Denso Corporation

Nippondenso Co., Ltd.

Nippon Soken, Inc.

Kabushiki Kaisha Toyota Chuo Kenkyusho

Tatsuhiko Nonoyama

Toshiatsu Nagaya

Hisaaki Takao

Kazumasa Takatori

Yasuyoshi Saito

Takahiko Homma

Masaya Nakamura

Shoei Teshima

Kouji Hiragami

Hiroshi Ueda

Takahiko Yoshida

Eturo Yasuda

Kazushi Asami

Hitoshi Shindo

Masatoshi Ikeda

Hayaki Teramoto

Kazuyuki Horie

Kiwamu Naito

Haruhiko Otsuka

Yasuyuki Tanaka

A stacked piezoelectric element obtained by alternately stacking a piezoelectric ceramic layer and an electrode layer, wherein said electrode layer mainly comprises an electrically conducting base metal electrode material, and the region held between the electrode layer positioned at the top of each ceramic layer and the electrode layer positioned at the bottom of each ceramic layer contains a material having no piezoelectricity, in which a constituent element of said material having no piezoelectricity is uniformly dispersed so as not to have local distribution of a distributed strength exceeding 2 times the distributed strength which is distributed in a largest number of places and is not 0.

Stacked piezoelectric element and production method thereof

To provide a production method of a polycrystalline ceramic body with excellent density, a preparation step, a mixing step, a forming step and a heat-treating step are performed. In the preparation step, a coarse particle ceramic powder, and a fine particle powder having an average particle diameter of &#x2153; or less of the average particle diameter of the coarse particle ceramic powder are prepared. In the mixing step, the coarse particle ceramic powder and the fine particle powder are mixed to produce a raw material mixture. In the forming step, the raw material mixture is formed to a shaped body. In the heat-treating step, the shaped body is heated and thereby sintered to produce a polycrystalline ceramic body. In the heat-treating step, a temperature elevating process and a first holding process are performed and at the same time, a second holding process and/or a cooling process are performed. In the temperature elevating process, heating is started to elevate the temperature and in the first holding process, the shaped body is held at a temperature T&#xb0; C. In the second holding process, the shaped body is held at a temperature T&#xb0; C. lower than the temperature T&#xb0; C. In the cooling process, the shaped body is cooled at a temperature dropping rate of 60&#xb0; C./h or less from the temperature T&#xb0; C.

Production method of polycrystalline ceramic body

A piezoelectric actuatorincludes a piezoelectric element, which has a pair of electrodes formed on the surface of a piezoelectric ceramic member, as a drive source. The piezoelectric actuatorsatisfies at least one of the following requirements (a) to (c):

Piezoelectric actuator

The piezoelectric actuator includes a piezoelectric element () including a sheet of piezoelectric ceramic and electrodes formed at least part of the surface of the sheet of piezoelectric ceramic, and a holding member () holding the piezoelectric element ();

This invention provides a piezoelectric ceramic composition that does not contain lead, can be sintered at a normal pressure and is excellent in at least one of a piezoelectric constant, an electro-mechanical coupling coefficient, a dielectric loss, a relative dielectric constant and a Curie point, its production method, and a piezoelectric device and a dielectric device each utilizing the piezoelectric ceramic composition. The invention relates to a piezoelectric composition expressed by the general formula {Li(KNa)}(NbSb)O, each of x, y and z respectively falling within composition ranges of 0&#x2266;x&#x2266;0.2, 0&#x2266;y&#x2266;1.0 and 0&#x2266;z&#x2266;0.2 (with the exception of x=z=0), and its production method. The invention further relates to a piezoelectric device having a piezoelectric body formed of the piezoelectric ceramic composition described above and a dielectric device having a dielectric body formed of the piezoelectric ceramic composition described above.

