc sec and 8-12 Gcsec.
- Ceramics, Refractories and Glass