JP2004083386A - Dielectric material and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dielectric material capable of obtaining a high product Qf of quality factor and resonant frequency even if it has a low dielectric constant εr. <P>SOLUTION: The dielectric material is a sintered compact in which an α<SB>4</SB>β<SB>2</SB>O<SB>9</SB>-type crystal phase is a main phase. Especially, the sintered compact containing an Mg<SB>4</SB>Nb<SB>2</SB>O<SB>9</SB>crystal phase as a main phase exhibits characteristics that the dielectric constant εr is about 13, and the product Qf of the quality factor, measured by a resonance method at any frequency of 8-11 GHz, and the resonance frequency is higher than 240,000 (GHz). <P>COPYRIGHT: (C)2004,JPO

Description

【００２３】
図２に示すように、εｒは、ｘ、つまり（Ｍｇ_ｘＣａ_{（１−ｘ）}）_２Ｎｂ_２Ｏ_７においてＣａをＭｇで置換する量（以下、Ｍｇ置換量）が多くなるにつれて低下する傾向にある。したがって、本発明の目的の一つである、低いεｒを得るためには、Ｍｇ置換量を多くすればよいことがわかる。
一方、図３に示すように、Ｑ・ｆは、Ｍｇ置換量の増加とともに向上するが、０．７（ｍｏｌ比、以下同様）近傍をピークにそれ以上のＭｇ置換量では逆に低下する傾向を示す。したがって、Ｑ・ｆを確保する上では、Ｍｇ置換量を０．４〜０．９、望ましくは０．６５〜０．７５の範囲とすべきことがわかった。図２に示すように、Ｍｇ置換量が０．４〜０．９の範囲ではεｒは２５以下、さらにＭｇ置換量が０．６５〜０．７５の範囲ではεｒは２０以下となる。ここで、図３をも考慮すれば、Ｍｇ置換量は、０．４〜０．９、望ましくは０．５〜０．８、さらに望ましくは０．６５〜０．７５とすべきである。
【００２４】
図４は、Ｍｇ置換量が
０（組成＝Ｃａ_２Ｎｂ_２Ｏ_７）、
０．４０（組成＝（Ｍｇ_０．４０Ｃａ_０．６０）_２Ｎｂ_２Ｏ_７）、
０．６０（組成＝（Ｍｇ_０．６０Ｃａ_０．４０）_２Ｎｂ_２Ｏ_７）、
０．６７５（組成＝（Ｍｇ_{０．６７５}Ｃａ_{０．３２５}）_２Ｎｂ_２Ｏ_７）
の配合組成から得た焼結体のＸ線回折結果を示す図である。
また、図５は、Ｍｇ置換量が
０．７０（組成＝（Ｍｇ_０．７０Ｃａ_０．３０）_２Ｎｂ_２Ｏ_７）、
０．７２５（組成＝（Ｍｇ_{０．７２５}Ｃａ_{０．２７５}）_２Ｎｂ_２Ｏ_７）、
０．８０（組成＝（Ｍｇ_０．８０Ｃａ_０．２０）_２Ｎｂ_２Ｏ_７）、
１．００（組成＝Ｍｇ_２Ｎｂ_２Ｏ_７）
の配合組成から得た焼結体のＸ線回折結果を示す図である。
【００２５】
図４および図５に基づいて、各焼結体を構成する結晶相を確認した。その結果を図６に示してある。図４〜図６に示すように、Ｍｇ置換量が０（組成式＝Ｃａ_２Ｎｂ_２Ｏ_７）の焼結体はＣａ_２Ｎｂ_２Ｏ_７相のみからなる単相組織であるが、Ｍｇ置換量が０．４０および０．６０の焼結体は、Ｃａ_２Ｎｂ_２Ｏ_７相のほかに、ＣａＮｂ_２Ｏ_６相およびＭｇ_４Ｎｂ_２Ｏ_９相が出現する。図４より、Ｍｇ置換量が０．４０および０．６０の焼結体は、Ｃａ_２Ｎｂ_２Ｏ_７相の存在量は少なく、ＣａＮｂ_２Ｏ_６相およびＭｇ_４Ｎｂ_２Ｏ_９相が主体をなすことがわかる。さらに、Ｍｇ置換量が０．６７５と多い焼結体では、Ｃａ_２Ｎｂ_２Ｏ_７相は存在しておらず、ＣａＮｂ_２Ｏ_６相およびＭｇ_４Ｎｂ_２Ｏ_９相の２相組織となる。さらに、Ｍｇ置換量が０．７と多い焼結体では、ＣａＮｂ_２Ｏ_６相およびＭｇ_４Ｎｂ_２Ｏ_９相の他に、Ｍｇ_５Ｎｂ_４Ｏ_１５相が観察された。さらにまた、Ｍｇ置換量が０．７２５あるいは０．８０に増えると、ＭｇＮｂ_２Ｏ_６相が出現する。そして、置換量が１．０になると、ＣａＮｂ_２Ｏ_６相およびＭｇ_４Ｎｂ_２Ｏ_９相は消失し、Ｍｇ_５Ｎｂ_４Ｏ_１５相およびＭｇＮｂ_２Ｏ_６相の２相組織となる。
【００２６】
焼結体を構成する結晶相と、図２を比較検討すると、Ｃａ_２Ｎｂ_２Ｏ_７相のみからなる単相組織よりも、さらに他の結晶相が混在することにより、焼結体のεｒが低減していることがわかる。また、図３との比較においては、ＣａＮｂ_２Ｏ_６相およびＭｇ_４Ｎｂ_２Ｏ_９相の２つの結晶相が存在する場合に、高いＱ・ｆが得られていることがわかる。
【００２７】
（実施例１）
以上の知見に基づいて、Ｍｇ_４Ｎｂ_２Ｏ_９相単相からなる焼結体およびＣａＮｂ_２Ｏ_６相単相からなる焼結体を得ることを目的とする実験を行った。その結果を実施例１として以下に示す。
平均粒径０．１μｍのＭｇＯ粉末を１９．４ｇおよび平均粒径１．５μｍのＮｂ_２Ｏ_３粉末を３１．１ｇを配合して原料粉末を得た。配合は、焼結後において化学量論的にＭｇ_４Ｎｂ_２Ｏ_９となるように、その比が定められた。この原料粉末をボール・ミルに投入して１６時間湿式混合した。
混合された原料粉末を１２０℃で２４時間乾燥後、２００ｋｇｆ／ｃｍ^２の圧力でプレスして円柱状（６０ｍｍφ）の成形体を得た。この成形体を、仮焼きした。仮焼きの雰囲気は大気とし、１１００℃で２時間加熱・保持した。仮焼き後に、仮焼き体をボール・ミルに投入して粉砕を行った後に１２０℃で２４時間乾燥して完成粉末を得た。得られた完成粉末の平均粒径は、０．５〜５μｍの範囲内にあった。
