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US 6,143,679 AGranted
Layered crystal structure oxide
AssigneeSony Corporation
InventorsNaomi Nagasawa, Akio Machida, Takaaki Ami, Masayuki Suzuki
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AssigneeSony Corporation
InventorsNaomi Nagasawa, Akio Machida, Takaaki Ami, Masayuki Suzuki
Estimating the term…
Provided are a layered crystal structure oxide showing ferroelectricity or paraelectricity and a process for easily producing the same. A raw material containing Bi.sub.2 O.sub.3 as a flux is heated up to 1330.degree. C. or higher and 1450.degree. C. or lower at a suitable temperature-elevating rate (heating step); the raw material is maintained at this heating temperature for prescribed time (constant temperature step); and then, it is slowly cooled down to 800.degree. C. or higher and 1300.degree. C. or lower at a rate of 1.degree. C./hour or more and 20.degree. C./hour or less (slow cooling step). This makes it possible to evaporate the flux and take out directly Bi.sub.2 SrTa.sub.2 O.sub.9. In this Bi.sub.2 SrTa.sub.2 O.sub.9, Bi is partially substituted with Sr, and oxygen is selectively deficient or disordered. Or, Bi and O in the fluorite layer are relatively displaced each other in the polarization direction.
A layered crystal structure oxide comprising bismuth (Bi), oxygen (O), a first element Me comprising at least one element selected from the group consisting of sodium (Na), potassium (K), calcium (Ca), barium (Ba), strontium (Sr), lead (Pb) and bismuth (Bi), and a second element R comprising at least one element selected from the group consisting of iron (Fe), titanium (Ti), vanadium (V), niobium (Nb), tantalum (Ta), tungsten (W) and copper (Cu), wherein the crystal structure oxide having a stoichiometric composition of (Bi.sub.2 O.sub.2).sup.2+ Me.sub.m-1 R.sub.m O.sub.3m+1).sup.2-, wherein m is any integer from 2, 3, 4 and 5, wherein the crystal structure having a property selected from the group of properties consisting of at least a part of the bismuth being substituted by one of the other elements constituting the layered crystal structure oxide being substituted;
A layered crystal structure oxide comprising bismuth (Bi), a first element Me comprising at least one element selected from the group consisting of sodium (Na), potassium (K), calcium (Ca), barium (Ba), strontium (Sr), lead (Pb) and bismuth (Bi), a second element R comprising at least one element selected from the group consisting of iron (Fe), titanium (Ti), vanadium (V), niobium (Nb), tantalum (Ta), tungsten (W) and copper (Cu), and oxygen (O), said structure oxide having a stoichmetric composition of (Bi.sub.2 O.sub.2).sup.2+ (Me.sub.m-1 R.sub.m O.sub.3m+1).sup.2- wherein m is any integer from 2, 3, 4 and 5, wherein at least a part of the bismuth is substituted by one of the other elements constituting the layered crystal structure oxide.
A layered crystal structure oxide comprising bismuth (Bi), a first element Me comprising at least one element selected from the group consisting of sodium (Na), potassium (K), calcium (Ca), barium (Ba), strontium (Sr), lead (Pb) and bismuth (Bi), a second element R comprising a least one element selected from the group consisting of iron (Fe), titanium (Ti), vanadium (V), niobium (Nb), tantalum (Ta), tungsten (W) and copper (Cu), and oxygen (O), said structure oxide having a stoichmetric composition of (Bi.sub.2 O.sub.2).sup.2+ (Me.sub.m-1 R.sub.m O.sub.3+1), wherein m is any integer from 2, 3, 4 and 5, wherein at least a part of at least one element constituting the layered crystal structure oxide is deficient or disordered.
A layered crystal structure oxide comprising bismuth (Bi), a first element Me comprising at least one element selected from the group consisting of sodium (Na), potassium (K), calcium (Ca), barium (Ba), strontium (Sr), lead (Pb) and bismuth (Bi), a second element R comprising at least one element selected from the group consisting of iron (Fe), titanium (Ti), vanadium (v), niobium (Nb), tantalum (Ta), tungsten (W) and copper (Cu), and oxygen (O), the layered crystal structure oxide having a stoichmetric composition of (Bi.sub.2 O.sub.2).sup.2+ (Me.sub.m-1 R.sub.m O.sub.3m+1).sup.2- wherein m is selected from 2, 3, 4 and 5, wherein the layered crystal structure oxide contains a fluorite layer, and a cation and an anion in said fluorite layer are relatively displaced by 3% or more of a unit lattace length in a polarization axis direction.
Dependencies are inferred from the claim text.