High temperature piezoelectric material

A piezoelectric device having a maximum operational temperature of at least 800° C., the piezoelectric device comprising a piezoelectric material, the piezoelectric material being a langanite,

• wherein the langanite is an aluminum substituted langanite represented by La3Nb0.5Ga5.5x AlxO14, wherein 0.5>×≧0.

A piezoelectric device comprising a piezoelectric material, the piezoelectric material having a maximum operational temperature of at least 800° C.,

• wherein the piezoelectric material is a rare earth calcium oxyborate,
• wherein the piezoelectric material has a time constant τ=ε0Kρ, where K is the relative permittivity, ρ is the resistivity, and ε0 is the permittivity of free space, the time constant being equal to or greater than approximately 3700 microseconds at 600° C.

A piezoelectric device, comprising an (zyw)-θ cut single crystal of a rare earth calcium oxyborate,

• the (zyw)-θ cut single crystal having a cut angle θ between approximately 30° and approximately 60°.

A piezoelectric device, comprising an (zyw)-θ cut single crystal of a rare earth calcium oxyborate,

• the (zyw)-θ cut single crystal having a cut angle θ between approximately 30°and approximately 60°,
• wherein the rare earth calcium oxyborate has a time constant τ=ε0 Kρ, where K represents relative permittivity, ρ represents electrical resistivity, and ε0 represents permittivity of free space,
• the time constant being equal to greater than approximately 100 microseconds at 800° C.