完成粉末に有機バインダを加えて造粒、分級した後、２ｔ／ｃｍ^２の圧力でプレスして円柱状（１２ｍｍφ）の成形体を得た。成形後、１３００℃、１３５０℃および１３７０℃で４時間保持することにより、本発明による焼結体（実施例１）を得た。得られた焼結体について、ＪＩＳ　Ｒ　１６２７に準じて、εｒおよびＱ・ｆ（測定周波数　８．５〜１０ＧＨｚ）を測定した。測定結果を表２に示すとともに、焼結温度とεｒの関係を図７に、また焼結温度とＱ・ｆの関係を図８に示す。
比較例として、平均粒径０．３μｍのＣａＣＯ_３粉末を１３．７ｇおよび平均粒径１．５μｍのＮｂ_２Ｏ_５粉末を３６．３ｇを配合した原料粉末を用いる以外は、以上と同様の工程を経て焼結体（比較例１）を得た。なお、配合は、焼結後において化学量論的にＣａＮｂ_２Ｏ_６となるように、その比が定められた。この比較例１についても、ＪＩＳ　Ｒ　１６２７に準じて、εｒおよびＱ・ｆ（測定周波数８．５〜１０ＧＨｚ）を測定した。測定結果を表２に示すとともに、焼結温度とεｒの関係を図７に、また焼結温度とＱ・ｆの関係を図８に示す。
【００２８】
【表２】

【００２９】
表２および図７に示すように、実施例１による焼結体（Ｍｇ_４Ｎｂ_２Ｏ_９と表示）のεｒは、焼結温度に係わらず、約１３を示している。これに対して比較例１による焼結体（ＣａＮｂ_２Ｏ_６と表示）は、εｒが約１７を示している。
また、表２および図８に示すように、実施例１による焼結体は、２３００００ＧＨｚあるいは２４００００ＧＨｚを超える高いＱ・ｆを得ることができる。これに対して比較例１による焼結体は、Ｑ・ｆが６００００〜８００００ＧＨｚ程度であり、実施例１による焼結体よりも低い値にあることがわかる。
【００３０】
実施例１による焼結体（焼結温度１３５０℃）の相構成を確認するため、Ｘ線回折を行った。その結果を図９に示すが、Ｍｇ_４Ｎｂ_２Ｏ_９相のみからなる単相組織であることがわかった。
【００３１】
（実施例２）
次に、Ｍｇ_４Ｎｂ_２Ｏ_９のＭｇの一部をＢａ、ＳｒおよびＣａで置換した組成系の焼結体を作成して、実施例１と同様にεｒおよびＱ・ｆを測定するとともに、温度特性（以下、ＴＣＦ）を測定した。その結果を実施例２として示す。なお、測定に供した焼結体の組成は以下の組成式のｙ（置換量）を適宜変動させたものである。また、これら焼結体は実施例１と同様の手法（焼結温度は１３２５℃）で得た。
Ｂａ置換材：（Ｍｇ_１−ｙＢａ_ｙ）_４Ｎｂ_２Ｏ_９
Ｓｒ置換材：（Ｍｇ_１−ｙＳｒ_ｙ）_４Ｎｂ_２Ｏ_９
Ｃａ置換材：（Ｍｇ_１−ｙＣａ_ｙ）_４Ｎｂ_２Ｏ_９
【００３２】
図１０にεｒ、図１１にＱ・ｆ（測定周波数　８〜１１ＧＨｚ）および図１２にＴＣＦの測定結果を示す。また、表３にこれらの測定結果をまとめて示す。なお、ＴＣＦは、共振周波数の温度による変化率を、対応する温度の変化分で除した値であり、ここでは、−４０〜８５℃での共振周波数を測定することにより求めた。
図１０に示すように、Ｂａ、ＳｒおよびＣａでＭｇを置換する量が増えるにしたがって、εｒは若干であるが大きくなる傾向を示す。Ｂａ、ＳｒおよびＣａのいずれで置換する場合であっても、２０以下のεｒを得るためには、置換量を０．２５以下にする必要がある。
また、図１１に示すように、Ｂａ、ＳｒおよびＣａによるＭｇの置換によって、Ｑ・ｆが低下する傾向にある、しかし、ＢａはＳｒおよびＣａよりもその低下の程度が小さい。
次に、ＴＣＦは、図１２に示すように、Ｂａ、ＳｒおよびＣａによりその変動の傾向が異なっている。その中で、Ｂａ置換材は、その置換量によってＴＣＦが−２０〜２０ｐｐｍ／Ｋの範囲で正の値および負の値を採る。つまり、図１２は、Ｂａ置換材は、特定の置換量でＴＣＦが０（ゼロ）になることを示唆している。
【００３３】
【表３】

【００３４】
以上説明したように、実施例１で示したＭｇ_４Ｎｂ_２Ｏ_９系の材料のＭｇをＢａ、ＳｒおよびＣａの１種または２種以上で置換することにより、εｒ、Ｑ・ｆおよびＴＣＦを調整することが可能である。その中で、Ｂａ置換量が０．４３７５の材料は、１３２５℃の焼結温度において、ＴＣＦが−１．３５ｐｐｍ／Ｋ、Ｑ・ｆが１２０９４３ＧＨｚ、εｒが２３．９３の特性を得ている。
【００３５】
実施例２の中で、前述したＢａ置換材（（Ｍｇ_１−ｙＢａ_ｙ）_４Ｎｂ_２Ｏ_９）　　の相構成を確認するため、Ｘ線回折を行った。その結果を図１３に示す。図１３に示すように、Ｂａ置換量が０（ｙ＝０．００）の焼結体は、その組織がＭｇ_４Ｎｂ_２Ｏ_９のみからなる単相組織となっているのに対して、ＢａでＭｇを置換していくと、Ｂａ（Ｍｇ_１／３Ｎｂ_２／３）Ｏ_３の結晶相が現れる。Ｂａ置換量が０．５（ｙ＝０．５０）の焼結体では、Ｂａ（Ｍｇ_１／３Ｎｂ_２／３）Ｏ_３相がＭｇ_４Ｎｂ_２Ｏ_９相よりも顕著となる。これら焼結体は、Ｍｇ_４Ｎｂ_２Ｏ_９相とＢａ（Ｍｇ_１／３Ｎｂ_２／３）Ｏ_３相の２相で焼結体の主相を構成している。
【００３６】
（実施例３）
（１−ｘ）（Ｍｇ_４Ｎｂ_２Ｏ_９）＋ｘ（Ｍｇ_４Ｔａ_２Ｏ_９）の組成となるように平均粒径０．１μｍのＭｇＯ粉末、平均粒径１．５μｍのＮｂ_２Ｏ_５粉末および平均粒径１．５μｍのＴａ_２Ｏ_５粉末を配合した後に、実施例１と同様に成形体を得た。この成形体を１３５０℃、１３７５℃、１４００℃、１４５０℃および１５００℃で焼結して焼結体を得た。得られた焼結体について、ＪＩＳ　Ｒ　１６２７に準じて、εｒおよびＱ・ｆ（測定周波数　８〜１１ＧＨｚ）を測定した。εｒの測定結果を表４および図１５に、またＱ・ｆの測定結果を表５および図１６に示す。
【００３７】
はじめに、εｒに対するＭｇ_４Ｎｂ_２Ｏ_９とＭｇ_４Ｔａ_２Ｏ_９の配合比の影響についてみると、Ｍｇ_４Ｔａ_２Ｏ_９の比率が多くなるとεｒが低下することがわかる。したがって、低いεｒを得るという本発明の目的に対してＮｂおよびＴａはともに望ましい元素であるが、その中でもＴａが最も望ましいということができる。
