【発明の詳細な説明】[Detailed description of the invention]
本発明は高誘電率系磁器組成物に係り、複合酸
化物の固相反応によつて合成された
Pb（Mg1/3・Nb2/3）O3−PbTiO3
系酸化物で、特に低温度焼結が可能で、高誘電
率、かつ誘電体損失が小さく、温度変化率の優れ
た高誘電率系磁器組成物に関するものである。従
来、高誘電率磁器組成物として、チタン酸バリウ
ムBaTiO3、スズ酸バリウムNaSnO3、チタン酸カ
ルシウムCaTiO3などを基本として、その置換固
溶体あるいは他の結晶構造を有する化合物との複
合誘電体磁器が、種々の要求特性に対して、広く
実用化されている。これ等の磁器誘電体は、特性
改善の為に常温での誘電率を最大にすると誘電率
の温度変化が大きくなり、一方誘電率の温度変化
を小さくすれば誘電率の最大値が減少するなど実
用上種々の問題点があり、その改善が望まれてい
た。更に、通常1200〜1400℃附近の高温領域で焼
結を必要とするために焼結時、多量の熱エネルギ
ーを必要とし、更に高温下の焼成炉材の熱的劣化
損失が激しく、従つて焼成装置の保全費がかさむ
等の欠点があつた。また最近急速に普及しつつあ
る積層磁器コンデンサにあつては、製造法上、内
部電極を磁器誘電体に埋込んだ状態で焼結する必
要があり、焼結温度が1200℃を超える従来の磁器
誘電体では、1300℃以上の高温で安定ではあるが
高価な貴金属・白金、パラジウムもしくはこれ等
の合金を使用しなければならなかつた。もし1000
℃程度の低温度焼結可能な磁器誘電体を積層磁器
コンデンサとして用いることが可能であれば、埋
込み内部電極に銀系、ニツケル系、アルミ系等の
安価な金属材料を内部電極として使用出来ること
になり、製造コスト面で極めて有利である。もち
ろん低温度焼結で得られた磁器誘電体は、絶縁抵
抗が高く、誘電率が比較的大きく、誘電体損失が
小さく、かつ温度変化率の優れたものが必要とさ
れる。従来、これ等の条件を備えた低温度焼結に
よる安定な磁気誘電体は少なく、その実現が望ま
れていた。
本発明者等は、上述の要請に鑑み、鋭意研究の
結果、本発明に到達したものであり、その要旨
は、
PbO ………68.67〜69.19重量％
MgO ………3.67〜4.09 重量％
Nb2O5 ………24.17〜26.99重量％
TiO2 ………0.25〜2.97 重量％
の範囲からなることを特徴とするPb（Mg1/3・
Nb2/3）O3−PbTiO3系高誘電率系磁器組成物で
あり
すなわち、本発明は1100℃附近の低温領域で焼
結することが可能で、かつ特性の優れた高誘電率
系磁器組成物を提供するものである。
以下実施例によつて本発明を詳述する。
出発原料として酸化鉛（PbO）、酸化ニオブ
（Nb2O5）、酸化マグネシウム（MgO）、酸化チタ
ン（TiO3）
を用い、第１表に示した配合比となるように秤量
した。これ等の原料配合物を合成樹脂ボールミル
で、湿式混合した後、700〜850℃で２時間仮焼
し、化学反応を行なわせしめた。この反応物を、
ふたたびボールミルを用いて、粒子径数μ程度に
粉破混合する。
この混合物に粘結剤としてポリビニールアルコ
ール（PVA）を適当量加え、約３トン／cm2の成
形圧力で直径16.5mm、厚さ0.6mmの円板状成形物
を作成した。成形物は高温での鉛成分の蒸発を防
ぐ為、マグネシア磁器製容器に密閉して、約1100
℃で２時間本焼成する。こうして得られた磁気素
体の両端面に銀電極を焼付する。このようにして
製造した試料を、それぞれ電気特性を測定した結
果を第１表に示す。
ここで誘電率εｓおよび誘電体損失（tanδ）
は、周波数1KHzで測定した。絶縁抵抗は、直流
500Vを印加して、室温20℃でで測定した。
温度特性は、室温20℃を基準として−25℃、＋
85℃容量変化率を求めた。
The present invention relates to a high-permittivity ceramic composition, which is a Pb(Mg1/3・Nb2/3)O 3 -PbTiO 3- based oxide synthesized by a solid-phase reaction of a composite oxide, and in particular a low-temperature sintered oxide. The present invention relates to a high dielectric constant ceramic composition that can be bonded, has a high dielectric constant, has low dielectric loss, and has an excellent temperature change rate. Conventionally, high dielectric constant ceramic compositions have been made based on barium titanate BaTiO 3 , barium stannate NaSnO 3 , calcium titanate CaTiO 3 , etc., and their substituted solid solutions or composite dielectric ceramics with compounds having other crystal structures. , has been widely put into practical use for various required characteristics. For these porcelain dielectrics, if the dielectric constant at room temperature is maximized to improve the characteristics, the temperature change in the dielectric constant becomes large, while if the temperature change in the dielectric constant is made small, the maximum value of the dielectric constant decreases. There are various problems in practical use, and improvements have been desired. Furthermore, since sintering is normally required in a high temperature range of around 1200 to 1400°C, a large amount of thermal energy is required during sintering, and furthermore, the thermal deterioration loss of the firing furnace material at high temperatures is severe; There were drawbacks such as increased equipment maintenance costs. Furthermore, in