Ngk Spark Plug Company, Limited

Takayuki Matsuoka

Masato Yamazaki

Kazushige Ohbayashi

Hideto Yamada

Toshiaki Kurahashi

Kazuaki Kitamura

Yasuyuki Okimura

Hisashi Kozuka

Katsuya Yamagiwa

Takashi Kasashima

Takeshi Mitsuoka

Yoshiteru Honda

A lead-free piezoelectric ceramic composition including an alkali niobate/tantalate perovskite oxide main phase having piezoelectric properties and a different metal oxide. The mole ratio (Na/K) between Na (sodium) and K (potassium) in the main phase is 0.40&#x3c;(Na/K)&#x3c;3.0. The main phase has a crystal structure in which (i) first spots corresponding to a primitive lattice period and (ii) second spots corresponding to the lattice period two times the primitive lattice period and being weaker than the first spots appear in an electron beam diffraction image entering from the &#x3c;100&#x3e; direction with the main phase represented as a pseudo-cubic crystal system. Also, the area ratio of a crystal phase reflecting the second spots in the main phase is 33% or less, and the maximum grain size of crystals reflecting the second spots in the main phase is 25 nm or less.

Lead-free piezoelectric ceramic composition, piezoelectric element using the same, and method of manufacturing lead-free piezoelectric ceramic composition

A lead-free piezoelectric ceramic composition including an alkali niobate/tantalate perovskite oxide main phase having piezoelectric properties and a different metal oxide subphase. The mole ratio (Na/K) between Na (sodium) and K (potassium) in the main phase assumes a value in a range represented by 0.40&#x3c;(Na/K)&#x3c;3.0. The main phase has a crystal structure in which (i) first spots corresponding to a primitive lattice period and (ii) second spots corresponding to the lattice period two times the primitive lattice period and being weaker than the first spots appear in an electron beam diffraction image entering from the &#x3c;100&#x3e; direction with the main phase represented as a pseudo-cubic crystal system.

A lead-free piezoelectric ceramic composition includes a first crystal phase made of an alkali niobate/tantalate type perovskite oxide having piezoelectric properties, and a second crystal phase made of an M-Ti&#x2014;O spinel compound (where the element M is a monovalent to quadrivalent element).

Unleaded piezoelectric ceramic composition, piezoelectric element using same, device, and method for manufacturing unleaded piezoelectric ceramic composition

A lead-free piezo-electric porcelain composition which contains a main phase having voids and which is formed of a first crystal phase composed of an alkali niobate/tantalate-based perovskite oxide having piezo-electric characteristics; and a sub-phase containing a second crystal phase composed of an ABO-based compound (where the element A is a monovalent element and the element B is one or more divalent to hexavalent elements). The sub-phase fills voids present in the main phase.

Lead-free piezo-electric porcelain composition, piezo-electric element using the same, and method for producing lead-free piezo-electric porcelain composition

A lead-free piezoelectric ceramic composition mainly includes a first crystal phase (KNN phase) and a second crystal phase (NTK phase). In the first crystal phase (KNN phase), a plurality of crystal grains formed of an alkali niobate/tantalate perovskite oxide having piezoelectric characteristics is bound to each other in a deposited state. The second crystal phase (NTK phase) is formed of a compound containing titanium (Ti) and fills spaces between the crystal grains in the first crystal phase.

Lead-free piezoelectric ceramic composition, method for producing same, piezoelectric element using lead-free piezoelectric ceramic composition, ultrasonic processing machine, ultrasonic drive device, and sensing device

A lead-free piezoelectric ceramic composition includes a first crystal phase of alkali niobate/tantalate type perovskite oxide having piezoelectric properties and a second crystal phase of A-Ti&#x2014;B&#x2014;O composite oxide (where the element A is an alkali metal; the element B is at least one of Nb and Ta; and the contents of the element A, the element B and Ti are not zero). Examples of the second crystal phase are those represented by ATiBO, and x preferably satisfies 0&#x2266;x&#x2266;0.15.

Lead-free piezoelectric ceramic composition, piezoelectric element comprising same, knock sensor, and process for production of lead-free piezoelectric ceramic composition

The present invention provides a piezoelectric ceramic composition having a high thermal resistance and a high piezoelectric distortion constant and a piezoelectric element using the piezoelectric ceramic composition. The piezoelectric ceramic composition of the present invention contains Na, Bi, Ti, Cr and O, wherein the content ratio of Na, Bi, Ti and Cr in terms of oxides thereof falls within the following composition range: aNaO-bBiO-cTiO-dCrOwhere a, b, c and d are mole fractions; 0.030&#x2266;a&#x2266;0.042; 0.330&#x2266;b&#x2266;0.370; 0.580&#x2266;c&#x2266;0.620; 0&#x3c;d&#x2266;0.017; and a+b+c+d=1. The piezoelectric ceramic composition preferably has a main crystal phase of bismuth layer-structured ferroelectric, more preferably NaBiTiOcrystal. The piezoelectric element of the present invention includes a piezoelectric body formed of the piezoelectric ceramic composition and at least a pair of electrodes held in contact with the piezoelectric body.

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Aichi, Japan

Takayuki Matsuoka