次に、εｒに対する焼結温度の影響についてみると、Ｍｇ_４Ｎｂ_２Ｏ_９とＭｇ_４Ｔａ_２Ｏ_９の配合比によって異なる結果が得られている。Ｍｇ_４Ｔａ_２Ｏ_９の比率が０〜０．７の範囲では焼結温度が高くなるにつれてεｒは低くなる。これに対してＭｇ_４Ｔａ_２Ｏ_９の比率が０．７を超えると焼結温度が高くなるのにつれてεｒは高くなる。もっとも、Ｍｇ_４Ｎｂ_２Ｏ_９とＭｇ_４Ｔａ_２Ｏ_９の配合比による影響に比べて焼結温度による影響は小さい。
【００３８】
また、Ｑ・ｆに対するＭｇ_４Ｎｂ_２Ｏ_９とＭｇ_４Ｔａ_２Ｏ_９の配合比の影響についてみると、統一した傾向が現れていない。例えば、焼結温度が１３５０℃の場合Ｑ・ｆの顕著な変動はないが、焼結温度が１４００℃、１４５０℃と高い場合にはＭｇ_４Ｔａ_２Ｏ_９の比率が多いほどＱ・ｆは高くなる傾向にある。
さらに、Ｑ・ｆに対する焼結温度の影響についてみると、Ｍｇ_４Ｔａ_２Ｏ_９の比率が０〜０．４の範囲では１３７５℃の焼結温度でＱ・ｆが最も高くなっている。Ｍｇ_４Ｔａ_２Ｏ_９の比率が０．４を超えると焼結温度が高くなるにつれて概ねＱ・ｆも高くなる傾向にある。
【００３９】
以上のような傾向を示すことが確認されたが、本実施例においては、１３５０℃程度の焼結温度において、１１あるいは１１以下程度のεｒで２３００００ＧＨｚを超えるＱ・ｆ特性を得ることができる。この材料は１４００℃を超える焼結温度を選択することにより、Ｑ・ｆを２８００００ＧＨｚ以上の値とすることも可能である。特に、焼結後に化学量論的にＭｇ_４Ｔａ_２Ｏ_９となるように配合組成を定めた焼結体は、１３５０℃の焼結においてεｒが１０以下、２３００００ＧＨｚを超えるＱ・ｆ特性を得ることができる。また、この焼結体は焼結温度を１４００℃程度に上げることにより、１０近傍のεｒで２８００００ＧＨｚを超えるＱ・ｆ特性を得ることができる。
【００４０】
以上の焼結体の中で、焼結後に化学量論的にＭｇ_４Ｔａ_２Ｏ_９となるように配合組成を定めた焼結体について、相構成を確認するためにＸ線回折を行った。その結果、図１４に示すように、１３５０℃、１４００℃、１４５０℃および１５００℃のいずれの温度で焼結した焼結体も、Ｍｇ_４Ｔａ_２Ｏ_９相が主相をなすことが確認された。
【００４１】
【表４】

【００４２】
【表５】

【００４３】
【発明の効果】
以上説明したように、本発明によれば、α_４β_２Ｏ_９型の結晶相が実質的に主相をなす焼結体、代表的には、αとしてＭｇを、またβとしてＮｂを選択したＭｇ_４Ｎｂ_２Ｏ_９相を主相とする焼結体は、１３程度の低いεｒでありながら２４００００ＧＨｚを超える高いＱ・ｆを得ることができる。しかもこの特性は、１４００℃以下の温度で焼結した材料で得ることができる。
また、βとしてＮｂに代えてＴａを選択した焼結体は、εｒを１１程度に低減しつつ、２８００００ＧＨｚ以上のＱ・ｆを得ることが可能である。
さらに、Ｍｇ_４Ｎｂ_２Ｏ_９のＭｇの一部をＢａで置換したα_４β_２Ｏ_９型の結晶相とＡ（Ｂ’Ｂ”）Ｏ_３型の結晶相との２相を含む焼結体は、温度特性の向上に有効である。
【図面の簡単な説明】
【図１】本発明による誘電体材料を得るための製造プロセスを示す図である。
【図２】（Ｍｇ_ｘＣａ_{（１−ｘ）}）_２Ｎｂ_２Ｏ_７の配合組成から得た焼結体のｘの値とεｒの関係を示すグラフである。
【図３】（Ｍｇ_ｘＣａ_{（１−ｘ）}）_２Ｎｂ_２Ｏ_７の配合組成から得た焼結体のｘの値とＱ・ｆの関係を示すグラフである。
【図４】（Ｍｇ_ｘＣａ_{（１−ｘ）}）_２Ｎｂ_２Ｏ_７の配合組成から得た焼結体のＸ線回折結果を示す図である。
【図５】（Ｍｇ_ｘＣａ_{（１−ｘ）}）_２Ｎｂ_２Ｏ_７の配合組成から得た焼結体のＸ線回折結果を示す図である。
【図６】（Ｍｇ_ｘＣａ_{（１−ｘ）}）_２Ｎｂ_２Ｏ_７の配合組成から得た焼結体のｘの値と出現する結晶相の関係を示す図である。
【図７】Ｍｇ_４Ｎｂ_２Ｏ_９およびＣａＮｂ_２Ｏ_６の配合組成から得た焼結体の焼結温度とεｒの関係を示すグラフである。
【図８】Ｍｇ_４Ｎｂ_２Ｏ_９およびＣａＮｂ_２Ｏ_６の配合組成から得た焼結体の焼結温度とＱ・ｆの関係を示すグラフである。
【図９】Ｍｇ_４Ｎｂ_２Ｏ_９の配合組成から得た焼結体のＸ線回折結果を示す図である。
【図１０】Ｍｇ_４Ｎｂ_２Ｏ_９のＭｇの一部をＢａ、ＳｒおよびＣａで置換した配合組成から得た焼結体のεｒと当該置換量との関係を示す図である。
【図１１】Ｍｇ_４Ｎｂ_２Ｏ_９のＭｇの一部をＢａ、ＳｒおよびＣａで置換した配合組成から得た焼結体のＱ・ｆと当該置換量との関係を示す図である。
【図１２】Ｍｇ_４Ｎｂ_２Ｏ_９のＭｇの一部をＢａ、ＳｒおよびＣａで置換した配合組成から得た焼結体の温度特性ＴＣＦと当該置換量との関係を示す図である。
【図１３】Ｍｇ_４Ｎｂ_２Ｏ_９のＭｇの一部をＢａ、ＳｒおよびＣａで置換した配合組成から得た焼結体のＸ線回折結果を示す図である。
【図１４】Ｍｇ_４Ｔａ_２Ｏ_９の配合組成から得た焼結体のＸ線回折結果を示す図である。
【図１５】（１−ｘ）（Ｍｇ_４Ｎｂ_２Ｏ_９）＋ｘ（Ｍｇ_４Ｔａ_２Ｏ_９）の配合組成から得た焼結体のεｒとｘとの関係を示す図である。
【図１６】（１−ｘ）（Ｍｇ_４Ｎｂ_２Ｏ_９）＋ｘ（Ｍｇ_４Ｔａ_２Ｏ_９）の配合組成から得た焼結体のＱ・ｆとｘとの関係を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a dielectric material, and more particularly to a dielectric material suitable for use in a high frequency band such as a microwave and a millimeter wave.
