Matsushita Electric Industrial Co., Ltd.

Matsushita Electronics Corporation

Masamitsu Nishida

Hiromu Ouchi

Syunichiro Kawashima

Ichiro Ueda

Junichi Kato

Koichi Kugimiya

Keiichi Takahashi

Hamae Ando

Kojiro Okuyama

Shigeru Hayakawa

Kazunori Numata

Hiroyuki Hase

Yoshihiro Matsuo

Hiroshi Sogou

Yoichirou Yokotani

Toshiyuki Asahi

Tsuneharu Nitta

Hiroshi Asano

Yoichiro Yokotani

Kouichi Kugimiya

Takuya Fujimaru

The present invention provides a piezoelectric ceramic composition that can be manufactured easily by an ordinary sintering method, is free from lead, and has a large frequency constant, a small grain size, and a high mechanical Q. This composition is expressed by a formula of (1-v-w)&lsqb;(Li Na K ) RO &rsqb;.vLMnO .wBi Na TiO . The present invention also provides a piezoelectric ceramic composition, including at least one selected from Mn, Cr, and Co that is added to a composition expressed by a formula of (Li Na K ) RO so as to have a ratio thereof to the whole of 0.01 to 1 wt % in terms of MnO , Cr O , and CoO, respectively. In the above-mentioned formulae, 0&lE;v&lE;0.05, 0&lE;0.2, v&plus;w>0, 0.2&lE;x&lE;0.97, 0&lE;y&lE;0.8, x&plus;y&gE;0.8, 0.98&lE;z&lE;1, L indicates at least one element selected from the rare earth elements, and R denotes at least one element selected from Nb, Ta, and Sb.

Piezoelectric ceramic composition and piezoelectric element containing the same

The present invention provides a piezoelectric ceramic composition that is free from lead and has a small grain size, a high coupling coefficient, a high mechanical Q, and a large frequency constant. This composition is characterized by being expressed by a formula of (Li Na K ) Ma Nb Mb O , wherein 0.03&lE;x&lE;0.2, 0&lE;y&lE;0.2, 0.98&lE;z&lE;1, 0<w&lE;0.05, Ma indicates at least one element selected from the alkaline-earth metals, and Mb denotes at least one element selected from Bi, Sb, and the rare earth elements.

The piezoelectric ceramic composition of the present invention contains, as a main component, a material having a composition represented by Formula: CaM Bi Ti (Nb Ta ) O , where M is at least one element selected from the group consisting of Ca, Sr, and Ba; 0.0&lE;A&lE;1.0; and 0.0&lE;X&lE;0.6.

Piezoelectric ceramic composition and piezoelectric element using the same

Piezoelectric ceramic compositions

A piezoelectric ceramic composition comprises a composite oxide of Pb, Ti and Zr as a main component and Mn and at least one metal element selected from the group consisting of Y, Dy, Er, Ho, Tm, Lu and Yb as subsidiary components. A piezoelectric device comprises such a piezoelectric ceramic composition.

Piezoelectric ceramic composition and piezoelectric device using the same

A piezoelectric ceramic composition represents a composition formula, (Pb.sub.u A.sub.1-u).sub.v {(Zn.sub.1/3 Nb.sub.2/3).sub.w (Sn.sub.1/3 Nb.sub.2/3).sub.x Ti.sub.y Zr.sub.z }.sub.2-v O.sub.3, where the symbol A is at least one component selected from a group consisting of La, Nd, Pr, and Bi, and u, v, w, x, y, and z are within ranges represented by the following Equations, characterized in that 0.1 to 3 mole percent of a Mn compound calculated in terms of MnO.sub.2 is added to said piezoelectric ceramic composition.

Piezoelectric ceramic composition and piezoelectric transformer

A dielectric ceramic composite material comprising a dielectric ceramics and a glass having a softening temperature lower than the sintering temperature of the dielectric ceramics, wherein said particles of the dielectric ceramics are randomly dispersed in a matrix of the glass. This composite material can be formed by molding a mixture of the dielectric ceramics powder and glass powder at first, and by firing this mold (including a film thereof) at the softening temperature of the glass or higher. The obtained dielectric ceramics composite material can be extensively utilized as various ceramic functional elements or electronic components incorporated in various piezoelectric, pyroelectric, ferroelectric memory, actuator elements and many others.

Dielectric ceramics composite material

In an agitating mill for producing the objective fine powder, the agitating medium having an average particle diameter of no more than 0.6 mm is charged in an annular gap between the external side wall of the agitator and the internal side wall of the milling vessel. Thereby the agitator can be rotated at a peripheral speed of no less than 30 m/s, and it results in a high grinding rate and reduced amount of impurity which means worn-out grinding media included in the objective fine powder.

Agitating mill and method for milling

High-frequency dielectric ceramics which contains the oxide of a complex perovskite structure as the main component, have a mean crystal gain size of sintered ceramic controlled to within the range of 5 .mu.m to 20 .mu.m and a porosity not exceeding 7% and provides high unloaded Q without requiring long-hour sintering or heat treatment.

Dielectric ceramics

A piezoelectric ceramic comprising at least two kinds of ceramic domains that are different from each other either in composition or in piezoelectric characteristics. It is made possible to produce a piezoelectric ceramic with better piezoelectric characteristics than that composed of a single kind of ceramic domain by having the compositions or the piezoelectric characteristics of each ceramic domain properly selected. For example, it is possible to obtain a piezoelectric ceramic of an extremely small rate of change in resonance frequency in response to a change in temperature by having a ceramic domain with a positive rate of change in resonance frequency in response to a change in temperature and the one with a negative rate of change in resonance frequency in response to a change in temperature combined.

Piezoelectric ceramics and their production methods

Provided is a method for milling ceramic powder which comprises wet-milling at least one ceramic powder by a media agitating mill wherein the volume of liquid is 4 times or less the net-volume of the ceramic powder. A dispersing agent is added and milling is carried out using grinding media of 1 mm, or less, in diameter. Further, a media agitating mill used for the above method is provided which comprises a milling chamber, grinding media and an agitator wherein the peripheral speed of the agitator is 10 m/s or more, the grinding media have a diameter of 1 mm or less and packing fraction of the grinding media is 65-85 vol %. A method for making a sintered body from fine powder produced by the above milling method is also disclosed.

Media agitating mill and method for milling ceramic powder

A method for milling ceramic powder and making a sintered body from the powder produced by such method are disclosed. A preferred embodiment includes wet-milling at least one ceramic powder by a media agitating mill wherein the volume of liquid is not more than 4 times the net-volume of the ceramic powder, a dispersing agent is added and milling is carried out using grinding media of not larger than 1 mm in diameter. A media agitating mill used for the above method is provided which includes a milling chamber, grinding media and an agitator wherein the peripheral speed of the agitator is at least 10 m/s, the grinding media having a diameter of not larger than 1 mm and the packing fraction of the grinding media is 65-85% by volume.

A dielectric ceramic composition consisting essentially of:

Dielectric ceramic compositions

Plural number of thermo-plastic organic films having ceramic green layer(s) and a layer to become electrode thereon are laminated, thereby to form laminated body, which is hot-pressed to impregnate the organic film substance into the ceramic green layers and into layers to become electrodes, and then is fired; thereby, the ceramic layers are formed very thin, thereby producing a capacitor of large capacitance per volume.

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Osaka, Japan

Masamitsu Nishida