Piezoelectric ceramic composition, its production method, and piezoelectric device and dielectric device

This invention provides a piezoelectric ceramic composition that does not contain lead, can be sintered at a normal pressure and has a high electro-mechanical coupling coefficient and a small dielectric loss, its production method, and a piezoelectric device utilizing the piezoelectric ceramic composition. The invention relates to a piezoelectric composition containing a compound expressed by the general formula {Li(KNa)}(NbTa)O, each of x, y and z respectively falling within composition range of 0&#x2266;x&#x2266;0.2, 0&#x2266;y&#x2266;1.0 and 0&#x2266;z&#x2266;0.4, as its main component, and further containing nickel or a nickel-containing compound. To provide a piezoelectric device that does not contain lead, can be sintered at a normal pressure and has a high electro-mechanical coupling coefficient Kp and a small dielectric loss, the piezoelectric ceramic composition of the invention is expressed by the general formula {Li(KNa)}(NbTa(MnW)O, each of x, y, z and n respectively falling within a composition range of 0&#x2266;x&#x2266;0.2, 0&#x2266;y&#x2266;1.0, 0&#x2266;z&#x2266;0.4 and 0&#x3c;n&#x2266;0.1.

Piezoelectric ceramic composition, its production method and piezoelectric device

A piezoelectric ceramic composition not containing lead, able to be sintered at ordinary pressure, and superior to the past in at least one of the properties unique to piezoelectric ceramic compositions such as the piezoelectric dconstant, that is, a piezoelectric ceramic composition having a compound of a general formula {Li(KNa)}(NbTaSb)Owhere x, y, z, and w are in the ranges of 0&#x2266;x&#x2266;0.2, 0&#x2266;y&#x2266;1, 0&#x3c;z&#x2266;0.4, and 0&#x3c;w&#x2266;0.2 as a main ingredient, where the piezoelectric ceramic composition contains at least one metal element selected from (1) palladium, silver, gold, ruthenium, rhodium, rhenium, osmium, iridium, and platinum, (2) nickel, iron, manganese, copper, and zinc, or (3) magnesium, calcium, strontium, and barium as an added element, and a method of production of the same and a piezoelectric element and dielectric element utilizing that piezoelectric ceramic composition.

Piezoelectric ceramic composition and method of production of same, piezoelectric element, and dielectric element

In a pair of electrodes where a potential difference is changed in accordance with acidity or basicity of oil, a reference electrode is made of cobalt or a cobalt alloy, and a sensitive electrode is made of tungsten or a tungsten alloy. The sensitive electrode is used in combination with the reference electrode. Accordingly, it is possible to provide a pair of electrodes for detecting the acidity or the basicity of the oil which use a novel electrode material not hazardous to the environment and at the same time, suited for use in a semiconductor fabrication technique.

Pair of electrodes for detecting acidity or basicity of oil

A brazing sheet for vacuum brazing is provided wherein the sheet is cladded with an aluminum alloy brazing filler metal having a content of Mg sufficient for vacuum brazing but less than 1.2 wt. % and wherein the Mg.sub.2 Si particle size among Mg contained in the metal is not more than 5 .mu.m as a typical value.

Brazing sheet for vacuum brazing

A vacuum pump is first driven to start evacuation from the interior of a furnace. At the time when the furnace pressure reaches 8.times.10.sup.-5 Torr, a heater is driven to start elevating the furnace temperature. Then, at the time when the furnace temperature reaches 565.degree. C. that corresponds to the solidus line temperature for a brazing filler metal of Al - 10% Si alloy containing Mg of 0.6 wt. %, a motor is driven to close a shutter, thereby vacuum brazing aluminum with evacuation control under a high-vacuum level. By controlling the evacuation after reaching a high-vacuum level, the amount of water vapor in the furnace becomes sufficiently small and Mg vapor is highly densified, which permits brazing of satisfactory quality even with a brazing filler metal containing Mg of 1.2 wt. % or less, in combination with use of such a brazing filler metal as having the Mg.sub.2 Si particle size fined to be 5 .mu.m as a typical value through soaking and the thickness of a surface oxide film thinned to be 80 .ANG. through etching. Thus, Mg's specific functions such as breakage of an oxide film, gettering and reducing can be sufficiently developed even if the Mg content in the brazing filler metal is lowered, with the result of saving resources.

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Chiryu, Japan

Tatsuhiko Nonoyama