[0002]
[Prior art]
Dielectric materials have been developed for the purpose of improving the relative dielectric constant εr (hereinafter simply referred to as εr) or the product of the quality factor and the resonance frequency Q · f (hereinafter simply referred to as Q · f). However, dielectric materials used in high frequency bands such as microwaves and millimeter waves are required to exhibit a certain predetermined low value rather than a high εr. Therefore, the conventionally developed dielectric material has an εr of about 20 to 60, and thus is not suitable as a dielectric material for high frequency band applications as described above.
[0003]
For this reason, recently, development of dielectric materials for high frequency bands has been active. For example, Japanese Patent Application Laid-Open No. 2000-327412 describes a substantially MgO crystal phase and MgAl.₂O₄A dielectric ceramic composition for high frequency in which only the crystal phase is precipitated is disclosed. This ceramic composition is an excellent material that exhibits an εr in the vicinity of 9 and can obtain a Q · f exceeding 70000.
Japanese Patent Laid-Open No. 2000-247738 discloses (Y_2-xR_x) Ba (Cu_1-yZn_y) O₅(R is at least one element selected from the group consisting of Yb, Tm, Er, Ho, Dy, Gd, Eu and Sm), or a part or all of Cu of this solid solution is Zn A high frequency dielectric ceramic composition comprising a substituted solid solution is disclosed. This porcelain composition has a relative dielectric constant εr of about 15 and a Q · f of about 210,000.
[0004]
[Patent Document 1]
Japanese Unexamined Patent Publication No. 2000-327412 (pages 3 to 4)
[Patent Document 2]
JP 2000-247738 A (page 3)
[0005]
[Problems to be solved by the invention]
As described above, low εr and high Q · f dielectric materials have been developed. However, development of a dielectric material having a higher Q · f at a lower εr is required.
Moreover, it is desirable for the manufacturing cost reduction that the sintering temperature at the time of obtaining dielectric material is lower temperature. For example, it is desired to develop a dielectric material having a low εr and a high Q · f that can be sintered at a temperature of 1400 ° C. or lower.
Accordingly, an object of the present invention is to provide a dielectric material capable of obtaining a high Q · f even with a lower εr. Another object of the present invention is to obtain such a dielectric material by sintering at a relatively low temperature.
[0006]
[Means for Solving the Problems]
In order to lower εr, the present inventor₂Nb₂O₇The composition shown by was investigated. As a result, it was confirmed that the εr of the material obtained by sintering the composition obtained by replacing Ca in the composition with a predetermined amount of Mg was 20 or less, and that Q · f at that time was 10,000 (GHz) or more. did.
The inventors initially stated that the crystalline phase of this sintered body was (Mg_xCa_(1-x))₂Nb₂O₇I guessed it would be. However, depending on the amount of Mg substitution, this sintered body becomes Ca₂Nb₂O₇Phase, CaNb₂O₆Phase, Mg₄Nb₂O₉Phase, Mg₅Nb₄O₁₅Phase and MgNb₂O₆It has been found that five crystalline phases of the phase can appear. Furthermore, among these five crystal phases, CaNb₂O₆Phase and Mg₄Nb₂O₉It was found that the sintered body in which two crystal phases of the phase appeared had a low εr and a high Q · f.
[0007]
Therefore, CaNb₂O₆Phase and Mg₄Nb₂O₉In order to confirm which crystalline phase of the phase is effective for εr and Q · f, CaNb₂O₆Sintered body and Mg for obtaining single phase structure of phase₄Nb₂O₉A sintered body for obtaining a single phase structure of the phase was prepared. Then, εr and Q · f were measured for these two sintered bodies. As a result, Mg₄Nb₂O₉It was found that the sintered body produced to obtain a single phase structure of the phase realized a low value of relative dielectric constant εr of about 13, and Q · f exceeding 240000 was obtained. That is, such a low εr and a high Q · f are α₄β₂O₉This is due to the crystal structure.
The present invention is based on the above knowledge, and α₄β₂O₉Provided is a dielectric material comprising a sintered body in which a crystal phase of a mold substantially forms a main phase.
[0008]
In the dielectric material of the present invention, α can be selected from one or more divalent metal elements and β can be selected from one or more pentavalent metal elements. Furthermore, the divalent metal element can be selected from one or more alkaline earth metal elements, and the pentavalent metal element can be selected from one or more transition metal elements. In particular, Mg is recommended as the divalent metal element. As the pentavalent metal element, one or two of Nb and Ta are recommended.
[0009]
In the above dielectric material, Mg is selected as α and Nb is selected as β.₄Nb₂O₉A sintered body having a phase as a main phase can obtain characteristics such that εr is 20 or less, and Q · f measured by a resonance method at any frequency of 8 to 11 GHz is 200000 (GHz) or more. The sintered body according to the present invention can be densified by heating and holding in a temperature range of 1400 ° C. or lower, further 1350 ° C. or lower.
[0010]
Next, Mg₄Nb₂O₉When a composition in which a part of Mg in the inside is replaced with Ba is sintered, Mg₄Nb₂O₉In addition to the phase, Ba (Mg_1/3Nb_2/3) O₃A phase appears. And Mg₄Nb₂O₉Phase and Ba (Mg_1/3Nb_2/3) O₃It was confirmed that the sintered body composed of the phase was excellent in temperature characteristics. In other words, α₄β₂O₉Type crystal phase and A (B'B ") O₃The sintered body that forms the main phase with the crystalline phase of the mold is α₄β₂O₉It is possible to improve the temperature characteristics of the sintered body having the crystal phase of the mold as the main phase.
Therefore, the present invention₄β₂O₉Type crystal phase and A (B'B ") O₃A dielectric material comprising a sintered body having two phases of a crystal phase of a mold is provided.
[0011]
In the above dielectric material, α can be selected from one or more divalent metal elements and β can be selected from one or more pentavalent metal elements. Further, A is one or more divalent metal elements, B ′ is one or more divalent metal elements different from A, and B ″ is one pentavalent metal element. Or it can select from 2 or more types.
[0012]
The dielectric material having the above structure is substantially α after sintering.₄β₂O₉Type crystal phase, or α₄β₂O₉Type crystal phase and A (B'B ") O₃Obtained by the raw material powder adjusting step of adjusting the raw material powder so that the crystal phase of the mold becomes the main phase, the calcining step of heating and holding the raw material powder in a temperature range of 800 to 1300 ° C, and the calcining step A dielectric material manufacturing method comprising: a pulverizing step of pulverizing a calcined body; and a sintering step of heating and holding the pulverized powder obtained in the pulverizing step in a temperature range of 1250 to 1500 ° C. Can be obtained by: Needless to say, it is desirable to apply the above-described elements as α, β, A, B ′ and B ″.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the dielectric material of the present invention will be described in more detail.
The dielectric material of the present invention (first dielectric material) is α₄β₂O₉It is comprised from the sintered compact from which the crystal phase of a type | mold forms a main phase substantially. As a typical example of being the main phase α₄β₂O₉Although a single-phase structure of the type crystal phase can be listed, the present invention is not limited to this and α₄β₂O₉It is sufficient if the mold crystal phase is substantially the main phase. Here, whether or not it is substantially the main phase is determined by, for example, α by X-ray diffraction.₄β₂O₉It is judged by whether or not the diffraction intensity of the mold is recognized as the highest.