the case of multilayer porcelain capacitors, which are rapidly becoming popular these days, the manufacturing method requires that the internal electrodes be sintered while being embedded in a porcelain dielectric material, which is different from conventional porcelain capacitors whose sintering temperature exceeds 1200°C. For the dielectric, it was necessary to use precious metals such as platinum, palladium, or alloys of these, which are stable at high temperatures of 1,300°C or higher, but are expensive. If 1000
If it is possible to use a ceramic dielectric material that can be sintered at a low temperature of about ℃ as a multilayer ceramic capacitor, it is possible to use inexpensive metal materials such as silver, nickel, and aluminum for the embedded internal electrodes. This makes it extremely advantageous in terms of manufacturing costs. Of course, the porcelain dielectric obtained by low-temperature sintering is required to have high insulation resistance, relatively large dielectric constant, small dielectric loss, and excellent temperature change rate. Conventionally, there have been few stable magnetic dielectric materials that meet these conditions and are produced by low-temperature sintering, and the realization of such materials has been desired. In view of the above requirements, the present inventors have arrived at the present invention as a result of intensive research, and the gist thereof is as follows: PbO...68.67-69.19% by weight MgO...3.67-4.09% by weight Nb 2 Pb (Mg1/ 3 ・
Nb2/3)O3 - PbTiO3 -based high dielectric constant ceramic composition.In other words, the present invention is a high dielectric constant ceramic composition that can be sintered at a low temperature around 1100℃ and has excellent properties. It is something that provides something. The present invention will be explained in detail below with reference to Examples. Lead oxide (PbO), niobium oxide (Nb 2 O 5 ), magnesium oxide (MgO), and titanium oxide (TiO 3 ) were used as starting materials and were weighed so as to have the compounding ratios shown in Table 1. These raw material mixtures were wet mixed in a synthetic resin ball mill and then calcined at 700 to 850°C for 2 hours to cause a chemical reaction. This reactant,
Using the ball mill again, the powder is mixed to a particle size of several microns. An appropriate amount of polyvinyl alcohol (PVA) was added as a binder to this mixture, and a disc-shaped molded product with a diameter of 16.5 mm and a thickness of 0.6 mm was produced at a molding pressure of about 3 tons/cm 2 . The molded product was sealed in a magnesia porcelain container to prevent the lead component from evaporating at high temperatures.
Main firing at ℃ for 2 hours. Silver electrodes are baked onto both end faces of the magnetic body thus obtained. Table 1 shows the results of measuring the electrical properties of the samples produced in this way. Here, permittivity εs and dielectric loss (tanδ)
was measured at a frequency of 1KHz. Insulation resistance is DC
Measurement was performed at room temperature of 20°C with 500V applied. Temperature characteristics are -25℃ and +25℃ based on room temperature 20℃.
The rate of change in capacity at 85°C was determined.
