Ceramics

Most of the conventional piezoelectric applications require ceramics in simple shapes such as disks, rings and rectangular forms. STEM has in-house dry-pressing, isostatic pressing and lapping-polishing capability to manufacture ceramics in these simple forms to the requirements and dimensions of our customers with fine tolerances.

Additionally, certain underwater applications require ceramics in thin-shell form with spherical, cylindrical, or other novel geometries. STEM team of experts have years of experience producing ceramics in thin-shell spherical or axisymmetric forms with multimode resonance behavior, engineered resonance frequency, and increased bandwidth, operating in a wide frequency range from 20 kHz to 1 MHz.

Piezoelectric ceramics in the fiber form are attractive due to their anisotropic properties and increased flexibility. Their main use is in the design and fabrication of compliant and flexible piezocomposite structures with high strain response and high acoustic sensitivity. Piezocomposites with 1-3 connectivity or active fiber composites require full or hollow fiber forms. Piezoceramic fibers are drawn using a novel, composition-independent technique developed by STEM Ltd, which allows us to fabricate fibers of any ceramic composition in full and hollow fiber form.

Fibers

Pb-based Compositions

Lead zirconate titanate (PZT) ceramics are the commercial front-runner piezoelectric materials. However, customized lead-based compositions with higher electromechanical properties offer unique advantages over PZT. STEM Ltd has developed several lead-based piezoelectric ceramic compositions which provide better sensor performance for underwater applications.

Pb-free Compositions

Lead zirconate titanate (PZT) ceramics are the commercial front-runner piezoelectric materials. However, even in electronic equipment, these materials are gradually being restricted due to the toxicity of lead. Thus, various lead-free alternative piezoelectric materials are being investigated for transducer applications. STEM Ltd has expertise in the synthesis of lead-free piezoelectric ceramic powders and bulk ceramics in a variety of compositions.

Template Particles

Anisometric template particles, i.e., microscale single crystal particles with non-equiaxed morphology, are used in the fabrication of crystallographically textured ceramics as templates. STEM Ltd has expertise in the synthesis of anisometric template particles in a variety of compositions.

Compositions :

- Barium Titanate [BaTiO3]

- Strontium Titanate [SrTiO3]

- Sodium Niobate [NaNbO3]

- Potassium Strontium Niobate [KSr2Nb5O15]

- Bismuth Titanate [Bi4Ti3O12]

- Barium Hexaferrite [BaFe12O19 ]

Texture Ceramics

Polycrystalline ceramics with grains oriented (textured) along special crystallographic directions provide single crystal-like superior performance in certain directions. Textured ceramics are usually fabricated by a combination of templated grain growth and tape casting, but these methods are not suitable for mass production. STEM Ltd has developed a novel technique to mass-produce textured ceramics in bulk forms.

Compositions :
- Potasium Strontium Niobate [KSr2Nb5O15]

- Potasium Sodium Niobate [(K,Na)NbO3]

- Lead Magnesium Nioobate – Lead Zirconate Titanate [Pb(Mg,Nb)O3 – Pb(Zr,Ti)O3]