[0014]
In the dielectric material of the present invention, α can be selected from one or more divalent metal elements, particularly alkaline earth metal elements. Specifically, it can be selected from one or more of Mg, Ca, Sr, Ba and the like.
β is selected from one or more pentavalent metal elements. Specifically, it is one or more of Ta, Nb, and V. Thus, for example, Ca₄Nb₂O₉, Sr₄Nb₂O₉, Ba₄Nb₂O₉, Mg₄Ta₂O₉, Ba₄Ta₂O₉, Ca₄V₂O₉, Sr₄V₂O₉, Ba₄V₂O₉A sintered body having a crystal phase such as a main phase substantially is the subject of the present invention.
Here, α includes a combination of elements that are divalent on average. For example, K⁺, B³⁺And Mg²⁺ ₂The combination of these three elements is applicable. K⁺ ₂And B³⁺ ₂A combination of these two elements may be used. Similarly, β may be a combination of elements that are pentavalent on average. For example, Sn⁴⁺And Se⁶⁺A combination of these two elements may be used. Since the elements to be combined have different atomic radii, the lattice characteristics and the like can be changed to match the temperature characteristics. Furthermore, ions having different valences can be implanted into α or β to generate oxygen vacancies and improve dielectric loss. K⁺As a monovalent ion instead of Na,⁺, Ag⁺, In⁺, Tl⁺, Rb⁺, Cs⁺, Cu⁺and so on. B³⁺As a trivalent ion to replace Nd, Nd³⁺, Pr³⁺, Ce³⁺, U³⁺, La³⁺, Bi³⁺, Fe³⁺and so on. Furthermore, Sn⁴⁺As a tetravalent ion instead of Mn,⁴⁺, Ge⁴⁺, Ti⁴⁺, Ru⁴⁺, Pt⁴⁺, W⁴⁺, Hf⁴⁺, Zr⁴⁺, Tb⁴⁺and so on. Furthermore, Se⁶⁺As an alternative to hexavalent ions, S⁶⁺, Mo⁶⁺, W⁶⁺, U⁶⁺, Cr⁶⁺, Mn⁶⁺and so on.
In the above dielectric material, Mg is selected as α and Nb is selected as β₄Nb₂O₉As shown in the examples described later, the sintered body whose phase is the main phase has an εr of about 13 and can obtain a Q · f exceeding 240000 in the vicinity of a measurement frequency of 10 GHz by the resonance method.
[0015]
Another dielectric material (second dielectric material) according to the present invention is α₄β₂O₉Type crystal phase and A (B'B ") O₃It consists of a sintered body comprising two phases of a mold crystal phase. Where α₄β₂O₉Type crystal phase and A (B'B ") O₃When two phases with a crystalline phase of the mold are included, α₄β₂O₉Occupancy of the crystalline phase of the mold and A (B′B ″) O₃It is judged by whether or not the total occupancy of the crystal phase of the mold is recognized to be larger than the other crystal phases. The present invention is α₄β₂O₉Type crystal phase and A (B'B ") O₃Needless to say, it includes a case of only two crystal phases of the type.
[0016]
Α and β of the second dielectric material can be selected from the same elements as those of the first dielectric material described above.
A (B′B ″) O constituting the second dielectric material₃Type crystal phase is called perovskite type crystal structure and is generally ABO₃Expressed as a mold. Among these, A is selected from one or more divalent metal elements. Therefore, specifically, it can be selected from one or more of Mg, Ca, Sr, Ba and the like.
B 'is also selected from one or more divalent metal elements, but it is assumed that B' is an element different from A. As described above, the second dielectric material is Mg₄Nb₂O₉It was discovered by sintering a composition in which a part of Mg in the inside is replaced with Ba, and Ba in which a part of Mg is substituted corresponds to A, and Mg corresponds to B ′. From the above, the same element is selected for α and B ′.
B ″ is selected from one or more pentavalent metal elements as in β described above. Similarly, the same element is selected for B ″ and β as in the relationship between α and B ′. Will be.
Mg is selected as α and B ′, Ba is selected as A, and Nb is selected as β and B ″.₄Nb₂O₉Phase and Ba (Mg_1/3Nb_2/3) O₃A sintered body having a two-phase structure of phases is obtained. This sintered body can be regulated in the range of −80 to 80 ppm / K, desirably −40 to 40 ppm / K, and more desirably −20 to 20 ppm / K under various production conditions. In this sintered body, Q · f of 100,000 GHz or more is obtained while the temperature characteristic is in the vicinity of 0 ppm / K. Moreover, εr of this sintered body can be around 20.
[0017]
Next, a method for producing the dielectric material of the present invention will be described. The gist of this manufacturing method is shown in FIG. Hereafter, each process is demonstrated sequentially, referring FIG.
As a raw material powder for obtaining the first dielectric material of the present invention, αCO₃Powder and β₂O₅Prepare powder. Here, α is one or more of divalent metal elements, particularly alkaline earth metal elements, as described above. Here, description will be made assuming that Mg is selected as α. Β is preferably one or more of pentavalent metal elements. Here, description will be made assuming that Nb is selected as β.
MgCO₃Powder and Nb₂O₅The powder is Mg after sintering₄Nb₂O₉The compounding composition is determined so that the crystal phase forms a main phase, preferably a single phase structure. In the present invention, the composition may be slightly deviated from the stoichiometric composition. A slight compositional deviation from the stoichiometric composition can actually occur on an industrial production scale, and even if a slight compositional deviation occurs, the structure of the sintered body is Mg.₄Nb₂O₉This is because the effects of the present invention can be fully enjoyed if the phase is substantially a main phase, preferably a single-phase structure.
[0018]
By passing the above raw material powder through the steps shown below, a sintered body having a structure defined in the present invention can be obtained. Here, MgCO₃Powder and Nb₂O₅Although the powder is exemplified, a powder having another composition may be used as the raw material powder as long as the structure defined in the present invention is finally obtained. For example, MgCO₃Instead of the powder, MgO powder or Mg (OH) powder can also be used. Also, other powders can be added for sintering aids and other purposes. What is necessary is just to select the particle size of each raw material powder suitably in the range of 0.1-10 micrometers.
[0019]
The above raw material powder is mixed. For mixing, a known mixing means such as a ball mill may be used. Although it depends on the operating conditions of the ball mill, a uniform mixed state can be obtained if the mixing operation is performed for about 10 to 20 hours.
The mixed raw material powder is formed into a predetermined shape by a means such as a press and then subjected to calcining. The calcination is desirably performed in a temperature range of 800 to 1300 ° C. This is because if it is less than 800 ° C., the effect of calcining cannot be obtained sufficiently. On the other hand, when the temperature exceeds 1300 ° C., the calcined body becomes hard, and the subsequent pulverization process takes time. A desirable calcining temperature is 900 to 1250 ° C., and a more desirable calcining temperature is 1000 to 1150 ° C. The calcining time may be appropriately selected between 1 and 5 hours. The calcining atmosphere is an oxygen-containing atmosphere, typically air.
[0020]
After the calcining, the calcined body is pulverized. For the pulverization, for example, a ball mill can be used. The pulverized powder (hereinafter referred to as finished powder) is formed into a predetermined shape by means such as a press and then sintered. The finished powder is preferably carried out until the average particle size is about 0.1 to 20 μm.