【表】
第１表において、試料No.1、８は本発明の範
囲外のものであり、比較の為示した。
第１表より明らかなように、本発明範囲内のも
のは、比誘電率（εｓ）が約21400の高い値を示
し、誘電体損失（tanδ）は0.2〜4.8％の極めて
小さな値を示している状態でしかも1100℃付近
の、低温度で焼結が可能である。すなわち、この
組成範囲からはずれるものでは第１表に示すよう
に望ましい特性を得ることはできなかつた。
その限定理由を具体的に述べる。
酸化鉛（PbO）が68.67重量％以下、酸化マグ
ネシウム（MgO）が4.09重量％を越えた場合、
誘電率が低下して、実用的でない。又、焼成温度
が上昇して好ましくない。
酸化チタン（TiO2）が0.25重量％以下、酸化ニ
オブ（Nb2O5）が26.99重量％以下でも同様であ
る。
更に酸化鉛（PbO）が69.19重量％以上を越
え、酸化マグネシウム（MgO）が3.67重量％以
下、酸化ニオブ（Nb2O5）が24.17重量％以下、酸
化チタン（TiO2）が2.97重量％を越えた場合、誘
電率が低下、誘電体損失（tanδ）が大きくなり
実用的でない。
なお、実施例においてMgOは炭酸塩の形で用
いたが他の形の例えば硝酸塩のものでも本発明の
技術思想に包含されることは明らかである。
以上の様に本発明の
Pb（Mg1/3・Nb2/3）O3−PbTiO3
系高誘電率磁器組成物によると、低温度焼結が可
能となり、かつ誘電率（εｓ）が高く、誘電体損
失（tanδ）、容量変化率の極めて良好な新規な磁
器組成物が得られ、また積層磁器コンデンサに使
用した場合、埋込内部電極に銀系・ニツケル系・
アルミ系の如き低融点金属の使用が可能となつ
た。
したがつて、従来の高温領域焼結材に比較して
多量の熱エネルギー、焼結炉材等の保全費に格段
の効果があるので省エネルギーの観点からコスト
面で極めて有利な高誘電率系磁器組成物を提供す
ることができるので工業上の利益に大なるものが
ある。[Table] In Table 1, Samples No. 1 and 8 are outside the scope of the present invention and are shown for comparison. As is clear from Table 1, those within the scope of the present invention exhibit a high relative dielectric constant (εs) of about 21400, and a very small dielectric loss (tan δ) of 0.2 to 4.8%. It is possible to sinter at low temperatures, around 1100°C, even when the material is present. That is, if the composition deviated from this range, it was not possible to obtain the desired properties as shown in Table 1. The reason for this limitation will be explained in detail. If lead oxide (PbO) is 68.67% by weight or less and magnesium oxide (MgO) exceeds 4.09% by weight,
The dielectric constant decreases, making it impractical. Moreover, the firing temperature increases, which is not preferable. The same applies if titanium oxide (TiO 2 ) is 0.25% by weight or less and niobium oxide (Nb 2 O 5 ) is 26.99% by weight or less. Furthermore, lead oxide (PbO) exceeds 69.19% by weight or more, magnesium oxide (MgO) exceeds 3.67% by weight, niobium oxide (Nb 2 O 5 ) exceeds 24.17% by weight, and titanium oxide (TiO 2 ) exceeds 2.97% by weight. If it exceeds this, the dielectric constant decreases and the dielectric loss (tan δ) increases, making it impractical. Although MgO was used in the form of carbonate in the examples, it is clear that other forms such as nitrate are also included in the technical idea of the present invention. As described above, the Pb(Mg1/3・Nb2/3)O 3 -PbTiO 3 based high dielectric constant ceramic composition of the present invention enables low temperature sintering, has a high dielectric constant (εs), and has a high dielectric constant. A new ceramic composition with extremely good body loss (tan δ) and capacitance change rate was obtained, and when used in a multilayer ceramic capacitor, silver-based, nickel-based,
It became possible to use low melting point metals such as aluminum. Therefore, compared to conventional sintered materials in high-temperature ranges, high-permittivity porcelain is extremely effective in terms of cost from the perspective of energy saving, as it is significantly effective in reducing the amount of thermal energy and maintenance costs for sintering furnace materials, etc. There are great industrial benefits as a result of the ability to provide compositions.