Sintering is performed in a temperature range of 1250 to 1500 ° C. If it is less than 1250 ° C., the sintering does not proceed sufficiently, and the density is insufficient. On the other hand, if the temperature exceeds 1500 ° C., the material may be melted. A desirable sintering temperature is 1270 to 1400 ° C, and a more desirable sintering temperature is 1300 to 1370 ° C. The sintering time is appropriately determined depending on conditions such as the sintering temperature, the material composition, and the particle size of the finished powder, but is set in the range of 2 to 20 hours if the sintering temperature is the above. The sintering atmosphere may be an oxygen-containing atmosphere such as the air, but is preferably an oxygen atmosphere.
[0021]
Before proceeding to the description of the embodiments according to the present invention, experimental data in the process of completing the present invention will first be shown.
(Mg_xCa_(1-x))₂Nb₂O₇In the chemical formula shown, the raw material powder was blended so that x had the value shown in Table 1. The raw material powder used was MgCO having an average particle size of 0.3 to 1.5 μm.₃Powder, CaCO₃Powder and Nb₂O₅It is a powder. This raw material powder was put into a ball mill and mixed for 16 hours.
The mixed raw material powder was formed into a cylindrical shape and then calcined. The atmosphere of calcination was air, and it was heated and held at 1100 ° C. for 2 hours. After calcination, the calcined body was put into a ball mill and pulverized. The particle size of the finished powder obtained was in the range of 0.5-5 μm.
After forming the finished powder, it was held at 1350 ° C. for 4 hours to obtain a sintered body. About the obtained sintered compact, (epsilon) r and Q * f (measuring frequency 8.5-10GHz) were measured according to JISR1627 (the test method of the dielectric property of the fine ceramics for microwaves). Q · f is a value obtained by multiplying the reciprocal of tan δ indicating loss by the resonance (measurement) frequency. The measurement results are also shown in Table 1. FIG. 2 shows the relationship between x and εr, and FIG. 3 shows the relationship between x and Q · f.
Moreover, about some of the obtained sintered compacts, the crystal phase was identified by X-ray diffraction. The results are shown in FIG. 4 and FIG.
[0022]
[Table 1]

[0023]
As shown in FIG. 2, εr is x, that is, (Mg_xCa_(1-x))₂Nb₂O₇, The amount of Ca to be replaced with Mg tends to decrease as the amount of Mg (hereinafter referred to as Mg replacement amount) increases. Therefore, it can be seen that in order to obtain a low εr, which is one of the objects of the present invention, the amount of Mg substitution should be increased.
On the other hand, as shown in FIG. 3, Q · f improves with an increase in the amount of Mg substitution, but tends to decrease in the vicinity of 0.7 (mol ratio, the same applies hereinafter) with a peak near 0.7 (molar ratio) Indicates. Therefore, in order to secure Q · f, it has been found that the Mg substitution amount should be 0.4 to 0.9, preferably 0.65 to 0.75. As shown in FIG. 2, εr is 25 or less when the Mg substitution amount is in the range of 0.4 to 0.9, and εr is 20 or less when the Mg substitution amount is within the range of 0.65 to 0.75. Here, considering FIG. 3 as well, the Mg substitution amount should be 0.4 to 0.9, preferably 0.5 to 0.8, and more preferably 0.65 to 0.75.
[0024]
FIG. 4 shows that the amount of Mg substitution is
0 (composition = Ca₂Nb₂O₇),
0.40 (composition = (Mg_0.40Ca_0.60)₂Nb₂O₇),
0.60 (composition = (Mg_0.60Ca_0.40)₂Nb₂O₇),
0.675 (composition = (Mg_0.675Ca_0.325)₂Nb₂O₇)
It is a figure which shows the X-ray-diffraction result of the sintered compact obtained from the mixing | blending composition.
FIG. 5 shows that the amount of Mg substitution is
0.70 (composition = (Mg_0.70Ca_0.30)₂Nb₂O₇),
0.725 (composition = (Mg_0.725Ca_0.275)₂Nb₂O₇),
0.80 (composition = (Mg_0.80Ca_0.20)₂Nb₂O₇),
1.00 (composition = Mg₂Nb₂O₇)
It is a figure which shows the X-ray-diffraction result of the sintered compact obtained from the mixing | blending composition.
[0025]
Based on FIG. 4 and FIG. 5, the crystal phase which comprises each sintered compact was confirmed. The result is shown in FIG. As shown in FIGS. 4 to 6, the Mg substitution amount is 0 (composition formula = Ca₂Nb₂O₇) Sintered body is Ca₂Nb₂O₇A sintered body having a single-phase structure composed of only a phase but with Mg substitution amounts of 0.40 and 0.60 is Ca₂Nb₂O₇In addition to the phase, CaNb₂O₆Phase and Mg₄Nb₂O₉A phase appears. From FIG. 4, the sintered bodies having Mg substitution amounts of 0.40 and 0.60 are Ca₂Nb₂O₇The amount of phase present is small and CaNb₂O₆Phase and Mg₄Nb₂O₉It can be seen that the phase is the subject. Furthermore, in a sintered body having a high Mg substitution amount of 0.675, Ca₂Nb₂O₇There is no phase, CaNb₂O₆Phase and Mg₄Nb₂O₉It becomes a two-phase structure of phases. Furthermore, in a sintered body having a high Mg substitution amount of 0.7, CaNb₂O₆Phase and Mg₄Nb₂O₉In addition to the phase, Mg₅Nb₄O₁₅A phase was observed. Furthermore, when the Mg substitution amount increases to 0.725 or 0.80, MgNb₂O₆A phase appears. And when the amount of substitution becomes 1.0, CaNb₂O₆Phase and Mg₄Nb₂O₉Phase disappears, Mg₅Nb₄O₁₅Phase and MgNb₂O₆It becomes a two-phase structure of phases.
[0026]
When comparing the crystal phase constituting the sintered body and FIG.₂Nb₂O₇It can be seen that the εr of the sintered body is reduced by the presence of other crystal phases in addition to the single-phase structure consisting only of the phases. In addition, in comparison with FIG.₂O₆Phase and Mg₄Nb₂O₉It can be seen that a high Q · f is obtained when there are two crystalline phases.
[0027]
Example 1
Based on the above knowledge, Mg₄Nb₂O₉Sintered body composed of single phase and CaNb₂O₆An experiment aimed at obtaining a sintered body composed of a single phase was conducted. The results are shown below as Example 1.
19.4 g of MgO powder with an average particle size of 0.1 μm and Nb with an average particle size of 1.5 μm₂O₃The raw material powder was obtained by blending 31.1 g of the powder. The formulation is stoichiometrically Mg after sintering.₄Nb₂O₉The ratio was determined so that This raw material powder was put into a ball mill and wet mixed for 16 hours.
200 kgf / cm after drying the mixed raw material powder at 120 ° C. for 24 hours²A cylindrical (60 mmφ) shaped body was obtained by pressing at a pressure of 5 mm. This compact was calcined. The atmosphere of calcination was air, and it was heated and held at 1100 ° C. for 2 hours. After calcination, the calcined body was put into a ball mill and pulverized, and then dried at 120 ° C. for 24 hours to obtain a finished powder. The average particle size of the finished powder obtained was in the range of 0.5-5 μm.
After adding an organic binder to the finished powder and granulating and classifying it, 2 t / cm²A cylindrical (12 mmφ) shaped body was obtained by pressing at a pressure of 1 mm. After molding, the sintered body (Example 1) according to the present invention was obtained by holding at 1300 ° C., 1350 ° C. and 1370 ° C. for 4 hours. About the obtained sintered compact, (epsilon) r and Qf (measuring frequency 8.5-10GHz) were measured according to JISR1627. The measurement results are shown in Table 2, the relationship between the sintering temperature and εr is shown in FIG. 7, and the relationship between the sintering temperature and Q · f is shown in FIG.
As a comparative example, CaCO having an average particle size of 0.3 μm₃13.7 g of powder and Nb with an average particle size of 1.5 μm₂O₅A sintered body (Comparative Example 1) was obtained through the same process as described above except that raw material powder containing 36.3 g of powder was used. Note that the composition is stoichiometrically CaNb after sintering.₂O₆The ratio was determined so that For Comparative Example 1, εr and Q · f (measurement frequency: 8.5 to 10 GHz) were measured according to JIS R 1627. The measurement results are shown in Table 2, the relationship between the sintering temperature and εr is shown in FIG. 7, and the relationship between the sintering temperature and Q · f is shown in FIG.
[0028]
[Table 2]

[0029]
As shown in Table 2 and FIG. 7, the sintered body according to Example 1 (Mg₄Nb₂O₉Εr) is approximately 13 regardless of the sintering temperature. In contrast, the sintered body (CaNb) according to Comparative Example 1₂O₆) Shows that εr is about 17.
Further, as shown in Table 2 and FIG. 8, the sintered body according to Example 1 can obtain a high Q · f exceeding 230000 GHz or 240000 GHz. In contrast, the sintered body according to Comparative Example 1 has a Q · f of about 60,000 to 80,000 GHz, which is lower than the sintered body according to Example 1.
[0030]
In order to confirm the phase structure of the sintered body (sintering temperature 1350 ° C.) according to Example 1, X-ray diffraction was performed. The result is shown in FIG.₄Nb₂O₉It was found to be a single-phase structure consisting only of phases.
[0031]
(Example 2)
Next, Mg₄Nb₂O₉A sintered body having a composition system in which a part of Mg in the steel was replaced with Ba, Sr and Ca was prepared, and εr and Q · f were measured in the same manner as in Example 1, and temperature characteristics (hereinafter referred to as TCF) were measured. did. The result is shown as Example 2. In addition, the composition of the sintered compact used for the measurement is obtained by appropriately changing y (substitution amount) in the following composition formula. Moreover, these sintered compacts were obtained by the same method as Example 1 (sintering temperature is 1325 degreeC).
Ba substitution material: (Mg_1-yBa_y)₄Nb₂O₉
Sr substitution material: (Mg_1-ySr_y)₄Nb₂O₉
Ca replacement material: (Mg_1-yCa_y)₄Nb₂O₉
[0032]
FIG. 10 shows εr, FIG. 11 shows Q · f (measurement frequency: 8 to 11 GHz), and FIG. 12 shows TCF measurement results. Table 3 summarizes the measurement results. The TCF is a value obtained by dividing the rate of change of the resonance frequency due to temperature by the corresponding change in temperature, and here it was obtained by measuring the resonance frequency at −40 to 85 ° C.
As shown in FIG. 10, εr tends to increase slightly as the amount of substitution of Mg with Ba, Sr and Ca increases. In order to obtain εr of 20 or less, it is necessary to make the substitution amount 0.25 or less in any case of substitution with Ba, Sr or Ca.
Further, as shown in FIG. 11, the substitution of Mg with Ba, Sr and Ca tends to lower Q · f, but Ba has a lower degree of decrease than Sr and Ca.
Next, as shown in FIG. 12, the tendency of fluctuation of TCF varies depending on Ba, Sr, and Ca. Among them, the Ba substitution material takes a positive value and a negative value in the range of TCF of -20 to 20 ppm / K depending on the substitution amount. That is, FIG. 12 suggests that the Ba substitution material has a TCF of 0 (zero) at a specific substitution amount.
[0033]
[Table 3]

[0034]
As explained above, Mg shown in Example 1₄Nb₂O₉It is possible to adjust εr, Q · f and TCF by substituting Mg of the system material with one or more of Ba, Sr and Ca. Among them, a material having a Ba substitution amount of 0.4375 has characteristics such that TCF is −1.35 ppm / K, Q · f is 120943 GHz, and εr is 23.93 at a sintering temperature of 1325 ° C.
[0035]
In Example 2, the Ba replacement material ((Mg_1-yBa_y)₄Nb₂O₉) X-ray diffraction was performed to confirm the phase composition. The result is shown in FIG. As shown in FIG. 13, the sintered body with the Ba substitution amount of 0 (y = 0.00) has a microstructure of Mg.₄Nb₂O₉In contrast to the single-phase structure consisting only of Ba, when Mg is replaced with Ba, Ba (Mg_1/3Nb_2/3) O₃The crystal phase appears. In a sintered body having a Ba substitution amount of 0.5 (y = 0.50), Ba (Mg_1/3Nb_2/3) O₃Phase is Mg₄Nb₂O₉It becomes more prominent than the phase. These sintered bodies are Mg₄Nb₂O₉Phase and Ba (Mg_1/3Nb_2/3) O₃The main phase of the sintered body is composed of two phases.
[0036]
Example 3
(1-x) (Mg₄Nb₂O₉) + X (Mg₄Ta₂O₉) MgO powder having an average particle size of 0.1 μm and Nb having an average particle size of 1.5 μm₂O₅Ta powder with an average particle size of 1.5 μm₂O₅After blending the powder, a molded body was obtained in the same manner as in Example 1. This molded body was sintered at 1350 ° C., 1375 ° C., 1400 ° C., 1450 ° C. and 1500 ° C. to obtain a sintered body. About the obtained sintered compact, (epsilon) r and Q * f (measuring frequency 8-11GHz) were measured according to JISR1627. The measurement results of εr are shown in Table 4 and FIG. 15, and the measurement results of Q · f are shown in Table 5 and FIG.
[0037]
First, Mg for εr₄Nb₂O₉And Mg₄Ta₂O₉The effect of the mixing ratio of Mg₄Ta₂O₉It can be seen that as the ratio increases, εr decreases. Therefore, Nb and Ta are both desirable elements for the purpose of the present invention to obtain a low εr, but Ta can be said to be most desirable among them.
Next, regarding the influence of sintering temperature on εr, Mg₄Nb₂O₉And Mg₄Ta₂O₉Different results are obtained depending on the blending ratio. Mg₄Ta₂O₉In the range of 0 to 0.7, εr decreases as the sintering temperature increases. On the other hand, Mg₄Ta₂O₉If the ratio exceeds 0.7, εr increases as the sintering temperature increases. However, Mg₄Nb₂O₉And Mg₄Ta₂O₉The influence of the sintering temperature is smaller than the influence of the mixing ratio.
[0038]
Mg for Q · f₄Nb₂O₉And Mg₄Ta₂O₉Looking at the effects of the blending ratio, there is no uniform tendency. For example, when the sintering temperature is 1350 ° C., there is no significant change in Q · f, but when the sintering temperature is as high as 1400 ° C. or 1450 ° C., Mg₄Ta₂O₉The larger the ratio, the higher the Q · f tends to be.
Furthermore, regarding the influence of sintering temperature on Q · f, Mg₄Ta₂O₉In the range of 0 to 0.4, Q · f is highest at a sintering temperature of 1375 ° C. Mg₄Ta₂O₉If the ratio exceeds 0.4, Q · f tends to increase as the sintering temperature increases.
[0039]
Although it was confirmed that the above tendency was exhibited, in this example, at a sintering temperature of about 1350 ° C., Q · f characteristics exceeding 230,000 GHz can be obtained with an εr of 11 or about 11 or less. By selecting a sintering temperature of this material exceeding 1400 ° C., Q · f can be set to a value of 280000 GHz or more. In particular, stoichiometrically Mg after sintering₄Ta₂O₉The sintered body whose composition is determined so as to obtain a Q · f characteristic in which εr is 10 or less and exceeds 230,000 GHz in sintering at 1350 ° C. In addition, by increasing the sintering temperature to about 1400 ° C., this sintered body can obtain Q · f characteristics exceeding 280000 GHz with εr in the vicinity of 10.
[0040]
Among the above sintered bodies, stoichiometrically Mg after sintering₄Ta₂O₉X-ray diffraction was performed to confirm the phase structure of the sintered body in which the composition was determined so that As a result, as shown in FIG. 14, the sintered body sintered at any temperature of 1350 ° C., 1400 ° C., 1450 ° C. and 1500 ° C.₄Ta₂O₉It was confirmed that the phase was the main phase.
[0041]
[Table 4]

[0042]
[Table 5]

[0043]
【The invention's effect】
As explained above, according to the present invention, α₄β₂O₉A sintered body in which the crystalline phase of the mold substantially forms the main phase, typically Mg with α as Mg and β as Nb₄Nb₂O₉A sintered body having a phase as a main phase can obtain a high Q · f exceeding 240,000 GHz while having a low εr of about 13. Moreover, this characteristic can be obtained with a material sintered at a temperature of 1400 ° C. or lower.
Further, a sintered body in which Ta is selected as β instead of Nb can obtain Q · f of 280000 GHz or more while reducing εr to about 11.
Furthermore, Mg₄Nb₂O₉In which a part of Mg is replaced with Ba₄β₂O₉Type crystal phase and A (B'B ") O₃A sintered body containing two phases of a mold crystal phase is effective in improving temperature characteristics.
[Brief description of the drawings]
FIG. 1 shows a manufacturing process for obtaining a dielectric material according to the present invention.
FIG. 2 (Mg_xCa_(1-x))₂Nb₂O₇It is a graph which shows the value of x of the sintered compact obtained from the compounding composition of, and the relationship of (epsilon) r.
FIG. 3 (Mg_xCa_(1-x))₂Nb₂O₇It is a graph which shows the value of x of the sintered compact obtained from the compounding composition of, and the relationship of Q * f.
FIG. 4 (Mg_xCa_(1-x))₂Nb₂O₇It is a figure which shows the X-ray-diffraction result of the sintered compact obtained from the mixing | blending composition.
FIG. 5 (Mg_xCa_(1-x))₂Nb₂O₇It is a figure which shows the X-ray-diffraction result of the sintered compact obtained from the mixing | blending composition.
FIG. 6 (Mg_xCa_(1-x))₂Nb₂O₇It is a figure which shows the relationship between the value of x of the sintered compact obtained from the compounding composition of, and the crystal phase which appears.
FIG. 7: Mg₄Nb₂O₉And CaNb₂O₆It is a graph which shows the relationship between the sintering temperature of the sintered compact obtained from the mixing | blending composition, and (epsilon) r.
FIG. 8: Mg₄Nb₂O₉And CaNb₂O₆It is a graph which shows the relationship between the sintering temperature and Q * f of the sintered compact obtained from the compounding composition.
FIG. 9: Mg₄Nb₂O₉It is a figure which shows the X-ray-diffraction result of the sintered compact obtained from the mixing | blending composition.
FIG. 10: Mg₄Nb₂O₉It is a figure which shows the relationship between (epsilon) r of the sintered compact obtained from the compounding composition which substituted a part of Mg of Ba, Sr, and Ca, and the said substitution amount.
FIG. 11: Mg₄Nb₂O₉It is a figure which shows the relationship between Q * f of the sintered compact obtained from the compounding composition which substituted a part of Mg of Ba, Sr, and Ca, and the said substitution amount.
FIG. 12: Mg₄Nb₂O₉It is a figure which shows the relationship between the temperature characteristic TCF of the sintered compact obtained from the compounding composition which substituted a part of Mg of Ba, Sr, and Ca, and the said substitution amount.
FIG. 13: Mg₄Nb₂O₉It is a figure which shows the X-ray-diffraction result of the sintered compact obtained from the compounding composition which substituted a part of Mg with Ba, Sr, and Ca.
FIG. 14 Mg₄Ta₂O₉It is a figure which shows the X-ray-diffraction result of the sintered compact obtained from the mixing | blending composition.
FIG. 15: (1-x) (Mg₄Nb₂O₉) + X (Mg₄Ta₂O₉It is a figure which shows the relationship between (epsilon) r and x of the sintered compact obtained from the compounding composition of ().
FIG. 16: (1-x) (Mg₄Nb₂O₉) + X (Mg₄Ta₂O₉It is a figure which shows the relationship between Q * f of a sintered compact obtained from the compounding composition of x), and x.

Claims (9)

A dielectric material comprising a sintered body in which an α ₄ β ₂ O ₉ type crystal phase substantially forms a main phase. The dielectric material according to claim 1, wherein α is one or more divalent metal elements and β is one or more pentavalent metal elements. The dielectric material according to claim 2, wherein the divalent metal element is an alkaline earth metal element, and the pentavalent metal element is a transition metal element. The dielectric material according to claim 3, wherein the divalent metal element is Mg and the pentavalent metal element is one or two of Nb and Ta. 5. The dielectric according to claim 1, wherein the dielectric constant εr is 20 or less, and Q · f measured at any frequency of 8 to 11 GHz by a resonance method is 200,000 (GHz) or more. Body material. A dielectric material comprising a sintered body having two phases of an α ₄ β ₂ O ₉ type crystal phase and an A (B′B ″) O ₃ type crystal phase. The α is one or more divalent metal elements, the β is one or more pentavalent metal elements, the A is one or more divalent metal elements, the B 7. The dielectric according to claim 6, wherein 'is one or more of divalent metal elements different from A, and B ″ is one or more of pentavalent metal elements. material. The dielectric material according to claim 7, wherein the temperature characteristic is in a range of -20 to 20 ppm / K. After sintering, the α ₄ β ₂ O ₉ type crystal phase or the α ₄ β ₂ O ₉ type crystal phase and the A (B′B ″) O ₃ type crystal phase A raw material powder adjusting step of adjusting the raw material powder to be,
A calcining step of heating and holding the raw material powder in a temperature range of 800 to 1300 ° C;
A crushing step of crushing the calcined body obtained in the calcining step;
A sintering step of heating and holding the pulverized powder obtained in the pulverization step in a temperature range of 1250 to 1500 ° C .;
A method for producing a dielectric material, comprising:

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